Is a Black Hole a Cold Place?

[astrolabe]

Hello All,

Since it looks as if new threads are becoming somewhat more prevalent why not add to the pile! This idea follows the gravity well concept in the the arena of BH phenom and is (hopefully) to encompass the observations of jets and accretion discs.

WRT Gravity and deep Gravity wells, specifically Black Holes, It occurred to me that matter that has fallen inward past the event horizon may have achieved an absolute state of rest. I think this can only occur if matter has entirely shed ALL of it's physical properties including it's energy states, whatever and however much they might be. The amount of energy even in one single atom or particle is considerable- to say the least- nevermind an entire Galaxy with a massive Black Hole at it's center!

So it's no wonder to me that in gaining perfect rest all motion should cease-all energy wavelengths would be infinite. Well, it doesn't require too much of a leap to say, oh m'gosh, Absolute Zero is the same thing, no motion, no energy- at all. And since the average background temperature of the Universe is only 2.73 K, with some differences, it COULD be that AZ is entirely possible in nature (or nearly so) especially since the Boomerang Nebula because of IT'S jets has cooled down to 1 degree Kelvin. So, maybe a BH is the coldest place yet when one sees the energy output from the accretion disc via the jets as matter and it's reduction to various energy states proceeds to at last gain rest at Absolute Zero (or colder-who knows!) by finally giving up whatever is left of that energy state's heat and motion. So high heat in the accretion disc meets the absolute cold of a BH and one would expect a storm of course to brew and to me that is exactly what happens just at or a little before the Event Horizon.

Just thinking out loud here, don't mind me.

[neufer]

It occurred to me that matter that has fallen inward past the event horizon may have achieved an absolute state of rest. I think this can only occur if matter has entirely shed ALL of it's physical properties including it's energy states, whatever and however much they might be. The amount of energy even in one single atom or particle is considerable- to say the least- nevermind an entire Galaxy with a massive Black Hole at it's center!

A black hole is the antithesis of a state of rest.

Space-time, itself, is constantly cascading into a black hole.

A black hole has the maximal entropy that can be squeezed within a fixed volume.

[Chris Peterson]

So it's no wonder to me that in gaining perfect rest all motion should cease-all energy wavelengths would be infinite. Well, it doesn't require too much of a leap to say, oh m'gosh, Absolute Zero is the same thing, no motion, no energy- at all. And since the average background temperature of the Universe is only 2.73 K, with some differences, it COULD be that AZ is entirely possible in nature (or nearly so) especially since the Boomerang Nebula because of IT'S jets has cooled down to 1 degree Kelvin.

Nit: the units are Kelvins; there's no such thing as a degree Kelvin.

It is basically undefined what happens to matter once it passes the event horizon. Mass, charge, and angular momentum are conserved and those values for the black hole change accordingly. A typical black hole behaves as a blackbody, and is indeed cold- a few nanokelvins- damn close to absolute zero. But the temperature is dependent on the mass of the black hole, and also on its rotation rate (smaller will be hotter, faster rotating will be hotter). Curiously, all non-rotating black holes of a given mass will have the same temperature. Very small black holes could be hotter than the Sun- although not for long, since they would have short lifetimes (it isn't known if such small black holes even exist).

Because typical stellar mass black holes are colder than the CMB, they absorb energy from the background and actually grow faster than they can evaporate due to Hawking radiation.

[astrolabe]

Hello Chris,

Thank you for your information and the relief that I'm not as wacko as some might think. As pretty much a person educated basically by this Forum it is reassuring that as I sit and think, trying to put pieces of info and logic together, that on rare occasions I do get moments where the pieces kinda fall into place.

Thanks again for your elaboration.

[neufer]

It is basically undefined what happens to matter once it passes the event horizon.

I was watching a NOVA Science NOW the other night where Neil deGrasse Tyson described the experience of passing through the event horizon and being confronted by a blaze of light from all the photons that had been trapped inside that event horizon. In a sense, the event horizon acts like a thermos bottle holding in radiation that simply can't be seen from the outside.

One doesn't estimate the temperature of hot soup based upon the thermal radiation outside of the thermos bottle.

The temperature of a black hole can either be described as:

1) extremely hot (just inside the event horizon),
2) extremely cold (just outside the event horizon),
3) indeterminate and/or
4) meaningless.

Take your pick.

Mass, charge, and angular momentum are conserved and those values for the black hole change accordingly. A typical black hole behaves as a blackbody, and is indeed cold- a few nanokelvins- damn close to absolute zero. But the temperature is dependent on the mass of the black hole, and also on its rotation rate (smaller will be hotter, faster rotating will be hotter). Curiously, all non-rotating black holes of a given mass will have the same temperature. Very small black holes could be hotter than the Sun- although not for long, since they would have short lifetimes (it isn't known if such small black holes even exist).

Because typical stellar mass black holes are colder than the CMB, they absorb energy from the background and actually grow faster than they can evaporate due to Hawking radiation.

[Chris Peterson]

I was watching a NOVA Science NOW the other night where Neil deGrasse Tyson described the experience of passing through the event horizon and being confronted by a blaze of light from all the photons that had been trapped inside that event horizon. In a sense, the event horizon acts like a thermos bottle holding in radiation that simply can't be seen from the outside.

Maybe, but that's pure speculation. There are lots of models for what happens to matter once it's "inside" a black hole- none of which have been tested in any way, AFAIK.

The temperature of a black hole can either be described as:

1) extremely hot (just inside the event horizon),
2) extremely cold (just outside the event horizon),
3) indeterminate and/or
4) meaningless.

Which is why it is always important in a scientific discussion to define your terms if there is any risk of confusion. However, in the case of the temperature of a black hole, "temperature" is generally used unqualified, and simply means the temperature determined by examining what radiates from it- the same definition of temperature most commonly used for other astronomical bodies.

[harry]

G'day from the land of ozzzzzzzz

Could quark matter be matter found in stellar black holes?

http://aps.arxiv.org/abs/0908.2672
Can stellar mass black holes be quark stars?

Authors: Z. Kovacs, K. S. Cheng, T. Harko
(Submitted on 19 Aug 2009)

Abstract: We investigate the possibility that stellar mass black holes, with masses in the range of $3.8M_{\odot}$ and $6M_{\odot}$, respectively, could be in fact quark stars in the Color-Flavor-Locked (CFL) phase. Depending on the value of the gap parameter, rapidly rotating CFL quark stars can achieve much higher masses than standard neutron stars, thus making them possible stellar mass black hole candidates. Moreover, quark stars have a very low luminosity and a completely absorbing surface - the infalling matter on the surface of the quark star is converted into quark matter. A possibility of distinguishing CFL quark stars from stellar mass black holes could be through the study of thin accretion disks around rapidly rotating quark stars and Kerr type black holes, respectively. Furthermore, we show that the radiation properties of accretion disks around black holes and CFL quark stars are also very similar. However, strange stars exhibit a low luminosity, but high temperature bremsstrahlung spectrum, which, in combination with the emission properties of the accretion disk, may be the key signature to differentiate massive strange stars from black hole.

[rstevenson]

$3.8M_{\odot}$

I'm sure that was meaningful when it was input by the original author in their original application, but for some reason arxiv outputs this sort of symbology instead. Perhaps they need to adjust the encoding of their web pages or some such. But in the meantime, can someone offer a translation?

Rob

[neufer]

$3.8M_{\odot}$

I'm sure that was meaningful when it was input by the original author in their original application, but for some reason arxiv outputs this sort of symbology instead. Perhaps they need to adjust the encoding of their web pages or some such. But in the meantime, can someone offer a translation?

Almost all stellar mass black holes are measured in solar masses.

[rstevenson]

$3.8M_{\odot}$

I'm sure that was meaningful when it was input by the original author in their original application, but for some reason arxiv outputs this sort of symbology instead. Perhaps they need to adjust the encoding of their web pages or some such. But in the meantime, can someone offer a translation?

Almost all stellar mass black holes are measured in solar masses.

Hi Art,
I'm seeing a string set off by dollar signs at each end, with, inside these, 3.8M and an underscore, then a pair of curly braces with, inside them, a foreslash followed by 'odot'. I guess I'm assuming these are control codes or some such and that I should be seeing something else. But maybe not. Maybe that's the way it should look, in which case I need to go do some reading.

Rob

[harry]

G'day from the land of ozzzzz

I reposted the ABS from the paper. It refers to Sun mass ratio.

ABSTRACT
We investigate the possibility that stellar mass black holes, with masses in
the range of 3.8M⊙ and 6M⊙, respectively, could be in fact quark stars in
the Color-Flavor-Locked (CFL) phase. Depending on the value of the gap parameter,
rapidly rotating CFL quark stars can achieve much higher masses
than standard neutron stars, thus making them possible stellar mass black
hole candidates. Moreover, quark stars have a very low luminosity and a completely
absorbing surface - the infalling matter on the surface of the quark
star is converted into quark matter. A possibility of distinguishing CFL quark
stars from stellar mass black holes could be through the study of thin accretion
disks around rapidly rotating quark stars and Kerr type black holes,
respectively. Furthermore, we show that the radiation properties of accretion
disks around black holes and CFL quark stars are also very similar. However,
strange stars exhibit a low luminosity, but high temperature bremsstrahlung
spectrum, which, in combination with the emission properties of the accretion
disk, may be the key signature to differentiate massive strange stars from
black hole.

[rstevenson]

Ah! There it is. Thanks Harry.

Let's see what happens when I copy and paste it... 3.8M⊙ and 6M⊙

Nice.

I just checked the web page at arxiv and here. This forum uses UTF8 encoding on the pages, and arxiv has no encoding specified. I'll bet that's why the odot symbol is coming across as code.

Rob

[harry]

G'day from the land of ozzzz

Don't forget to dot the "i" and cross the "T".

Thats a joke from down under. We know that the people from the North do not joke,,,,,,,,,,,,,smile.

[Chris Peterson]

Let's see what happens when I copy and paste it... 3.8M⊙ and 6M⊙

Nice.

Well, not really. What you've done is included an invalid HTML character, which means that different people will see different things, depending on this site's encoding and their browser capabilities. It works because that's a standard Unicode character, and most browsers will interpret it as such. But it isn't technically legal HTML being generated.

No browser will correctly interpret the code as seen in the abstract, because it is LaTeX markup, not any sort of HTML. There might be browser plugins, but that will definitely be an uncommon setup. The problem is how arxiv handles constructing the abstracts. What it ought to be doing is recognizing the original was submitted in LaTex format, and running the abstract through a converter to produce legal HTML (in this case, escaped Unicode, or possibly the ⊙ escape with the right document encoding).

[harry]

G'day

Well there you go.

We learn something everyday.

[astrolabe]

Hello neufer,

Space-time, itself, is constantly cascading into a black hole.

Agreed.

A black hole is the antithesis of a state of rest.

Not agreed, not fact. Simply because all opinions beyond the event horizon, no matter how learned, are open and subject to debate- mine included!