Saturday, May 6, 2023

3985 - BLACKHOLES - the most massive?

 

-   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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