Wobbly Dark Matter Signals at Cherenkov Telescopes from Long-Lived Mediator Decays

Abstract

Imaging Atmospheric Cherenkov Telescope (IACT) searches for dark matter often perform observations in "wobble mode", i.e. collecting data from the signal region and from a corresponding background control region at the same time, enabling efficient simultaneous determination and subtraction of background. This observation strategy is possibly compromised in scenarios where dark matter annihilates to long-lived mediators that can traverse astrophysical distances before decaying to produce the gamma rays observed by the IACTs. In this paper, we show that this challenge comes with several interesting features and opportunities: in addition to signal contamination in the background control region, the gamma-ray spectrum changes with the observing direction angle and typically exhibits a hard excess at high energies. This affects signal reconstruction via subtraction of the background control region measurements in non-trivial ways. Such features represent a significant departure from the canonical picture, and offer novel handles to identify a dark matter signal and to extract underlying dark matter parameters. arXiv:1812.08694v1 [astro-ph.HE]

Bouncing Dark Matter

“…The indirect detection signatures from such cascade processes in dark sectors have been discussed in various papers, see e.g. [30][31][32][33][34][35]. The most interesting phenomenological aspect of bouncing DM is that the associated cross sections can be significantly larger than σv canonical .…”

Loop dominated signals from neutrino portal dark matter

“…2 Scenarios where sterile neutrinos are light enough to be produced directly in dark matter annihilation or decay can also produce interesting dark matter signatures (see e.g. [6,25,[29][30][31]), but we do not consider such scenarios in this paper.…”

“…The exact number of heavy sterile neutrinos is irrelevant for our discussions; hence, we leave it unspecified.2 Scenarios where sterile neutrinos are light enough to be produced directly in dark matter annihilation or decay can also produce interesting dark matter signatures (see, e.g., Refs [6,27,[31][32][33]…”

Vector self-interacting dark matter

“…It is sufficient to note that for the range of dark photon masses of interest there is always a sufficiently small ε (large Λ) such that the basic phenomenology is valid. In the small mixing limit, mediators are very long lived and may be targets for recently proposed indirect detection techniques [76][77][78][79] To demonstrate the phenomenology of kinetic mixing, we examine the bounds on our scenario coming from direct detection experiments. The W -nucleon (N ) scattering amplitude, iM N , is…”