The EDGES 21 cm anomaly and properties of dark matter

Constraining dark matter through 21 cm observations

Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21 cm line signal. If dark matter (DM) decays or annihilates the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21 cm signal can then be used to constrain the proposed DM cand...

The imprint of warm dark matter on the cosmological 21-cm signal

We investigate the effects of warm dark matter (WDM) on the cosmic 21-cm signal. If dark matter exists as WDM instead of cold dark matter (CDM), its non-negligible velocities can inhibit the formation of low-mass haloes that normally form first in CDM models, therefore delaying star formation. The absence of early sources delays the build-up of UV and X-ray backgrounds that affect the 21-cm rad...

Decaying Dark Matter and the PAMELA Anomaly

Astrophysical and cosmological observations do not require the dark matter particles to be absolutely stable. If they are indeed unstable, their decay into positrons might occur at a sufficiently large rate to allow the indirect detection of dark matter through an anomalous contribution to the cosmic positron flux. In this paper we discuss the implications of the excess in the positron fraction...

CMB and 21-cm signals for dark matter with a long-lived excited state

White Noise from Dark Matter: 21 cm Observations of Early Baryon Collapse

In concordance cosmology, dark matter density perturbations generated by inflation lead to nonlinear, virialized minihalos, into which baryons collapse at redshift z ∼ 20. We survey here novel baryon evolution produced by a modification of the power spectrum from white noise density perturbations at scales below k ∼ 10h Mpc (the smallest scales currently measured with the Lyman-α forest). Exoti...