Black hole mergers (split from LIGO/VIRGO)

[geordief]

8 hours ago, swansont said:

Black holes have no optical signal to correlate with the GW signal. So, AFAIK, that has no effect. But VIRGO being online does, since it's a third detector.

Does a binary black  hole merger have an em signal?

Might this latest observation bring closer capturing a binary black hole merger using that em or optical signal?

Edited October 17, 2017 by geordief

[swansont]

8 hours ago, geordief said:

Does a binary black  hole merger have an em signal?

Might this latest observation bring closer capturing a binary black hole merger using that em or optical signal?

There was no optical signal with the previous mergers. They're black holes. Any EM signal has to come from matter outside the black holes.

[geordief]

6 minutes ago, swansont said:

There was no optical signal with the previous mergers. They're black holes. Any EM signal has to come from matter outside the black holes.

Okay  but we do not actually have a location for them to know where to look ,do we? ...Is it entirely ruled out as a possibility?

 

All the energy externally produced **just  goes into gravitational waves? There is nothing  else that  could be produced ?

 

** if that is a correct description

 

 

Edited October 17, 2017 by geordief

[swansont]

3 minutes ago, geordief said:

Okay  but we do not actually have a location for them to know where to look ,do we? ...Is it entirely ruled out as a possibility?

 

All the energy externally produced **just  goes into gravitational waves? There is nothing  else that  could be produced ?

 

** if that is a correct description

One of the links above says black hole mergers "are completely dark". Which should be expected, as they are black holes. No light is going to escape.

[geordief]

19 minutes ago, swansont said:

One of the links above says black hole mergers "are completely dark". Which should be expected, as they are black holes. No light is going to escape.

The gravitational wave's signal  that was received (from the first BH merger)was described at the time  as being  amazingly accurate. Does that imply that the interior structure  of the Black Holes  involved was well   understood ?

Or just that the precision of the signal received   was close enough to what was predicted to discount any other possible interpretations?

Edited October 17, 2017 by geordief

[swansont]

1 hour ago, geordief said:

The gravitational wave's signal  that was received (from the first BH merger)was described at the time  as being  amazingly accurate. Does that imply that the interior structure  of the Black Holes  involved was well   understood ?

Or just that the precision of the signal received   was close enough to what was predicted to discount any other possible interpretations?

The signals matched the models, which are based on GR, which does not tell us anything about the internal structure of a BH.

I am not aware of any competing models on which to base an interpretation (but I am also not an astronomer/astrophysicist/cosmologist)

[geordief]

30 minutes ago, swansont said:

The signals matched the models, which are based on GR, which does not tell us anything about the internal structure of a BH.

I am not aware of any competing models on which to base an interpretation (but I am also not an astronomer/astrophysicist/cosmologist)

Hope I am not getting off the subject but is there anything at all known or theorized about the internal structure of a black hole?  (discounting theories about the singularity said to lie at the centre)

For instance does the concept of "further in"  mean anything and if it does  what might happen as things go "further in"?

 

 

 

 

[swansont]

41 minutes ago, geordief said:

Hope I am not getting off the subject but is there anything at all known or theorized about the internal structure of a black hole?  (discounting theories about the singularity said to lie at the centre)

For instance does the concept of "further in"  mean anything and if it does  what might happen as things go "further in"?

Not as far as I am aware. There's no way to test ideas, even if we had a black hole to play with. It's the Hotel California. Signals can check out but they never leave.

[Strange]

3 hours ago, geordief said:

Okay  but we do not actually have a location for them to know where to look ,do we? ...Is it entirely ruled out as a possibility?

All the energy externally produced **just  goes into gravitational waves? There is nothing  else that  could be produced ?

** if that is a correct description

The last black hole merger was located accurately enough that it should have been possible to find an optical counterpart. The fact none was found was taken as confirmation of current models. There would only be EM radiation if there were matter involved and a pair of black holes would b expected to have cleared the space around them. Unless they had happened to capture a gas cloud or star shortly before the merger, there would be no radiation.

[Strange]

.

46 minutes ago, geordief said:

Hope I am not getting off the subject but is there anything at all known or theorized about the internal structure of a black hole?  (discounting theories about the singularity said to lie at the centre)

For instance does the concept of "further in"  mean anything and if it does  what might happen as things go "further in"?

GR models the curvature of space-time and tells us that all paths lead to the centre. That is the only tested (and therefore confirmed) model we have.

String theory has the concept of a fuzzball: https://en.wikipedia.org/wiki/Fuzzball_(string_theory)

I am not aware that other theories of quantum gravity have produced alternative descriptions.

Edited October 17, 2017 by Strange
moved

[geordief]

I have read that the temperature of BHs is about absolute zero

Why is this?Nothing has any freedom to move? Is there any concept of one location in a BH being any way different from any other?

[MigL]

A BH has entropy related to the surface area of its event horizon.
Anything that can be assigned an entropy, can be assigned a temperature.

[Strange]

2 hours ago, geordief said:

I have read that the temperature of BHs is about absolute zero

Why is this?Nothing has any freedom to move? Is there any concept of one location in a BH being any way different from any other?

The temperature of a black hole is inversely proportional to its mass. So very small black holes could be hot.

http://xaonon.dyndns.org/hawking/