Impact of Cosmic-Ray Physics on Dark Matter Indirect Searches

Abstract

The quest for the elusive dark matter (DM) that permeates the Universe (and in general the search for signatures of physics beyond the Standard Model at astronomical scales) provides a unique opportunity and a tough challenge to the high energy astrophysics community. In particular, the so-called DMindirect searches—mostly focused on a class of theoretically well-motivated DM candidates such as the weakly interacting massive particles—are affected by a complex astrophysical background of cosmic radiation. The understanding and modeling of such background require a deep comprehension of an intricate classical plasma physics problem, i.e., the interaction between high energy charged particles, accelerated in peculiar astrophysical environments, and magnetohydrodynamic turbulence in the interstellar medium of our galaxy. In this review we highlight several aspects of this exciting interplay between the most recent claims of DM annihilation/decay signatures from the sky and the galactic cosmic-ray research field. Our purpose is to further stimulate the debate about viable astrophysical explanations, discussing possible directions that would help breaking degeneracy patterns in the interpretation of current data. We eventually aim to emphasize how a deep knowledge on the physics of CR transport is therefore required to tackle the DM indirect search program at present and in the forthcoming years.

Features in cosmic-ray lepton data unveil the properties of nearby cosmic accelerators

“…Even though alternative CR propagation scenarios may be invoked to account for the unexpected production of positrons [51], as well as interpretations based on dark matter annihilation (see for instance the recent review [52] and references therein), lepton pair emission from pulsar wind nebulae seems to be a more natural candidate. We will assess their contribution in the next paragraph.…”

New Physics of Strong Interaction and Dark Universe

“…Photons, charged leptons and neutrinos can be considered as the most important carriers of such information; their spectra are measured by space detectors and telescopes with ever increasing accuracy and completeness. Obviously, due to lack of hopeful results from collider experiments, our constant efforts to study the DM characteristics in the recent time inevitably reduce to different ideas and suggestions on indirect searches of DM manifestations in astrophysical data [82][83][84][85][86][87][88].…”

Exploring a cosmic-ray origin of the multiwavelength emission in M31

“…Noting that for the heavier cosmic-ray protons the radiative energy losses of equation (8) are unimportant, we can consider only the propagation of the CRp by diffusion. The steady-state distribution of cosmic-ray protons has a characteristic diffusion timescale of t D (E) ≈ r 2 h /D(E) [36,[110][111][112][113], which gives us an injection source term n CRp (E)/t D (E). We then have for the power injected into CRp:…”