3FGL J1924.8-1034 : A Spatially-Extended Stable Unidentified GeV Source?

TL;DR

This paper reports the identification of a spatially-extended, stable gamma-ray source, 3FGL J1924.8-1034, which could be a dark matter subhalo candidate based on its spectral and spatial properties.

Contribution

The study presents the discovery of a new candidate dark matter subhalo through gamma-ray spatial extension and spectral analysis using Fermi-LAT data.

Findings

3FGL J1924.8-1034 is spatially extended at 5.4σ confidence.

Its gamma-ray spectrum fits dark matter annihilation into bar{b} with ~43 GeV mass.

No significant variability was observed.

Abstract

Milky Way-like galaxies are predicted to host a very large number of dark matter subhalos. Some massive and nearby subhalos could generate detectable gamma-rays, appearing as unidentified, spatially-extended and stable gamma-ray sources. We search for such sources in the third Fermi Large Area Telescope source List (3FGL) and report the identification of a new candidate, 3FGL J1924.8-1034. With the Fermi-LAT Pass 8 data, we find that 3FGL J1924.8-1034 is spatially-extended at a high confidence level of $5.4\sigma$, with a best-fit extension radius of $\sim0.15^{\circ}$. No significant variability has been found and its gamma-ray spectrum is well fitted by the dark matter annihilation into $b\bar{b}$ with a mass of $\sim 43$ GeV. All these facts make 3FGL J1924.8-1034 a possible dark matter subhalo candidate. However, due to the limited angular resolution, the possibility of that the spatial extension of 3FGL J1924.8-1034 is caused by the contamination from the other un-resolved point source can not be ruled out.