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DTSTAMP:20260814T113655Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20110131T173000Z
DTEND:20110131T183000Z
UID:event756@bu.edu
URL:http://physics.bu.edu/internal/events/show/756
SUMMARY:Exploring the String Axiverse with Astrophysical Black Holes
DESCRIPTION:Featuring Sergei Dubovsky\, NYU\n\nPart of the HET Seminar Seri
	es.\n\nAbstract:\nRecent advances in X-ray astronomy open the possibility f
	or high precision spin and mass determination for astrophysical black holes
	 starting the era of precision black hole physics.  These observations turn
	 astrophysical black holes into sensitive probes of ultra-light axion-like 
	particles motivated by the strong CP problem and string theory (the ``Axive
	rse").  When the axion Compton wavelength matches the black hole size\, the
	 axions develop superradiant atomic bound states around the black hole "nuc
	leus" through the Penrose superradiance process. This results in mass gaps 
	in the spectrum of rapidly rotating black holes\, gives rise to distinctive
	 gravity wave signals\, and modifies the near horizon metric. In particular
	\, the QCD axion with a decay constant of order of the Grand Unification sc
	ale affects the dynamics of stellar mass black holes. This opens the possib
	ility for the discovery of the QCD axion through ongoing measurements of bl
	ack hole spins.  The corresponding gravity wave signal may be within reach 
	of Advanced LIGO. Axions coupled to hidden gauge sectors--;-hidden valleys-
	-;-may trigger the avalanche instability in these sectors in the presence o
	f a black hole.  Electromagnetic echoes of hidden valley avalanches would b
	e observed as an exotic class of gamma ray bursts.
LOCATION:PRB 595\, 3 Cummington Mall\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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