What really are exotic supersymmetric black holes?

Question

I have just read (in the black holes chapter 14 on p244 of this book Ref.1) that in string theory, when one adds an (electric?) charge $Q$ to a static black hole, one can arrive at an exotic supersymmetric black hole. This sentence is not explained further and there are several (I think related enough) things I dont understand about it, which can be summerized under the question what really is an exotic suppersymmetric black hole?

First, how exactly does the addition of a charge (if it is not outright a supercharge) lead to supersymmetry?

Second, what is meant by an exotic black hole, conversely to for example an extremal black hole that has just the maximum charge allowed given its mass?

Third, what does it mean for a black hole to be supersymmetric anyway?

References:

1. D. McMohan, String Theory Demystified, McGraw-Hill, 2009

Comments

Can you provide a link to or quote the source? Context may help.

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Brandon Enright

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@BrandonEnright ok, I have even found a PDF of the book and put it into the question.

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Dilaton

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@Dilaton: It is best to supply title, author, etc, of link, so we can reconstruct the link in case of future link rot.

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Qmechanic

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@Dilaton I've heard that extremal black holes are solitonic solutions of supergravity, preserving some degree supersymmetry. I myself do not understand what it means, but I know it is important.

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Prathyush

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Dear Dilaton, the adjective "exotic" in front of a black hole isn't a technical term with a particular meaning. It just means that, subjectively to the author, the black hole is unusual for the author of the sentence, usually because she is used to Schwarzschild-like neutral black holes from the undergrad courses. At any rate, there exists a maximum Q given a fixed mass for which the black hole is "extremal" and such black holes often preserve a part of the supersymmetry (if it was there to start with), have infinite throats near the event horizon, and other qualitative differences from neutr.

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Luboš Motl

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Thanks Lumo, darn I really thought that exotic is a technical term. David McMohan bazinga me :-D. Maybe I should complain the next time he appears on TRF. What an extremal black hole is I have understood now I think, but the notion of a black hole to be (or to preserve) supersymmetric still confuses me, even though I know a but what it means for a Lagrangian to be supersymmetric etc ... I mean how should the presence of a black hole break supersymmetry if it is not such an extremal one? Hoping my confusion provokes an answer I can visibly appreciate by upvote :-P

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Dilaton

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There are exotic spheres, exotic differential structures in maths etc. but these things aren't really too exotic. ;-)

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Luboš Motl

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@LubošMotl yep, David McMohan that rascal (!) really bazingaed me about this :-P. Do you have an answer to the rest ;-)?

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Dilaton

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The link is dead already.....

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Dimensio1n0

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@dimension10 ah I see, that was a link to a PDF. I now added in a more stable link to amazone.

This post imported from StackExchange Physics at 2014-03-09 16:18 (UCT), posted by SE-user Dilaton