- 3985
- BLACKHOLES - the
most massive? These massive black holes
sit in the center of galaxies, but they have more than five billion solar
masses, an astonishingly large amount of mass. The largest black hole we know
of is “Phoenix A”, a black hole with up to 100 billion solar masses.
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-------------------- 3985 - BLACKHOLES - the most massive?
- Black holes
are the most massive objects that we know of in the Universe. Not stellar mass
black holes, not supermassive black holes (SMBHs,) but ultra-massive black
holes (UMBHs.)
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Supermassive black holes are rare and elusive, and their origins are
unclear. Astrophysicists have traced their origins back to the Universe’s
‘Cosmic Noon‘ around 10 to 11 billion years ago.
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- Astronomers
found that one possible formation channel for ultra-massive black holes is from
the extreme merger of massive galaxies that are most likely to happen in the
epoch of the ‘cosmic noon,'” .
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- These
blackhoes are extremely rare. Creating them in scientific simulations requires
a massive, complex simulation. This is where “Astrid” comes in. It’s a
large-scale cosmological hydrodynamical simulator that runs on the Frontera
supercomputer at the University of Texas, Austin.
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- Astrid’s large-scale
simulations can track things like dark matter, temperature, metallicity, and
neutral hydrogen. Simulations like Astrid are ranked by the number of particles
their simulations contain.
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- The science
goal of Astrid is to study galaxy formation, the coalescence of supermassive
black holes, and re-ionization over the cosmic history. Astronomers know that
galaxies grow large through mergers.
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- They found
three ultra-massive black holes that assembled their mass during the cosmic
noon, the time 11 billion years ago when star formation. Cosmic Noon is an important time period in
the history of the Universe. Astronomers think that half of all stars were born
during the period.
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- It
corresponds to redshift z=2 to z=3, or when the Universe was about 2 to 3
billion years old. At that time, large quantities of gas flowed from the
intergalactic medium into galaxies. Galaxies formed about half of their stellar
mass during cosmic noon.
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- Each of the
galaxy masses is 10 times the mass of our own Milky Way, and a supermassive
black hole sits in the center of each galaxy.
These quasar triplet systems are the progenitor of those rare
ultra-massive blackholes after those triplets gravitationally interact and
merge with each other.
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- “Quasars”
name is misleading. It means a quasi-stellar object, but the name stems from a
time before astronomers knew what they were. Quasars are a subset of active
galactic nuclei but are extremely luminous. The luminosity comes from all of
the material falling into the blackhoe at a galaxy’s center.
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Astrophysicists have determined a theoretical upper mass limit for black
holes at about 50 billion solar masses, and these blackholes approache that
limit. They find that ultramassive black
holes with extreme masses of <50 billion solar masses> can be formed in
the rare events that are multiple massive galaxy mergers happening around z =
2, the epoch when both star formation and AGN reach their peak activity.
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- The future
space-based NASA Laser Interferometer Space Antenna (LISA) gravitational wave
observatory will give us a much better understanding the how these massive
black holes merge and/or coalescence, along with the hierarchical structure,
formation, and the galaxy mergers along the cosmic history.
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- This is an
exciting time for astrophysicists, and it’s good that we can have simulation to
allow theoretical predictions for those observations.
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May 5, 2023 BLACKHOLES - the
most massive? 3985
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--------------------- --- Saturday, May 6, 2023
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