Speaker
Description
Pulsar timing arrays have detected a nanohertz gravitational-wave
background, most naturally associated with supermassive black hole
binaries. The low-frequency shape of this signal may also probe the
environments in which those binaries evolve, including possible
interactions with ultralight dark matter. I will discuss recent work
using PTA data to test this possibility, focusing on predictive model
comparison. An earlier analysis found that a ULDM interpretation of the
low-frequency suppression can prefer particle masses and dark-matter
fractions compatible with existing constraints, motivating a closer
comparison with non-ULDM explanations. In the current work, we compare
simplified and realistic ultralight-dark-matter implementations with
phenomenological environmental and gravitational-wave-only models using
leave-one-out cross-validation. Current PTA data are compatible with
ultralight-dark-matter-induced suppression, but do not yet decisively
prefer it over more generic environmental descriptions of supermassive
black hole binary evolution.
| Research Area | Dark Matter: theory |
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