Cosmological constraints to dark matter with two- and many-body decays

Abstract

We present a study of cosmological implications of generic dark matter decays. We consider twobody and many-body decaying scenarios. In the two-body case the massive particle has a possibly relativistic kick velocity and thus possesses a dynamical equation of state. This has implications to the expansion history of the universe. We use recent observational data from the cosmic microwave background, baryon acoustic oscillations and supernovae Type Ia to obtain constraints on the lifetime of the dark matter particle. We find that for an energy splitting where more than 40% of the dark matter particle energy is transferred to massless, relativistic particles in the two-body case, or more than 50% in the many-body case, lifetimes less than the age of the universe are excluded at more than 95% confidence. When the energy splitting falls to 10% the lifetime is constrained to be more than roughly half the age.PACS numbers: 98.80.-k, 95.35.+d

Dynamical Dark Matter from thermal freeze-out

“…(4.6). Indeed, the behavior of w eff (t) is constrained [35,36] by a combination of CMB data [19,37]; observations of baryon acoustic oscillations in galaxies [38][39][40] and in the Lyman-α forest [41,42]; and measurements of the redshifts and luminosity distances of Type-Ia supernovae [43]. Moreover, modifications to the expansion rate of the universe can also affect the light-element abundances generated during the BBN epoch.…”

Dark matter with two- and many-body decays and supernovae type Ia

“…On the other hand our results rely only on comparisons to supernovae while the other plotted results were compared against other, and in many cases, several other data sets. It would therefore be of interest to implement the derived two-body and many-body decay scenarios to a multitude of cosmological probes [58], as well as generic particle physics models (e.g., dynamical dark matter [59,60]). …”

Constraining dark-matter ensembles with supernova data

“…For example, baryon acoustic oscillations and the properties of the CMB both provide information about the expansion history of the universe. These considerations have been used to constrain darkmatter decays within single-component dark-matter scenarios [27], and it would be interesting to examine the extent to which these complementary probes of the expansion history at different redshifts constrain the parameter space of DDM ensembles as well. In addition, decays within the dark sector can also give rise to characteristic features within the matter power spectrum which can yield information about the structure of the decaying ensemble [34].…”

“…In particular, we investigate how information about the expansion rate of the universe at low redshifts gleaned from the relationship between the redshifts and luminosity distances of Type Ia supernovae can be used to constrain DDM ensembles which decay primarily to other, lighter states within the dark sector which act as dark radiation. This technique for constraining decays within the dark sector, which has previously been applied to scenarios involving a single unstable particle species [26,27], is particularly relevant for constraining scenarios within the DDM framework.…”