[Paper Review] Indirect detection of Dark matter with gamma-rays - status and perspectives

Jan Conrad|arXiv (Cornell University)|Mar 29, 2011

Dark Matter and Cosmic Phenomena35 references3 citations

TL;DR

This paper reviews the status and future prospects of indirect dark matter detection via gamma-rays, focusing on results from Fermi-LAT and ground-based Imaging Air Cherenkov Telescopes (IACTs) like H.E.S.S., MAGIC, and VERITAS. It concludes that with improved sensitivity from next-generation instruments like the Cherenkov Telescope Array (CTA), gamma-ray searches—particularly in dwarf galaxies—could probe the canonical WIMP annihilation cross-section ($\sim 3 \times 10^{-26}\,\text{cm}^3\text{s}^{-1}$) within the next decade, assuming controllable astrophysical backgrounds.

ABSTRACT

In my contribution I review the status of indirect detection of dark matter with gamma-rays, including results of the Fermi Gamma-ray Space Telescope as well as Imaging Air Cherenkov Telescopes (IACT), like H.E.S.S., MAGIC and VERITAS. I will also briefly address the perspectives for the next generation IACT, the Cherenkov Telescope Array

Motivation & Objective

• To assess the current status of indirect dark matter detection using gamma-ray observations from Fermi-LAT and ground-based IACTs.
• To evaluate the sensitivity of existing and upcoming instruments to WIMP annihilation signals, particularly in the context of spectral and spatial signatures.
• To identify the most promising astrophysical targets—such as dwarf galaxies and the Galactic halo—where gamma-ray signals from dark matter could be detected.
• To project the potential of next-generation instruments, especially the Cherenkov Telescope Array (CTA), in probing the canonical WIMP annihilation cross-section.

Proposed method

• Analysis of gamma-ray data from Fermi-LAT and IACTs (H.E.S.S., MAGIC, VERITAS) to constrain WIMP annihilation cross-sections.
• Use of stacking techniques across multiple dwarf galaxies to enhance sensitivity to low-mass WIMPs.
• Application of spectral line and continuum emission models to distinguish dark matter signals from astrophysical backgrounds.
• Sensitivity projections based on realistic simulations of CTA, including energy threshold improvements and array configuration effects.
• Comparison of instrumental performance metrics such as energy resolution, field of view, and effective area across satellite and ground-based telescopes.
• Incorporation of astrophysical uncertainties, including substructure boosts and density profiles, in sensitivity estimates for Galactic Center and halo searches.

Experimental results

Research questions

• RQ1 Can gamma-ray observations from Fermi-LAT and IACTs detect a spectral line or continuum feature indicative of WIMP annihilation or decay?
• RQ2 What is the expected sensitivity of the Cherenkov Telescope Array (CTA) to WIMP annihilation, particularly in the 100 GeV to 1 TeV mass range?
• RQ3 How do astrophysical backgrounds in the Galactic halo and Galactic Center affect the detectability of dark matter signals?
• RQ4 To what extent can stacking of dwarf galaxy observations improve constraints on low-mass WIMPs?
• RQ5 Can future gamma-ray instruments probe the canonical WIMP annihilation cross-section ($\sim 3 \times 10^{-26}\,\text{cm}^3\text{s}^{-1}$) in the most favorable targets?

Key findings

• Fermi-LAT has significantly improved constraints on WIMP annihilation, particularly in the 100 GeV mass range, approaching the canonical WIMP cross-section of $\sim 3 \times 10^{-26}\,\text{cm}^3\text{s}^{-1}$.
• Stacking analyses of dwarf galaxies could achieve sensitivity to $<\sigma v> \sim 10^{-27}\,\text{cm}^3\text{s}^{-1}$ for WIMPs around 50 GeV with 10 years of Fermi-LAT data.
• For high-mass WIMPs (500 GeV–1 TeV), ground-based IACTs like H.E.S.S. could reach $<\sigma v> \sim 10^{-25}\,\text{cm}^3\text{s}^{-1}$ with 50 hours of on-source observation.
• H.E.S.S. II, with its upgraded five-telescope configuration, is expected to reduce the energy threshold and improve sensitivity for halo and Galactic Center searches.
• CTA simulations suggest it could probe $<\sigma v> \sim 10^{-27}\,\text{cm}^3\text{s}^{-1}$ at masses around 100 GeV, assuming substructure boosts and 100 hours of observation time.
• The paper concludes that gamma-ray detection of WIMPs remains viable, especially in dwarf galaxies, and that CTA may access parameter space complementary to direct detection experiments.