Exploring the string axiverse with precision black hole physics

Journal Article · Tue Feb 15 00:00:00 EST 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.83.044026· OSTI ID:21513100

Arvanitaki, Asimina ^[1]; Dubovsky, Sergei ^[2]

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1. Berkeley Center for Theoretical Physics, University of California, Berkeley, California, 94720 (United States)
2. Department of Physics, Stanford University, Stanford, California, 94305 (United States)

It has recently been suggested that the presence of a plenitude of light axions, an Axiverse, is evidence for the extra dimensions of string theory. We discuss the observational consequences of these axions on astrophysical black holes through the Penrose superradiance process. When an axion Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole ''nucleus'' forming a gravitational atom in the sky. The occupation number of superradiant atomic levels, fed by the energy and angular momentum of the black hole, grows exponentially. The black hole spins down and an axion Bose-Einstein condensate cloud forms around it. When the attractive axion self-interactions become stronger than the gravitational binding energy, the axion cloud collapses, a phenomenon known in condensed matter physics as 'bosenova'. The existence of axions is first diagnosed by gaps in the mass vs spin plot of astrophysical black holes. For young black holes the allowed values of spin are quantized, giving rise to ''Regge trajectories'' inside the gap region. The axion cloud can also be observed directly either through precision mapping of the near-horizon geometry or through gravitational waves coming from the bosenova explosion, as well as axion transitions and annihilations in the gravitational atom. Our estimates suggest that these signals are detectable in upcoming experiments, such as Advanced LIGO, AGIS, and LISA. Current black hole spin measurements imply an upper bound on the QCD axion decay constant of 2x10{sup 17} GeV, while Advanced LIGO can detect signals from a QCD axion cloud with a decay constant as low as the GUT scale. We finally discuss the possibility of observing the {gamma}-rays associated with the bosenova explosion and, perhaps, the radio waves from axion-to-photon conversion for the QCD axion.

• OSTI ID: 21513100
• Journal Information: Physical Review. D, Particles Fields, Vol. 83, Issue 4; Other Information: DOI: 10.1103/PhysRevD.83.044026; (c) 2011 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCURACY
ANNIHILATION
ASTROPHYSICS
AXIONS
BINDING ENERGY
BLACK HOLES
BOSE-EINSTEIN CONDENSATION
COMPTON WAVELENGTH
GAMMA RADIATION
GRAVITATIONAL WAVES
MASS
OCCUPATION NUMBER
PHOTONS
QUANTUM CHROMODYNAMICS
RADIOWAVE RADIATION
REGGE TRAJECTORIES
SPIN
STRING MODELS
STRING THEORY
SUPERRADIANCE
ANGULAR MOMENTUM
BOSONS
COMPOSITE MODELS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EMISSION
ENERGY
ENERGY-LEVEL TRANSITIONS
EXTENDED PARTICLE MODEL
FIELD THEORIES
GOLDSTONE BOSONS
INTERACTIONS
IONIZING RADIATIONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
M-THEORY
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PROPERTIES
PHOTON EMISSION
PHYSICS
POSTULATED PARTICLES
QUANTUM FIELD THEORY
QUARK MODEL
RADIATIONS
STIMULATED EMISSION