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Title: Discretising the velocity distribution for directional dark matter experiments

Abstract

Dark matter (DM) direct detection experiments which are directionally-sensitive may be the only method of probing the full velocity distribution function (VDF) of the Galactic DM halo. We present an angular basis for the DM VDF which can be used to parametrise the distribution in order to mitigate astrophysical uncertainties in future directional experiments and extract information about the DM halo. This basis consists of discretising the VDF in a series of angular bins, with the VDF being only a function of the DM speed v within each bin. In contrast to other methods, such as spherical harmonic expansions, the use of this basis allows us to guarantee that the resulting VDF is everywhere positive and therefore physical. We present a recipe for calculating the event rates corresponding to the discrete VDF for an arbitrary number of angular bins N and investigate the discretisation error which is introduced in this way. For smooth, Standard Halo Model-like distribution functions, only N=3 angular bins are required to achieve an accuracy of around 10–30% in the number of events in each bin. Shortly after confirmation of the DM origin of the signal with around 50 events, this accuracy should be sufficient to allowmore » the discretised velocity distribution to be employed reliably. For more extreme VDFs (such as streams), the discretisation error is typically much larger, but can be improved with increasing N. This method paves the way towards an astrophysics-independent analysis framework for the directional detection of dark matter.« less

Authors:
 [1];  [2]
  1. Institut de Physique Théorique, CNRS, URA 2306 & CEA/Saclay,F-91191 Gif-sur-Yvette (France)
  2. (United Kingdom)
Publication Date:
Sponsoring Org.:
SCOAP3, CERN, Geneva (Switzerland)
OSTI Identifier:
22458437
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 07; Other Information: PUBLISHER-ID: JCAP07(2015)019; OAI: oai:repo.scoap3.org:11064; cc-by Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; ASTROPHYSICS; DETECTION; DISTRIBUTION FUNCTIONS; NONLUMINOUS MATTER; ORIGIN; PROBES; SIGNALS; VELOCITY

Citation Formats

Kavanagh, Bradley J., and School of Physics & Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD. Discretising the velocity distribution for directional dark matter experiments. United States: N. p., 2015. Web. doi:10.1088/1475-7516/2015/07/019.
Kavanagh, Bradley J., & School of Physics & Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD. Discretising the velocity distribution for directional dark matter experiments. United States. doi:10.1088/1475-7516/2015/07/019.
Kavanagh, Bradley J., and School of Physics & Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD. Mon . "Discretising the velocity distribution for directional dark matter experiments". United States. doi:10.1088/1475-7516/2015/07/019.
@article{osti_22458437,
title = {Discretising the velocity distribution for directional dark matter experiments},
author = {Kavanagh, Bradley J. and School of Physics & Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD},
abstractNote = {Dark matter (DM) direct detection experiments which are directionally-sensitive may be the only method of probing the full velocity distribution function (VDF) of the Galactic DM halo. We present an angular basis for the DM VDF which can be used to parametrise the distribution in order to mitigate astrophysical uncertainties in future directional experiments and extract information about the DM halo. This basis consists of discretising the VDF in a series of angular bins, with the VDF being only a function of the DM speed v within each bin. In contrast to other methods, such as spherical harmonic expansions, the use of this basis allows us to guarantee that the resulting VDF is everywhere positive and therefore physical. We present a recipe for calculating the event rates corresponding to the discrete VDF for an arbitrary number of angular bins N and investigate the discretisation error which is introduced in this way. For smooth, Standard Halo Model-like distribution functions, only N=3 angular bins are required to achieve an accuracy of around 10–30% in the number of events in each bin. Shortly after confirmation of the DM origin of the signal with around 50 events, this accuracy should be sufficient to allow the discretised velocity distribution to be employed reliably. For more extreme VDFs (such as streams), the discretisation error is typically much larger, but can be improved with increasing N. This method paves the way towards an astrophysics-independent analysis framework for the directional detection of dark matter.},
doi = {10.1088/1475-7516/2015/07/019},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 07,
volume = 2015,
place = {United States},
year = {Mon Jul 13 00:00:00 EDT 2015},
month = {Mon Jul 13 00:00:00 EDT 2015}
}