We present new cosmological hydrodynamic simulations that incorporate Dark Matter Annihilation Feedback ( DMAF ) , whereby energy released from the annihilation of dark matter particles through decay channels such as photon or positron-electron pairs provide additional heating sources for local baryonic material .
For annihilation rates comparable to WIMP-like particles , we find that the key influence of DMAF is to inhibit gas accretion onto halos .
Such diminished gas accretion early in the lifetimes of halos results in reduced gas fractions in smaller halos , and the delayed halo formation times of larger structures , suggesting that DMAF could impact the stellar age distribution in galaxies , and morphology of dwarfs .
For a dark matter particle mass of m _ { \chi } \sim 10 MeV , there is a ‘ critical halo mass ’ of \sim 10 ^ { 13 } M _ { \odot } at z = 0 , below which there are large differences when compared to \Lambda CDM , such as a reduction in the abundance of halo structures as large as 25 percent , reduced gas content by 50 percent and central gas densities reduced down to 10 percent within halos of mass \sim 10 ^ { 12 } M _ { \odot } but with increasing effects in smaller halos .
Higher dark matter particle mass models have a smaller ‘ critical halo mass ’ .
For a m _ { \chi } \sim 100 MeV model , we find differences start appearing below halo masses of \sim 10 ^ { 12 } M _ { \odot } and a m _ { \chi } \gtrsim 1 GeV model , this mass scale lies below the resolution of our simulations , though we still observe changes in the morphology of dwarf galaxies .