Strong constraints on light dark matter interpretation of the EDGES signal

By R. Barkana, N. Outmezguine, D. Redigolo, T. Volansky. Physical Review D, 2018

168 citations recorded by the source corpus.

Recently the EDGES collaboration reported an anomalous absorption signal in the sky-averaged 21-cm spectrum around $z=17$. Such a signal may be understood as an indication for an unexpected cooling of the hydrogen gas during or prior to the so called Cosmic Dawn era. Here we explore the possibility that dark matter cooled the gas through velocity-dependent, Rutherford-like interactions. We argue that such interactions require a light mediator that is highly constrained by 5th force experiments and limits from stellar cooling. Consequently, only a hidden or the visible photon can in principle mediate such a force. Neutral hydrogen thus plays a sub-leading role and the cooling occurs via the residual free electrons and protons. We find that these two scenarios are strongly constrained by the predicted dark matter self-interactions and by limits on millicharged dark matter respectively. We conclude that the 21-cm absorption line is unlikely to be the result of gas cooling via the scattering with a dominant component of the dark matter. An order 1\% subcomponent of millicharged dark matter remains a viable explanation.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b4ca0d069648f11369936627178220d2563ec171

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Citations in the corpus

Fundamental physics with the Square Kilometre Array (2018, background): “The signal amplitude could possibly be evidence of interactions between (a subcomponent of) dark matter and baryons (e.g., Barkana, 2018; Barkana et al., 2018; Muñoz & Loeb, 2018), which may have led to cooling of the IGM prior to reionisation.”
Direct detection of strongly interacting sub-GeV dark matter via electron recoils (2019, unknown): “[61–70, 105–110].”
Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR (2020, background): “…14−21, is considerably stronger and wider than predicted (Fraser et al. 2018), and, depending on the additional mechanism invoked to explain it (e.g. Barkana et al. 2018; Berlin et al. 2018; Ewall-Wice et al. 2018; Fialkov & Barkana 2019; Mirocha & Furlanetto 2019), could also have an impact on…”
Physics beyond colliders at CERN: beyond the Standard Model working group report (2019, background): “20Even with subcomponent DM, it is likely excluded by direct detection [235, 236].”