Dark catalysis

Abstract

Abstract.Recently it was shown that dark matter with mass of order the weak scale can be charged under a new long-range force, decoupled from the Standard Model, with only weak constraints from early Universe cosmology. Here we consider the implications of an additional charged particle C that is light enough to lead to significant dissipative dynamics on galactic times scales. We highlight several novel features of this model, which can be relevant even when the C particle constitutes only a small fraction of the number density (and energy density). We assume a small asymmetric abundance of the C particle whose charge is compensated by a heavy X particle so that the relic abundance of dark matter consists mostly of symmetric X andX, with a small asymmetric component made up of X and C. As the universe cools, it undergoes asymmetric recombination binding the free Cs into (XC) dark atoms efficiently. Even with a tiny asymmetric component, the presence of C particles catalyzes tight coupling between the heavy dark matter X and the dark photon plasma that can lead to a significant suppression of the matter power spectrum on small scales and lead to some of the strongest bounds on such dark matter theories. We find a viable parameter space where structure formation constraints are satisfied and significant dissipative dynamics can occur in galactic haloes but show a large region is excluded. Our model shows that subdominant components in the dark sector can dramatically affect structure formation.

Make dark matter charged again

“…In a companion paper [61], we consider the case where in addition to the weak-scale X dark matter particle, there is a light dissipative component which can lead to a dark matter disk. Unlike the previous study [34,35] where the halo comprised of a separate CDM species, all of dark matter would be composed of charged components.…”

“…It is also of interest for DoubleDisk dark matter Ref. [61] as it opens the possibility of all dark matter being charged while allowing a dark matter disk. We also suggest interesting implications for charged dark matter that have not yet been investigated, including using the radial dependence of ellipticity to disentangle the impact of velocity anisotropies from that of anisotropic potentials, and the modification of the dwarf galaxy populations in both mass and internal structure, with important consequences for small-scale issues [62][63][64][65].…”

Signatures of mirror stars

“…Understanding the possible signatures of Dark Complexity is therefore an important and timely challenge. There has been significant progress along these lines in recent years; for instance models of DM featuring additional interactions or a small number of states [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Although these approaches capture some of the possibilities of Dark Complexity, their relative simplicity still limits the range of phenomena that can be explored.…”

“…where the cooling rate dP brems dV (which is a function of the density) will be defined in Section 5, and we can take T star to be the stellar core temperature as an overestimate of the cooling timescale 4 . We can compare this to the evaporation timescale 21) where N is the toal number of captured particles. We find that for all the benchmark stars where mirror capture is important compared to self-capture, this cooling timescale is a few orders of magnitude larger than the evaporation timescale, meaning that captured matter cools faster than it can evaporate.…”

Accretion of dissipative dark matter onto active galactic nuclei

“…For simplicity, we also neglect the possibility of kinetic mixing between the hidden vector and the SM photon. Numerous studies of this sort of hidden sector have been presented in the literature [38,39,41,43,44,68,[90][91][92][93][94][95][96][97][98][99][100][101][102][103]. As will be shown below, additional (possibly short-range) interactions between the hidden proton and electron may be necessary in order for the cooling process to be efficient.…”