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Les Houches Lectures on Indirect Detection of Dark Matter

by Tracy R. Slatyer

This Submission thread is now published as

Submission summary

Authors (as registered SciPost users): Tracy Slatyer
Submission information
Preprint Link: https://arxiv.org/abs/2109.02696v3  (pdf)
Date accepted: 2022-01-13
Date submitted: 2022-01-06 05:48
Submitted by: Slatyer, Tracy
Submitted to: SciPost Physics Lecture Notes
Ontological classification
Academic field: Physics
Specialties:
  • Gravitation, Cosmology and Astroparticle Physics
  • High-Energy Physics - Phenomenology
Approaches: Theoretical, Phenomenological

Abstract

These lectures, presented at the 2021 Les Houches Summer School on Dark Matter, provide an introduction to key methods and tools of indirect dark matter searches, as well as a status report on the field circa summer 2021. Topics covered include the possible effects of energy injection from dark matter on the early universe, methods to calculate both the expected energy distribution and spatial distribution of particles produced by dark matter interactions, an outline of theoretical models that predict diverse signals in indirect detection, and a discussion of current constraints and some claimed anomalies. These notes are intended as an introduction to indirect dark matter searches for graduate students, focusing primarily on intuition-building estimates and useful concepts and tools.

Author comments upon resubmission

I thank all three referees for their helpful remarks. Changes made in response to referee 2 and 3’s comments are given below.

List of changes

-At referee 2's request, I have added a plot of the photon/positron/neutrino spectra for various final states. I have also referenced section 4.2.3 and figure 7 in the initial discussion of Sommerfeld enhancement.

-I have corrected a typo relating to the diffusion coefficient pointed out by Referee 2 (and the student volunteer reviewer).

-I have added a footnote where the simplifying assumption of DM homogeneity is discussed, clarifying that this is a preliminary example to make the calculation easier to follow, and that realistically the average annihilation rate at late times will be much higher than expected from the cosmological average density. I have also added a parenthetical comment as a reminder of this point in the lead-in to Eqs. 14-15.

-Regarding referee 2's requests to add further details on DM limits from the extra-galactic gamma-ray background (EGB) and neutrino searches, I have retitled the section on current indirect detection signals to clarify that this is intended as a selection of constraints rather than a comprehensive review of indirect searches. I have added a brief discussion of the EGB constraints as a competitive channel and provided a reference for further reading, and slightly expanded the discussion of neutrino signals from DM annihilation/decay with some additional references. I have added a mention of the EGB applications of non-Poissonian template fitting, and citations to the papers mentioned by the referee, in section 6.6.

-As requested by referee 3, I have added a parenthetical comment and a sentence to the discussion of freezeout on pages 3-4 to emphasize where these numbers are (conservative) bounds, not central-value predictions.

-As requested by referee 3, I have added a brief discussion of "hard" final states with peaked gamma-ray spectra on page 12.

-To address a comment by referee 3, on page 33 in v1 (now page 35) I have added context to clarify that I was discussing the expected extension of TeV gamma-ray halos observed by HAWC, not electron/positron diffusion more generally.

-As requested by referee 3, I have reworded my comments on anti-helium detection slightly to clarify the unexpectedness of this signal.

-I have added the citations suggested by the referees, and a few others suggested by other readers.

Published as SciPost Phys. Lect. Notes 53 (2022)

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