BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//RLASKEY//CALENDEROUS//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260918T121013Z
LAST-MODIFIED:20151125T143725Z
DTSTART:20151202T203000Z
DTEND:20151202T213000Z
UID:event1484@bu.edu
URL:http://physics.bu.edu/internal/events/show/1484
SUMMARY:Discovering the QCD Axion with Black Holes and Gravitational Waves
DESCRIPTION:Featuring Masha Baryakhtar\, Perimeter\n\nPart of the HET Semin
	ar Series.\n\nWhen a particle’s Compton wavelength is comparable to the h
	orizon size of a black hole\, the particle can bind to the black hole\, for
	ming a "gravitational atom." To form atoms with stellar black holes\, the p
	article must be ultralight\, with mass at or below 10^-11 eV. If such a par
	ticle exists\, the levels of the atom can be populated by extracting energy
	 and angular momentum from the black hole through a process known as black 
	hole superradiance; for bosons\, the occupation number of the levels grows 
	exponentially and the black hole spins down. One candidate for such an ultr
	alight boson is the QCD axion\, proposed to solve the strong-CP problem. Bl
	ack hole spin measurements result in new limits on the axion in the mass ra
	nge 6*10^−13 eV < ma < 2*10^−11 eV. In addition\, axions transitioning 
	between levels of the gravitational atom and annihilating to gravitons can 
	produce observable gravitational wave signals. These signals are coherent\,
	 monochromatic and last for many years. With its target sensitivity\, Advan
	ced LIGO has the chance to observe a transition event or thousands of annih
	ilation events from systems in the Milky Way.  With the help of black hole 
	superradiance\, Advanced LIGO could not only be the first experiment to obs
	erve gravitational waves\, but may discover the QCD axion in the process.
LOCATION:PRB 595\, 3 Cummington Mall\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
END:VCALENDAR