Search for gamma-ray spectral lines with the DArk Matter Particle Explorer

TL;DR

This study uses five years of DAMPE data with improved analysis techniques to search for gamma-ray spectral lines indicative of dark matter, setting new constraints on dark matter properties despite no detections.

Contribution

The paper introduces a novel analysis using DAMPE data, including the first use of BgoOnly data, to enhance sensitivity in gamma-ray line searches for dark matter detection.

Findings

No gamma-ray line signals detected between 10 and 300 GeV.

Constraints on dark matter annihilation cross section and decay lifetime established.

DAMPE achieves comparable or better limits than Fermi-LAT despite smaller acceptance.

Abstract

The DArk Matter Particle Explorer (DAMPE) is well suitable for searching for monochromatic and sharp $\gamma$-ray structures in the GeV$-$TeV range thanks to its unprecedented high energy resolution. In this work, we search for $\gamma$-ray line structures using five years of DAMPE data. To improve the sensitivity, we develop two types of dedicated data sets (including the BgoOnly data which is the first time to be used in the data analysis for the calorimeter-based gamma-ray observatories) and adopt the signal-to-noise ratio optimized regions of interest (ROIs) for different DM density profiles. No line signals or candidates are found between 10 and 300 GeV in the Galaxy. The constraints on the velocity-averaged cross section for $\chi\chi \to \gamma\gamma$ and the decay lifetime for $\chi \to \gamma\nu$, both at 95% confidence level, have been calculated and the systematic uncertainties have been taken into account. Comparing to the previous Fermi-LAT results, though DAMPE has an acceptance smaller by a factor of $\sim 10$, similar constraints on the DM parameters are achieved and below 100 GeV the lower limits on the decay lifetime are even stronger by a factor of a few. Our results demonstrate the potential of high-energy-resolution observations on dark matter detection.