L. Strigari - Texas A&M Univ.

L. Strigari
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Name
L. Strigari
Affiliation
Texas A&M Univ.
City
College Station
Country
United States

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Cosmology and Nongalactic Astrophysics (34)
 
High Energy Physics - Phenomenology (32)
 
Astrophysics of Galaxies (21)
 
High Energy Astrophysical Phenomena (18)
 
High Energy Physics - Experiment (11)
 
Nuclear Theory (2)
 
Physics - Instrumentation and Detectors (2)
 
Nuclear Experiment (2)
 
Earth and Planetary Astrophysics (1)

Publications Authored By L. Strigari

Non-standard neutrino interactions (NSI) affect both their propagation through matter and their detection, with bounds on NSI parameters coming from various astrophysical and terrestrial neutrino experiments. In this paper, we show that NSI can be probed in future direct dark matter detection experiments through both elastic neutrino-electron scattering and coherent neutrino-nucleus scattering, and that these channels provide complementary probes of NSI. We show NSI can increase the event rate due to solar neutrinos, with a sharp increase for lower nuclear recoil energy thresholds that are within reach for upcoming detectors. Read More

For models in which dark matter annihilation is Sommerfeld-enhanced, the annihilation cross section increases at low relative velocities. Dwarf spheroidal galaxies (dSphs) have low characteristic dark matter particle velocities and are thus ideal candidates to study such models. In this paper we model the dark matter phase space of dSphs as isotropic and spherically-symmetric, and determine the $J$-factors for several of the most important targets for indirect dark matter searches. Read More

We investigate constraints on the abundance of primordial black holes (PBHs) in the mass range 10^{15}-10^{17} g using data from the Cosmic Microwave Background (CMB) and MeV extragalactic gamma-ray background (EGB). Hawking radiation from PBHs with lifetime greater than the age of the universe leaves an imprint on the CMB through modification of the ionization history and the damping of CMB anisotropies. Using a model for redshift dependent energy injection efficiencies, we show that a combination of temperature and polarization data from Planck provides the strongest constraint on the abundance of PBHs for masses \sim 10^{15}-10^{16} g, while the EGB dominates for masses \gtrsim 10^{16} g. Read More

Light neutral mediators, with mass $\lesssim 1$ GeV, are common features of extensions to the Standard Model (SM). Current astrophysical and terrestrial experiments have constrained the model parameter space, and planned experiments around the world promise continued improvement in sensitivity. In this paper we study the prospects for probing light neutral mediators using terrestrial stopped pion and reactor sources in combination with ultra-low threshold nuclear and electron recoil detectors. Read More

We search for excess gamma-ray emission coincident with the positions of confirmed and candidate Milky Way satellite galaxies using 6 years of data from the Fermi Large Area Telescope (LAT). Our sample of 45 stellar systems includes 28 kinematically confirmed dark-matter-dominated dwarf spheroidal galaxies (dSphs) and 17 recently discovered systems that have photometric characteristics consistent with the population of known dSphs. For each of these targets, the relative predicted gamma-ray flux due to dark matter annihilation is taken from kinematic analysis if available, and estimated from a distance-based scaling relation otherwise, assuming that the stellar systems are dark-matter-dominated dSphs. Read More

We use the APOSTLE cosmological hydrodynamic simulations to examine the effects of tidal stripping on cold dark matter (CDM) sub haloes that host three of the most luminous Milky Way (MW) dwarf satellite galaxies: Fornax, Sculptor, and Leo I. We identify simulated satellites that match the observed spatial and kinematic distributions of stars in these galaxies, and track their evolution after infall. We find $\sim$ 30$\%$ of subhaloes hosting satellites with present-day stellar mass $10^6$-$10^8$ $M_{\odot}$ experience $>20\%$ stellar mass loss after infall. Read More

The proposed Mitchell Institute Neutrino Experiment at Reactor (MINER) experiment at the Nuclear Science Center at Texas A&M University will search for coherent elastic neutrino-nucleus scattering within close proximity (about 2 meters) of a 1 MW TRIGA nuclear reactor core using low threshold, cryogenic germanium and silicon detectors. Given the Standard Model cross section of the scattering process and the proposed experimental proximity to the reactor, as many as 5 to 20 events/kg/day are expected. We discuss the status of preliminary measurements to characterize the main backgrounds for the proposed experiment. Read More

Line-of-sight integrals of the squared density, commonly called the J-factor, are essential for inferring dark matter annihilation signals. The J-factors of dark matter-dominated dwarf spheroidal satellite galaxies (dSphs) have typically been derived using Bayesian techniques, which for small data samples implies that a choice of priors constitutes a non-negligible systematic uncertainty. Here we report the development of a new fully frequentist approach to construct the profile likelihood of the J-factor. Read More

We analyze future direct data matter detection experiments using Effective Field Theory (EFT) operators with light, $\lesssim 100$ MeV mass mediators. We compare the nuclear recoil energy spectra from these operators to the predicted high energy solar neutrino spectrum. A set of operators that generate spectra similar to the neutrino background is identified, however this set is distinct from those that mimic the neutrino background for heavy, $\gtrsim 100$ MeV mass mediators. Read More

By lowering their energy threshold direct dark matter searches can reach the neutrino floor with experimental technology now in development. The 7Be flux can be detected with $\sim 10$ eV nuclear recoil energy threshold and 50 kg-yr exposure. The pep flux can be detected with $\sim 3$ ton-yr exposure, and the first detection of the CNO flux is possible with similar exposure. Read More

Distinguishing a dark matter interaction from an astrophysical neutrino-induced interaction will be major challenge for future direct dark matter searches. In this paper, we consider this issue within non-relativistic Effective Field Theory (EFT), which provides a well-motivated theoretical framework for determining nuclear responses to dark matter scattering events. We analyze the nuclear energy recoil spectra from the different dark matter-nucleon EFT operators, and compare to the nuclear recoil energy spectra that is predicted to be induced by astrophysical neutrino sources. Read More

2016Feb
Authors: R. Adhikari, M. Agostini, N. Anh Ky, T. Araki, M. Archidiacono, M. Bahr, J. Baur, J. Behrens, F. Bezrukov, P. S. Bhupal Dev, D. Borah, A. Boyarsky, A. de Gouvea, C. A. de S. Pires, H. J. de Vega, A. G. Dias, P. Di Bari, Z. Djurcic, K. Dolde, H. Dorrer, M. Durero, O. Dragoun, M. Drewes, G. Drexlin, Ch. E. Düllmann, K. Eberhardt, S. Eliseev, C. Enss, N. W. Evans, A. Faessler, P. Filianin, V. Fischer, A. Fleischmann, J. A. Formaggio, J. Franse, F. M. Fraenkle, C. S. Frenk, G. Fuller, L. Gastaldo, A. Garzilli, C. Giunti, F. Glück, M. C. Goodman, M. C. Gonzalez-Garcia, D. Gorbunov, J. Hamann, V. Hannen, S. Hannestad, S. H. Hansen, C. Hassel, J. Heeck, F. Hofmann, T. Houdy, A. Huber, D. Iakubovskyi, A. Ianni, A. Ibarra, R. Jacobsson, T. Jeltema, J. Jochum, S. Kempf, T. Kieck, M. Korzeczek, V. Kornoukhov, T. Lachenmaier, M. Laine, P. Langacker, T. Lasserre, J. Lesgourgues, D. Lhuillier, Y. F. Li, W. Liao, A. W. Long, M. Maltoni, G. Mangano, N. E. Mavromatos, N. Menci, A. Merle, S. Mertens, A. Mirizzi, B. Monreal, A. Nozik, A. Neronov, V. Niro, Y. Novikov, L. Oberauer, E. Otten, N. Palanque-Delabrouille, M. Pallavicini, V. S. Pantuev, E. Papastergis, S. Parke, S. Pascoli, S. Pastor, A. Patwardhan, A. Pilaftsis, D. C. Radford, P. C. -O. Ranitzsch, O. Rest, D. J. Robinson, P. S. Rodrigues da Silva, O. Ruchayskiy, N. G. Sanchez, M. Sasaki, N. Saviano, A. Schneider, F. Schneider, T. Schwetz, S. Schönert, S. Scholl, F. Shankar, R. Shrock, N. Steinbrink, L. Strigari, F. Suekane, B. Suerfu, R. Takahashi, N. Thi Hong Van, I. Tkachev, M. Totzauer, Y. Tsai, C. G. Tully, K. Valerius, J. W. F. Valle, D. Venos, M. Viel, M. Vivier, M. Y. Wang, C. Weinheimer, K. Wendt, L. Winslow, J. Wolf, M. Wurm, Z. Xing, S. Zhou, K. Zuber

We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved - cosmology, astrophysics, nuclear, and particle physics - in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. Read More

2016Jan
Authors: M. L. Ahnen, S. Ansoldi, L. A. Antonelli, P. Antoranz, A. Babic, B. Banerjee, P. Bangale, U. Barres de Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, E. Bernardini, B. Biasuzzi, A. Biland, O. Blanch, S. Bonnefoy, G. Bonnoli, F. Borracci, T. Bretz, E. Carmona, A. Carosi, A. Chatterjee, R. Clavero, P. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, E. de Oña Wilhelmi, C. Delgado Mendez, F. Di Pierro, D., Dominis Prester, D. Dorner, M. Doro, S. Einecke, D. Eisenacher Glawion, D. Elsaesser, A. Fernández-Barral, D. Fidalgo, M. V. Fonseca, L. Font, K. Frantzen, C. Fruck, D. Galindo, R. J. García López, M. Garczarczyk, D. Garrido Terrats, M. Gaug, P. Giammaria, N. Godinović, A. González Muñoz, D. Guberman, A. Hahn, Y. Hanabata, M. Hayashida, J. Herrera, J. Hose, D. Hrupec, G. Hughes, W. Idec, K. Kodani, Y. Konno, H. Kubo, J. Kushida, A. La Barbera, D. Lelas, E. Lindfors, S. Lombardi, F. Longo, M. López, R. López-Coto, A. López-Oramas, E. Lorenz, P. Majumdar, M. Makariev, K. Mallot, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, B. Marcote, M. Mariotti, M. Martínez, D. Mazin, U. Menzel, J. M. Miranda, R. Mirzoyan, A. Moralejo, E. Moretti, D. Nakajima, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, K. Nilsson, K. Nishijima, K. Noda, R. Orito, A. Overkemping, S. Paiano, J. Palacio, M. Palatiello, D. Paneque, R. Paoletti, J. M. Paredes, X. Paredes-Fortuny, M. Persic, J. Poutanen, P. G. Prada Moroni, E. Prandini, I. Puljak, W. Rhode, M. Ribó, J. Rico, J. Rodriguez Garcia, T. Saito, K. Satalecka, C. Schultz, T. Schweizer, S. N. Shore, A. Sillanpää, J. Sitarek, I. Snidaric, D. Sobczynska, A. Stamerra, T. Steinbring, M. Strzys, L. Takalo, H. Takami, F. Tavecchio, P. Temnikov, T. Terzić, D. Tescaro, M. Teshima, J. Thaele, D. F. Torres, T. Toyama, A. Treves, V. Verguilov, I. Vovk, J. E. Ward, M. Will, M. H. Wu, R. Zanin, J. Aleksić, M. Wood, B. Anderson, E. D. Bloom, J. Cohen-Tanugi, A. Drlica-Wagner, M. N. Mazziotta, M. Sánchez-Conde, L. Strigari

We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. Read More

We discuss prospects for probing short-range sterile neutrino oscillation using neutrino-nucleus coherent scattering with ultra-low energy ($\sim 10$ eV - 100 eV) recoil threshold cryogenic Ge detectors. The analysis is performed in the context of a specific and contemporary reactor-based experimental proposal, developed in cooperation with the Nuclear Science Center at Texas A\&M University, and references developing technology based upon economical and scalable detector arrays. The baseline of the experiment is substantially shorter than existing measurements, as near as about 2 meters from the reactor core, and is moreover variable, extending continuously up to a range of about 10 meters. Read More

We use cosmological simulations to identify dark matter subhalo host candidates of the Fornax dwarf spheroidal galaxy using the stellar kinematic properties of Fornax. We consider cold dark matter (CDM), warm dark matter (WDM), and decaying dark matter (DDM) simulations for our models of structure formation. The subhalo candidates in CDM typically have smaller mass and higher concentrations at z = 0 than the corresponding candidates in WDM and DDM. Read More

We discuss prospects for probing Z-prime and non-standard neutrino interactions using neutrino-nucleus coherent scattering with ultra-low energy (~ 10 eV) threshold Si and Ge detectors. The analysis is performed in the context of a specific and contemporary reactor-based experimental proposal, developed in cooperation with the Nuclear Science Center at Texas A&M University, and referencing available technology based upon economical and scalable detector arrays. For expected exposures, we show that sensitivity to the Z-prime mass is on the order of several TeV, and is complementary to the LHC search with low mass detectors in the near term. Read More

Many particle dark matter models predict that the dark matter undergoes cascade annihilations, i.e. the annihilation products are 4-body final states. Read More

The search for weakly interacting massive particles (WIMPs) by direct detection faces an encroaching background due to coherent neutrino-nucleus scattering. As the sensitivity of these experiments improves, the question of how to best distinguish a dark matter signal from neutrinos will become increasingly important. A proposed method of overcoming this so-called 'neutrino floor' is to utilize the directional signature that both neutrino and dark matter induced recoils possess. Read More

The recent excess in the CMS measurements of $eejj$ and $e\nu jj$ channels and the emergence of PeV comsic neutrino events at the IceCube experiment share an intriguing implication for a leptoquark with a 600-650 GeV mass. We investigate the CMS constraints on the flavor structure of a scenario with the minimal leptoquark Yukawa couplings and correlate such a scenario to the resonant enhancement in the very high energy shower event rates at the IceCube. We find for a single leptoquark, the CMS signals require large couplings to the third generation leptons. Read More

2015Apr
Affiliations: 1The DES Collaboration, 2The DES Collaboration, 3The DES Collaboration, 4The DES Collaboration, 5The DES Collaboration, 6The DES Collaboration, 7The DES Collaboration, 8The DES Collaboration, 9The DES Collaboration, 10The DES Collaboration, 11The DES Collaboration, 12The DES Collaboration, 13The DES Collaboration, 14The DES Collaboration, 15The DES Collaboration, 16The DES Collaboration, 17The DES Collaboration, 18The DES Collaboration, 19The DES Collaboration, 20The DES Collaboration, 21The DES Collaboration, 22The DES Collaboration, 23The DES Collaboration, 24The DES Collaboration, 25The DES Collaboration, 26The DES Collaboration, 27The DES Collaboration, 28The DES Collaboration, 29The DES Collaboration, 30The DES Collaboration, 31The DES Collaboration, 32The DES Collaboration, 33The DES Collaboration, 34The DES Collaboration, 35The DES Collaboration, 36The DES Collaboration, 37The DES Collaboration, 38The DES Collaboration, 39The DES Collaboration, 40The DES Collaboration, 41The DES Collaboration, 42The DES Collaboration, 43The DES Collaboration, 44The DES Collaboration, 45The DES Collaboration, 46The DES Collaboration, 47The DES Collaboration, 48The DES Collaboration, 49The DES Collaboration, 50The DES Collaboration, 51The DES Collaboration, 52The DES Collaboration, 53The DES Collaboration, 54The DES Collaboration, 55The DES Collaboration, 56The DES Collaboration, 57The DES Collaboration, 58The DES Collaboration, 59The DES Collaboration, 60The DES Collaboration, 61The DES Collaboration, 62The DES Collaboration, 63The DES Collaboration, 64The DES Collaboration, 65The DES Collaboration, 66The DES Collaboration, 67The DES Collaboration, 68The DES Collaboration, 69The DES Collaboration, 70The DES Collaboration, 71The DES Collaboration, 72The DES Collaboration

We present Magellan/M2FS, VLT/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of 62.8 +/- 0. Read More

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. Read More

2015Mar
Authors: The Fermi-LAT Collaboration, The DES Collaboration, :, A. Drlica-Wagner, A. Albert, K. Bechtol, M. Wood, L. Strigari, M. Sanchez-Conde, L. Baldini, R. Essig, J. Cohen-Tanugi, B. Anderson, R. Bellazzini, E. D. Bloom, R. Caputo, C. Cecchi, E. Charles, J. Chiang, A. de Angelis, S. Funk, P. Fusco, F. Gargano, N. Giglietto, F. Giordano, S. Guiriec, M. Gustafsson, M. Kuss, F. Loparco, P. Lubrano, N. Mirabal, T. Mizuno, A. Morselli, T. Ohsugi, E. Orlando, M. Persic, S. Raino, N. Sehgal, F. Spada, D. J. Suson, G. Zaharijas, S. Zimmer, T. Abbott, S. Allam, E. Balbinot, A. H. Bauer, A. Benoit-Levy, R. A. Bernstein, G. M. Bernstein, E. Bertin, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, F. J. Castander, R. Covarrubias, C. B. D'Andrea, L. N. da Costa, D. L. DePoy, S. Desai, H. T. Diehl, C. E Cunha, T. F. Eifler, J. Estrada, A. E. Evrard, A. Fausti Neto, E. Fernandez, D. A. Finley, B. Flaugher, J. Frieman, E. Gaztanaga, D. Gerdes, D. Gruen, R. A. Gruendl, G. Gutierrez, K. Honscheid, B. Jain, D. James, T. Jeltema, S. Kent, R. Kron, K. Kuehn, N. Kuropatkin, O. Lahav, T. S. Li, E. Luque, M. A. G. Maia, M. Makler, M. March, J. Marshall, P. Martini, K. W. Merritt, C. Miller, R. Miquel, J. Mohr, E. Neilsen, B. Nord, R. Ogando, J. Peoples, D. Petravick, A. Pieres, A. A. Plazas, A. Queiroz, A. K. Romer, A. Roodman, E. S. Rykoff, M. Sako, E. Sanchez, B. Santiago, V. Scarpine, M. Schubnell, I. Sevilla, R. C. Smith, M. Soares-Santos, F. Sobreira, E. Suchyta, M. E. C. Swanson, G. Tarle, J. Thaler, D. Thomas, D. Tucker, A. Walker, R. H. Wechsler, W. Wester, P. Williams, B. Yanny, J. Zuntz

Due to their proximity, high dark-matter content, and apparent absence of non-thermal processes, Milky Way dwarf spheroidal satellite galaxies (dSphs) are excellent targets for the indirect detection of dark matter. Recently, eight new dSph candidates were discovered using the first year of data from the Dark Energy Survey (DES). We searched for gamma-ray emission coincident with the positions of these new objects in six years of Fermi Large Area Telescope data. Read More

In this work, we sift a simple supersymmetric framework of late invisible decays to/of the gravitino. We investigate two cases where the gravitino is the lightest supersymmetric particle or the next-to-lightest supersymmetric particle. The next-to-lightest supersymmetric particle decays into two dark matter candidates and has a long lifetime due to gravitationally suppressed interactions. Read More

We present the results of a search for unidentified emission lines in deep Suzaku X-ray spectra for the central regions of the four X-ray brightest galaxy clusters: Perseus, Coma, Virgo and Ophiuchus. We employ an optimized energy range for our analysis (3.2-5. Read More

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. Read More

Direct detection dark matter experiments looking for WIMP-nucleus elastic scattering will soon be sensitive to an irreducible background from neutrinos which will drastically affect their discovery potential. Here we explore how the neutrino background will affect future ton-scale experiments considering both spin-dependent and spin-independent interactions. We show that combining data from experiments using different targets can improve the dark matter discovery potential due to target complementarity. Read More

The Sculptor dwarf spheroidal galaxy contains two distinct stellar populations: one metal-rich and the other metal-poor. Several authors have argued that in order for these two populations to reside in the same gravitational potential, the dark matter halo must have a core similar to that observed in the stellar count profile. This would rule out the cuspy Navarro-Frenk-White (NFW) density profiles predicted for halos and subhalos by dark matter only simulations of the Lambda Cold Dark Matter (Lambda-CDM) cosmological model. Read More

We present a set of N-body simulations of a class of models in which an unstable dark matter particle decays into a stable non-interacting dark matter particle, with decay lifetime comparable to the Hubble time. We study the effects of the kinematic recoil velocity received by the stable dark matter on the structures of dark matter halos ranging from galaxy-cluster to Milky Way mass scales. For Milky Way-mass halos, we use high-resolution, zoom-in simulations to explore the effects of decays on Galactic substructure. Read More

2013Oct
Authors: The Fermi-LAT Collaboration, :, M. Ackermann, A. Albert, B. Anderson, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, E. Bissaldi, E. D. Bloom, E. Bonamente, A. Bouvier, T. J. Brandt, J. Bregeon, M. Brigida, P. Bruel, R. Buehler, S. Buson, G. A. Caliandro, R. A. Cameron, M. Caragiulo, P. A. Caraveo, C. Cecchi, E. Charles, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, F. D'Ammando, A. de Angelis, C. D. Dermer, S. W. Digel, E. do Couto e Silva, P. S. Drell, A. Drlica-Wagner, R. Essig, C. Favuzzi, E. C. Ferrara, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, M. Giroletti, G. Godfrey, G. A. Gomez-Vargas, I. A. Grenier, S. Guiriec, M. Gustafsson, M. Hayashida, E. Hays, J. Hewitt, R. E. Hughes, T. Jogler, T. Kamae, J. Knödlseder, D. Kocevski, M. Kuss, . Larsson, L. Latronico, M. Llena Garde, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, G. Martinez, M. Mayer, M. N. Mazziotta, P. F. Michelson, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, R. Nemmen, E. Nuss, T. Ohsugi, E. Orlando, J. F. Ormes, J. S. Perkins, F. Piron, G. Pivato, T. A. Porter, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, S. Ritz, M. Sànchez-Conde, N. Sehgal, C. Sgrò, E. J. Siskind, P. Spinelli, L. Strigari, D. J. Suson, H. Tajima, H. Takahashi, J. B. Thayer, L. Tibaldo, M. Tinivella, D. F. Torres, Y. Uchiyama, T. L. Usher, J. Vandenbroucke, G. Vianello, V. Vitale, M. Werner, B. L. Winer, K. S. Wood, M. Wood, G. Zaharijas, S. Zimmer

The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. Read More

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. Read More

Several direct detection experiments, including recently CDMS-II, have reported signals consistent with 5 to 10 GeV dark matter (DM) that appear to be in tension with null results from XENON and LUX experiments; these indicate a careful review of the theoretical basis, including the galactic DM velocity distribution function (VDF). We establish a VDF parameter space from DM-only cosmological simulations and illustrate that seemingly contradictory experimental results can be made consistent within this parameter space. Future experimental limits should be reported after they are marginalized over a range of VDF parameters. Read More

We explore systematic biases in the identification of dark matter in future direct detection experiments and compare the reconstructed dark matter properties when assuming a self-consistent dark matter distribution function and the standard Maxwellian velocity distribution. We find that the systematic bias on the dark matter mass and cross-section determination arising from wrong assumptions for its distribution function is of order ~1\sigma. A much larger systematic bias can arise if wrong assumptions are made on the underlying Milky Way mass model. Read More

For nearly a century, more mass has been measured in galaxies than is contained in the luminous stars and gas. Through continual advances in observations and theory, it has become clear that the dark matter in galaxies is not comprised of known astronomical objects or baryonic matter, and that identification of it is certain to reveal a profound connection between astrophysics, cosmology, and fundamental physics. The best explanation for dark matter is that it is in the form of a yet undiscovered particle of nature, with experiments now gaining sensitivity to the most well-motivated particle dark matter candidates. Read More

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. Read More

We examine the Velocity Distribution Function (VDF) in dark matter halos from Milky Way to cluster mass scales. We identify an empirical model for the VDF with a wider peak and a steeper tail than a Maxwell--Boltzmann distribution, and discuss physical explanations. We quantify sources of scatter in the VDF of cosmological halos and their implication for direct detection of dark matter. Read More

We estimate that there may be up to ~10^5 compact objects in the mass range 10^{-8} -10^{-2} solar mass per main sequence star that are unbound to a host star in the Galaxy. We refer to these objects as nomads; in the literature a subset of these are sometimes called free-floating or rogue planets. Our estimate for the number of Galactic nomads is consistent with a smooth extrapolation of the mass function of unbound objects above the Jupiter-mass scale, the stellar mass density limit, and the metallicity of the interstellar medium. Read More

2012Jan
Authors: The Fermi LAT Collaboration, M. Ackermann, A. Albert, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, E. Bottacini, T. J. Brandt, J. Bregeon, M. Brigida, P. Bruel, R. Buehler, T. H. Burnett, G. A. Caliandro, R. A. Cameron, P. A. Caraveo, J. M. Casandjian, C. Cecchi, E. Charles, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, S. Cutini, F. de Palma, C. D. Dermer, S. W. Digel, E. do Couto e Silva, P. S. Drell, A. Drlica-Wagner, R. Essig, L. Falletti, C. Favuzzi, S. J. Fegan, W. B. Focke, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, S. Guiriec, M. Gustafsson, D. Hadasch, M. Hayashida, X. Hou, R. E. Hughes, R. P. Johnson, A. S. Johnson, T. Kamae, H. Katagiri, J. Kataoka, J. Knodlseder, M. Kuss, J. Lande, L. Latronico, S. -H. Lee, A. M. Lionetto, M. Llena Garde, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, M. N. Mazziotta, J. E. McEnery, P. F. Michelson, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, M. Naumann-Godo, J. P. Norris, E. Nuss, T. Ohsugi, A. Okumura, E. Orlando, J. F. Ormes, M. Ozaki, D. Paneque, V. Pelassa, M. Pierbattista, F. Piron, G. Pivato, T. A. Porter, S. Raino, R. Rando, M. Razzano, A. Reimer, O. Reimer, S. Ritz, H. F. -W. Sadrozinski, N. Sehgal, C. Sgro, E. J. Siskind, P. Spinelli, L. Strigari, D. J. Suson, H. Tajima, H. Takahashi, T. Tanaka, J. G. Thayer, J. B. Thayer, L. Tibaldo, M. Tinivella, D. F. Torres, E. Troja, Y. Uchiyama, T. L. Usher, J. Vandenbroucke, V. Vasileiou, G. Vianello, V. Vitale, A. P. Waite, P. Wang, B. L. Winer, K. S. Wood, Z. Yang, S. Zalewski, S. Zimmer

Numerical simulations based on the Lambda-CDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the gamma-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard gamma-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. Read More

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. Read More

We present a search for Galactic dark matter (DM) satellites using the Large Area Telescope (LAT). N-body simulations based on the Lambda-CDM model of cosmology predict a large number of as yet unobserved Galactic DM satellites. These satellites could potentially produce gamma rays through the self-annihilation of DM particles. Read More

We study the abundance of satellites akin to the brightest, classical dwarf spheroidals around galaxies similar in magnitude and isolation to the Milky Way and M31 in the Sloan Digital Sky Survey. From a combination of photometric and spectroscopic redshifts, we bound the mean and the intrinsic scatter in the number of satellites down to ten magnitudes fainter than the Milky Way. Restricting to magnitudes brighter than Sagittarius, we show that the Milky Way is not a significant statistical outlier in its population of classical dwarf spheroidals. Read More

2011Aug
Authors: The Fermi-LAT Collaboration, :, M. Ackermann, M. Ajello, A. Albert, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, J. Bregeon, M. Brigida, P. Bruel, R. Buehler, T. H. Burnett, S. Buson, G. A. Caliandro, R. A. Cameron, B. Canadas, P. A. Caraveo, J. M. Casandjian, C. Cecchi, E. Charles, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, S. Cutini, A. de Angelis, F. de Palma, C. D. Dermer, S. W. Digel, E. do Couto e Silva, P. S. Drell, A. Drlica-Wagner, L. Falletti, C. Favuzzi, S. J. Fegan, E. C. Ferrara, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, S. Guiriec, M. Gustafsson, D. Hadasch, M. Hayashida, E. Hays, R. E. Hughes, T. E. Jeltema, G. Johannesson, R. P. Johnson, A. S. Johnson, T. Kamae, H. Katagiri, J. Kataoka, J. Knödlseder, M. Kuss, J. Lande, L. Latronico, A. M. Lionetto, M. Llena Garde, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, M. N. Mazziotta, J. E. McEnery, J. Mehault, P. F. Michelson, W. Mitthumsiri, T. Mizuno, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, M. Naumann-Godo, J. P. Norris, E. Nuss, T. Ohsugi, A. Okumura, N. Omodei, E. Orlando, J. F. Ormes, M. Ozaki, D. Paneque, D. Parent, M. Pesce-Rollins, M. Pierbattista, F. Piron, G. Pivato, T. A. Porter, S. Profumo, S. Raino, M. Razzano, A. Reimer, O. Reimer, S. Ritz, M. Roth, H. F. -W. Sadrozinski, C. Sbarra, J. D. Scargle, T. L. Schalk, C. Sgro, E. J. Siskind, G. Spandre, P. Spinelli, L. Strigari, D. J. Suson, H. Tajima, H. Takahashi, T. Tanaka, J. G. Thayer, J. B. Thayer, D. J. Thompson, L. Tibaldo, M. Tinivella, D. F. Torres, E. Troja, Y. Uchiyama, J. Vandenbroucke, V. Vasileiou, G. Vianello, V. Vitale, A. P. Waite, P. Wang, B. L. Winer, K. S. Wood, M. Wood, Z. Yang, S. Zimmer, M. Kaplinghat, G. D. Martinez

Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Read More

2011Mar
Authors: The MAGIC Collaboration, J. Aleksić1, E. A. Alvarez2, L. A. Antonelli3, P. Antoranz4, M. Asensio5, M. Backes6, J. A. Barrio7, D. Bastieri8, J. Becerra González9, W. Bednarek10, A. Berdyugin11, K. Berger12, E. Bernardini13, A. Biland14, O. Blanch15, R. K. Bock16, A. Boller17, G. Bonnoli18, D. Borla Tridon19, I. Braun20, T. Bretz21, A. Cañellas22, E. Carmona23, A. Carosi24, P. Colin25, E. Colombo26, J. L. Contreras27, J. Cortina28, L. Cossio29, S. Covino30, F. Dazzi31, A. De Angelis32, E. De Cea del Pozo33, B. De Lotto34, C. Delgado Mendez35, A. Diago Ortega36, M. Doert37, A. Domínguez38, D. Dominis Prester39, D. Dorner40, M. Doro41, D. Elsaesser42, D. Ferenc43, M. V. Fonseca44, L. Font45, C. Fruck46, R. J. García López47, M. Garczarczyk48, D. Garrido49, G. Giavitto50, N. Godinović51, D. Hadasch52, D. Häfner53, A. Herrero54, D. Hildebrand55, D. Höhne-Mönch56, J. Hose57, D. Hrupec58, B. Huber59, T. Jogler60, S. Klepser61, T. Krähenbühl62, J. Krause63, A. La Barbera64, D. Lelas65, E. Leonardo66, E. Lindfors67, S. Lombardi68, M. López69, E. Lorenz70, M. Makariev71, G. Maneva72, N. Mankuzhiyil73, K. Mannheim74, L. Maraschi75, M. Mariotti76, M. Martínez77, D. Mazin78, M. Meucci79, J. M. Miranda80, R. Mirzoyan81, H. Miyamoto82, J. Moldón83, A. Moralejo84, P. Munar-Adrover85, D. Nieto86, K. Nilsson87, R. Orito88, I. Oya89, S. Paiano90, D. Paneque91, R. Paoletti92, S. Pardo93, J. M. Paredes94, S. Partini95, M. Pasanen96, F. Pauss97, M. A. Perez-Torres98, M. Persic99, L. Peruzzo100, M. Pilia101, J. Pochon102, F. Prada103, P. G. Prada Moroni104, E. Prandini105, I. Puljak106, I. Reichardt107, R. Reinthal108, W. Rhode109, M. Ribó110, J. Rico111, S. Rügamer112, A. Saggion113, K. Saito114, T. Y. Saito115, M. Salvati116, K. Satalecka117, V. Scalzotto118, V. Scapin119, C. Schultz120, T. Schweizer121, M. Shayduk122, S. N. Shore123, A. Sillanpää124, J. Sitarek125, D. Sobczynska126, F. Spanier127, S. Spiro128, A. Stamerra129, B. Steinke130, J. Storz131, N. Strah132, T. Surić133, L. Takalo134, H. Takami135, F. Tavecchio136, P. Temnikov137, T. Terzić138, D. Tescaro139, M. Teshima140, M. Thom141, O. Tibolla142, D. F. Torres143, A. Treves144, H. Vankov145, P. Vogler146, R. M. Wagner147, Q. Weitzel148, V. Zabalza149, F. Zandanel150, R. Zanin151, M. Fornasa152, R. Essig153, N. Sehgal154, L. E. Strigari155
Affiliations: 1IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 2Universidad Complutense, E-28040 Madrid, Spain, 3INAF National Institute for Astrophysics, I-00136 Rome, Italy, 4Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 5Universidad Complutense, E-28040 Madrid, Spain, 6Technische Universität Dortmund, D-44221 Dortmund, Germany, 7Universidad Complutense, E-28040 Madrid, Spain, 8Università di Padova and INFN, I-35131 Padova, Italy, 9Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 10University of Łódź, PL-90236 Lodz, Poland, 11Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 12Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 13Deutsches Elektronen-Synchrotron, 14ETH Zurich, CH-8093 Switzerland, 15IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 16Max-Planck-Institut für Physik, D-80805 München, Germany, 17ETH Zurich, CH-8093 Switzerland, 18INAF National Institute for Astrophysics, I-00136 Rome, Italy, 19Max-Planck-Institut für Physik, D-80805 München, Germany, 20ETH Zurich, CH-8093 Switzerland, 21Universität Würzburg, D-97074 Würzburg, Germany, 22Universitat de Barcelona, 23Max-Planck-Institut für Physik, D-80805 München, Germany, 24INAF National Institute for Astrophysics, I-00136 Rome, Italy, 25Max-Planck-Institut für Physik, D-80805 München, Germany, 26Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 27Universidad Complutense, E-28040 Madrid, Spain, 28IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 29Università di Udine, and INFN Trieste, I-33100 Udine, Italy, 30INAF National Institute for Astrophysics, I-00136 Rome, Italy, 31Università di Udine, and INFN Trieste, I-33100 Udine, Italy, 32Università di Udine, and INFN Trieste, I-33100 Udine, Italy, 33Institut de Ciències de l'Espai, 34Università di Udine, and INFN Trieste, I-33100 Udine, Italy, 35Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 36Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 37Technische Universität Dortmund, D-44221 Dortmund, Germany, 38Inst. de Astrofísica de Andalucía, 39Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 40ETH Zurich, CH-8093 Switzerland, 41Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain, 42Universität Würzburg, D-97074 Würzburg, Germany, 43Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 44Universidad Complutense, E-28040 Madrid, Spain, 45Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain, 46Max-Planck-Institut für Physik, D-80805 München, Germany, 47Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 48Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 49Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain, 50IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 51Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 52Institut de Ciències de l'Espai, 53Max-Planck-Institut für Physik, D-80805 München, Germany, 54Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 55ETH Zurich, CH-8093 Switzerland, 56Universität Würzburg, D-97074 Würzburg, Germany, 57Max-Planck-Institut für Physik, D-80805 München, Germany, 58Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 59ETH Zurich, CH-8093 Switzerland, 60Max-Planck-Institut für Physik, D-80805 München, Germany, 61IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 62ETH Zurich, CH-8093 Switzerland, 63Max-Planck-Institut für Physik, D-80805 München, Germany, 64INAF National Institute for Astrophysics, I-00136 Rome, Italy, 65Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 66Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 67Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 68Università di Padova and INFN, I-35131 Padova, Italy, 69Universidad Complutense, E-28040 Madrid, Spain, 70ETH Zurich, CH-8093 Switzerland, 71Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria, 72Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria, 73Università di Udine, and INFN Trieste, I-33100 Udine, Italy, 74Universität Würzburg, D-97074 Würzburg, Germany, 75INAF National Institute for Astrophysics, I-00136 Rome, Italy, 76Università di Padova and INFN, I-35131 Padova, Italy, 77IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 78IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 79Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 80Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 81Max-Planck-Institut für Physik, D-80805 München, Germany, 82Max-Planck-Institut für Physik, D-80805 München, Germany, 83Universitat de Barcelona, 84IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 85Universitat de Barcelona, 86Universidad Complutense, E-28040 Madrid, Spain, 87Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 88Max-Planck-Institut für Physik, D-80805 München, Germany, 89Universidad Complutense, E-28040 Madrid, Spain, 90Università di Padova and INFN, I-35131 Padova, Italy, 91Max-Planck-Institut für Physik, D-80805 München, Germany, 92Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 93Universidad Complutense, E-28040 Madrid, Spain, 94Universitat de Barcelona, 95Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 96Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 97ETH Zurich, CH-8093 Switzerland, 98IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 99Università di Udine, and INFN Trieste, I-33100 Udine, Italy, 100Università di Padova and INFN, I-35131 Padova, Italy, 101Università dell'Insubria, Como, I-22100 Como, Italy, 102Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain, 103Inst. de Astrofísica de Andalucía, 104Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy, 105Università di Padova and INFN, I-35131 Padova, Italy, 106Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 107IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 108Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 109Technische Universität Dortmund, D-44221 Dortmund, Germany, 110Universitat de Barcelona, 111ICREA, E-08010 Barcelona, Spain, 112Universität Würzburg, D-97074 Würzburg, Germany, 113Università di Padova and INFN, I-35131 Padova, Italy, 114Max-Planck-Institut für Physik, D-80805 München, Germany, 115Max-Planck-Institut für Physik, D-80805 München, Germany, 116INAF National Institute for Astrophysics, I-00136 Rome, Italy, 117Deutsches Elektronen-Synchrotron, 118Università di Padova and INFN, I-35131 Padova, Italy, 119Universidad Complutense, E-28040 Madrid, Spain, 120Università di Padova and INFN, I-35131 Padova, Italy, 121Max-Planck-Institut für Physik, D-80805 München, Germany, 122Max-Planck-Institut für Physik, D-80805 München, Germany, 123Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy, 124Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 125University of Łódź, PL-90236 Lodz, Poland, 126University of Łódź, PL-90236 Lodz, Poland, 127Universität Würzburg, D-97074 Würzburg, Germany, 128INAF National Institute for Astrophysics, I-00136 Rome, Italy, 129Università di Siena, and INFN Pisa, I-53100 Siena, Italy, 130Max-Planck-Institut für Physik, D-80805 München, Germany, 131Universität Würzburg, D-97074 Würzburg, Germany, 132Technische Universität Dortmund, D-44221 Dortmund, Germany, 133Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 134Tuorla Observatory, University of Turku, FI-21500 Piikkiö, Finland, 135Max-Planck-Institut für Physik, D-80805 München, Germany, 136INAF National Institute for Astrophysics, I-00136 Rome, Italy, 137Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria, 138Croatian MAGIC Consortium, Institute R. Boskovic, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia, 139Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy, 140Max-Planck-Institut für Physik, D-80805 München, Germany, 141Technische Universität Dortmund, D-44221 Dortmund, Germany, 142Universität Würzburg, D-97074 Würzburg, Germany, 143ICREA, E-08010 Barcelona, Spain, 144Università dell'Insubria, Como, I-22100 Como, Italy, 145Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria, 146ETH Zurich, CH-8093 Switzerland, 147Max-Planck-Institut für Physik, D-80805 München, Germany, 148ETH Zurich, CH-8093 Switzerland, 149Universitat de Barcelona, 150Inst. de Astrofísica de Andalucía, 151IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain, 152Inst. de Astrofísica de Andalucía, 153Stanford Linear Accelerator Center, Stanford, California, USA, 154Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California, USA, 155Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California, USA

We report the results of the observation of the nearby satellite galaxy Segue 1 performed by the MAGIC-I ground-based gamma-ray telescope between November 2008 and March 2009 for a total of 43.2 hours. No significant gamma-ray emission was found above the background. Read More

We investigate the reconstruction capabilities of Dark Matter mass and spin-independent cross-section from future ton-scale direct detection experiments using germanium, xenon or argon as targets. Adopting realistic values for the exposure, energy threshold and resolution of Dark Matter experiments which will come online within 5 to 10 years, the degree of complementarity between different targets is quantified. We investigate how the uncertainty in the astrophysical parameters controlling the local Dark Matter density and velocity distribution affects the reconstruction. Read More

Dark matter density profiles based upon Lambda-CDM cosmology motivate an ansatz velocity distribution function with fewer high velocity particles than the Maxwell-Boltzmann distribution or proposed variants. The high velocity tail of the distribution is determined by the outer slope of the dark matter halo, the large radius behavior of the Galactic dark matter density. N-body simulations of Galactic halos reproduce the high velocity behavior of this ansatz. Read More

2010Jul
Affiliations: 1Carnegie Observatories, 2Yale, 3UC Irvine, 4UC Irvine, 5Caltech, 6UC Irvine, 7UC Irvine, 8Stanford, 9Haverford, 10Pomona, 11UC Irvine, 12UC Irvine

We present the results of a comprehensive Keck/DEIMOS spectroscopic survey of the ultra-faint Milky Way satellite galaxy Segue 1. We have obtained velocity measurements for 98.2% of the stars within 67 pc (10 arcmin, or 2. Read More

We use new kinematic data from the ultra-faint Milky Way satellite Segue 1 to model its dark matter distribution and derive upper limits on the dark matter annihilation cross-section. Using gamma-ray flux upper limits from the Fermi satellite and MAGIC, we determine cross-section exclusion regions for dark matter annihilation into a variety of different particles including charged leptons. We show that these exclusion regions are beginning to probe the regions of interest for a dark matter interpretation of the electron and positron fluxes from PAMELA, Fermi, and HESS, and that future observations of Segue 1 have strong prospects for testing such an interpretation. Read More

We investigate the kinematic properties and stellar population of the Galactic satellite Willman 1 (Wil 1) by combining Keck/DEIMOS spectroscopy with KPNO mosaic camera imaging. Wil 1 is an ultra-low luminosity Milky Way companion. This object lies in a region of size-luminosity space (M_V ~ -2 mag, d ~ 38 kpc, r_half ~ 20 pc) also occupied by the Galactic satellites Bo\"otes II and Segue 1 and 2, but no other known old stellar system. Read More

Detecting the dark matter annihilation signal from Galactic substructure, or subhalos, is an important challenge for high-energy gamma-ray experiments. In this paper we discuss detection prospects by combining two different aspects of the gamma-ray signal: the angular distribution and the photon counts probability distribution function (PDF). The true PDF from subhalos has been shown recently (by Lee et al. Read More