8

It is actually the other way around: First a massive accretion disc can form, through which material looses angular momentum and accretes onto the star radially, hence being angular momentum poor. However, during the initial free-fall phase, before the disc forms, infalling material can be 'rejected' at the star, either via high pressure gradients or ...


7

Unfortunately, the answer is "No", because accretion rates are far too low -- and our ability to measure black hole masses is far too uncertain -- for this to be visible in reasonable times. Given our current ability to measure black hole masses, you'd typically have to wait millions or tens of millions of years to see any accretion-related changes....


6

As I understand the quote, the "artificial" thing about your accretion disk is not that it is bright, but that it doesn't emit X rays. In real life, SMBH accretion disks are usually exceptionally bright. The disk itself has a strong emission in the UV, called UV bump, that can easily exceed the emission of the whole host galaxy. Above and below the ...


5

When the stream of gas falls towards the disk it gains a significant fraction of the orbital kinetic energy (after all, it is falling from the top of the Roche lobe) which means that it is moving fast and then slows down sharply when it interacts with the disk. This produces a hot spot that in theory could reach $10^8$ K but in practice "merely" is ...


4

We can think of the magnetic field lines as part of its host gas in the jet, in the sense that when the gas moves, the magnetic lines of force must move with it - and vice versa. Magnetic field lines passing through an accretion disc are thus forced to rotate with the disc. The particles of ionised gas above and below the disc are then urged to rotate with ...


3

An accretion disc would be very bright! In an accretion disc, matter is orbiting, and different parts of the disc move at different speeds. This causes friction, and at speeds that are a good fraction of the speed of light, the friction (driven by turbulence) in the accretion disc is extreme. It will heat the disc to millions of degrees. It will be ...


3

The Milky Way's central supermassive black hole (SMBH) is feeding, albeit at a very low level. Radio emission from the accretion disk (and/or weak jets) is responsible for the long-lived "Sgr A*" radio source. Here is a paper from 2000 (Falcke et al.) arguing that VLBI (as used by the Event Horizon Telescope) should be able to image the "black ...


3

Consider an extremely transparent lens. If you photograph the lens, what the camera really picks up where the lens covers is the distorted image of what is behind the lens. Would you say that is still a photograph of the lens? I would say yes. If you take a picture of an object coated with Vantablack, the amount of light entering the camera from that object ...


1

There are multiple categories of Black Hole powered astrophysical jets: Microquasars: As their name implies, they are somewhat like a highly scaled-downed version of quasars, but unlike quasars, they are powered by accretion from a donor star. They contain stellar-mass black holes. Quasars: They are huge systems of accretion disk(s) around supermassive ...


1

This question was asked more roughly 8 years ago, and for 2 years there is a review article around which I found worth mentioning and summarizing. The manuscript is called Redefining the torus: A unifying view of AGN in the infrared and sub mm and work of Sebastian Florian Hönig. Here an excerpt of the abstract: The advent of high-angular resolution IR and ...


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