TY - JOUR

T1 - Non-parametric uncertainties in the dark matter velocity distribution

AU - Fowlie, Andrew

N1 - Publisher Copyright:
© 2019 IOP Publishing Ltd and Sissa Medialab.

PY - 2019/1/3

Y1 - 2019/1/3

N2 - We investigate the impact of uncertainty in the velocity distribution of dark matter on direct detection experiments. We construct an multinomial prior with a hyperparameter β that describes the strength of our belief in an isotropic Maxwell-Boltzmann velocity distribution. By varying β, we interpolate between a halo-independent and halo-dependent analysis. We present a novel approximation for the marginalisation of this prior that is applicable to any counting experiment. With this formula, we investigate the impact of the uncertainty in limits from XENON1T. For dark matter masses greater than about 60 GeV, we find extremely mild sensitivity to the distribution. Below about 60 GeV, the limit weakens by less than an order of magnitude if we assume an isotropic distribution in the galactic frame. If we permit anisotropic distributions, the limit further weakens, but at most by about two orders of magnitude. Lastly, we check the impact of parametric uncertainties and discuss the possible inclusion and impact of our technique in global fits.

AB - We investigate the impact of uncertainty in the velocity distribution of dark matter on direct detection experiments. We construct an multinomial prior with a hyperparameter β that describes the strength of our belief in an isotropic Maxwell-Boltzmann velocity distribution. By varying β, we interpolate between a halo-independent and halo-dependent analysis. We present a novel approximation for the marginalisation of this prior that is applicable to any counting experiment. With this formula, we investigate the impact of the uncertainty in limits from XENON1T. For dark matter masses greater than about 60 GeV, we find extremely mild sensitivity to the distribution. Below about 60 GeV, the limit weakens by less than an order of magnitude if we assume an isotropic distribution in the galactic frame. If we permit anisotropic distributions, the limit further weakens, but at most by about two orders of magnitude. Lastly, we check the impact of parametric uncertainties and discuss the possible inclusion and impact of our technique in global fits.

KW - Dark matter experiments

KW - Dark matter theory

UR - http://www.scopus.com/inward/record.url?scp=85062263778&partnerID=8YFLogxK

U2 - 10.1088/1475-7516/2019/01/006

DO - 10.1088/1475-7516/2019/01/006

M3 - Article

AN - SCOPUS:85062263778

SN - 1475-7516

VL - 2019

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

IS - 1

M1 - 006

ER -