2015/12/31 by Eric Braaten, Abhishek Mohapatra, Hong Zhang · 1 citation
Physics and Astronomy · #hep-ph #astro-ph.CO
paper · pdf · doi:10.1103/physrevlett.117.121801
published as Phys. Rev. Lett. 117, 121801 (2016) · 5 pages, 2 figures, Added calculations of unstable branch of axion stars. Added discussion of possible ways to detect dense axion stars. Removed EFT calculations that were not essential for this paper
arxiv created 2016/09/16 · arxiv updated 2016/09/20
If the dark matter particles are axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound systems of axions. In the previously known solutions for axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. The mass of these dilute axion stars cannot exceed a critical mass, which is about 10-14 M_\odot if the axion mass is 10-4~eV. We study axion stars using a simple approximation to the effective potential of the nonrelativistic effective field theory for axions. We find a new branch of dense axion stars in which gravity is balanced by the mean-field pressure of the axion Bose-Einstein condensate. The mass on this branch ranges from about 10-20 M_\odot to about M_\odot. If a dilute axion star with the critical mass accretes additional axions and collapses, it could produce a bosenova, leaving a dense axion star as the remnant.