9 research outputs found
Effect of Gravitational Focusing on Annual Modulation in Dark-Matter Direct-Detection Experiments
The scattering rate at dark-matter direct-detection experiments should
modulate annually due to the Earth's orbit around the Sun. The rate is
typically thought to be extremized around June 1, when the relative velocity of
the Earth with respect to the dark-matter wind is maximal. We point out that
gravitational focusing can alter this modulation phase. Unbound dark-matter
particles are focused by the Sun's gravitational potential, affecting their
phase-space density in the lab frame. Gravitational focusing can result in a
significant overall shift in the annual-modulation phase, which is most
relevant for dark matter with low scattering speeds. The induced phase shift
for light O(10) GeV dark matter may also be significant, depending on the
threshold energy of the experiment.Comment: 4 pages, 3 figures; v2, minor improvements, PRL versio
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Astrophysical Tests of Dark Matter with Maunakea Spectroscopic Explorer
We discuss how astrophysical observations with the Maunakea Spectroscopic
Explorer (MSE), a high-multiplexity (about 4300 fibers), wide field-of-view
(1.5 square degree), large telescope aperture (11.25 m) facility, can probe the
particle nature of dark matter. MSE will conduct a suite of surveys that will
provide critical input for determinations of the mass function, phase-space
distribution, and internal density profiles of dark matter halos across all
mass scales. N-body and hydrodynamical simulations of cold, warm, fuzzy and
self-interacting dark matter suggest that non-trivial dynamics in the dark
sector could have left an imprint on structure formation. Analysed within these
frameworks, the extensive and unprecedented datasets produced by MSE will be
used to search for deviations away from cold and collisionless dark matter
model. MSE will provide an improved estimate of the local density of dark
matter, critical for direct detection experiments, and will improve estimates
of the J-factor for indirect searches through self-annihilation or decay into
Standard Model particles. MSE will determine the impact of low mass
substructures on the dynamics of Milky Way stellar streams in velocity space,
and will allow for estimates of the density profiles of the dark matter halos
of Milky Way dwarf galaxies using more than an order of magnitude more tracers.
In the low redshift Universe, MSE will provide critical redshifts to pin down
the luminosity functions of vast numbers of satellite systems, and MSE will be
an essential component of future strong lensing measurements to constrain the
halo mass function. Across nearly all mass scales, the improvements offered by
MSE, in comparison to other facilities, are such that the relevant analyses are
limited by systematics rather than statistics
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Probing the Fundamental Nature of Dark Matter with the Large Synoptic Survey Telescope
Astrophysical and cosmological observations currently provide the only
robust, empirical measurements of dark matter. Future observations with Large
Synoptic Survey Telescope (LSST) will provide necessary guidance for the
experimental dark matter program. This white paper represents a community
effort to summarize the science case for studying the fundamental physics of
dark matter with LSST. We discuss how LSST will inform our understanding of the
fundamental properties of dark matter, such as particle mass, self-interaction
strength, non-gravitational couplings to the Standard Model, and compact object
abundances. Additionally, we discuss the ways that LSST will complement other
experiments to strengthen our understanding of the fundamental characteristics
of dark matter. More information on the LSST dark matter effort can be found at
https://lsstdarkmatter.github.io/
Dense genotyping of immune-related disease regions identifies nine new risk loci for primary sclerosing cholangitis.
Primary sclerosing cholangitis (PSC) is a severe liver disease of unknown etiology leading to fibrotic destruction of the bile ducts and ultimately to the need for liver transplantation. We compared 3,789 PSC cases of European ancestry to 25,079 population controls across 130,422 SNPs genotyped using the Immunochip. We identified 12 genome-wide significant associations outside the human leukocyte antigen (HLA) complex, 9 of which were new, increasing the number of known PSC risk loci to 16. Despite comorbidity with inflammatory bowel disease (IBD) in 72% of the cases, 6 of the 12 loci showed significantly stronger association with PSC than with IBD, suggesting overlapping yet distinct genetic architectures for these two diseases. We incorporated association statistics from 7 diseases clinically occurring with PSC in the analysis and found suggestive evidence for 33 additional pleiotropic PSC risk loci. Together with network analyses, these findings add to the genetic risk map of PSC and expand on the relationship between PSC and other immune-mediated diseases