Constraining dark matter annihilation with HSC low surface brightness galaxies

Abstract

Searches for dark matter annihilation signals have been carried out in a number of target regions such as the Galactic Center and Milky Way dwarf spheroidal galaxies (dSphs), among a few others. Here we propose low surface brightness galaxies (LSBGs) as novel targets for the indirect detection of dark matter emission. In particular, LSBGs are known to have very large dark matter contents and be less contaminated by extragalactic γ-ray sources (e.g., blazars) compared to star forming galaxies. We report on an analysis that uses eight LSBGs (detected by Subaru Hyper Suprime-Cam survey data) with known redshifts to conduct a search for γ-ray emission at the positions of these new objects in Fermi Large Area Telescope data. We found no excesses of γ-ray emission and set constraints on the dark matter annihilation cross-section. We exclude (at the 95% C.L.) dark matter scenarios predicting a cross-section higher than ∼ 10 −23 [cm 3 /s] for dark matter particles of mass 10 GeV self-annihilating in the bb channel. Although this constraint is weaker than the ones reported in recent studies using other targets, we note that in the near future, the number of detections of new LSBGs will increase by a few orders of magnitude. We forecast conservatively that using the full catalog of soon-to-be-detected LSBGs will allow us to exclude the canonical thermal relic cross-section for dark matter particles with masses up to several tens of GeV.

Constraining Dark matter annihilation with Dark Energy Survey Y3 LSBG sample

“…We finally apply the linear interpolation of the posterior distribution between each redshift bin and draw random values for every galaxy's redshift from the interpolated posterior distribution. To be conservative, we set the minimum distance to the objects being 25 Mpc, which is the nearest LSBG found in the HSC-LSBG sample in our previous analysis [15]. In Figure 2, we show the dN/dz for the red and blue LSBG sample with 1-σ errorbars evaluated by the error propagation from the jackknife error in the measured angular correlation.…”

“…For the concentration parameter, we apply the model [47]. For statistical uncertainties of the halo mass and density profile at 1-σ Gaussian error, we evaluate ∆ log M halo = 0.4 for scatter of the stellar-tohalo mass conversion [15] and ∆ log c = 0.1 [48].…”

“…In our previous work [15], low-surface brightness galaxies (LSBGs) have been proposed as target objects to probe the γ-ray signal (LSBGs have been used for the prove in a few works, such as Ref. [16]).…”

Dark matter constraints with stacked gamma rays scales with the number of galaxies

“…As described in Subsection III A 4, because of the very low γ-ray emission signal for our LSBGs, we apply the Bayesian method for the likelihood analysis, which is performed following the same approach of our previous work [27]. In the computation of the 95% C.L.…”

“…In our previous work [27], a low-surface-brightness galaxy (LSBG), which has less than ∼23 mag/arcmin 2 mean surface brightness, has been proposed as a new target to probe the DM annihilation signal in UGRB. LS-BGs are known to be highly dominated by DM [28,29] and have more massive halos than Milky Way dSphs, ∼10 9 M .…”