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#31 · October 22, 2020, 8:21 am

Quote from smAsh on October 22, 2020, 8:21 am
The Most Powerful Magnetic Fields Seen
In a Type-O Star and a Complex Magnetospheric Structure

NGC 1624-2 has a complex magnetospheric structure, observations reveal
by Tomasz Nowakowski , Phys.org
HST/COS spectra of NGC 1624-2 obtained at 6 different rotational phases, as computed using the ephemerides published by Wade et al. (2012). Credit: David-Uraz et al., 2020.
Using the Hubble Space Telescope (HST) and Canada-France-Hawaii Telescope (CFHT), astronomers have investigated a magnetized O-type star known as NGC 1624-2. Results of the study, presented in a paper published October 15 on the arXiv pre-print server, indicate that the star has a complex magnetospheric structure, what could have implications for our understanding of origin and evolution of magnetic fields in massive stars.
O-type stars are massive, luminous, blue stars of spectral type O. Astronomers are especially interested in finding and studying O stars exhibiting a detectable surface magnetic field. These objects could be progenitors of exotic objects and transients such as heavy stellar-mass black holes and pair instability supernovae, as well as magnetars.
NGC 1624-2 is the most strongly magnetized O-type star known to date. Previous observations that this star is surrounded by a giant magnetosphere that must be large and dense, as it absorbs up to 95 percent of the intrinsic circumstellar X-ray emission.
In order to get more insights into the powerful magnetosphere of NGC 1624-2, a team of astronomers led by Alexandre David-Uraz of University of Delaware in Newark, investigated this star using ultraviolet spectra from HST and spectropolarimetric observations conducted with CFHT.
The study found that NGC 1624-2 hosts a large and dense circumstellar magnetosphere with a complex structure. The line profile variations observed in the obtained spectra are different than those usually seen in other typical magnetic O-type stars, where the magnetosphere is formed by the interaction of a strong stellar wind and a global dipolar field.
"Instead, the observed line profiles appear to exhibit one of two morphologies, previously understood ... to correspond to either a magnetic pole-on or magnetic equator-on view of the magnetosphere," the astronomers explained.
The researchers excluded other possible hypotheses that could explain the observed line profile variations such as an error in the determination of the rotation period and short-term stochastic variations. Therefore, they concluded that NGC 1624-2's magnetosphere is likely more structured than previously assumed, and that its surface magnetic field might depart from a dipolar geometry.
According to the authors, the results of the study have implications for our understanding of the population of O-type stars in general. The findings suggest that the strongest field detected at the surface of an O-type star is also topologically complex.
"The perspective of the strongest known magnetic field on an O-star also being topologically complex provides us with crucial information regarding the formation and evolution of such fields on massive stars and further emphasizes the singular importance of this archetypal object," the scientists noted.
They added that further studies, including better spectropolarimetric phase coverage and surface mapping techniques such as Zeeman Doppler Imaging, are required to shed more light on the complex magnetosphere of NGC 1624-2.

The Most Powerful Magnetic Fields Seen

In a Type-O Star and a Complex Magnetospheric Structure

NGC 1624-2 has a complex magnetospheric structure, observations reveal

by Tomasz Nowakowski , Phys.org

Using the Hubble Space Telescope (HST) and Canada-France-Hawaii Telescope (CFHT), astronomers have investigated a magnetized O-type star known as NGC 1624-2. Results of the study, presented in a paper published October 15 on the arXiv pre-print server, indicate that the star has a complex magnetospheric structure, what could have implications for our understanding of origin and evolution of magnetic fields in massive stars.

O-type stars are massive, luminous, blue stars of spectral type O. Astronomers are especially interested in finding and studying O stars exhibiting a detectable surface magnetic field. These objects could be progenitors of exotic objects and transients such as heavy stellar-mass black holes and pair instability supernovae, as well as magnetars.

NGC 1624-2 is the most strongly magnetized O-type star known to date. Previous observations that this star is surrounded by a giant magnetosphere that must be large and dense, as it absorbs up to 95 percent of the intrinsic circumstellar X-ray emission.

In order to get more insights into the powerful magnetosphere of NGC 1624-2, a team of astronomers led by Alexandre David-Uraz of University of Delaware in Newark, investigated this star using ultraviolet spectra from HST and spectropolarimetric observations conducted with CFHT.

The study found that NGC 1624-2 hosts a large and dense circumstellar magnetosphere with a complex structure. The line profile variations observed in the obtained spectra are different than those usually seen in other typical magnetic O-type stars, where the magnetosphere is formed by the interaction of a strong stellar wind and a global dipolar field.

"Instead, the observed line profiles appear to exhibit one of two morphologies, previously understood ... to correspond to either a magnetic pole-on or magnetic equator-on view of the magnetosphere," the astronomers explained.

The researchers excluded other possible hypotheses that could explain the observed line profile variations such as an error in the determination of the rotation period and short-term stochastic variations. Therefore, they concluded that NGC 1624-2's magnetosphere is likely more structured than previously assumed, and that its surface magnetic field might depart from a dipolar geometry.

According to the authors, the results of the study have implications for our understanding of the population of O-type stars in general. The findings suggest that the strongest field detected at the surface of an O-type star is also topologically complex.

"The perspective of the strongest known magnetic field on an O-star also being topologically complex provides us with crucial information regarding the formation and evolution of such fields on massive stars and further emphasizes the singular importance of this archetypal object," the scientists noted.

They added that further studies, including better spectropolarimetric phase coverage and surface mapping techniques such as Zeeman Doppler Imaging, are required to shed more light on the complex magnetosphere of NGC 1624-2.

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Regards, Dan, a. k. a. smAshomAsh

#32 · October 23, 2020, 8:44 am

Quote from smAsh on October 23, 2020, 8:44 am
Galactic “Mystery Source” of Gamma Rays Identified: Record-Setting “Black Widow” Pulsar
TOPICS:Astronomy Astrophysics Max Planck Institute Neutron Star Pulsars
By MAX PLANCK INSTITUTE FOR GRAVITATIONAL PHYSICS OCTOBER 22, 2020
Super Heavyweight and Flyweight in a Cosmic Dance
Volunteer distributed computing project Einstein@Home discovers neutron star in unusual binary system.
After more than two decades, an international research team led by the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hannover has identified a Galactic “mystery source” of gamma rays: a heavy neutron star with a very low mass companion orbiting it. Using novel data analysis methods running on about 10,000 graphics cards in the distributed computing project Einstein@Home, the team identified the neutron star by its regularly pulsating gamma rays in a deep search of data from NASA’s Fermi satellite. Surprisingly, the neutron star is completely invisible in radio waves. The binary system was characterized with an observing campaign across the electromagnetic spectrum, and breaks several records.
An odd couple sets new records
“The binary star system and the neutron star at its heart, now known as PSR J1653-0158, set new records,” explains Lars Nieder, PhD student at the AEI Hannover and first author of the study published today in Astrophysical Journal Letters. “We have discovered the Galactic dance of a super heavyweight with a flyweight: At slightly more than twice the mass of our Sun, the neutron star is extraordinarily heavy. Its companion has about six times the density of lead, but only about 1% the mass of our Sun. This ‘odd couple’ orbits every 75 minutes, more quickly than all known comparable binaries.”
Illustration of the binary star system with the pulsar J1653-0158 (bottom) in comparison to the Earth-Moon system (top). All objects and orbits are shown to scale except for the pulsar, which is magnified 450 times. The binary star system with an orbital period of only 75 minutes is only slightly larger than the Earth-Moon system. Credit: Knispel/Clark/Max Planck Institute for Gravitational Physics/NASA
The neutron star also spins around its own axis at more than 30,000 rpm, making it one of the fastest rotating. At the same time, its magnetic field – usually extremely strong in neutron stars – is exceptionally weak. This record discovery was enabled by two important steps.
Step 1: Observing at many wavelengths
Astronomical observations from 2014 made it possible to determine the properties of the binary star’s orbits.
“That a neutron star is behind the gamma-ray source known since 1999 was considered probable since 2009. In 2014 after observations of the system with optical and X-ray telescopes it became clear that this is a very tight binary system. But all searches for the neutron star in it have so far been in vain,” says Dr. Colin Clark of the Jodrell Bank Centre for Astrophysics, co-author of the study and former PhD student at AEI Hannover.
Step 2: Harnessing computational power donated to Einstein@Home
To unambiguously prove the existence of a neutron star, not just its radio waves or gamma rays, but also their characteristic pulsations must be detected. The rotation of the neutron star causes this regular flashing, similar to the periodic twinkling of a distant lighthouse. The neutron star is then called a radio or gamma-ray pulsar, respectively.
“In binary systems like the one we have now discovered, pulsars are known as ‘black widows’ because, like spiders of the same name, they eat their partners, so to speak,” explains Clark. He adds: “The pulsar vaporizes its companion with its radiation and a particle wind, filling the star system with plasma that is impenetrable to radio waves.”
Gamma rays, on the other hand, are not stopped by these plasma clouds. The Large Area Telescope (LAT) on board NASA’s Fermi Gamma-ray Space Telescope detects this radiation.
The team used the 2014 data, further observations with the William Herschel Telescope on La Palma, and the precise sky position determined by the Gaia satellite to target and focus the computing power of the volunteer distributed computing project Einstein@Home. This also provided a more complete sketch of the companion star.
Finding a very close binary system with improved analysis
Improving on earlier methods developed for this purpose, they enlisted the help of tens of thousands of volunteers to search about a decade of archival data from the Fermi LAT for periodic pulsations. The volunteers donated idle compute cycles on the graphics cards (GPUs) of their computers to Einstein@Home. In less than two weeks, the team made a discovery that would have taken centuries of computing time on a conventional computer.
The entire sky as seen by the Fermi Gamma-ray Space Telescope and the new pulsar discovered by Einstein@Home. The field below the magnified inset shows the pulsar name and some of its measured characteristics, as well as its gamma-ray pulsations. The flags show the nationalities of the volunteers whose computers found the pulsar. Credit: Knispel/Max Planck Institute for Gravitational Physics/NASA/DOE/Fermi LAT Collaboration
“We have found a very tight binary system. In its center is the pulsar, which is about 20 kilometers in size and has twice the mass of our Sun. The remnant of a dwarf star orbits the pulsar at just 1.3 times the Earth-Moon distance in only 75 minutes at a speed of more than 700 kilometers per second,” explains Nieder. “This unusual duo might have originated from an extremely close binary system, in which matter originally flowed from the companion star onto the neutron star, increasing its mass and causing it to rotate faster and faster while simultaneously dampening its magnetic field.”
Searching for radio and gravitational waves
After identifying the gamma-ray pulsar, the team used their newly gained knowledge and searched again for its radio waves. They found no trace, although they used the largest and most sensitive radio telescopes in the world. PSR J1653-0158 thus becomes the second rapidly rotating pulsar from which no radio waves are seen. There are two possible explanations: Either the pulsar sends no radio waves towards Earth, or, more likely, the plasma cloud envelops the binary star system so completely that no radio waves reach Earth.
In a further step, they searched data from the first and second observing runs of the Advanced LIGO detectors for possible gravitational waves that the neutron star would emit if it were slightly deformed. Again, the search was unsuccessful.
Exciting future
“In the catalog of gamma-ray sources found by the Fermi satellite, there are dozens more that I would bet have binary pulsars in them,” says Prof. Bruce Allen, Director at the Max Planck Institute for Gravitational Physics in Hannover and Director and founder of Einstein@Home. “But so far no one has been able to detect the characteristic pulsation of their gamma rays. With Einstein@Home, we hope do just that — who knows what other surprises await us.”
Background information
Who made the discovery? The discovery was enabled by tens of thousands of Einstein@Home volunteers who have donated their CPU and GPU time to the project. Without them this study could not have been performed and this discovery could not have been made. The team is especially grateful to those volunteers whose computers discovered the pulsar: Yi-Sheng Wu of Taoyuan, Taiwan and Daniel Scott of Ankeny, Iowa, USA.
Neutron stars are compact remnants from supernova explosions and consist of exotic, extremely dense matter. They measure about 20 kilometers across and weigh more than our Sun. Because of their strong magnetic fields and fast rotation they emit beamed radio waves and energetic gamma rays similar to a cosmic lighthouse. If these beams point towards Earth during the neutron star’s rotation, it becomes visible as a pulsating radio or gamma-ray source – a so-called pulsar.
source: scitechdaily.com

Galactic “Mystery Source” of Gamma Rays Identified: Record-Setting “Black Widow” Pulsar

TOPICS:Astronomy Astrophysics Max Planck Institute Neutron Star Pulsars

By MAX PLANCK INSTITUTE FOR GRAVITATIONAL PHYSICS OCTOBER 22, 2020

Super Heavyweight and Flyweight in a Cosmic Dance

Volunteer distributed computing project Einstein@Home discovers neutron star in unusual binary system.

After more than two decades, an international research team led by the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hannover has identified a Galactic “mystery source” of gamma rays: a heavy neutron star with a very low mass companion orbiting it. Using novel data analysis methods running on about 10,000 graphics cards in the distributed computing project Einstein@Home, the team identified the neutron star by its regularly pulsating gamma rays in a deep search of data from NASA’s Fermi satellite. Surprisingly, the neutron star is completely invisible in radio waves. The binary system was characterized with an observing campaign across the electromagnetic spectrum, and breaks several records.

An odd couple sets new records

“The binary star system and the neutron star at its heart, now known as PSR J1653-0158, set new records,” explains Lars Nieder, PhD student at the AEI Hannover and first author of the study published today in Astrophysical Journal Letters. “We have discovered the Galactic dance of a super heavyweight with a flyweight: At slightly more than twice the mass of our Sun, the neutron star is extraordinarily heavy. Its companion has about six times the density of lead, but only about 1% the mass of our Sun. This ‘odd couple’ orbits every 75 minutes, more quickly than all known comparable binaries.”

Illustration of the binary star system with the pulsar J1653-0158 (bottom) in comparison to the Earth-Moon system (top). All objects and orbits are shown to scale except for the pulsar, which is magnified 450 times. The binary star system with an orbital period of only 75 minutes is only slightly larger than the Earth-Moon system. Credit: Knispel/Clark/Max Planck Institute for Gravitational Physics/NASA

The neutron star also spins around its own axis at more than 30,000 rpm, making it one of the fastest rotating. At the same time, its magnetic field – usually extremely strong in neutron stars – is exceptionally weak. This record discovery was enabled by two important steps.

Step 1: Observing at many wavelengths

Astronomical observations from 2014 made it possible to determine the properties of the binary star’s orbits.

“That a neutron star is behind the gamma-ray source known since 1999 was considered probable since 2009. In 2014 after observations of the system with optical and X-ray telescopes it became clear that this is a very tight binary system. But all searches for the neutron star in it have so far been in vain,” says Dr. Colin Clark of the Jodrell Bank Centre for Astrophysics, co-author of the study and former PhD student at AEI Hannover.

Step 2: Harnessing computational power donated to Einstein@Home

To unambiguously prove the existence of a neutron star, not just its radio waves or gamma rays, but also their characteristic pulsations must be detected. The rotation of the neutron star causes this regular flashing, similar to the periodic twinkling of a distant lighthouse. The neutron star is then called a radio or gamma-ray pulsar, respectively.

“In binary systems like the one we have now discovered, pulsars are known as ‘black widows’ because, like spiders of the same name, they eat their partners, so to speak,” explains Clark. He adds: “The pulsar vaporizes its companion with its radiation and a particle wind, filling the star system with plasma that is impenetrable to radio waves.”

Gamma rays, on the other hand, are not stopped by these plasma clouds. The Large Area Telescope (LAT) on board NASA’s Fermi Gamma-ray Space Telescope detects this radiation.

The team used the 2014 data, further observations with the William Herschel Telescope on La Palma, and the precise sky position determined by the Gaia satellite to target and focus the computing power of the volunteer distributed computing project Einstein@Home. This also provided a more complete sketch of the companion star.

Finding a very close binary system with improved analysis

Improving on earlier methods developed for this purpose, they enlisted the help of tens of thousands of volunteers to search about a decade of archival data from the Fermi LAT for periodic pulsations. The volunteers donated idle compute cycles on the graphics cards (GPUs) of their computers to Einstein@Home. In less than two weeks, the team made a discovery that would have taken centuries of computing time on a conventional computer.

New Pulsar Fermi Gamma ray Space Telescope

The entire sky as seen by the Fermi Gamma-ray Space Telescope and the new pulsar discovered by Einstein@Home. The field below the magnified inset shows the pulsar name and some of its measured characteristics, as well as its gamma-ray pulsations. The flags show the nationalities of the volunteers whose computers found the pulsar. Credit: Knispel/Max Planck Institute for Gravitational Physics/NASA/DOE/Fermi LAT Collaboration

“We have found a very tight binary system. In its center is the pulsar, which is about 20 kilometers in size and has twice the mass of our Sun. The remnant of a dwarf star orbits the pulsar at just 1.3 times the Earth-Moon distance in only 75 minutes at a speed of more than 700 kilometers per second,” explains Nieder. “This unusual duo might have originated from an extremely close binary system, in which matter originally flowed from the companion star onto the neutron star, increasing its mass and causing it to rotate faster and faster while simultaneously dampening its magnetic field.”

Searching for radio and gravitational waves

After identifying the gamma-ray pulsar, the team used their newly gained knowledge and searched again for its radio waves. They found no trace, although they used the largest and most sensitive radio telescopes in the world. PSR J1653-0158 thus becomes the second rapidly rotating pulsar from which no radio waves are seen. There are two possible explanations: Either the pulsar sends no radio waves towards Earth, or, more likely, the plasma cloud envelops the binary star system so completely that no radio waves reach Earth.

In a further step, they searched data from the first and second observing runs of the Advanced LIGO detectors for possible gravitational waves that the neutron star would emit if it were slightly deformed. Again, the search was unsuccessful.

Exciting future

“In the catalog of gamma-ray sources found by the Fermi satellite, there are dozens more that I would bet have binary pulsars in them,” says Prof. Bruce Allen, Director at the Max Planck Institute for Gravitational Physics in Hannover and Director and founder of Einstein@Home. “But so far no one has been able to detect the characteristic pulsation of their gamma rays. With Einstein@Home, we hope do just that — who knows what other surprises await us.”

Background information

Who made the discovery? The discovery was enabled by tens of thousands of Einstein@Home volunteers who have donated their CPU and GPU time to the project. Without them this study could not have been performed and this discovery could not have been made. The team is especially grateful to those volunteers whose computers discovered the pulsar: Yi-Sheng Wu of Taoyuan, Taiwan and Daniel Scott of Ankeny, Iowa, USA.

Neutron stars are compact remnants from supernova explosions and consist of exotic, extremely dense matter. They measure about 20 kilometers across and weigh more than our Sun. Because of their strong magnetic fields and fast rotation they emit beamed radio waves and energetic gamma rays similar to a cosmic lighthouse. If these beams point towards Earth during the neutron star’s rotation, it becomes visible as a pulsating radio or gamma-ray source – a so-called pulsar.

source: scitechdaily.com

Regards, Dan, a. k. a. smAshomAsh

#33 · November 15, 2020, 9:19 am

Quote from smAsh on November 15, 2020, 9:19 am
TON 618, most massive 'black hole' currently known.

Located in galaxy cluster PKS 0745-19, TON 618 is believed to be 66 billion M_{☉ (solar masses). With an absolute magnitude of −30.7, it shines with a luminosity of 4×10⁴⁰watts, or as brilliantly as 140 trillion Suns, making it one of the brightest objects in the known Universe.^[1]}
Like other quasars, TON 618 has a spectrum containing emission lines from cooler gas much further out than the accretion disc, in the broad-line region. The emission lines in the spectrum of TON 618 are unusually wide,^[6] indicating that the gas is travelling very fast; the hydrogen beta line shows it is moving around at 7,000 km/s.^[2] Hence the central black hole must be exerting a particularly strong gravitational force.

From Super to Ultra: Just How Big Can Black Holes Get?

December 18, 2012

A large elliptical galaxy at the center of the galaxy cluster PKS 0745-19. (X-ray: NASA/CXC/Stanford/Hlavacek-Larrondo, J. et al; Optical: NASA/STScI)
View large imageSome of the biggest black holes in the Universe may actually be even bigger than previously thought, according to a study using data from NASA's Chandra X-ray Observatory.
Astronomers have long known about the class of the largest black holes, which they call "supermassive" black holes. Typically, these black holes, located at the centers of galaxies, have masses ranging between a few million and a few billion times that of our sun.
This analysis has looked at the brightest galaxies in a sample of 18 galaxy clusters, to target the largest black holes. The work suggests that at least ten of the galaxies contain an ultramassive black hole, weighing between 10 and 40 billion times the mass of the sun. Astronomers refer to black holes of this size as "ultramassive" black holes and only know of a few confirmed examples.
"Our results show that there may be many more ultramassive black holes in the universe than previously thought," said study leader Julie Hlavacek-Larrondo of Stanford University and formerly of Cambridge University in the UK.
The researchers estimated the masses of the black holes in the sample by using an established relationship between masses of black holes, and the amount of X-rays and radio waves they generate. This relationship, called the fundamental plane of black hole activity, fits the data on black holes with masses ranging from 10 solar masses to a billion solar masses.
The black hole masses derived by Hlavacek-Larrondo and her colleagues were about ten times larger than those derived from standard relationships between black hole mass and the properties of their host galaxy. One of these relationships involves a correlation between the black hole mass and the infrared luminosity of the central region, or bulge, of the galaxy.
"These results may mean we don't really understand how the very biggest black holes coexist with their host galaxies," said co-author Andrew Fabian of Cambridge University. "It looks like the behavior of these huge black holes has to differ from that of their less massive cousins in an important way."
All of the potential ultramassive black holes found in this study lie in galaxies at the centers of massive galaxy clusters containing huge amounts of hot gas. Outbursts powered by the central black holes are needed to prevent this hot gas from cooling and forming enormous numbers of stars. To power the outbursts, the black holes must swallow large amounts of mass, in the form of hot gas. Because the largest black holes can swallow the most mass and power the biggest outbursts, ultramassive black holes had already been predicted to exist, to explain some of the most powerful outbursts seen. The extreme environment experienced by these galaxies may explain why the standard relations for estimating black hole masses do not apply.
These results can only be confirmed by making detailed mass estimates of the black holes in this sample, by observing and modeling the motion of stars or gas in the vicinity of the black holes. Such a study has been carried out for the black hole in the center of the galaxy M87, the central galaxy in the Virgo Cluster, the nearest galaxy cluster to earth. The mass of M87's black hole, as estimated from the motion of the stars, is significantly higher than the estimate using infrared data, approximately matching the correction in black hole mass estimated by the authors of this Chandra study.
"Our next step is to measure the mass of these monster black holes in a similar way to M87, and confirm they are ultramassive. I wouldn't be surprised if we end up finding the biggest black holes in the Universe," said Hlavacek-Larrondo. "If our results are confirmed, they will have important ramifications for understanding the formation and evolution of black holes across cosmic time."
In addition to the X-rays from Chandra, the new study also uses radio data from the NSF's Karl G. Jansky Very Large Array (JVLA) and the Australia Telescope Compact Array (ATCA) and infrared data from the 2 Micron All-Sky Survey (2MASS).
These results were published in the July 2012 issue of The Monthly Notices of the Royal Astronomical Society.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
More information, including images and other multimedia, can be found at:
http://www.nasa.gov/chandra
and
http://chandra.si.edu
source: nasa.gov_________

References[edit] (source: wikipedia.org)
^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h "NED results for object TON 618". NASA/IPAC EXTRAGALACTIC DATABASE.
^ Jump up to:^a ^b ^c Shemmer, O.; Netzer, H.; Maiolino, R.; Oliva, E.; Croom, S.; Corbett, E.; di Fabrizio, L. (2004). "Near-infrared spectroscopy of high-redshift active galactic nuclei: I. A metallicity-accretion rate relationship". The Astrophysical Journal. 614 (2): 547–557. arXiv:astro-ph/0406559. Bibcode:2004ApJ...614..547S. doi:10.1086/423607.
^ "1963: Maarten Schmidt Discovers Quasars". Observatories of the Carnegie Institution for Science. Retrieved 21 October 2017.
^ Iriarte, Braulio; Chavira, Enrique (1957). "Blue stars in the North Galactic Cap" (PDF). Boletín de los Observatorios de Tonantzintla y Tacubaya. 2 (16): 3–36. Retrieved 21 October 2017.
^ Colla, G.; Fanti, C.; Ficarra, A.; Formiggini, L.; Gandolfi, E.; Grueff, G.; Lari, C.; Padrielli, L.; Roffi, G.; Tomasi, P; Vigotti, M. (1970). "A catalogue of 3235 radio sources at 408 MHz". Astronomy & Astrophysics Supplement Series. 1 (3): 281. Bibcode:1970A&AS....1..281C.
^ Jump up to:^a ^b Ulrich, Marie-Helene (1976). "Optical spectrum and redshifts of a quasar of extremely high intrinsice luminosity: B2 1225+31". The Astrophysical Journal. 207: L73–L74. Bibcode:1976ApJ...207L..73U. doi:10.1086/182182.
^ Kaspi, Shai; Smith, Paul S.; Netzer, Hagai; Maos, Dan; Jannuzi, Buell T.; Giveon, Uriel (2000). "Reverberation measurements for 17 quasars and the size-mass-luminosity relations in active galactic nuclei". The Astrophysical Journal. 533 (2): 631–649. arXiv:astro-ph/9911476. Bibcode:2000ApJ...533..631K. doi:10.1086/308704.
^ Irving, Michael (21 February 2018). ""Ultramassive" black holes may be the biggest ever found – and they're growing fast". New Atlas.
^ "From Super to Ultra: Just How Big Can Black Holes Get?". NASA – Chandra X-Ray Observatory. 18 December 2012.

TON 618, most massive 'black hole' currently known.

Located in galaxy cluster PKS 0745-19, TON 618 is believed to be 66 billion M_{☉ (solar masses). With an absolute magnitude of −30.7, it shines with a luminosity of 4×10⁴⁰watts, or as brilliantly as 140 trillion Suns, making it one of the brightest objects in the known Universe.^[1]}

Like other quasars, TON 618 has a spectrum containing emission lines from cooler gas much further out than the accretion disc, in the broad-line region. The emission lines in the spectrum of TON 618 are unusually wide,^[6] indicating that the gas is travelling very fast; the hydrogen beta line shows it is moving around at 7,000 km/s.^[2] Hence the central black hole must be exerting a particularly strong gravitational force.

From Super to Ultra: Just How Big Can Black Holes Get?

December 18, 2012

A large elliptical galaxy at the center of the galaxy cluster PKS 0745-19. (X-ray: NASA/CXC/Stanford/Hlavacek-Larrondo, J. et al; Optical: NASA/STScI)
View large imageSome of the biggest black holes in the Universe may actually be even bigger than previously thought, according to a study using data from NASA's Chandra X-ray Observatory.

Astronomers have long known about the class of the largest black holes, which they call "supermassive" black holes. Typically, these black holes, located at the centers of galaxies, have masses ranging between a few million and a few billion times that of our sun.

This analysis has looked at the brightest galaxies in a sample of 18 galaxy clusters, to target the largest black holes. The work suggests that at least ten of the galaxies contain an ultramassive black hole, weighing between 10 and 40 billion times the mass of the sun. Astronomers refer to black holes of this size as "ultramassive" black holes and only know of a few confirmed examples.

"Our results show that there may be many more ultramassive black holes in the universe than previously thought," said study leader Julie Hlavacek-Larrondo of Stanford University and formerly of Cambridge University in the UK.

The researchers estimated the masses of the black holes in the sample by using an established relationship between masses of black holes, and the amount of X-rays and radio waves they generate. This relationship, called the fundamental plane of black hole activity, fits the data on black holes with masses ranging from 10 solar masses to a billion solar masses.

The black hole masses derived by Hlavacek-Larrondo and her colleagues were about ten times larger than those derived from standard relationships between black hole mass and the properties of their host galaxy. One of these relationships involves a correlation between the black hole mass and the infrared luminosity of the central region, or bulge, of the galaxy.

"These results may mean we don't really understand how the very biggest black holes coexist with their host galaxies," said co-author Andrew Fabian of Cambridge University. "It looks like the behavior of these huge black holes has to differ from that of their less massive cousins in an important way."

All of the potential ultramassive black holes found in this study lie in galaxies at the centers of massive galaxy clusters containing huge amounts of hot gas. Outbursts powered by the central black holes are needed to prevent this hot gas from cooling and forming enormous numbers of stars. To power the outbursts, the black holes must swallow large amounts of mass, in the form of hot gas. Because the largest black holes can swallow the most mass and power the biggest outbursts, ultramassive black holes had already been predicted to exist, to explain some of the most powerful outbursts seen. The extreme environment experienced by these galaxies may explain why the standard relations for estimating black hole masses do not apply.

These results can only be confirmed by making detailed mass estimates of the black holes in this sample, by observing and modeling the motion of stars or gas in the vicinity of the black holes. Such a study has been carried out for the black hole in the center of the galaxy M87, the central galaxy in the Virgo Cluster, the nearest galaxy cluster to earth. The mass of M87's black hole, as estimated from the motion of the stars, is significantly higher than the estimate using infrared data, approximately matching the correction in black hole mass estimated by the authors of this Chandra study.

"Our next step is to measure the mass of these monster black holes in a similar way to M87, and confirm they are ultramassive. I wouldn't be surprised if we end up finding the biggest black holes in the Universe," said Hlavacek-Larrondo. "If our results are confirmed, they will have important ramifications for understanding the formation and evolution of black holes across cosmic time."

In addition to the X-rays from Chandra, the new study also uses radio data from the NSF's Karl G. Jansky Very Large Array (JVLA) and the Australia Telescope Compact Array (ATCA) and infrared data from the 2 Micron All-Sky Survey (2MASS).

These results were published in the July 2012 issue of The Monthly Notices of the Royal Astronomical Society.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

More information, including images and other multimedia, can be found at:

http://www.nasa.gov/chandra
and
http://chandra.si.edu

source: nasa.gov_________

References[edit] (source: wikipedia.org)

^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h "NED results for object TON 618". NASA/IPAC EXTRAGALACTIC DATABASE.
^ Jump up to:^a ^b ^c Shemmer, O.; Netzer, H.; Maiolino, R.; Oliva, E.; Croom, S.; Corbett, E.; di Fabrizio, L. (2004). "Near-infrared spectroscopy of high-redshift active galactic nuclei: I. A metallicity-accretion rate relationship". The Astrophysical Journal. 614 (2): 547–557. arXiv:astro-ph/0406559. Bibcode:2004ApJ...614..547S. doi:10.1086/423607.
^ "1963: Maarten Schmidt Discovers Quasars". Observatories of the Carnegie Institution for Science. Retrieved 21 October 2017.
^ Iriarte, Braulio; Chavira, Enrique (1957). "Blue stars in the North Galactic Cap" (PDF). Boletín de los Observatorios de Tonantzintla y Tacubaya. 2 (16): 3–36. Retrieved 21 October 2017.
^ Colla, G.; Fanti, C.; Ficarra, A.; Formiggini, L.; Gandolfi, E.; Grueff, G.; Lari, C.; Padrielli, L.; Roffi, G.; Tomasi, P; Vigotti, M. (1970). "A catalogue of 3235 radio sources at 408 MHz". Astronomy & Astrophysics Supplement Series. 1 (3): 281. Bibcode:1970A&AS....1..281C.
^ Jump up to:^a ^b Ulrich, Marie-Helene (1976). "Optical spectrum and redshifts of a quasar of extremely high intrinsice luminosity: B2 1225+31". The Astrophysical Journal. 207: L73–L74. Bibcode:1976ApJ...207L..73U. doi:10.1086/182182.
^ Kaspi, Shai; Smith, Paul S.; Netzer, Hagai; Maos, Dan; Jannuzi, Buell T.; Giveon, Uriel (2000). "Reverberation measurements for 17 quasars and the size-mass-luminosity relations in active galactic nuclei". The Astrophysical Journal. 533 (2): 631–649. arXiv:astro-ph/9911476. Bibcode:2000ApJ...533..631K. doi:10.1086/308704.
^ Irving, Michael (21 February 2018). ""Ultramassive" black holes may be the biggest ever found – and they're growing fast". New Atlas.
^ "From Super to Ultra: Just How Big Can Black Holes Get?". NASA – Chandra X-Ray Observatory. 18 December 2012.

Regards, Dan, a. k. a. smAshomAsh

#34 · November 16, 2020, 12:36 pm

Quote from smAsh on November 16, 2020, 12:36 pm
Here's another referenced article on Ton 618:
"Ultramassive" black holes may be the biggest ever found – and they're growing fast
By Michael Irving
February 21, 2018
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An illustration of one of the ultramassive black holes discovered by the Spanish-Canadian team
NASA
VIEW 1 IMAGES

Since they're basically invisible, it can be hard to pin down just how big a black hole is. They can range anywhere from a few times the mass of the Sun up to millions or billions times that mass, but there's a potential class that are even bigger than that. A new study of data gathered by NASA's Chandra X-ray telescope has found that these so-called "ultramassive" black holes may be larger and more common than we thought.
The smallest class is the stellar mass black holes, which can be from about five to 30 times the mass of the Sun. In the middle there sits a proposed group known as intermediate-mass black holes, between 100 and 10,000 solar masses. And finally there's the heavyweights that lurk at the center of galaxies, supermassive black holes with masses of millions or even a few billion Suns.
But there's quite a gap between a million and billion, leading some astronomers to claim that there should be another class at the top for the very biggest. These ultramassive black holes would include objects of tens of billions of solar masses, such as S5 0014+813, which contains one of the largest known black holes at about 40 billion solar masses.
To learn more about these strange celestial objects, researchers in Canada and Spain examined Chandra data of 72 galaxies up to 3.5 billion light-years away, in one of the brightest and most massive galaxy clusters in the universe. The bigger a black hole, the bigger the jets of gas and matter they throw off, and astronomers can use the brightness of these jets to calculate the black hole's mass.
By analyzing the radio wave and X-ray emissions given off by these black holes, the team determined that the objects are on average about 10 times more massive than previously thought. In fact, about 40 percent of those studied were calculated to have masses of more than 10 billion Suns, which could comfortably class them as ultramassive.
The sheer size of these objects could turn our understanding of the formation of black holes and galaxies on its head. Previously it was believed that supermassive black holes and the galaxies around them form and grow in tandem, but these ultramassive black holes appear to be growing faster than their host galaxies. They may even be threatening to tear them apart.
"We have discovered black holes that are far larger and way more massive than anticipated," says Mar Mezcua, co-lead author of the study. "Are they so big because they had a head start or because certain ideal conditions allowed them to grow more rapidly over billions of years? For the moment, there is no way for us to know."
The research was published in the Monthly Notices of the Royal Astronomical Society.
Source: University of Montreal
source: newatlas.com

Here's another referenced article on Ton 618:

"Ultramassive" black holes may be the biggest ever found – and they're growing fast

By Michael Irving

February 21, 2018

An illustration of one of the ultramassive black holes discovered by the Spanish-Canadian team

NASA

VIEW 1 IMAGES

Since they're basically invisible, it can be hard to pin down just how big a black hole is. They can range anywhere from a few times the mass of the Sun up to millions or billions times that mass, but there's a potential class that are even bigger than that. A new study of data gathered by NASA's Chandra X-ray telescope has found that these so-called "ultramassive" black holes may be larger and more common than we thought.

The smallest class is the stellar mass black holes, which can be from about five to 30 times the mass of the Sun. In the middle there sits a proposed group known as intermediate-mass black holes, between 100 and 10,000 solar masses. And finally there's the heavyweights that lurk at the center of galaxies, supermassive black holes with masses of millions or even a few billion Suns.

But there's quite a gap between a million and billion, leading some astronomers to claim that there should be another class at the top for the very biggest. These ultramassive black holes would include objects of tens of billions of solar masses, such as S5 0014+813, which contains one of the largest known black holes at about 40 billion solar masses.

To learn more about these strange celestial objects, researchers in Canada and Spain examined Chandra data of 72 galaxies up to 3.5 billion light-years away, in one of the brightest and most massive galaxy clusters in the universe. The bigger a black hole, the bigger the jets of gas and matter they throw off, and astronomers can use the brightness of these jets to calculate the black hole's mass.

By analyzing the radio wave and X-ray emissions given off by these black holes, the team determined that the objects are on average about 10 times more massive than previously thought. In fact, about 40 percent of those studied were calculated to have masses of more than 10 billion Suns, which could comfortably class them as ultramassive.

The sheer size of these objects could turn our understanding of the formation of black holes and galaxies on its head. Previously it was believed that supermassive black holes and the galaxies around them form and grow in tandem, but these ultramassive black holes appear to be growing faster than their host galaxies. They may even be threatening to tear them apart.

"We have discovered black holes that are far larger and way more massive than anticipated," says Mar Mezcua, co-lead author of the study. "Are they so big because they had a head start or because certain ideal conditions allowed them to grow more rapidly over billions of years? For the moment, there is no way for us to know."

The research was published in the Monthly Notices of the Royal Astronomical Society.

Source: University of Montreal

source: newatlas.com

Regards, Dan, a. k. a. smAshomAsh

#35 · February 1, 2021, 11:43 am

Quote from smAsh on February 1, 2021, 11:43 am
One of the most violent events known to have occurred. One of the jets from this galaxy is oriented almost directly towards Earth. It's a tidal disruption event, a gamma ray burster, a 'quasar/ blazar' and is believed to have torn apart/ consumed a white dwarf star.
Swift J164449.3+573451, initially referred to as GRB 110328A, and sometimes abbreviated to Sw J1644+57, was a tidal disruption event, the destruction of a star by a supermassive black hole. It was first detected by the Swift Gamma-Ray Burst Mission on March 28, 2011.^[3] The event occurred in the center of a small galaxy in the Draco constellation, about 3.8 billion light-years away.^[4]
Studied by dozens of telescopes, it is one of the most puzzling cosmic blasts of high-energy radiation ever observed when it comes to brightness, variability and durability.^[5] It probably occurred when a star wandered too close to the central black hole in the galaxy, and was gravitationally torn apart and swallowed by it.^[3]^[6]^[7]^[8] Timing considerations suggest that the tidally disrupted star was a white dwarf and not a regular main sequence star.^[9]
Debris now encircles the black hole in an accretion disk, which launches bipolar jets at near the speed of light. Jet plasma emits the γ- and X-rays. The beam of radiation from one of these jets points directly toward Earth, enhancing the apparent brightness. Repetitive dimming and softening of the X-rays implies that the jet temporarily tilts away from us, due to precession of the warped disk.^[10]
The jets drive shocks into the surrounding interstellar medium, resulting in a radio to infrared afterglow. Detection of the relativistically expanding afterglow confirmed the identity of the host galaxy.^[11] Observed linear polarization of the infrared radiation is consistent with synchrotron emission from the afterglow shock.^[12]
"This is truly different from any explosive event we have seen before," said Joshua Bloom of the University of California at Berkeley, the lead author of the study published in the June 2011 issue of Science.^[8]^[13]
References[edit]
^ "Gamma-ray flash came from star being eaten by massive black hole". e! Science News. 2011-06-16. Retrieved 2011-06-17.
^ "NASA Telescopes Join Forces to Observe Unprecedented Explosion". Chandra Press Release: 7. 2011. Bibcode:2011cxo..pres....7. Retrieved 2011-04-21.
^ Jump up to:^a ^b Joshua S. Bloom; et al. (2011-03-30). "GRB 110328A / Swift J164449.3+573451: X-ray analysis and a mini-blazar analogy". Grb Coordinates Network. 11847: 1. Bibcode:2011GCN.11847....1B.
^ "GRB 110328A: Chandra Observes Extraordinary Event". Harvard-Smithsonian Center for Astrophysics. Retrieved 2011-04-21.
^ "NASA Telescopes Join Forces to Observe Unprecedented Explosion". Chandra Press Release: 7. 2011-04-07. Bibcode:2011cxo..pres....7. Retrieved 2011-04-22.
^ Barres de Almeida; De Angelis (2011-04-13). "Enhanced emission from GRB 110328A could be evidence for tidal disruption of a star". arXiv:1104.2528 [astro-ph.HE].
^ Coco, Alejandro (2011-04-10). "The Most Intense Cosmic Explosion Ever Seen". Scienceray. Archived from the original on 2011-07-24. Retrieved 2011-04-22.
^ Jump up to:^a ^b Bloom, Joshua S.; Giannios, Dimitrios; Metzger, Brian D.; Cenko, S. Bradley; Perley, Daniel A.; Butler, Nathaniel R.; Tanvir, Nial R.; Levan, Andrew J.; O'Brien, Paul T.; Strubbe, Linda E.; De Colle, Fabio; Ramirez-Ruiz, Enrico; Lee, William H.; Nayakshin, Sergei; Quataert, Eliot; King, Andrew R.; Cucchiara, Antonino; Guillochon, James; Bower, Geoffrey C.; Fruchter, Andrew S.; Morgan, Adam N.; Van Der Horst, Alexander J. (2011). "A Possible Relativistic Jetted Outburst from a Massive Black Hole Fed by a Tidally Disrupted Star". Science. 333 (6039): 203–6. arXiv:1104.3257. Bibcode:2011Sci...333..203B. doi:10.1126/science.1207150. PMID 21680812.
^ Krolik J.; Piran T. (2011-04-13). "Swift J1644+57: A White Dwarf Tidally Disrupted by a 10^4 M_{odot} Black Hole?". The Astrophysical Journal. 743 (2): 134. arXiv:1106.0923. Bibcode:2011ApJ...743..134K. doi:10.1088/0004-637X/743/2/134.
^ Saxton, C. J.; Soria, R.; Wu, K.; Kuin, N. P. M. (2012-01-25). "Long-term X-ray variability of Swift J1644+57". Monthly Notices of the Royal Astronomical Society. 422 (2): 1625. arXiv:1201.5210. Bibcode:2012MNRAS.422.1625S. doi:10.1111/j.1365-2966.2012.20739.x.
^ Zauderer, B. A.; Berger, E.; Soderberg, A. M.; Loeb, A.; Narayan, R.; Frail, D. A.; Petitpas, G. R.; Brunthaler, A.; Chornock, R.; Carpenter, J. M.; Pooley, G. G.; Mooley, K.; Kulkarni, S. R.; Margutti, R.; Fox, D. B.; Nakar, E.; Patel, N. A.; Volgenau, N. H.; Culverhouse, T. L.; Bietenholz, M. F.; Rupen, M. P.; Max-Moerbeck, W.; Readhead, A. C. S.; Richards, J.; Shepherd, M.; Storm, S.; Hull, C. L. H., B. A. (2011). "Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451". Nature. 476 (7361): 425–428. arXiv:1106.3568. Bibcode:2011Natur.476..425Z. doi:10.1038/nature10366. PMID 21866155.
^ Wiersema, K.; van der Horst, A. J.; Levan, A. J.; Tanvir, N. R.; Karjalainen, R.; Kamble, A.; Kouveliotou, C.; Metzger, B. D.; Russell, D. M.; Skillen, I.; Starling, R. L. C.; Wijers, R. A. M. J. (2011-12-13). "Polarimetry of the transient relativistic jet of GRB 110328 / Swift J164449.3+573451". Monthly Notices of the Royal Astronomical Society. 421 (3): 1942–1948. arXiv:1112.3042. Bibcode:2012MNRAS.421.1942W. doi:10.1111/j.1365-2966.2011.20379.x.
^ "Black hole eats star, triggers gamma-ray flash". Cosmos. June 17, 2011. Archived from the original on 18 June 2011. Retrieved 17 June2011.
source: https://en.wikipedia.org/wiki/GRB_110328A

One of the most violent events known to have occurred. One of the jets from this galaxy is oriented almost directly towards Earth. It's a tidal disruption event, a gamma ray burster, a 'quasar/ blazar' and is believed to have torn apart/ consumed a white dwarf star.

Swift J164449.3+573451, initially referred to as GRB 110328A, and sometimes abbreviated to Sw J1644+57, was a tidal disruption event, the destruction of a star by a supermassive black hole. It was first detected by the Swift Gamma-Ray Burst Mission on March 28, 2011.^[3] The event occurred in the center of a small galaxy in the Draco constellation, about 3.8 billion light-years away.^[4]

Studied by dozens of telescopes, it is one of the most puzzling cosmic blasts of high-energy radiation ever observed when it comes to brightness, variability and durability.^[5] It probably occurred when a star wandered too close to the central black hole in the galaxy, and was gravitationally torn apart and swallowed by it.^[3]^[6]^[7]^[8] Timing considerations suggest that the tidally disrupted star was a white dwarf and not a regular main sequence star.^[9]

Debris now encircles the black hole in an accretion disk, which launches bipolar jets at near the speed of light. Jet plasma emits the γ- and X-rays. The beam of radiation from one of these jets points directly toward Earth, enhancing the apparent brightness. Repetitive dimming and softening of the X-rays implies that the jet temporarily tilts away from us, due to precession of the warped disk.^[10]

The jets drive shocks into the surrounding interstellar medium, resulting in a radio to infrared afterglow. Detection of the relativistically expanding afterglow confirmed the identity of the host galaxy.^[11] Observed linear polarization of the infrared radiation is consistent with synchrotron emission from the afterglow shock.^[12]

"This is truly different from any explosive event we have seen before," said Joshua Bloom of the University of California at Berkeley, the lead author of the study published in the June 2011 issue of Science.^[8]^[13]

References[edit]

^ "Gamma-ray flash came from star being eaten by massive black hole". e! Science News. 2011-06-16. Retrieved 2011-06-17.
^ "NASA Telescopes Join Forces to Observe Unprecedented Explosion". Chandra Press Release: 7. 2011. Bibcode:2011cxo..pres....7. Retrieved 2011-04-21.
^ Jump up to:^a ^b Joshua S. Bloom; et al. (2011-03-30). "GRB 110328A / Swift J164449.3+573451: X-ray analysis and a mini-blazar analogy". Grb Coordinates Network. 11847: 1. Bibcode:2011GCN.11847....1B.
^ "GRB 110328A: Chandra Observes Extraordinary Event". Harvard-Smithsonian Center for Astrophysics. Retrieved 2011-04-21.
^ "NASA Telescopes Join Forces to Observe Unprecedented Explosion". Chandra Press Release: 7. 2011-04-07. Bibcode:2011cxo..pres....7. Retrieved 2011-04-22.
^ Barres de Almeida; De Angelis (2011-04-13). "Enhanced emission from GRB 110328A could be evidence for tidal disruption of a star". arXiv:1104.2528 [astro-ph.HE].
^ Coco, Alejandro (2011-04-10). "The Most Intense Cosmic Explosion Ever Seen". Scienceray. Archived from the original on 2011-07-24. Retrieved 2011-04-22.
^ Jump up to:^a ^b Bloom, Joshua S.; Giannios, Dimitrios; Metzger, Brian D.; Cenko, S. Bradley; Perley, Daniel A.; Butler, Nathaniel R.; Tanvir, Nial R.; Levan, Andrew J.; O'Brien, Paul T.; Strubbe, Linda E.; De Colle, Fabio; Ramirez-Ruiz, Enrico; Lee, William H.; Nayakshin, Sergei; Quataert, Eliot; King, Andrew R.; Cucchiara, Antonino; Guillochon, James; Bower, Geoffrey C.; Fruchter, Andrew S.; Morgan, Adam N.; Van Der Horst, Alexander J. (2011). "A Possible Relativistic Jetted Outburst from a Massive Black Hole Fed by a Tidally Disrupted Star". Science. 333 (6039): 203–6. arXiv:1104.3257. Bibcode:2011Sci...333..203B. doi:10.1126/science.1207150. PMID 21680812.
^ Krolik J.; Piran T. (2011-04-13). "Swift J1644+57: A White Dwarf Tidally Disrupted by a 10^4 M_{odot} Black Hole?". The Astrophysical Journal. 743 (2): 134. arXiv:1106.0923. Bibcode:2011ApJ...743..134K. doi:10.1088/0004-637X/743/2/134.
^ Saxton, C. J.; Soria, R.; Wu, K.; Kuin, N. P. M. (2012-01-25). "Long-term X-ray variability of Swift J1644+57". Monthly Notices of the Royal Astronomical Society. 422 (2): 1625. arXiv:1201.5210. Bibcode:2012MNRAS.422.1625S. doi:10.1111/j.1365-2966.2012.20739.x.
^ Zauderer, B. A.; Berger, E.; Soderberg, A. M.; Loeb, A.; Narayan, R.; Frail, D. A.; Petitpas, G. R.; Brunthaler, A.; Chornock, R.; Carpenter, J. M.; Pooley, G. G.; Mooley, K.; Kulkarni, S. R.; Margutti, R.; Fox, D. B.; Nakar, E.; Patel, N. A.; Volgenau, N. H.; Culverhouse, T. L.; Bietenholz, M. F.; Rupen, M. P.; Max-Moerbeck, W.; Readhead, A. C. S.; Richards, J.; Shepherd, M.; Storm, S.; Hull, C. L. H., B. A. (2011). "Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451". Nature. 476 (7361): 425–428. arXiv:1106.3568. Bibcode:2011Natur.476..425Z. doi:10.1038/nature10366. PMID 21866155.
^ Wiersema, K.; van der Horst, A. J.; Levan, A. J.; Tanvir, N. R.; Karjalainen, R.; Kamble, A.; Kouveliotou, C.; Metzger, B. D.; Russell, D. M.; Skillen, I.; Starling, R. L. C.; Wijers, R. A. M. J. (2011-12-13). "Polarimetry of the transient relativistic jet of GRB 110328 / Swift J164449.3+573451". Monthly Notices of the Royal Astronomical Society. 421 (3): 1942–1948. arXiv:1112.3042. Bibcode:2012MNRAS.421.1942W. doi:10.1111/j.1365-2966.2011.20379.x.
^ "Black hole eats star, triggers gamma-ray flash". Cosmos. June 17, 2011. Archived from the original on 18 June 2011. Retrieved 17 June2011.

source: https://en.wikipedia.org/wiki/GRB_110328A

Regards, Dan, a. k. a. smAshomAsh

#36 · February 23, 2021, 9:06 am

Quote from smAsh on February 23, 2021, 9:06 am
FEBRUARY 22, 2021
Researchers detect galactic source of gamma rays that could produce very high-energy cosmic rays
by Asociacion RUVID
Credit: Asociacion RUVID
IFIC researcher Francisco Salesa Greus, along with other members of the HAWC collaboration, have detected very high-energy photons from a galactic source that could produce cosmic rays. The detection of neutrinos through telescopes such as KM3NeT or IceCube would confirm the study. This finding has been published in The Astrophysical Journal Letters.
HAWC is a gamma ray observatory located in Mexico that enables the collection of information on the most violent phenomena that occur in the universe. Gamma rays are produced in very energetic astrophysical phenomena, such as supernova explosions or nuclei of active galaxies and are made up of high-energy photons that when they come into contact with the Earth's atmosphere are absorbed, which makes their observation difficult.
The analysis, led by Salesa, a researcher at the Institute of Corpuscular Physics (UV-CSIC), shows the detection of high-energy photons from a galactic source, HAWC J1825-134, whose spectrum continues uninterrupted up to levels of at least 200TeV, which would imply that this emission should have been created by even more powerful cosmic rays, on the order of petaelectronvolt (PeV), which shows their possible origin. In fact, there are more than 200 gamma ray sources that emit at energies of teraelectronvolts (TeV); but less than a dozen sources that emit more than 100TeV have been confirmed.
According to this study, the gamma rays observed by HAWC would be the result of the interaction of cosmic rays of higher energy with the molecules of a zone of high density of matter, a molecular cloud.
The result of being before one of the most powerful cosmic ray sources discovered so far could be confirmed with the detection of neutrinos from HAWC J1825-134 using neutrino telescopes such as KM3NeT or IceCube. This source stands out for being in an ideal position to be observed by the future KM3NeT.
"The results of the HAWC J1825-134 observations make this source a clear candidate for emitting high-energy neutrinos," says Francisco Salesa. With a telescope of the detection volume of KM3NeT it is expected to be able to observe this source during the period of operation of the detector. "HAWC J1825-134 has the advantage of being located in the southern celestial hemisphere, which is the part of the sky where KM3NeT is most sensitive," adds Salesa.
KM3NeT and IceCube telescopes
KM3NeT located at the bottom of the Mediterranean Sea and IceCube, located at the South Pole, are detectors for neutrinos, the smallest uncharged subatomic particles known to date. Regarding this research, both telescopes will work to confirm the results obtained by HAWC, in the event that the expected emission of neutrinos is observed as a product of the interaction of high-energy cosmic rays with matter and radiation at the source of production.
The KM3NeT detector, in which the IFIC participates actively, is currently under construction and already has several operational detection lines. KM3NeT is expected to be fully operational in the next few years.
Francisco Salesa, distinguished researcher of the GenT program of the Department of Innovation, Universities, Science and Digital Society of the Valencian Government, focuses his work mainly on Multi-Messenger Astronomy, which aims to study the astrophysical phenomena observed by different astroparticle detectors in spatial and/or temporal coincidence. Thus, even with little statistics it can be reliably affirmed that these events occurred in the same cosmic source and extract important information about the nature of the most energetic accelerators in the universe.
source: phys.org

FEBRUARY 22, 2021

Researchers detect galactic source of gamma rays that could produce very high-energy cosmic rays

by Asociacion RUVID

IFIC researcher Francisco Salesa Greus, along with other members of the HAWC collaboration, have detected very high-energy photons from a galactic source that could produce cosmic rays. The detection of neutrinos through telescopes such as KM3NeT or IceCube would confirm the study. This finding has been published in The Astrophysical Journal Letters.

HAWC is a gamma ray observatory located in Mexico that enables the collection of information on the most violent phenomena that occur in the universe. Gamma rays are produced in very energetic astrophysical phenomena, such as supernova explosions or nuclei of active galaxies and are made up of high-energy photons that when they come into contact with the Earth's atmosphere are absorbed, which makes their observation difficult.

The analysis, led by Salesa, a researcher at the Institute of Corpuscular Physics (UV-CSIC), shows the detection of high-energy photons from a galactic source, HAWC J1825-134, whose spectrum continues uninterrupted up to levels of at least 200TeV, which would imply that this emission should have been created by even more powerful cosmic rays, on the order of petaelectronvolt (PeV), which shows their possible origin. In fact, there are more than 200 gamma ray sources that emit at energies of teraelectronvolts (TeV); but less than a dozen sources that emit more than 100TeV have been confirmed.

According to this study, the gamma rays observed by HAWC would be the result of the interaction of cosmic rays of higher energy with the molecules of a zone of high density of matter, a molecular cloud.

The result of being before one of the most powerful cosmic ray sources discovered so far could be confirmed with the detection of neutrinos from HAWC J1825-134 using neutrino telescopes such as KM3NeT or IceCube. This source stands out for being in an ideal position to be observed by the future KM3NeT.

"The results of the HAWC J1825-134 observations make this source a clear candidate for emitting high-energy neutrinos," says Francisco Salesa. With a telescope of the detection volume of KM3NeT it is expected to be able to observe this source during the period of operation of the detector. "HAWC J1825-134 has the advantage of being located in the southern celestial hemisphere, which is the part of the sky where KM3NeT is most sensitive," adds Salesa.

KM3NeT and IceCube telescopes

KM3NeT located at the bottom of the Mediterranean Sea and IceCube, located at the South Pole, are detectors for neutrinos, the smallest uncharged subatomic particles known to date. Regarding this research, both telescopes will work to confirm the results obtained by HAWC, in the event that the expected emission of neutrinos is observed as a product of the interaction of high-energy cosmic rays with matter and radiation at the source of production.

The KM3NeT detector, in which the IFIC participates actively, is currently under construction and already has several operational detection lines. KM3NeT is expected to be fully operational in the next few years.

Francisco Salesa, distinguished researcher of the GenT program of the Department of Innovation, Universities, Science and Digital Society of the Valencian Government, focuses his work mainly on Multi-Messenger Astronomy, which aims to study the astrophysical phenomena observed by different astroparticle detectors in spatial and/or temporal coincidence. Thus, even with little statistics it can be reliably affirmed that these events occurred in the same cosmic source and extract important information about the nature of the most energetic accelerators in the universe.

source: phys.org

Regards, Dan, a. k. a. smAshomAsh

#37 · March 12, 2021, 9:54 am

Quote from smAsh on March 12, 2021, 9:54 am
MOST POWERFUL ENERGY EVER: PeVatron SOURCES!

Discovery of Potential Cosmic-Ray Accelerator in the Galaxy Opens Window in Search for the “PeVatron”
TOPICS:Astrophysics Chinese Academy Of Sciences
By CHINESE ACADEMY OF SCIENCES MARCH 11, 2021
Figure 1. Gamma-ray image above 10 TeV around SNR G106.3+2.7 as seen by the Tibet ASgamma experiment. PSF shows smearing by the angular resolution. Black/cyan contours represent the SNR shell and the location of nearby molecular clouds, respectively. The gray diamond is the location of the pulsar. The red star with a statistical error circle, the black X, the magenta cross and the blue triangle indicate the centroid of the gamma-ray emission region determined by the Tibet ASgamma experiment, the Fermi Gamma-ray Space Telescope, the VERITAS Cherenkov telescope and the HAWC experiment, respectively. Credit: Image by IHEP
The Tibet ASgamma experiment, a China-Japan joint research project, has discovered gamma rays beyond 100 TeV (tera electron volts) from G106.3+2.7, a supernova remnant (SNR) 2600 lightyears from Earth.
These gamma rays are of the highest energy ever observed from SNRs, and are probably produced in collisions between cosmic rays (protons) accelerated in G106.3+2.7 and a nearby molecular cloud.
“SNR G106.3+2.7 is thus the first candidate object with sufficient evidence in the Milky Way that can accelerate cosmic rays (protons) up to 1 PeV (peta electron volts),” said HUANG Jing, one of the leading researchers of the study from the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences. “It will open an important window in the search for the ‘PeVatron’,” she said.

The study was published online in Nature Astronomy.
Figure 2. The Tibet air-shower array located 4300 m above sea level in Tibet, China. Credit: Image by IHEP
Cosmic rays are protons and other atomic nuclei arriving from space. They have been detected in the 10⁹-10²⁰ eV energy range. Astrophysical sources that can accelerate cosmic rays up to PeV energies are called ‘PeVatrons’, which can reach 100 times more energetic than the highest energy achieved in any man-made accelerator on Earth.
PeVatrons are believed to exist in our galaxy, but none have been detected yet, making it a long-standing mystery in the universe. Since cosmic rays can be deflected by the galactic magnetic field due to their electric charge, their arrival directions observed on Earth do not point back to their place of origin. Therefore, it is impossible to find a ‘PeVatron’ by using the direction of cosmic rays.
Fortunately, cosmic rays, after accelerated at their sources, can collide with nearby molecular clouds and produce gamma rays. Gamma rays, with no electric charge, can travel straight from their sources to Earth, making it possible to trace their sources.
Figure 3. The Tibet muon-detector array under the existing cosmic-ray array. Credit: Image by IHEP
There are three criteria for the identification of a ‘PeVatron’, that is, gamma-ray emission beyond 100 TeV, coherence of the gamma-ray emission region and the location of a molecular cloud nearby, as well as exclusion of ‘leptonic origin’, namely source of high energy electrons of pulsars.
No astrophysical source ever detected meets the above three criteria so far. SNR G106.3+2.7 has been detected by the VERITAS Imaging Air Cherenkov Telescope at TeV energies and the Fermi Gamma-ray Space Telescope at GeV energies. However, neither of the two experiments is sensitive enough to 100 TeV gamma rays. Recently the HAWC experiment observed gamma-rays in the 40-100 TeV energy range from this SNR, but its gamma-ray emission region overlaps with PSR J2229+6114, the pulsar born in the supernova explosion of SNR G106.3+2.7 (Figure 1).
The Tibet ASgamma experiment team, using about two years’ data taken, observed ultrahigh-energy gamma rays up to and beyond 100 TeV from the supernova remnant (SNR) G106.3+2.7, and found that the gamma-ray emission region is far away from the pulsar at the northeast corner of G106.3+2.7 and in good agreement with the location of a nearby molecular cloud.
These observational facts suggest that cosmic-ray nuclei may be accelerated up to PeV energy in this SNR and then collide with the molecular cloud, thus producing gamma ray photons via the production and subsequent decay of neutral pions.
The important work shows that SNR G106.3+2.7 is a highly potential ‘PeVatron’ in our galaxy, which is a big step in the attempt to reveal the mysterious origin of cosmic rays.
Located at an altitude of 4300 m above sea level in the town of Yangbajing in Tibet, the Tibet ASgamma experiment has been operated jointly by China and Japan since 1990 (Figure 2). It involves 28 international institutions, including IHEP and ICRR, University of Tokyo, Japan.
Since 2014, the team has added water-Cherenkov-type muon detectors under the existing cosmic-ray array (Figure 3). This enabled them to suppress 99.92% of the cosmic-ray background noise and thus improve sensitivity significantly.
Reference: “Potential PeVatron supernova remnant G106.3+2.7 seen in the highest-energy gamma rays” by The Tibet AS? Collaboration, 1 March 2021, Nature Astronomy.
DOI: 10.1038/s41550-020-01294-9
source- scitechdaily.com

MOST POWERFUL ENERGY EVER: PeVatron SOURCES!

Discovery of Potential Cosmic-Ray Accelerator in the Galaxy Opens Window in Search for the “PeVatron”

TOPICS:Astrophysics Chinese Academy Of Sciences

By CHINESE ACADEMY OF SCIENCES MARCH 11, 2021

Figure 1. Gamma-ray image above 10 TeV around SNR G106.3+2.7 as seen by the Tibet ASgamma experiment. PSF shows smearing by the angular resolution. Black/cyan contours represent the SNR shell and the location of nearby molecular clouds, respectively. The gray diamond is the location of the pulsar. The red star with a statistical error circle, the black X, the magenta cross and the blue triangle indicate the centroid of the gamma-ray emission region determined by the Tibet ASgamma experiment, the Fermi Gamma-ray Space Telescope, the VERITAS Cherenkov telescope and the HAWC experiment, respectively. Credit: Image by IHEP

The Tibet ASgamma experiment, a China-Japan joint research project, has discovered gamma rays beyond 100 TeV (tera electron volts) from G106.3+2.7, a supernova remnant (SNR) 2600 lightyears from Earth.

These gamma rays are of the highest energy ever observed from SNRs, and are probably produced in collisions between cosmic rays (protons) accelerated in G106.3+2.7 and a nearby molecular cloud.

“SNR G106.3+2.7 is thus the first candidate object with sufficient evidence in the Milky Way that can accelerate cosmic rays (protons) up to 1 PeV (peta electron volts),” said HUANG Jing, one of the leading researchers of the study from the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences. “It will open an important window in the search for the ‘PeVatron’,” she said.

The study was published online in Nature Astronomy.

Figure 2. The Tibet air-shower array located 4300 m above sea level in Tibet, China. Credit: Image by IHEP

Cosmic rays are protons and other atomic nuclei arriving from space. They have been detected in the 10⁹-10²⁰ eV energy range. Astrophysical sources that can accelerate cosmic rays up to PeV energies are called ‘PeVatrons’, which can reach 100 times more energetic than the highest energy achieved in any man-made accelerator on Earth.

PeVatrons are believed to exist in our galaxy, but none have been detected yet, making it a long-standing mystery in the universe. Since cosmic rays can be deflected by the galactic magnetic field due to their electric charge, their arrival directions observed on Earth do not point back to their place of origin. Therefore, it is impossible to find a ‘PeVatron’ by using the direction of cosmic rays.

Fortunately, cosmic rays, after accelerated at their sources, can collide with nearby molecular clouds and produce gamma rays. Gamma rays, with no electric charge, can travel straight from their sources to Earth, making it possible to trace their sources.

Figure 3. The Tibet muon-detector array under the existing cosmic-ray array. Credit: Image by IHEP

There are three criteria for the identification of a ‘PeVatron’, that is, gamma-ray emission beyond 100 TeV, coherence of the gamma-ray emission region and the location of a molecular cloud nearby, as well as exclusion of ‘leptonic origin’, namely source of high energy electrons of pulsars.
No astrophysical source ever detected meets the above three criteria so far. SNR G106.3+2.7 has been detected by the VERITAS Imaging Air Cherenkov Telescope at TeV energies and the Fermi Gamma-ray Space Telescope at GeV energies. However, neither of the two experiments is sensitive enough to 100 TeV gamma rays. Recently the HAWC experiment observed gamma-rays in the 40-100 TeV energy range from this SNR, but its gamma-ray emission region overlaps with PSR J2229+6114, the pulsar born in the supernova explosion of SNR G106.3+2.7 (Figure 1).

The Tibet ASgamma experiment team, using about two years’ data taken, observed ultrahigh-energy gamma rays up to and beyond 100 TeV from the supernova remnant (SNR) G106.3+2.7, and found that the gamma-ray emission region is far away from the pulsar at the northeast corner of G106.3+2.7 and in good agreement with the location of a nearby molecular cloud.

These observational facts suggest that cosmic-ray nuclei may be accelerated up to PeV energy in this SNR and then collide with the molecular cloud, thus producing gamma ray photons via the production and subsequent decay of neutral pions.
The important work shows that SNR G106.3+2.7 is a highly potential ‘PeVatron’ in our galaxy, which is a big step in the attempt to reveal the mysterious origin of cosmic rays.

Located at an altitude of 4300 m above sea level in the town of Yangbajing in Tibet, the Tibet ASgamma experiment has been operated jointly by China and Japan since 1990 (Figure 2). It involves 28 international institutions, including IHEP and ICRR, University of Tokyo, Japan.

Since 2014, the team has added water-Cherenkov-type muon detectors under the existing cosmic-ray array (Figure 3). This enabled them to suppress 99.92% of the cosmic-ray background noise and thus improve sensitivity significantly.

Reference: “Potential PeVatron supernova remnant G106.3+2.7 seen in the highest-energy gamma rays” by The Tibet AS? Collaboration, 1 March 2021, Nature Astronomy.
DOI: 10.1038/s41550-020-01294-9

source- scitechdaily.com

Regards, Dan, a. k. a. smAshomAsh

#38 · March 13, 2021, 9:56 am

For context, the electromagnetic spectrum.

Regards, Dan, a. k. a. smAshomAsh

#39 · March 28, 2021, 9:05 am

Quote from smAsh on March 28, 2021, 9:05 am
NEAREST STAR CLUSTER STRETCHING IN TWO OPPPOSITE DIRECTIONS! Hyades cluster only located 153 light years from the Sun.

Tantalizing Evidence: Is the Nearest Star Cluster to the Sun Being Destroyed?
TOPICS:Astronomy Astrophysics European Space Agency GAIA
By EUROPEAN SPACE AGENCY (ESA) MARCH 26, 2021
The Hyades star cluster is gradually merging with the background of stars in the Milky Way. The cluster is located 153 light years away and is visible to the unaided eye because the brightest members form a ‘V’-shape of stars in the constellation of Taurus, the Bull. This image shows members of the Hyades as identified in the Gaia data. Those stars are marked in pink, and the shapes of the various constellations are traced in green. Stars from the Hyades can be seen stretching out from the central cluster to form two ‘tails’. These tails are known as tidal tails and it is through these that stars leave the cluster. The image was created using Gaia Sky. Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO; acknowledgement: S. Jordan/T. Sagrista.
Data from ESA’s Gaia star mapping satellite have revealed tantalizing evidence that the nearest star cluster to the Sun is being disrupted by the gravitational influence of a massive but unseen structure in our galaxy.
If true, this might provide evidence for a suspected population of ‘dark matter sub-halos’. These invisible clouds of particles are thought to be relics from the formation of the Milky Way, and are now spread across the galaxy, making up an invisible substructure that exerts a noticeable gravitational influence on anything that drifts too close.
ESA Research Fellow Tereza Jerabkova and colleagues from ESA and the European Southern Observatory made the discovery while studying the way a nearby star cluster is merging into the general background of stars in our galaxy. This discovery was based on Gaia’s Early third Data Release (EDR3) and data from the second release.

The true extent of the Hyades tidal tails have been revealed for the first time by data from the ESA’s Gaia mission. The Gaia data has allowed the former members of the star cluster (shown in pink) to be traced across the whole sky. Those stars are marked in pink, and the shapes of the various constellations are traced in green. The image was created using Gaia Sky. Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO; acknowledgement: S. Jordan/T. Sagrista
The team chose the Hyades as their target because it is the nearest star cluster to the Sun. It is located just over 153 light-years away, and is easily visible to skywatchers in both northern and southern hemispheres as a conspicuous ‘V’ shape of bright stars that marks the head of the bull in the constellation of Taurus. Beyond the easily visible bright stars, telescopes reveal a hundred or so fainter ones contained in a spherical region of space, roughly 60 light-years across.
A star cluster will naturally lose stars because as those stars move within the cluster they tug at each other gravitationally. This constant tugging slightly changes the stars’ velocities, moving some to the edges of the cluster. From there, the stars can be swept out by the gravitational pull of the galaxy, forming two long tails.
One tail trails the star cluster, the other pulls out ahead of it. They are known as tidal tails, and have been widely studied in colliding galaxies but no one had ever seen them from a nearby open star cluster, until very recently.
The key to detecting tidal tails is spotting which stars in the sky are moving in a similar way to the star cluster. Gaia makes this easy because it is precisely measuring the distance and movement of more than a billion stars in our galaxy. “These are the two most important quantities that we need to search for tidal tails from star clusters in the Milky Way,” says Tereza.
Previous attempts by other teams had met with only limited success because the researchers had only looked for stars that closely matched the movement of the star cluster. This excluded members that left earlier in its 600–700 million year history and so are now traveling on different orbits.
To understand the range of orbits to look for, Tereza constructed a computer model that would simulate the various perturbations that escaping stars in the cluster might feel during their hundreds of millions of years in space. It was after running this code, and then comparing the simulations to the real data that the true extent of the Hyades tidal tails were revealed. Tereza and colleagues found thousands of former members in the Gaia data. These stars now stretch for thousands of light-years across the galaxy in two enormous tidal tails.
But the real surprise was that the trailing tidal tail seemed to be missing stars. This indicates that something much more brutal is taking place than the star cluster gently ‘dissolving’.
Running the simulations again, Tereza showed that the data could be reproduced if that tail had collided with a cloud of matter containing about 10 million solar masses. “There must have been a close interaction with this really massive clump, and the Hyades just got smashed,” she says.
But what could that clump be? There are no observations of a gas cloud or star cluster that massive nearby. If no visible structure is detected even in future targeted searches, Tereza suggests that object could be a dark matter sub-halo. These are naturally occurring clumps of dark matter that are thought to help shape the galaxy during its formation. This new work shows how Gaia is helping astronomers map out this invisible dark matter framework of the galaxy.
“With Gaia, the way we see the Milky Way has completely changed. And with these discoveries, we will be able to map the Milky Way’s sub-structures much better than ever before,” says Tereza. And having proved the technique with the Hyades, Tereza and colleagues are now extending the work by looking for tidal tails from other, more distant star clusters.
Reference: “The 800 pc long tidal tails of the Hyades star cluster: Possible discovery of candidate epicyclic overdensities from an open star cluster” by Tereza Jerabkova, Henri M. J. Boffin, Giacomo Beccari, Guido de Marchi, Jos H. J. de Bruijne and Timo Prusti, 24 March 2021, Astronomy and Astrophysics.
DOI: 10.1051/0004-6361/202039949
source: scitechdaily.com

NEAREST STAR CLUSTER STRETCHING IN TWO OPPPOSITE DIRECTIONS! Hyades cluster only located 153 light years from the Sun.

Tantalizing Evidence: Is the Nearest Star Cluster to the Sun Being Destroyed?

TOPICS:Astronomy Astrophysics European Space Agency GAIA

By EUROPEAN SPACE AGENCY (ESA) MARCH 26, 2021

The Hyades star cluster is gradually merging with the background of stars in the Milky Way. The cluster is located 153 light years away and is visible to the unaided eye because the brightest members form a ‘V’-shape of stars in the constellation of Taurus, the Bull. This image shows members of the Hyades as identified in the Gaia data. Those stars are marked in pink, and the shapes of the various constellations are traced in green. Stars from the Hyades can be seen stretching out from the central cluster to form two ‘tails’. These tails are known as tidal tails and it is through these that stars leave the cluster. The image was created using Gaia Sky. Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO; acknowledgement: S. Jordan/T. Sagrista.

Data from ESA’s Gaia star mapping satellite have revealed tantalizing evidence that the nearest star cluster to the Sun is being disrupted by the gravitational influence of a massive but unseen structure in our galaxy.

If true, this might provide evidence for a suspected population of ‘dark matter sub-halos’. These invisible clouds of particles are thought to be relics from the formation of the Milky Way, and are now spread across the galaxy, making up an invisible substructure that exerts a noticeable gravitational influence on anything that drifts too close.

ESA Research Fellow Tereza Jerabkova and colleagues from ESA and the European Southern Observatory made the discovery while studying the way a nearby star cluster is merging into the general background of stars in our galaxy. This discovery was based on Gaia’s Early third Data Release (EDR3) and data from the second release.

The true extent of the Hyades tidal tails have been revealed for the first time by data from the ESA’s Gaia mission. The Gaia data has allowed the former members of the star cluster (shown in pink) to be traced across the whole sky. Those stars are marked in pink, and the shapes of the various constellations are traced in green. The image was created using Gaia Sky. Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO; acknowledgement: S. Jordan/T. Sagrista

The team chose the Hyades as their target because it is the nearest star cluster to the Sun. It is located just over 153 light-years away, and is easily visible to skywatchers in both northern and southern hemispheres as a conspicuous ‘V’ shape of bright stars that marks the head of the bull in the constellation of Taurus. Beyond the easily visible bright stars, telescopes reveal a hundred or so fainter ones contained in a spherical region of space, roughly 60 light-years across.

A star cluster will naturally lose stars because as those stars move within the cluster they tug at each other gravitationally. This constant tugging slightly changes the stars’ velocities, moving some to the edges of the cluster. From there, the stars can be swept out by the gravitational pull of the galaxy, forming two long tails.

One tail trails the star cluster, the other pulls out ahead of it. They are known as tidal tails, and have been widely studied in colliding galaxies but no one had ever seen them from a nearby open star cluster, until very recently.

The key to detecting tidal tails is spotting which stars in the sky are moving in a similar way to the star cluster. Gaia makes this easy because it is precisely measuring the distance and movement of more than a billion stars in our galaxy. “These are the two most important quantities that we need to search for tidal tails from star clusters in the Milky Way,” says Tereza.

Previous attempts by other teams had met with only limited success because the researchers had only looked for stars that closely matched the movement of the star cluster. This excluded members that left earlier in its 600–700 million year history and so are now traveling on different orbits.

To understand the range of orbits to look for, Tereza constructed a computer model that would simulate the various perturbations that escaping stars in the cluster might feel during their hundreds of millions of years in space. It was after running this code, and then comparing the simulations to the real data that the true extent of the Hyades tidal tails were revealed. Tereza and colleagues found thousands of former members in the Gaia data. These stars now stretch for thousands of light-years across the galaxy in two enormous tidal tails.

But the real surprise was that the trailing tidal tail seemed to be missing stars. This indicates that something much more brutal is taking place than the star cluster gently ‘dissolving’.

Running the simulations again, Tereza showed that the data could be reproduced if that tail had collided with a cloud of matter containing about 10 million solar masses. “There must have been a close interaction with this really massive clump, and the Hyades just got smashed,” she says.

But what could that clump be? There are no observations of a gas cloud or star cluster that massive nearby. If no visible structure is detected even in future targeted searches, Tereza suggests that object could be a dark matter sub-halo. These are naturally occurring clumps of dark matter that are thought to help shape the galaxy during its formation. This new work shows how Gaia is helping astronomers map out this invisible dark matter framework of the galaxy.

“With Gaia, the way we see the Milky Way has completely changed. And with these discoveries, we will be able to map the Milky Way’s sub-structures much better than ever before,” says Tereza. And having proved the technique with the Hyades, Tereza and colleagues are now extending the work by looking for tidal tails from other, more distant star clusters.

Reference: “The 800 pc long tidal tails of the Hyades star cluster: Possible discovery of candidate epicyclic overdensities from an open star cluster” by Tereza Jerabkova, Henri M. J. Boffin, Giacomo Beccari, Guido de Marchi, Jos H. J. de Bruijne and Timo Prusti, 24 March 2021, Astronomy and Astrophysics.
DOI: 10.1051/0004-6361/202039949

source: scitechdaily.com

Regards, Dan, a. k. a. smAshomAsh

#40 · March 28, 2021, 9:08 am

Quote from smAsh on March 28, 2021, 9:08 am
Strongest x-ray source in specific bands, the Hoinga 'supernova' remnant nebula!

“Hoinga” Surprise – Debris of Stellar Explosion Found at Unusual Location
TOPICS:Astronomy Astrophysics Max Planck Institute Supernova
By MAX-PLANCK-GESELLSCHAFT MARCH 26, 2021
Composite X-ray and radio image of Hoinga (see also Fig.2 and Fig.3). The X-rays discovered by eROSITA are emitted by the hot debris of the exploded progenitor, whereas the radio antennae detect synchrotron emission from relativistic electrons, which are decelerated at the outer remnant layer. Credit: eROSITA/MPE (X-ray), CHIPASS / SPASS / N. Hurley-Walker, ICRAR-Curtin (Radio)
eROSITA space telescope finds largest supernova remnant ever discovered with X-rays.
In the first all-sky survey by the eROSITA X-ray telescope onboard SRG, astronomers at the Max Planck Institute for Extraterrestrial Physics have identified a previously unknown supernova remnant, dubbed “Hoinga.” The finding was confirmed in archival radio data and marks the first discovery of a joint Australian-eROSITA partnership established to explore our Galaxy using multiple wavelengths, from low-frequency radio waves to energetic X-rays. The Hoinga supernova remnant is very large and located far from the galactic plane – a surprising first finding – implying that the next years might bring many more discoveries.
Massive stars end their lives in gigantic supernova explosions when the fusion processes in their interiors no longer produce enough energy to counter their gravitational collapse. But even with hundreds of billions of stars in a galaxy, these events are pretty rare. In our Milky Way, astronomers estimate that a supernova should happen on average every 30 to 50 years. While the supernova itself is only observable on a timescale of months, their remnants can be detected for about 100 000 years. These remnants are composed of the material ejected by the exploding star at high velocities and forming shocks when hitting the surrounding interstellar medium.
Cutout of the first SRG/eROSITA all-sky survey. The Hoinga supernova remnant is marked. The large bright source in the lower quadrant of the image is from the supernova remnant “Vela” with “Pupis-A”. The image colours are correlated with the energies of the detected X-ray photons. Red represents the 0.3-0.6 keV energy range, green the 0.6-1.0 keV and blue the 1.0-2.3 keV waveband. Credit: SRG / eROSITA
About 300 such supernova remnants are known today – much less than the estimated 1200 that should be observable throughout our home Galaxy. So, either astrophysicists have misunderstood the supernova rate or a large majority has been overlooked so far. An international team of astronomers are now using the all-sky scans of the eROSITA X-ray telescope to look for previously unknown supernova remnants. With temperatures of millions of degrees, the debris of such supernovae emits high-energy radiation, i.e. they should show up in the high-quality X-ray survey data.

“We were very surprised that the first supernova remnant popped up straight away,” says Werner Becker at the Max Planck Institute for Extraterrestrial Physics. Named after the first author’s hometown’s Roman name, “Hoinga” is the largest supernova remnant ever discovered in X-rays. With a diameter of about 4.4 degrees, it covers an area about 90 times bigger than the size of the full Moon. “Moreover, it lies very far off the galactic plane, which is very unusual,” he adds. Most previous searches for supernova remnants have concentrated on the disk of our galaxy, where star formation activity is highest and stellar remnants therefore should be more numerous, but it seems that many supernova remnants have been overlooked by this search strategy.
After the astronomers found the object in the eROSITA all-sky data, they turned to other resources to confirm its nature. Hoinga is – although barely – visible also in data taken by the ROSAT X-ray telescope 30 years ago, but nobody noticed it before due to its faintness and its location at high galactic latitude. However, the real confirmation came from radio data, the spectral band where 90% of all known supernova remnants were found so far.
“We went through archival radio data and it had been sitting there, just waiting to be discovered,” marvels Natasha Walker-Hurley, from the Curtin University node of the International Centre for Radio Astronomy Research in Australia. “The radio emission in 10-year-old surveys clearly confirmed that Hoinga is a supernova remnant, so there may be even more of these out there waiting for keen eyes.”
The eROSITA X-ray telescope will perform a total of eight all-sky surveys and is about 25 times more sensitive than its predecessor ROSAT. Both observatories were designed, build and are operated by the Max Planck Institute for Extraterrestrial Physics. The astronomers expected to discover new supernova remnants in its X-ray data over the next few years, but they were surprised to identify one so early in the program. Combined with the fact that the signal is already present in decades-old data, this implies that many supernova remnants might have been overlooked in the past due to low-surface brightness, being in unusual locations or because of other nearby emissions from brighter sources. Together with upcoming radio surveys, the eROSITA X-ray survey shows great promise for finding many of the missing supernova remnants, helping to solve this long-standing astrophysical mystery.
Reference: “Hoinga: A supernova remnant discovered in the SRG/eROSITA All-Sky Survey eRASS1” by W. Becker, N. Hurley-Walker, Ch. Weinberger, L. Nicastro, M. Mayer, A. Merloni and J. Sanders, Accepted, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202040156
source: scitechdaily.com
(we copy paste articles thusly because if article, website, or document is scrubbed from the internet, altered, edited, or added to- we've got the original version)

Strongest x-ray source in specific bands, the Hoinga 'supernova' remnant nebula!

“Hoinga” Surprise – Debris of Stellar Explosion Found at Unusual Location

TOPICS:Astronomy Astrophysics Max Planck Institute Supernova

By MAX-PLANCK-GESELLSCHAFT MARCH 26, 2021

Composite X-ray and radio image of Hoinga (see also Fig.2 and Fig.3). The X-rays discovered by eROSITA are emitted by the hot debris of the exploded progenitor, whereas the radio antennae detect synchrotron emission from relativistic electrons, which are decelerated at the outer remnant layer. Credit: eROSITA/MPE (X-ray), CHIPASS / SPASS / N. Hurley-Walker, ICRAR-Curtin (Radio)

eROSITA space telescope finds largest supernova remnant ever discovered with X-rays.

In the first all-sky survey by the eROSITA X-ray telescope onboard SRG, astronomers at the Max Planck Institute for Extraterrestrial Physics have identified a previously unknown supernova remnant, dubbed “Hoinga.” The finding was confirmed in archival radio data and marks the first discovery of a joint Australian-eROSITA partnership established to explore our Galaxy using multiple wavelengths, from low-frequency radio waves to energetic X-rays. The Hoinga supernova remnant is very large and located far from the galactic plane – a surprising first finding – implying that the next years might bring many more discoveries.

Massive stars end their lives in gigantic supernova explosions when the fusion processes in their interiors no longer produce enough energy to counter their gravitational collapse. But even with hundreds of billions of stars in a galaxy, these events are pretty rare. In our Milky Way, astronomers estimate that a supernova should happen on average every 30 to 50 years. While the supernova itself is only observable on a timescale of months, their remnants can be detected for about 100 000 years. These remnants are composed of the material ejected by the exploding star at high velocities and forming shocks when hitting the surrounding interstellar medium.

Cutout of the first SRG/eROSITA all-sky survey. The Hoinga supernova remnant is marked. The large bright source in the lower quadrant of the image is from the supernova remnant “Vela” with “Pupis-A”. The image colours are correlated with the energies of the detected X-ray photons. Red represents the 0.3-0.6 keV energy range, green the 0.6-1.0 keV and blue the 1.0-2.3 keV waveband. Credit: SRG / eROSITA

About 300 such supernova remnants are known today – much less than the estimated 1200 that should be observable throughout our home Galaxy. So, either astrophysicists have misunderstood the supernova rate or a large majority has been overlooked so far. An international team of astronomers are now using the all-sky scans of the eROSITA X-ray telescope to look for previously unknown supernova remnants. With temperatures of millions of degrees, the debris of such supernovae emits high-energy radiation, i.e. they should show up in the high-quality X-ray survey data.

“We were very surprised that the first supernova remnant popped up straight away,” says Werner Becker at the Max Planck Institute for Extraterrestrial Physics. Named after the first author’s hometown’s Roman name, “Hoinga” is the largest supernova remnant ever discovered in X-rays. With a diameter of about 4.4 degrees, it covers an area about 90 times bigger than the size of the full Moon. “Moreover, it lies very far off the galactic plane, which is very unusual,” he adds. Most previous searches for supernova remnants have concentrated on the disk of our galaxy, where star formation activity is highest and stellar remnants therefore should be more numerous, but it seems that many supernova remnants have been overlooked by this search strategy.

After the astronomers found the object in the eROSITA all-sky data, they turned to other resources to confirm its nature. Hoinga is – although barely – visible also in data taken by the ROSAT X-ray telescope 30 years ago, but nobody noticed it before due to its faintness and its location at high galactic latitude. However, the real confirmation came from radio data, the spectral band where 90% of all known supernova remnants were found so far.

“We went through archival radio data and it had been sitting there, just waiting to be discovered,” marvels Natasha Walker-Hurley, from the Curtin University node of the International Centre for Radio Astronomy Research in Australia. “The radio emission in 10-year-old surveys clearly confirmed that Hoinga is a supernova remnant, so there may be even more of these out there waiting for keen eyes.”

The eROSITA X-ray telescope will perform a total of eight all-sky surveys and is about 25 times more sensitive than its predecessor ROSAT. Both observatories were designed, build and are operated by the Max Planck Institute for Extraterrestrial Physics. The astronomers expected to discover new supernova remnants in its X-ray data over the next few years, but they were surprised to identify one so early in the program. Combined with the fact that the signal is already present in decades-old data, this implies that many supernova remnants might have been overlooked in the past due to low-surface brightness, being in unusual locations or because of other nearby emissions from brighter sources. Together with upcoming radio surveys, the eROSITA X-ray survey shows great promise for finding many of the missing supernova remnants, helping to solve this long-standing astrophysical mystery.

Reference: “Hoinga: A supernova remnant discovered in the SRG/eROSITA All-Sky Survey eRASS1” by W. Becker, N. Hurley-Walker, Ch. Weinberger, L. Nicastro, M. Mayer, A. Merloni and J. Sanders, Accepted, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202040156

source: scitechdaily.com

(we copy paste articles thusly because if article, website, or document is scrubbed from the internet, altered, edited, or added to- we've got the original version)

Regards, Dan, a. k. a. smAshomAsh

THE MOST!

The Most Powerful Magnetic Fields Seen

In a Type-O Star and a Complex Magnetospheric Structure

NGC 1624-2 has a complex magnetospheric structure, observations reveal

The Most Powerful Magnetic Fields Seen

In a Type-O Star and a Complex Magnetospheric Structure

NGC 1624-2 has a complex magnetospheric structure, observations reveal

Super Heavyweight and Flyweight in a Cosmic Dance

An odd couple sets new records

Step 1: Observing at many wavelengths

Step 2: Harnessing computational power donated to Einstein@Home

Finding a very close binary system with improved analysis

Searching for radio and gravitational waves

Exciting future

Background information

Super Heavyweight and Flyweight in a Cosmic Dance

An odd couple sets new records

Step 1: Observing at many wavelengths

Step 2: Harnessing computational power donated to Einstein@Home

Finding a very close binary system with improved analysis

Searching for radio and gravitational waves

Exciting future

Background information

References[edit] (source: wikipedia.org)

References[edit] (source: wikipedia.org)

"Ultramassive" black holes may be the biggest ever found – and they're growing fast

"Ultramassive" black holes may be the biggest ever found – and they're growing fast

References[edit]

References[edit]

Researchers detect galactic source of gamma rays that could produce very high-energy cosmic rays

Researchers detect galactic source of gamma rays that could produce very high-energy cosmic rays

eROSITA space telescope finds largest supernova remnant ever discovered with X-rays.

eROSITA space telescope finds largest supernova remnant ever discovered with X-rays.

smAsho mIssion