PIRSA:14100049  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Discovering the QCD Axion with Black Holes and Gravitational Waves
Speaker(s): Masha Baryakhtar
Abstract: In the next few years, Advanced LIGO will be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant around or above the GUT scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom". Due to superradiance, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. I will discuss the promising gravitational wave signals from axions transitioning between levels of the gravitational atom and axions annihilating to gravitons. Events for axions in the range 10^−13 to 10^−10 eV can be visible at aLIGO. The signals produced are long-lasting, monochromatic, and can be distinguished from ordinary astrophysical sources. These signatures are also promising for lighter axions at future, lower-frequency, GW observatories. I will also present our updated exclusion on the QCD axion mass range of 6*10^−13 eV < ma < 1.5*10^−11 eV imposed by black hole spin measurements.
Date: 28/10/2014 - 1:00 pm
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