Dissipative dark matter explains rotation curves

Abstract

Dissipative dark matter, where dark matter particles interact with a massless (or very light) boson, is studied. Such dark matter can arise in simple hidden sector gauge models, including those featuring an unbroken U(1) ′ gauge symmetry, leading to a dark photon. Previous work has shown that such models can not only explain the LSS and CMB, but potentially also dark matter phenomena on small scales, such as the inferred cored structure of dark matter halos. In this picture, dark matter halos of disk galaxies not only cool via dissipative interactions but are also heated via ordinary supernovae (facilitated by an assumed photon -dark photon kinetic mixing interaction). This interaction between the dark matter halo and ordinary baryons, a very special feature of these types of models, plays a critical role in governing the physical properties of the dark matter halo. Here, we further study the implications of this type of dissipative dark matter for disk galaxies. Building on earlier work, we develop a simple formalism which aims to describe the effects of dissipative dark matter in a fairly model independent way. This formalism is then applied to generic disk galaxies. We also consider specific examples, including NGC 1560 and a sample of dwarf galaxies from the LITTLE THINGS survey. We find that dissipative dark matter, as developed here, does a fairly good job accounting for the rotation curves of the galaxies considered. Not only does dissipative dark matter explain the linear rise of the rotational velocity of dwarf galaxies at small radii, but it can also explain the observed wiggles in rotation curves which are known to be correlated with corresponding features in the disk gas distribution.

Dissipative dark matter and the rotation curves of dwarf galaxies

“…This improves upon previous work of [56] which used the gas density via a Kennicutt-Schmidt type relation. The resulting halo rotation curve then depends on only one parameter λ (assumed to be spatially independent as a zeroth order approximation) and tested against the full LITTLE THINGS sample of 26 dwarf galaxies.…”

“…These types of models are also consistent with other cosmological probes, such as δN ef f (BBN) and δN ef f (CMB) [63,41]. The small scale structure of dark matter, especially the dark matter distribution around galaxies, has been pursued in [39,64,65,66,67,41,42,56].…”

“…Such a scaling relation has in fact been observed to hold for spiral and irregular galaxies [32]. In addition to modelling Σ SN via an exponential disk, the previous paper [56] further considered modelling Σ SN in terms of the baryonic gas density via a Kennicutt-Schmidt type relation [57,58]. This allowed a connection between the supernovae distribution with current local properties of a given galaxy.…”

Producing a new fermion in coherent elastic neutrino-nucleus scattering: from neutrino mass to dark matter

“…This suggests that ∼ 25% of the energy budget would be carried away by χ. Given the astrophysical uncertainties associated to Supernova 1987A, exotic particles can carry away up to 50% of the total energy of the collapse [45,46]. This corresponds again roughly to a new cross section of similar magnitude as the SM one.…”

“…A detailed analysis of such a scenario is beyond the scope of this project as it would require a significant extension of the Boltzmann equations given in Eq. (46). In such extension, the late-time entropy injection would be avoided.…”