Unraveling the Mystery: X-Rays from Black Holes

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Discussion Overview

The discussion centers around the detection of X-rays from black holes, exploring the mechanisms behind this phenomenon, particularly in relation to accretion disks and other potential sources of X-ray emissions. The scope includes theoretical explanations, competing models, and the implications of these observations in astrophysics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how X-rays can be emitted from black holes despite light not escaping, suggesting the role of the accretion disk.
  • Another participant explains that as the accretion disk falls into a black hole, it releases gravitational potential energy, heating the disk and allowing X-rays to escape, as they are emitted from regions outside the event horizon.
  • A different viewpoint suggests that heating may also result from the compression of dusty gas and friction, rather than solely from gravitational potential energy conversion.
  • Another participant adds that the differential rotation of the accretion disk contributes to heating, but emphasizes that the energy source is gravitational potential energy.
  • One participant introduces multiple processes that can produce X-rays in quasars, including thermal, synchrotron, and inverse Compton emissions, noting that X-rays can originate from both the disk and jets, depending on the specific conditions.
  • A later reply asserts that while objects falling into black holes do not necessarily emit radiation, the presence of accretion disks ensures that some gravitational potential energy is converted into observable radiation.
  • Another participant mentions various models explaining X-ray emissions, including those related to accretion disks and interactions with neutron stars, while also referencing ongoing mysteries like gamma-ray bursts.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms behind X-ray emissions from black holes, with no consensus reached on a singular explanation. Multiple competing models and processes are acknowledged, indicating an unresolved discussion.

Contextual Notes

Some claims rely on specific definitions of energy conversion and the conditions under which radiation is emitted, which may not be universally agreed upon. The discussion also highlights the complexity of interactions in the vicinity of black holes, suggesting a need for further exploration of these phenomena.

blumfeld0
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Light cannot escape from a black hole; however, x-rays have been detected from black holes. How is this possible?

is it because of the accretion disk? where does it come from?
is that all there is to the answer?

thanks
 
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As the accretion disc falls into a black hole it releases massive amounts of gravitational potential energy which heats the disc up. The hot accretion disc then emits x-ray radiation. The x-rays do not come from the black hole and they can escape because they are nowhere near the event horizon.
 
Kurdt said:
As the accretion disc falls into a black hole it releases massive amounts of gravitational potential energy which heats the disc up. The hot accretion disc then emits x-ray radiation.
Can one simply say that gravitational potential energy is converted into heat? Is it not rather the compression of dusty gas, with accompanying friction that does the heating? I do not recall reading that a solo object falling straight into a black hole releases energy; it needs to be in an accretion disk as far as I know.
 
The accretion disk rotates differentially which also causes the heating but the energy has to come from somwhere and that is the gravitational potential.
 
There are several processes that can produce X-rays in a quasar, including thermal, synchrotron and inverse compton emission. Sometimes the X-rays come from the disk, other times from a jet. A disk (or something disk-like) is thought to be present in every quasar, while jets only appear in some of them.

It's true that an object falling into a black hole does not necessarily need to emit radiation -- there are orbits that pass through the event horizon. In that case, the gravitational potential energy would be converted to kinetic energy rather than radiation. However, disks are thought to appear in all quasars, so some of the gravitational potential energy invariably gets converted into radiation. There is a massive pool of energy and, whatever form it takes in the short-run (infall, magnetic fields, jets, winds), there is some radiation mechanism that can occur and make the process observable.
 
XRFs

blumfeld0 said:
Light cannot escape from a black hole; however, x-rays have been detected from black holes
There is no signal which can escape from a black hole. It is for that it is called black hole. The emission of X-radiation can be produced by several phenomena like the synchrotron radiation and the inverse Compton effect. But the principal cause is always ignored. There are several models which try to explain that like the model of accretion disc, coalescence between a black hole and neutron star, and there is also several telescopes embarked on satellite which observe this phenomenon for a long time.
One quotes also the mystery of gamma ray bursts (GRBs) who lasts since more than 30 without real resolution.
Thanks
 

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