by BeAChooser » Tue Nov 01, 2022 10:13 pm
https://phys.org/news/2022-11-supermass ... giant.html
Did supermassive black holes collapse directly out of giant clouds of gas? It could depend on magnetic fields
Roughly a half-century ago, astronomers realized that the powerful radio source coming from the center of our galaxy (Sagitarrius A*) was a "monster" black hole. Since then, they have found that supermassive black holes (SMBHs) reside at the center of most massive galaxies. This leads to what is known as Active galactic nuclei (AGN) or quasars, where the central region of a galaxy is so energetic that it outshines all of the stars in its galactic disk. In all that time, astronomers have puzzled over how these behemoths (which play a crucial role in galactic evolution) originated.
Astronomers suspect that the seeds that formed SMBHs were created from giant clouds of dust that collapsed without first becoming stars—aka, Direct collapse black holes (DCBHs). However, the role of magnetic fields in the formation of DCBHs has remained unclear since none of the previous studies have been able to simulate the full accretion periods. To investigate this, an international team of astronomers ran a series of 3D cosmological magneto-hydrodynamic (MHD) simulations that accounted for DCBH formation and showed that magnetic fields grow with the accretion disks and stabilize them over time.
… snip …
The existence of SMBHs was originally proposed to explain the existence of high-redshift primordial SMBHs that existed within 1 billion years after the Big Bang. But as Latif and his colleagues explain, there were inconsistencies between what astrophysicists theoretically predicted and what astronomers have observed. In particular, there's the role that magnetic fields played in the accretion of material with primordial dust clouds, which eventually resulted in gravitational collapse and the formation of DCBHs.
"The standard model of physics does not provide any constraints on the initial magnetic field strength, and some models predict small B-fields of the order of 10-20 G," said Latif. "They are about many orders of magnitude smaller than observed fields (about 1G). Therefore, the scientific community thought that their role might be only secondary."
This mystery has persisted because previous attempts to simulate the formation of DCBHs numerically have been limited in scope. Previous simulations have lacked the computing power to simulate the accretion process's full length, which is considered comparable to the expected lifetime of SMSs—1.6 million years. Thanks to advances in supercomputing during the past decade, different research groups have conducted numerical simulations in the past decade that show that magnetic fields can be amplified within a short period.
Similarly, there's increasing evidence that magnetic fields were present roughly 13 billion years ago when DCBHs are expected to have formed. To address this mystery, Latif and his colleagues conducted a series of 3D cosmological magneto-hydrodynamic (MHD) models that accounted for a lifetime of 1.6 million years:
Their findings are consistent with previous research by Latif and his colleagues (and other groups) that show how magnetic fields play a vital role in the formation of massive stars and black holes. These studies have shown how magnetic fields are amplified (increase in Jean mass) by accreting disks of gas and dust. These fields are responsible for reducing fragmentation and stabilizing the disks, eventually allowing these disks to achieve the mass necessary (aka. Jean mass) to experience gravitational collapse and form supermassive stars and black holes.
"Such strong magnetic fields can even launch jets and outflows and also help in transporting angular momentum, which is considered an obstacle for forming stars," explained Latif. "Therefore, they will have important implications for the magnetization of interstellar and intergalactic mediums (similar to what we observe in the local universe) and shaping the formation of high redshift galaxies as well as the evolution of massive black holes."
Notice … there's no mention of plasma or electric current in either the article or the paper itself:
https://arxiv.org/pdf/2210.05611.pdf . They don't say where the magnetic fields that get “amplified” come from . They seem to believe in they just popped into existence out of nothing and then are frozen-in, I guess, although they don't use that term. In their simulations they "ASSUME" a "SEED" magnetic field of 10 ^^ -14 G which is “amplified” to 1G.
Comments?
[url]https://phys.org/news/2022-11-supermassive-black-holes-collapse-giant.html[/url]
[quote][b]Did supermassive black holes collapse directly out of giant clouds of gas? It could depend on magnetic fields[/b]
Roughly a half-century ago, astronomers realized that the powerful radio source coming from the center of our galaxy (Sagitarrius A*) was a "monster" black hole. Since then, they have found that supermassive black holes (SMBHs) reside at the center of most massive galaxies. This leads to what is known as Active galactic nuclei (AGN) or quasars, where the central region of a galaxy is so energetic that it outshines all of the stars in its galactic disk. In all that time, astronomers have puzzled over how these behemoths (which play a crucial role in galactic evolution) originated.
Astronomers suspect that the seeds that formed SMBHs were created from giant clouds of dust that collapsed without first becoming stars—aka, Direct collapse black holes (DCBHs). However, the role of magnetic fields in the formation of DCBHs has remained unclear since none of the previous studies have been able to simulate the full accretion periods. To investigate this, an international team of astronomers ran a series of 3D cosmological magneto-hydrodynamic (MHD) simulations that accounted for DCBH formation and showed that magnetic fields grow with the accretion disks and stabilize them over time.
… snip …
The existence of SMBHs was originally proposed to explain the existence of high-redshift primordial SMBHs that existed within 1 billion years after the Big Bang. But as Latif and his colleagues explain, there were inconsistencies between what astrophysicists theoretically predicted and what astronomers have observed. In particular, there's the role that magnetic fields played in the accretion of material with primordial dust clouds, which eventually resulted in gravitational collapse and the formation of DCBHs.
"The standard model of physics does not provide any constraints on the initial magnetic field strength, and some models predict small B-fields of the order of 10-20 G," said Latif. "They are about many orders of magnitude smaller than observed fields (about 1G). Therefore, the scientific community thought that their role might be only secondary."
This mystery has persisted because previous attempts to simulate the formation of DCBHs numerically have been limited in scope. Previous simulations have lacked the computing power to simulate the accretion process's full length, which is considered comparable to the expected lifetime of SMSs—1.6 million years. Thanks to advances in supercomputing during the past decade, different research groups have conducted numerical simulations in the past decade that show that magnetic fields can be amplified within a short period.
Similarly, there's increasing evidence that magnetic fields were present roughly 13 billion years ago when DCBHs are expected to have formed. To address this mystery, Latif and his colleagues conducted a series of 3D cosmological magneto-hydrodynamic (MHD) models that accounted for a lifetime of 1.6 million years:
Their findings are consistent with previous research by Latif and his colleagues (and other groups) that show how magnetic fields play a vital role in the formation of massive stars and black holes. These studies have shown how magnetic fields are amplified (increase in Jean mass) by accreting disks of gas and dust. These fields are responsible for reducing fragmentation and stabilizing the disks, eventually allowing these disks to achieve the mass necessary (aka. Jean mass) to experience gravitational collapse and form supermassive stars and black holes.
"Such strong magnetic fields can even launch jets and outflows and also help in transporting angular momentum, which is considered an obstacle for forming stars," explained Latif. "Therefore, they will have important implications for the magnetization of interstellar and intergalactic mediums (similar to what we observe in the local universe) and shaping the formation of high redshift galaxies as well as the evolution of massive black holes."[/quote]
Notice … there's no mention of plasma or electric current in either the article or the paper itself: https://arxiv.org/pdf/2210.05611.pdf . They don't say where the magnetic fields that get “amplified” come from . They seem to believe in they just popped into existence out of nothing and then are frozen-in, I guess, although they don't use that term. In their simulations they "ASSUME" a "SEED" magnetic field of 10 ^^ -14 G which is “amplified” to 1G.
Comments?