Searching for Afterglow: Light Dark Matter Boosted by Supernova Neutrinos

Abstract

A novel analysis is performed, incorporating time-of-flight (TOF) information to study the interactions of dark matter (DM) with standard model particles. After supernova (SN) explosions, DM with mass $m_{\chi }\lesssim \mathcal{O}(\mathrm{MeV})$ in the halo can be boosted by SN neutrinos (SN$\nu$) to relativistic speed. The SN$\nu$ boosted DM (BDM) arrives on Earth with TOF which depends only on $m_{\chi }$ and is independent of the cross section. These BDMs can interact with detector targets in low-background experiments and manifest as afterglow events after the arrival of SN$\nu$. The characteristic TOF spectra of the BDM events can lead to large background suppression and unique determination of $m_{\chi }$. New cross section constraints on $\sqrt{{\sigma }_{\chi e}{\sigma }_{\chi \nu }}$ are derived from SN1987a in the Large Magellanic Cloud with data from the Kamiokande and Super-Kamiokande experiments. Potential sensitivities for the next galactic SN with Hyper-Kamiokande are projected. This analysis extends the existing bounds on $\sqrt{{\sigma }_{\chi e}{\sigma }_{\chi \nu }}$ over a broad range of $r_{\chi }={\sigma }_{\chi \nu }/{\sigma }_{\chi e}$. In particular, the improvement is by 1-3 orders of magnitude for $m_{\chi }<\mathcal{O}(100\mathrm{keV})$ for ${\sigma }_{\chi e}\sim {\sigma }_{\chi \nu }$. Prospects of exploiting TOF information in other astrophysical systems to probe exotic physics with other DM candidates are discussed.

Comments: PRL accepted, matched published version. Code availability added in this revision