I would like some help with trying to understand just what it means when we say that even the largest of black holes will decay in around ten to the hundredth years or so. What I'm trying to wrap my mind around is this. At this rate of decay how much time does it take the black hole to lose one gram of mass or how much mass does such a black whole lose per year to this process?

This section of the wikipedia article on Hawking Radiation gives the forumla. Not sure if it's much help (and I know I can't decode it for you heh).

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Using E = mc^2, mass loss = 10^(-44) kg/sec = 10^(-41) gm/s => mass-loss = +/- 10^(35) years-per-gram That's 100,000,000,000,000,000,000,000,000,000,000,000 years to lose one gram!

So a black hole will not last "forever," but evaporation occurs extremely slowly

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For the record, a black hole can't even begin to evaporate until the CMB drops below the "temperature" of the event horizon, which for a stellar-mass object won't be for billions, if not trillions of years more.

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The theoretical Hawking radiation emitted (power) by a black hole is inversely proportional to the black hole’s mass. The energy emitted by a one solar mass black hole is (using the theoretical Hawking formula) 10^-69 Watt.

A black hole of one solar mass, in a theoretical universe in which there was no radiation would “evaporate” in roughly 10^67 years which is essentially eternal as compared to the BBT estimated universe age of 14x10^9.

A black hole 10^-15 x Solar mass (or equivalently 2*10^15 kg) will theoretically emit roughly 100 Watts.

Comments:
1. Black holes formed by the collapse of individual stars range from a lower theoretical limit of 1.3 to 3 solar masses up to a maximum theoretical limit of around 10 solar masses.

2. So, all black holes formed by stellar collapse since the beginning of the universe, should be observable.

Hello All

William said


The inward vector forces are so extreme: that makes black holes get bigger rather than evaporate. So the question is how does the black holes release matter. By jets created by the internal properties of plasma. These jets eject matter 1000's of light years into space reforming the galaxies. In smaller compacted matter such as Neutron, quarks and normal stars a similar jet is created internally by the compacted matter.( google "Jet is a Jet"). The main strema thought is that the jets are created by the infalling matter. In my opinion this cannot create a jet with enough drive to send it 1000's of light years into space without being pulled back by the black hole.


How do you know that?

Comments:
I agree with you, but ! where did you get the 10 max solar mass.

If you assume the Big Bang is correct than you maybe correct.


We know that out there, the processes are very complax and not idle. We have star collsions, starformation, star rejuvination, black holes forming and black holes merging within the envelope of the galaxy, we have galaxies colliding, two, three, four and so on at the same time.

So the chances of seeing and original star formed black hole is going to be rear to say the least.

The process within a sprial galaxy such as the MW is that stars and black holes will do their thing time and time again and as they move towards the centre of the galaxy they will merge and form larger black holes. Near the centre of the MW we notice a SWARM of black holes and a large one several million times that of our sun.

The dating process is altered every time a star goes though a phase of supernova or rejuvination.

Sorry but this is misnomer.

SMBH's do NOT release any Matter. Once anything goes past the Event Horizon it cannot come back out through the event horizon in ANY form. (They do however, IMHO, release Non-Baryonic/Exotic Matter from the 'Other End'

The dynamics of the accretion disc is where the 'jets' are formed and are jetted perpendicular to the surface of the accretion disc. That is an accumulation of already created matter.

The question then becomes...is there high enough Gamma Radiation Energy to be able to create NEW electron/proton baryon Matter?

Whether that happens or not seems to be immaterial, as ALL of that 'jetted material' is sent out into the Extra-galactic medium as very hot gas where stars do not seem to be able to form from it.

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According to Edward Harrison, in his book Cosmology: the Science of the Universe (Cambridge University Press, 2nd Ed., 2000, P. 262) the lifetime of a black hole against Hawking radiation is t = M³x10⁶² years, where t is the lifetime and M is the black hole mass, in units of solar masses. I trust Harrison as a source, but I have seen others make the numerical factor as high as 10⁶⁶, so there must be something subjective about the calculation. The effective temperature looks like T = 10^-7M^-1 Kelvins, where the mass is once again in solar masses (same source). So a one solar mass black hole will last about 10⁶² years, as long as it does not absorb any mass for the entire 10⁶² years. That's hardly likely for any real black hole, where a dust grain per century should be about enough to offset the energy lost.

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The lifetime of a stellar produced black hole is essentially eternal, based on the standard cosmological model. i.e. Black holes of 1.3 solar mass or larger do not "evaporate". A black hole could possibly merge with another black hole, however, the "black hole" material is essentially eternal.

"A black hole 10^-15 x Solar mass (or equivalently 2*10^15 kg) will theoretically emit roughly 100 Watts."
The following is a link to Wikipedia article, which includes an equation for non-rotating, uncharged black holes. See paragraph “Black Hole Evaporation”. If 10^-15 solar mass is entered into the “evaporation equation”, the resultant is 89 Watts.

http://en.wikipedia.org/wiki/Hawking_radiation

As noted in the Wikipedia article there is neither laboratory nor astronomical observational evidence, to prove or disprove the existence of Hawking radiation, however, I believe there is general theoretical agreement that stellar formed black holes (which are no smaller than 1.3 solar masses) are essentially eternal. (i.e. The Hawking radiation from a one solar mass black hole is very, very, small and will not in any practical manner change the black hole.)

From the Wikipedia article:


"1. Black holes formed by the collapse of individual stars range from a lower theoretical limit of 1.3 to 3 solar masses up to a maximum theoretical limit of around 10 solar masses." I am not sure if there is firm observational evidence that confirms the relationship to stellar mass and the black hole produced, from the stellar explosion. Perhaps observational evidence will come but at a price.

Attached is a link to the “near” earth star (7,500 light years), “Eta Carinea”, that is approximately 100 to 150 solar masses and that is at the end of its life.

http://chandra.harvard.edu/photo/2007/etacar/

Hello All

RussT said

What you say is main stream thought. It maybe correct.

The big bang did not originate from one spot but uniformly throughout. The process would have occured via a process of releasing subatomic matter. Not that I agree with the Big Bang theory.

The option of the plasma within the compacted cores such as black holes creating a vortex within the plasma is an option we cannot close our eyes to.
To do so is to entrap us in a line of thought.

BOZO, please be aware of Rule 13:I'm not accusing you of "hijacking", just suggesting that if you were to run any further with the above on this thread, you might run into a Rule 13 conflict.

Grant Hutchison

The following is a link to a paper by Andreas Müller, “Black Holes:Observations & Evidence”

(Blob’s link to this paper in the BH FAQ questions does not work.)

http://arxiv.org/pdf/astro-ph/0701228

The paper provides a summary of current BH theory and observations related to astronomical phenomena including AGN (active galactic nuclei), that are directly associated with black holes. It seems to be a good review paper.

Andreas’ paper supports the statement that stellar produced black holes are essentially eternal.

Comment:
A 10^15g (10^-18 Solar mass) black hole would theoretically emit (assuming Hawking Radiation is real) roughly 4x10^8 Watts, which should be observable.

Hello All

I think I have been read out of context. At the present moment I'm discussing this with some cosmologists.

I have read the above link before and I will read it again and again.

I'll be back.

This in follow-up to my comment #9 on Eta Carinae which is at the end of its short cycle and may collapse to a BH.

Eta Carinae: Another picture and discussion.

http://www.badastronomy.com/bablog/2...ock-tick-tock/


If the stellar to BH theoretical process is correct, Eta Carinae will, as it is over 100 solar mass, go straight to a black hole, without the supernova explosion, except..(see comment).

From C. Fry’s paper: “Mass Limits for Black Hole Formation”


http://arxiv.org/pdf/astro-ph/9902315


Comments;
For some reason, there is discussion of Eta Carinae being a possible hypernova. Not sure what a hypernova is. Perhaps the gamma burst is due to the very rapid stellar rotation? Might be a subject for a new thread if there is new information.


The following is a simplified method of identifying black holes.

http://www.sciencecartoonsplus.com/galastro2.htm#

Wikipedia: Hypernova

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In reply to 01101001's comment.

I think hypernova are different from supernova. Would the term hypernova apply to SN 2006GY? SN 2006GY, I believe was a type II super nova, that should have by theory have collapsed to a BH. It is interesting that it did not, and that it was very, very luminous.

1) From a practical standpoint could Eta Carinae suffer the same fate and is 7500 light years, sufficient distance?
2) From a perspective of stellar evolution in the early universe, is SN 2006GY the norm, rather than the exception?
3) There was also some discussion in another thread concerning standard candles, which is a separate subject.

http://arxiv.org/pdf/astro-ph/0612617

SN 2006GY: Discovery of the most luminous SUPERNOVA EVER RECORDED, POWERED BY THE DEATH OF AN EXTREMELY MASSIVE STAR LIKE ETA CARINAE

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Right.

But since there is no known mechanism to produce BHs of such low mass, they must be "primordial," and in the 14 byr since the Big Bang, wouldn't all such holes have evaporated long ago?

I'm not sure of the math, but my impression is, if the Hawking temperature is above the CMB background temperature, the radiation would decrease its mass "relatively" quickly, which would further increase its temperature, leading to a gradual run away snow-ball effect.

As I recall, these would go out in a final blaze of glory, but all such events--if they ever did occur--should have happened long and far away?

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