Is the Matter in a Black Hole's Accretion Disc Entering the BH or Circling It?

[abhiroop_k]

has the matter in the accretion discs for a black hole entered the BH or is it circling the actual BH?...

 

[Nabeshin]

The matter has not crossed the event horizon of the black hole. If it had, it would not be visible (nor would it be orbiting).

 

[abhiroop_k]

i learned (via some documentary) that a BH can be spotted by observing the distortion caused in the light from distant stars as it isn't visible directly...why isn't the accretion disc used for locating a BH in space?...

 

[Ken G]

Accretion disks are much more common ways to identify black holes than is gravitational lensing. For example, quasars, the most distant objects we can see in the constant sky, are accretion disks of supermassive black holes.

 

[Nabeshin]

The simple fact is not all black holes will have accretion disks. Furthermore, depending on the configuration, it may be difficult to spot the accretion disk. The features are generally going to be quite small, so it's not as if you'll be looking in a telescope and seeing a literal disk around a dark object. It will instead appear as a point source, so it's not (at least completely) trivial to say that it's an accretion disk and not a star (Of course it's actually not that hard to differentiate between the two, they have different light profiles in general).

 

[ibysaiyan]

has the matter in the accretion discs for a black hole entered the BH or is it circling the actual BH?...

If the matter had passed through the EH then it would appear to be at a standstill to the reference frame of a stationary observer as the speeds get closer to 'c' aka time dilation.

 

[ibysaiyan]

i learned (via some documentary) that a BH can be spotted by observing the distortion caused in the light from distant stars as it isn't visible directly...why isn't the accretion disc used for locating a BH in space?...

As mentioned by Nabeshin: Not all Black holes are known to have accreting matter.Also going by what you're suggesting if we are to use the accretion disc as a property to discover black holes then that follows upon the assumption that light reaches us but this isn't always the case due to Fraunhofer radiation (I think)


I personally believe that taking the red shift light reaching to us can't be a viable source.Recently I read an article about how much data we have gathered from Hubbles Space telescope yet the uncertainty i.e the number of galaxies observed seems high which is to say that quite often the forehead galaxies distort the incoming light from the distant galaxies,so to get over this issue James webb Telescope shall operate soon.

Regards
ibysaiyan

 

[abhiroop_k]

thanks