Simulating the Galactic population of axion clouds around stellar-origin black holes: Gravitational wave signals in the 10–100 kHz band
Creators
-
1.
Northwestern University
-
2.
California Institute of Technology
-
3.
University of California, Davis
Abstract
Ultralight scalar fields can experience runaway “superradiant” amplification near spinning black holes, resulting in a macroscopic “axion cloud,” which slowly dissipates via continuous monochromatic gravitational waves. For a particular range of boson masses, , an axion cloud will radiate in the 10–100 kHz band of the levitated sensor detector (LSD). Using fiducial models of the mass, spin, and age distributions of stellar-origin black holes, we simulate the present-day Milky Way population of these hypothetical objects. As a first step toward assessing the LSD’s sensitivity to the resultant ensemble of gravitational wave signals, we compute the corresponding signal-to-noise ratios which build up over a nominal integration time of , assuming the projected sensitivity of the 1 m LSD prototype currently under construction, as well as for future 10 m and 100 m concepts. For a 100 m cryogenic instrument, hundreds of resolvable signals could be expected if the boson mass is around , and this number diminishes with increasing up to . The much larger population of unresolved sources will produce a confusion foreground which could be detectable by a 10-m instrument if 𝜇 ∈ (3–4.5)×10⁻¹¹ eV or by a 100-m instrument if 𝜇 ∈ (3–6)×10⁻¹¹ eV.
Copyright and License
© 2024 American Physical Society.
Acknowledgement
We would like to thank Vedant Dhruv for making public his Mathematica notebook for scalar bound-states in Kerr. We also thank Timothy Kovachy for clarifying issues of numerical precision when using Mathematica’s root-finding routines and Richard Brito for several clarifying discussions on axion clouds and their gravitational-wave emission. J. S., A. G., and S. L. are supported by the W. M. Keck Foundation. A. G., G. W., and N. A. are supported in part by NSF grants PHY-2110524 and PHY-2111544, the Heising-Simons Foundation, the John Templeton Foundation, and ONR Grant No. N00014-18-1-2370. N. A. is partially supported by the CIERA Postdoctoral Fellowship from the Center for Interdisciplinary Exploration and Research in Astrophysics at Northwestern University and the University of California, Davis. S. L. is also supported by EPSRC International Quantum Technologies Network Grant No. EP/W02683X/1 and is grateful for EPSRC support through Standard Research Studentship (DTP) EP/R51312X/1. V. K. is supported by a CIFAR Senior Fellowship and through Northwestern University through the D. I. Linzer Distinguished University Professorship. A. L. is supported by the Fannie and John Hertz Foundation. This work used the Quest computing facility at Northwestern.
Data Availability
No data were created or analyzed beyond what is included in this article.
Files
PhysRevD.110.123025.pdf
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2409.03714 (arXiv)
Funding
- W. M. Keck Foundation
- National Science Foundation
- PHY-2110524
- National Science Foundation
- PHY-2111544
- Heising-Simons Foundation
- John Templeton Foundation
- Office of Naval Research
- N00014-18-1-2370
- Northwestern University
- University of California, Davis
- Engineering and Physical Sciences Research Council
- EP/W02683X/1
- Engineering and Physical Sciences Research Council
- EP/R51312X/1
- Hertz Foundation
Dates
- Accepted
-
2024-10-29
Caltech Custom Metadata
- Publication Status
- Published