Anticipating the XRISM search for the decay of resonantly produced sterile neutrino dark matter
Abstract
The sterile neutrino (N1) features in multiple extensions of the standard model and is a compelling dark matter candidate, especially as the decay of N1 with mass ms = 7.1 keV is a possible source for the unexplained 3.55 keV X-ray line reported in galaxy clusters. This particle will be accessible to the XRISM X-ray mission over the next 12 months. We revisit the physics behind N1 and the uncertainty in its parameters. We compare predictions for the ms = 7.1 keV N1 mixing angle, $\sin ^{2}(2\theta)\,$, and half-mode mass, Mhm, as described in the neutrino minimal standard model (νMSM) extension to existing X-ray observations and structure formation constraints. The strongest available constraints rule out N1 as a dark matter candidate, and a more optimistic reading of the data prefers $\sin ^{2}(2\theta)\,$ = 5 × 10-11 and Mhm = 3.5 × 108 ${\, \rm M_\odot }$. We highlight that the most promising upcoming opportunity for a detection is to find a line of velocity dispersion ~500 $\, {\rm km}\, {\rm s}^{-1}$ in the Virgo cluster with XRISM, and then draw up a list of future objects of study to determine: (i) whether the line is from dark matter generally, and (ii) if from dark matter, whether that candidate is indeed N1.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2023
- DOI:
- 10.1093/mnras/stad2237
- arXiv:
- arXiv:2303.15513
- Bibcode:
- 2023MNRAS.524.6345L
- Keywords:
-
- neutrinos;
- dark matter;
- early Universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- High Energy Physics - Phenomenology
- E-Print:
- 13 pages, 6 figures. Accepted version. Identified error in previous version for CLASS calculation, corrected in this version. Contact: m.r.lovell@durham.ac.uk