Strong constraints on thermal relic dark matter from Fermi-LAT observations of the Galactic Center

Abstract

The extended excess toward the Galactic Center (GC) in gamma rays inferred from Fermi-LAT observations has been interpreted as being due to dark matter (DM) annihilation. Here, we perform new likelihood analyses of the GC and show that, when including templates for the stellar galactic and nuclear bulges, the GC shows no significant detection of a DM annihilation template, even after generous variations in the Galactic diffuse emission models and a wide range of DM halo profiles. We include Galactic diffuse emission models with combinations of three-dimensional inverse Compton maps, variations of interstellar gas maps, and a central source of electrons. For the DM profile, we include both spherical and ellipsoidal DM morphologies and a range of radial profiles from steep cusps to kiloparsec-sized cores, motivated in part by hydrodynamical simulations. Our derived upper limits on the dark matter annihilation flux place strong constraints on DM properties. In the case of the pure b-quark annihilation channel, our limits on the annihilation cross section are more stringent than those from the Milky Way dwarfs up to DM masses of approximately TeV and rule out the thermal relic cross section up to approximately 300 GeV. Better understanding of the DM profile, as well as the Fermi-LAT data at its highest energies, would further improve the sensitivity to DM properties.

Status, Challenges and Directions in Indirect Dark Matter Searches

“…The shaded area represents the systematic uncertainty from the Fermi-LAT collaboration analysis, and it is obtained as the envelope of the predictions of the gamma-ray flux under different assumptions on diffuse gamma-ray emission, galaxy morphology, gas distributions in the galaxy or cosmic-ray distribution and propagation, but, in any case, without any new physics. A similar conclusion is reached in [107], where diffuse galactic emission, inverse-Compton emission and a central source of electrons can explain the Fermi-LAT data without a dark matter component, practically ruling out thermal dark matter as the explanation of the galactic centre gamma-ray excess.…”

“…Indirect searches for dark matter have indeed been performed by gamma-ray telescopes (MAGIC, e.g., [84][85][86], H.E.S.S., e.g., [87][88][89][90], VERITAS [91,92]), X-ray telescopes (XMM-Newton, e.g., [93][94][95][96], NuSTAR, e.g., [97][98][99], Suzaku, e.g., [100][101][102][103]), cosmic-ray detectors (HAWC [104][105][106]), detectors in space (Fermi-LAT, e.g., [107][108][109], DAMPE, e.g., [110], CALET [111], AMS [112]) and neutrino telescopes (IceCube, e.g., [113][114][115], ANTARES, e.g., [116][117][118], Baikal, e.g., [119][120][121], Baksan [122] or Super-Kamiokande, e.g., [123][124][125]). Many of these detectors have upgrade programs underway, in different stages of R&D or implementation (CTA [126], IceCube-Gen2 [127], KM3NET [128]<...>…”

Observable signatures of scotogenic Dirac model

“…The recent research [94] had a discussion on dark matter annihilation to account for the extended excess of gamma ray from the Milky Way Galactic Center, which is observed by Fermi-LAT. Constraints on the annihilation rate of τ + τ − final states had been set.…”

“…Constraints on the annihilation rate of τ + τ − final states had been set. We show it in figure 10, where the blue and pink lines stand for upper limits from Fermi-LAT, assuming different dark matter spatial morphologies [94]. With the dark matter mass increased, the exclusion capabilities will become weaker.…”

Cosmic-ray signatures of dark matter from a flavor dependent gauge symmetry model with neutrino mass mechanism

“…These limits are subject to about one order of magnitude variation from uncertainty on the halo shape and resulting J-factors [12], which however is independent of the annihilation channel. Most recently very strict limits on hadronic and the DM þ DM → τ þ þ τ − channel based on the morphology of γ-ray flux from the galactic center have been brought forward [13], giving explicitly no such constraint on DM þ DM → e þ þ e − channel and DM þ DM → μ þ þ μ − channel.…”