340 research outputs found
Prospects for indirect MeV Dark Matter detection with Gamma Rays in light of Cosmic Microwave Background Constraints
The self-annihilation of dark matter particles with mass in the MeV range can
produce gamma rays via prompt or secondary radiation. The annihilation rate for
such light dark matter particles is however tightly constrained by cosmic
microwave background (CMB) data. Here we explore the possibility of discovering
MeV dark matter annihilation with future MeV gamma-ray telescopes taking into
account the latest and future CMB constraints. We study the optimal energy
window as a function of the dominant annihilation final state. We consider both
the (conservative) case of the dwarf spheroidal galaxy Draco and the (more
optimistic) case of the Galactic center. We find that for certain channels,
including those with one or two monochromatic photon(s) and one or two neutral
pion(s), a detectable gamma-ray signal is possible for both targets under
consideration, and compatible with CMB constraints. For other annihilation
channels, however, including all leptonic annihilation channels and two charged
pions, CMB data rule out any significant signal of dark matter annihilation at
future MeV gamma-ray telescopes from dwarf galaxies, but possibly not for the
Galactic center.Comment: 10 pages, 6 figures, version to appear on PR
Gravitational lensing by wave dark matter halos
Wave Dark Matter (WaveDM) has recently gained attention as a viable candidate
to account for the dark matter content of the Universe. In this paper we
explore the extent to which dark matter halos in this model, and under what
conditions, are able to reproduce strong lensing systems. First, we
analytically explore the lensing properties of the model -- finding that a pure
WaveDM density profile, a soliton profile, produces a weaker lensing effect
than other similar cored profiles. Then we analyze models with a soliton
embedded in an NFW profile, as has been found in numerical simulations of
structure formation. We use a benchmark model with a boson mass of
, for which we see that there is a bi-modality in the
contribution of the external NFW part of the profile, and actually some of the
free parameters associated with it are not well constrained. We find that for
configurations with boson masses -- , a range of
masses preferred by dwarf galaxy kinematics, the soliton profile alone can fit
the data but its size is incompatible with the luminous extent of the lens
galaxies. Likewise, boson masses of the order of , which
would be consistent with Lyman- constraints and consist of more compact
soliton configurations, necessarily require the NFW part in order to reproduce
the observed Einstein radii. We then conclude that lens systems impose a
conservative lower bound and that the NFW envelope around the
soliton must be present to satisfy the observational requirements.Comment: 26 pages, 7 figures, Publishe
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