Singularities in the Gravitational Capture of Dark Matter through Long-Range Interactions

Abstract

We re-examine the gravitational capture of dark matter (DM) through long-range interactions. We demonstrate that neglecting the thermal motion of target particles, which is often a good approximation for short-range capture, results in parametrically inaccurate results for long-range capture. When the particle mediating the scattering process has a mass that is small in comparison to the momentum transfer in scattering events, correctly incorporating the thermal motion of target particles results in a quadratic, rather than logarithmic, sensitivity to the mediator mass, which substantially enhances the capture rate. We quantitatively assess the impact of this finite temperature effect on the captured DM population in the Sun as a function of mediator mass. We find that capture of DM through light dark photons, as in e.g. mirror DM, can be powerfully enhanced, with self-capture attaining a geometric limit over much of parameter space. For visibly-decaying dark photons, thermal corrections are not large in the Sun, but may be important in understanding long-range DM capture in more massive bodies such as Population III stars. We additionally provide the first calculation of the long-range DM self-evaporation rate.

v2: version accepted for publication in JCAP; 30 pages, 5 figures

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Cited by in corpus (6)

• Evaporation Barrier for Dark Matter in Celestial Bodies
• Premature Black Hole Death of Population III Stars by Dark Matter
• The linear response theory approach to the sub-GeV dark matter in the Sun
• Sensitivity of WIMP bounds on the velocity distribution in the limit of a massless mediator
• Dark matter scattering in astrophysical media: collective effects
• A new probe of dark matter-baryon interactions in compact stellar systems