[APEX] Measuring the S1 stream with dark matter detectors

Jay Benesch benesch at jlab.org
Thu Nov 8 06:43:12 EST 2018


Dark matter hurricane: Measuring the S1 stream with dark matter detectors
Ciaran A. J. O’Hare, Christopher McCabe, N. Wyn Evans, GyuChul Myeong, 
and Vasily Belokurov
Phys. Rev. D 98, 103006 – Published 7 November 2018


The recently discovered S1 stream passes through the Solar neighborhood 
on a low inclination, counterrotating orbit. The progenitor of S1 is a 
dwarf galaxy with a total mass comparable to the present-day Fornax 
dwarf spheroidal, so the stream is expected to have a significant DM 
component. We compute the effects of the S1 stream on WIMP and axion 
detectors as a function of the density of its unmeasured dark component. 
In WIMP detectors the S1 stream supplies more high energy nuclear 
recoils so will marginally improve DM detection prospects. We find that 
even if S1 comprises less than 10% of the local density, multiton xenon 
WIMP detectors can distinguish the S1 stream from the bulk halo in the 
relatively narrow mass range between 5 and 25 GeV. In directional WIMP 
detectors such as CYGNUS, S1 increases DM detection prospects more 
substantially since it enhances the anisotropy of the WIMP signal. 
Finally, we show that axion haloscopes possess by far the greatest 
potential sensitivity to the S1 stream if its dark matter component is 
sufficiently cold. Once the axion mass has been discovered, the 
distinctive velocity distribution of S1 can easily be extracted from the 
axion power spectrum.

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