http://arxiv.org/abs/2209.02741
Pulsar timing arrays (PTAs) are sensitive to oscillations in the gravitational potential along the line-of-sight due to ultralight particle pressure. We calculate the probing power of PTAs for ultralight bosons across all frequencies, from those larger than the inverse observation time to those smaller than the inverse distance to the pulsar. We show that since the signal amplitude grows faster compared to the degradation in PTA sensitivity at frequencies smaller than inverse observation time, the discovery potential can be extended towards lower masses by over three decades, maintaining high precision. We demonstrate that existing 15-year PTA data can robustly detect or rule out an ultralight component in the mass range $10^{-26}!-!10^{-23}\,{\rm eV}$ with fraction down to percent level of the total dark matter. Non-detection, together with other bounds in different mass regimes, will imply that ultralight scalar/axion can comprise at most $1-10\%$ of dark matter in the $10^{-30}!-!10^{-17}$ eV regime. With 30 years of observation, current PTAs can extend the reach down to $0.1 \%$, while next-generation PTAs such as SKA can probe the $0.01\%$ level. We also generalize the analysis and derive predictions for probing ultralight vector (i.e. dark photon) and spin-2 dark matter components.
C. Unal, F. Urban and E. Kovetz
Thu, 8 Sep 22
61/77
Comments: 6 pages, 3 figures, comments welcome
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