Kavli Affiliate: Risa H. Wechsler
| First 5 Authors: Noah Glennon, Nathan Musoke, Ethan O. Nadler, Chanda Prescod-Weinstein, Risa H. Wechsler
| Summary:
We explore how dynamical friction in an ultralight dark matter (ULDM)
background is affected by dark matter self-interactions. We calculate the force
of dynamical friction on a point mass moving through a uniform ULDM background
with self-interactions, finding that the force of dynamical friction vanishes
for sufficiently strong repulsive self-interactions. Using the pseudospectral
solver $texttt{UltraDark.jl}$, we show with simulations that reasonable values
of the ULDM self-interaction strength and particle mass cause $mathcal{O}(1)$
differences in the acceleration of an object like a supermassive black hole
(SMBH) traveling near the center of a soliton, relative to the case with no
self-interactions. For example, repulsive self-interactions with $lambda =
10^{-90}$ yield a deceleration due to dynamical friction $approx70%$ smaller
than a model with no self-interactions. We discuss the observational
implications of our results for SMBHs near soliton centers and for massive
satellite galaxies falling into ultralight axion halos and show that outcomes
are dependent on whether a self-interaction is present or not.
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