NuSTAR tests of sterile-neutrino dark matter: New Galactic bulge observations and combined impact

Abstract

We analyze two dedicated NuSTAR observations with exposure ∼190 ks located ∼10°from the Galactic plane, one above and the other below, to search for x-ray lines from the radiative decay of sterile-neutrino dark matter. These fields were chosen to minimize astrophysical x-ray backgrounds while remaining near the densest region of the dark matter halo. We find no evidence of anomalous x-ray lines in the energy range 5-20 keV, corresponding to sterile neutrino masses 10-40 keV. Interpreted in the context of sterile neutrinos produced via neutrino mixing, these observations provide the leading constraints in the mass range 10-12 keV, improving upon previous constraints in this range by a factor ∼2. We also compare our results to Monte Carlo simulations, showing that the fluctuations in our derived limit are not dominated by systematic effects. An updated model of the instrumental background, which is currently under development, will improve NuSTAR's sensitivity to anomalous x-ray lines, particularly for energies 3-5 keV.

Neutrino dark matter and the Higgs portal: improved freeze-in analysis

“…2 Among them, the CHANDRA satellite provides the strongest limits [17]. Most recent bounds from the X-ray microcalorimeter NuSTAR [65], looking at the Galactic Bulge, are displayed in dark cyan. The limits from searches for sterile neutrino decay lines using the Gamma-ray Burst Monitor onboard the Fermi Gamma-Ray Space Telescope (Fermi-GBM) [66] are shown in red.…”

Status, Challenges and Directions in Indirect Dark Matter Searches

“…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]<...>…”

“…The integrated effect of decays at different redshifts during the evolution of the universe would result in a broad X-ray band today on top of the the diffuse X-ray astrophysical background. The non-detection of such feature has already allowed to constrain the (M s , sin 2 (2θ)) parameter space of sterile neutrino dark matter with X-ray telescopes [93][94][95][99][100][101][102][152][153][154]. The left plot of Figure 5 shows that X-ray telescopes alone have a strong constraining power on the (M s , sin 2 (2θ)) plane, in this case illustrated on the νMSSM model, a minimal extension of the standard model that includes neutrino masses and which incorporates a dark matter candidate in the form of a right-handed neutrino of a few keV [155].…”

Constraints on general neutrino interactions with exotic fermion from neutrino-electron scattering experiments

“…several tens of keV DM, strong constraints have been obtained using INTEGRAL [54][55][56] and NuSTAR [57,58]. The bound on the lifetime of decaying DM depends on the specific model parameters and decay topologies.…”