Reference : Making sense of the local Galactic escape speed estimates in direct dark matter searches
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
Making sense of the local Galactic escape speed estimates in direct dark matter searches
Lavalle, Julien [Laboratoire Univers & Particules de Montpellier (LUPM), CNRS-IN2P3 & Université Montpellier II (UMR-5299), Place Eugène Bataillon, F-34095 Montpellier Cedex 05, France]
Magni, Stefano mailto [University of Luxembourg > Luxembourg Centre for Systems Biomedicine (LCSB) > > ; Université Montpellier 2 > Laboratoire Univers et Particules de Montpellier]
Physical Review. D
American Physical Society
Yes (verified by ORBilu)
[en] Dark matter ; Models beyond the standard model ; Galactic halo
[en] Direct detection (DD) of dark matter (DM) candidates in the ≲10 GeV mass range is very sensitive to the tail of their velocity distribution. The important quantity is the maximum weakly interacting massive particle speed in the observer's rest frame, i.e. in average the sum of the local Galactic escape speed v[SUB]esc[/SUB] and of the circular velocity of the Sun v[SUB]c[/SUB]. While the latter has been receiving continuous attention, the former is more difficult to constrain. The RAVE Collaboration has just released a new estimate of v[SUB]esc[/SUB] [T. Piffl et al., Astron. Astrophys. 562, A91 (2014)] that supersedes the previous one [M. C. Smith, et al. Mon. Not. R. Astron. Soc. 379, 755 (2007)], which is of interest in the perspective of reducing the astrophysical uncertainties in DD. Nevertheless, these new estimates cannot be used blindly as they rely on assumptions in the dark halo modeling which induce tight correlations between the escape speed and other local astrophysical parameters. We make a self-consistent study of the implications of the RAVE results on DD assuming isotropic DM velocity distributions, both Maxwellian and ergodic. Taking as references the experimental sensitivities currently achieved by LUX, CRESST-II, and SuperCDMS, we show that (i) the exclusion curves associated with the best-fit points of P14 may be more constraining by up to ˜40 % with respect to standard limits, because the underlying astrophysical correlations induce a larger local DM density, and (ii) the corresponding relative uncertainties inferred in the low weakly interacting massive particle mass region may be moderate, down to 10-15% below 10 GeV. We finally discuss the level of consistency of these results with other independent astrophysical constraints. This analysis is complementary to others based on rotation curves.

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