Evidence has been mounting that cosmic acceleration behaves as if simply due to a constant of nature Lambda, a small intrinsic curvature term (reciprocal area) which appears naturally in the Einstein equation.(adsbygoogle = window.adsbygoogle || []).push({});

For more about this, google "prejudices against constant" and have a look at the top hit:

http://arxiv.org/abs/1002.3966

Why all these prejudices against a constant?

However in extreme circumstances some physical constants appear to "run"--that is change with radically increasing energy or decreasing scale. One approach to quantum gravity, the Asymptotic Safety approach, suggests that Lambda may increase with increasing energy, or energy density.

So what would happen to black holes if you could increase Lambda? Intuitively they should lose mass, dwindle down to nothing. Can we get a handle on this?

Here's a paper that was published inPhysical Review Lettersin 2004:

http://prl.aps.org/abstract/PRL/v93/i2/e021102

Their premise, namely "big rip" from "phantom dark energy" has gone somewhat out of style with researchers since it seems more and more likely that Lambda is just a curvature constant of nature (not some evolving "energy" field). But we can still look at their analysis and conclusions. Here is the preprint:

http://arxiv.org/pdf/gr-qc/0402089v3.pdf

I found another more recent paper along related lines. This time it is a 2010 paper by Maurice van Putten at the Uni Orléans:

http://arxiv.org/abs/1003.0604

Extended black hole cosmologies in de Sitter space

He derives a bound on BH mass which is proportional to the inverse square root of Lambda.

I haven't made a thorough search by any means.

It does seem that, as one would intuitively expect, as you increase Lambda it restricts what mass a BH can retain and black holes must eventually shrink.

An unbounded increase in Lambda (as when the fixed point is approached in Asymptotic Safety QG) would wipe out black holes.

Any comments?

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# Lambda as black hole buster

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