Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jeffreyH on 18/04/2014 15:13:34
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It is thought that in the immediate vicinity of a black hole's event horizon matter is drawn in and leaves a void. Some material rotates in an accretion disc. Are there any other theories explaining this empty space around the black hole?
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http://en.wikipedia.org/wiki/Supermassive_black_hole
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Would you have a link to what you mean? Spinning black holes can take matter with it (framedragging), while also, depending on matters momentum/vector (relative the black hole) fling it back out again. I don't think you can have a boundary constantly devoid of matter though, around a black hole? Or you can, depending on observer dependencies?
from the aspect of being at a event horizon, relative observing it from afar you mean?
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The massive black hole at the center of our galaxy does not seem to very active at the moment, so one assumes that it is surrounded by a void - the vacuum of space. Astronomers are hoping that this will change any day now, as the G2 gas cloud (http://www.natureworldnews.com/articles/6531/20140405/dinner-time-milky-ways-black-hole-about-to-consume-a-cloud-of-gas.htm) approaches the closest point on its elliptical orbit around this unseen focus.
I expect that other galaxies with an active galactic nucleus will have an accretion disk, and there will be a continuous band of matter (in the form of a super-hot plasma) extending from the accretion disk all the way down to the event horizon. This is not to say that the density of matter will be uniform across the whole accretion disk. It is thought that perhaps 30% of the mass-energy equivalent of matter could be radiated away during this death-spiral into the event horizon.
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Would you have a link to what you mean? Spinning black holes can take matter with it (framedragging), while also, depending on matters momentum/vector (relative the black hole) fling it back out again. I don't think you can have a boundary constantly devoid of matter though, around a black hole? Or you can, depending on observer dependencies?
from the aspect of being at a event horizon, relative observing it from afar you mean?
I am really looking for informed opinions and data sources so I can't supply specific links.
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The massive black hole at the center of our galaxy does not seem to very active at the moment, so one assumes that it is surrounded by a void - the vacuum of space. Astronomers are hoping that this will change any day now, as the G2 gas cloud (http://www.natureworldnews.com/articles/6531/20140405/dinner-time-milky-ways-black-hole-about-to-consume-a-cloud-of-gas.htm) approaches the closest point on its elliptical orbit around this unseen focus.
I expect that other galaxies with an active galactic nucleus will have an accretion disk, and there will be a continuous band of matter (in the form of a super-hot plasma) extending from the accretion disk all the way down to the event horizon. This is not to say that the density of matter will be uniform across the whole accretion disk. It is thought that perhaps 30% of the mass-energy equivalent of matter could be radiated away during this death-spiral into the event horizon.
Any gas cloud data would be very interesting. Is there any specific data on the s stars? Are they theoretical or from observations?
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Here is a link to a PDF of observations of G2. There are some puzzles in there.
arxiv.org/pdf/1209.2272
I am going to bet on it not being consumed.
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Are there any data on the velocities of the s star orbitals? I also noted that a magnetar has been discovered.
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The Max Plank Institute (http://www.mpe.mpg.de/ir/GC) has been monitoring the galactic black hole for some time, and doing computer modelling:
The paths they show are real stars, seen in high-resolution images. They have not been watching them long enough for them to trace out an entire orbit at this time.
Looking at the orbits of stars around the galactic black hole allows you to estimate the mass of the (assumed) black hole quite accurately.
However, it does not tell you anything about the mass of the objects orbiting the black hole. To do this, you would need to study the orbits of some planets orbiting these stars. However, the extreme distance to the galactic center makes it very hard to detect any planets around these stars.
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Data on the distance in Schwarzschild radii against velocity would be very interesting. How would this match against expected time dilation? Is there any data on an accretion disk? This looks promising.
http://arxiv.org/abs/1303.2115
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Some data here on gas interacting with Sagittarius A*.
http://www.cam.ac.uk/research/news/our-galaxys-giant-black-hole-rejects-food-because-its-too-hot-0
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Well it isn't going as predicted at the galactic centre.
http://blogs.scientificamerican.com/dark-star-diaries/2014/05/02/cloud-bound-for-milky-ways-black-hole-puzzles-astronomers/
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Just had a look at the diagram on wikipedia for the s star orbitals arouns Sag A*. This can't be accurate as the focal points are out for quite a few of the orbits. Is there any better data for the orbits?
http://en.wikipedia.org/wiki/Sagittarius_A*