9 research outputs found
Dark Matter Disc Enhanced Neutrino Fluxes from the Sun and Earth
As disc galaxies form in a hierarchical cosmology, massive merging satellites
are preferentially dragged towards the disc plane. The material accreted from
these satellites forms a dark matter disc that contributes 0.25 - 1.5 times the
non-rotating halo density at the solar position. Here, we show the importance
of the dark disc for indirect dark matter detection in neutrino telescopes.
Previous predictions of the neutrino flux from WIMP annihilation in the Earth
and the Sun have assumed that Galactic dark matter is spherically distributed
with a Gaussian velocity distribution, the standard halo model. Although the
dark disc has a local density comparable to the dark halo, its higher phase
space density at low velocities greatly enhances capture rates in the Sun and
Earth. For typical dark disc properties, the resulting muon flux from the Earth
is increased by three orders of magnitude over the SHM, while for the Sun the
increase is an order of magnitude. This significantly increases the sensitivity
of neutrino telescopes to fix or constrain parameters in WIMP models. The flux
from the Earth is extremely sensitive to the detailed properties of the dark
disc, while the flux from the Sun is more robust. The enhancement of the muon
flux from the dark disc puts the search for WIMP annihilation in the Earth on
the same level as the Sun for WIMP masses < 100 GeV.Comment: 7 pages, 4 figures, added a short paragraph to the discussion
section, conclusions unchanged, published versio
The impact of the Large Magellanic Cloud on dark matter direct detection signals
We study the effect of the Large Magellanic Cloud (LMC) on the dark matter (DM) distribution in the Solar neighborhood, utilizing the Auriga magneto-hydrodynamical simulations of Milky Way (MW) analogues that have an LMC-like system. We extract the local DM velocity distribution at different times during the orbit of the LMC around the MW in the simulations. As found in previous idealized simulations of the MW-LMC system, we find that the DM particles in the Solar neighborhood originating from the LMC analogue dominate the high speed tail of the local DM speed distribution. Furthermore, the native DM particles of the MW in the Solar region are boosted to higher speeds as a result of a response to the LMC's motion. We simulate the signals expected in near future xenon, germanium, and silicon direct detection experiments, considering DM interactions with target nuclei or electrons. We find that the presence of the LMC causes a considerable shift in the expected direct detection exclusion limits towards smaller cross sections and DM masses, with the effect being more prominent for low mass DM. Hence, our study shows, for the first time, that the LMC's influence on the local DM distribution is significant even in fully cosmological MW analogues
Probing the Local Velocity Distribution of WIMP Dark Matter with Directional Detectors
We explore the ability of directional nuclear-recoil detectors to constrain
the local velocity distribution of weakly interacting massive particle (WIMP)
dark matter by performing Bayesian parameter estimation on simulated
recoil-event data sets. We discuss in detail how directional information, when
combined with measurements of the recoil-energy spectrum, helps break
degeneracies in the velocity-distribution parameters. We also consider the
possibility that velocity structures such as cold tidal streams or a dark disk
may also be present in addition to the Galactic halo. Assuming a
carbon-tetrafluoride detector with a 30-kg-yr exposure, a 50-GeV WIMP mass, and
a WIMP-nucleon spin-dependent cross-section of 0.001 pb, we show that the
properties of a cold tidal stream may be well constrained. However, measurement
of the parameters of a dark-disk component with a low lag speed of ~50 km/s may
be challenging unless energy thresholds are improved.Comment: 38 pages, 15 figure
The predicted luminous satellite populations around SMC- and LMC-mass galaxies â a missing satellite problem around the LMC?
Recent discovery of many dwarf satellite galaxies in the direction of the Small and Large Magellanic Clouds (SMC and LMC) provokes questions of their origins, and what they can reveal about galaxy evolution theory. Here, we predict the satellite stellar mass function of Magellanic Cloud-mass host galaxies using abundance matching and reionization models applied to the Caterpillar simulations. Specifically focusing on the volume within 50 kpc of the LMC, we predict a mean of 4-8 satellites with stellar mass Mâ > 10[superscript 4] M[subscript â] , and 3-4 satellites with 80 10[superscript 5] M [subscript â] (Mâ > 10[superscript 4] M[subscript â]) within the virial volume of each, and 1-3 (1-7) within a single 1.5Âș diameter field of view, making their discovery likely. Key words: galaxies: dwarf â galaxies: Magellanic Clouds â galaxies: haloes â= methods: numericalNational Science Foundation (U.S.) (CAREER Grant AST-1255160
Snowmass2021: Vera C. Rubin Observatory as a Flagship Dark Matter Experiment
Establishing that Vera C. Rubin Observatory is a flagship dark matter experiment is an essential pathway toward understanding the physical nature of dark matter. In the past two decades, wide-field astronomical surveys and terrestrial laboratories have jointly created a phase transition in the ecosystem of dark matter models and probes. Going forward, any robust understanding of dark matter requires astronomical observations, which still provide the only empirical evidence for dark matter to date. We have a unique opportunity right now to create a dark matter experiment with Rubin Observatory Legacy Survey of Space and Time (LSST). This experiment will be a coordinated effort to perform dark matter research, and provide a large collaborative team of scientists with the necessary organizational and funding supports. This approach leverages existing investments in Rubin. Studies of dark matter with Rubin LSST will also guide the design of, and confirm the results from, other dark matter experiments. Supporting a collaborative team to carry out a dark matter experiment with Rubin LSST is the key to achieving the dark matter science goals that have already been identified as high priority by the high-energy physics and astronomy communities
Snowmass2021: Vera C. Rubin Observatory as a Flagship Dark Matter Experiment
Establishing that Vera C. Rubin Observatory is a flagship dark matter experiment is an essential pathway toward understanding the physical nature of dark matter. In the past two decades, wide-field astronomical surveys and terrestrial laboratories have jointly created a phase transition in the ecosystem of dark matter models and probes. Going forward, any robust understanding of dark matter requires astronomical observations, which still provide the only empirical evidence for dark matter to date. We have a unique opportunity right now to create a dark matter experiment with Rubin Observatory Legacy Survey of Space and Time (LSST). This experiment will be a coordinated effort to perform dark matter research, and provide a large collaborative team of scientists with the necessary organizational and funding supports. This approach leverages existing investments in Rubin. Studies of dark matter with Rubin LSST will also guide the design of, and confirm the results from, other dark matter experiments. Supporting a collaborative team to carry out a dark matter experiment with Rubin LSST is the key to achieving the dark matter science goals that have already been identified as high priority by the high-energy physics and astronomy communities
Snowmass Theory Frontier: Astrophysics and Cosmology
International audienceWe summarize progress made in theoretical astrophysics and cosmology over the past decade and areas of interest for the coming decade. This Report is prepared as the TF09 "Astrophysics and Cosmology" topical group summary for the Theory Frontier as part of the Snowmass 2021 process