Astrophysical Interplay in Dark Matter Searches

I discuss recent progress in dark matter searches, focusing in particular on how rigorous modeling the dark matter distribution in the Galaxy and in its satellite galaxies improves our interpretation of the limits on the annihilation and elastic scattering cross sections. Looking forward to indirect and direct searches that will operate during the next decade, I review methods for extracting the properties of the dark matter in these experiments in the presence of unknown Galactic model parameters.Comment: Contribution to proceedings of CETUP* workshop in Lead, South Dakota, July 10 - August 1, 201

Kinematics of Milky Way Satellites: Mass Estimates, Rotation Limits, and Proper Motions

In the past several years high resolution kinematic data sets from Milky Way satellite galaxies have confirmed earlier indications that these systems are dark matter dominated objects. Further understanding of what these galaxies reveal about cosmology and the small scale structure of dark matter relies in large part on a more detailed interpretation of their internal kinematics. This article discusses a likelihood formalism that extracts important quantities from the kinematic data, including the amplitude of rotation, proper motion, and the mass distribution. In the simplest model the projected error on the rotational amplitude is shown to be $\sim 0.5$ km s$^{-1}$ with $\sim 10^3$ stars from either classical or ultra-faint satellites. The galaxy Sculptor is analyzed for the presence of a rotational signal; no significant detection of rotation is found, and given this result limits are derived on the Sculptor proper motion. A criteria for model selection is discussed that determines the parameters required to describe the dark matter halo density profiles and the stellar velocity anisotropy. Applied to four data sets with a wide range of velocities, the likelihood is found to be more sensitive to variations in the slope of the dark matter density profile than variations in the velocity anisotropy. Models with variable radial velocity anisotropy are shown to be preferred relative to those in which this quantity is constant at all radii in the galaxy.Comment: 20 pages. To appear in Advances in Astronomy, Dwarf-Galaxy Cosmology issu

Megaton Water Cerenkov Detectors and Astrophysical Neutrinos

Although formal proposals have not yet been made, the UNO and Hyper-Kamiokande projects are being developed to follow-up the tremendously successful program at Super-Kamiokande using a detector that is 20-50 times larger. The potential of such a detector to continue the study of astrophysical neutrinos is considered and contrasted with the program for cubic kilometer neutrino observatories.Comment: 4 pages Submitted to the Proceedings of the 2004 Neutrino Oscillation Workshop, Otranto Ital

New Constraints on Isospin-Violating Dark Matter

We derive bounds on the dark matter annihilation cross-section for low-mass (5-20 GeV) dark matter annihilating primarily to up or down quarks, using the Fermi-LAT bound on gamma-rays from Milky Way satellites. For models in which dark matter-Standard Model interactions are mediated by particular contact operators, we show that these bounds can be directly translated into bounds on the dark matter-proton scattering cross-section. For isospin-violating dark matter, these constraints are tight enough to begin to constrain the parameter-space consistent with experimental signals of low-mass dark matter. We discuss possible models that can evade these bounds.Comment: 6 pages, 2 figures, LaTeX, some clarifications and minor errors corrected, citations adde

Implication of neutrino backgrounds on the reach of next generation dark matter direct detection experiments

As direct dark matter experiments continue to increase in size, they will become sensitive to neutrinos from astrophysical sources. For experiments that do not have directional sensitivity, coherent neutrino scattering (CNS) from several sources represents an important background to understand, as it can almost perfectly mimic an authentic WIMP signal. Here we explore in detail the effect of neutrino backgrounds on the discovery potential of WIMPs over the entire mass range of 500 MeV to 10 TeV. We show that, given the theoretical and measured uncertainties on the neutrino backgrounds, direct detection experiments lose sensitivity to light (~10 GeV) and heavy (~100 GeV) WIMPs with a spin-independent cross section below 10^{-45} cm^2 and 10^{-49} cm^2, respectively.Comment: 15 pages, 12 figures, 7Be fluxes revised, conclusions unchange

Solar neutrino physics with low-threshold dark matter detectors

Dark matter detectors will soon be sensitive to Solar neutrinos via two distinct channels: coherent neutrino-nucleus scattering and neutrino electron elastic scattering. We establish an analysis method for extracting Solar model properties and neutrino properties from these measurements, including the possible effects of sterile neutrinos which have been hinted at by some reactor experiments and cosmological measurements. Even including sterile neutrinos, through the coherent scattering channel a 1 ton-year exposure with a low-threshold Germanium detector could improve on the current measurement of the normalization of the $^8$B Solar neutrino flux down to 3% or less. Combining with the elastic scattering data will provide constraints on both the high and low energy survival probability, and will improve on the uncertainty on the active-to-sterile mixing angle by a factor of two. This sensitivity to active-to-sterile transitions is competitive and complementary to forthcoming dedicated short baseline sterile neutrino searches with nuclear decays.Comment: 12 pages, 4 figures, 3 table

WIMP searches with gamma rays in the Fermi era: challenges, methods and results

The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments.Comment: 72 pages, 7 figures, Invited review for Journal of Experimental and Theoretical Physics,v3: added a few references, addressed referee comment