Multiwavelength analysis of low surface brightness galaxies to study possible dark matter signature

Abstract

Low Surface Brightness (LSB) galaxies are thought to be one of the most dark matter (DM) dominated galaxies in our Universe. They have very diffuse, low surface density stellar disks that have poor star formation rates and hence appear faint in optical images. LSB galaxies are also very rich in neutral hydrogen (HI) gas which usually extends well beyond their stellar disks. Their extended HI rotation curves indicate the presence of very massive DM halos compared to normal bright galaxies and their mass to light (M/L) ratios are high, which is typical for dark matter dominated galaxies. Hence, LSB galaxies are ideal laboratories for the indirect detection of DM using observations of γ-ray emission which could possibly originate from pair-annihilation (or decay) of the weakly interacting massive particles (WIMPs) in their halos. In this paper we have searched for WIMP annihilation or decay signatures in four LSB galaxies, UGC 12632, UGC 12732, UGC 11707, UGC 3371. Here we present analysis of nearly nine years data from the Fermi Large Area Telescope (LAT). Above 100 MeV, no excess emission was detected from the LSB galaxies. We have then determined the stacked γ-ray flux using spectra expected for WIMP annihilation. With the RX-DMFIT code, we have also predicted the possible upper limits for the detection of radio emission associated with WIMP annihilation from LSB galaxies. We have compared our results with different proposed theoretical WIMP models to examine the constraints on the parameter space of the DM models. We also discuss the possibility of detecting a positive signal from LSB galaxies using the upcoming ground-based γ-ray telescope, the Cherenkov Telescope Array.