Dissipative dark matter and the rotation curves of dwarf galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foot, R., E-mail: rfoot@unimelb.edu.au

2016-07-01

There is ample evidence from rotation curves that dark matter halos around disk galaxies have nontrivial dynamics. Of particular significance are: a) the cored dark matter profile of disk galaxies, b) correlations of the shape of rotation curves with baryonic properties, and c) Tully-Fisher relations. Dark matter halos around disk galaxies may have nontrivial dynamics if dark matter is strongly self interacting and dissipative. Multicomponent hidden sector dark matter featuring a massless 'dark photon' (from an unbroken dark U(1) gauge interaction) which kinetically mixes with the ordinary photon provides a concrete example of such dark matter. The kinetic mixing interactionmore » facilitates halo heating by enabling ordinary supernovae to be a source of these 'dark photons'. Dark matter halos can expand and contract in response to the heating and cooling processes, but for a sufficiently isolated halo could have evolved to a steady state or 'equilibrium' configuration where heating and cooling rates locally balance. This dynamics allows the dark matter density profile to be related to the distribution of ordinary supernovae in the disk of a given galaxy. In a previous paper a simple and predictive formula was derived encoding this relation. Here we improve on previous work by modelling the supernovae distribution via the measured UV and H α fluxes, and compare the resulting dark matter halo profiles with the rotation curve data for each dwarf galaxy in the LITTLE THINGS sample. The dissipative dark matter concept is further developed and some conclusions drawn.« less

Prospects for detecting supersymmetric dark matter in the Galactic halo.

PubMed

Springel, V; White, S D M; Frenk, C S; Navarro, J F; Jenkins, A; Vogelsberger, M; Wang, J; Ludlow, A; Helmi, A

2008-11-06

Dark matter is the dominant form of matter in the Universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species. In this case, annihilation of dark matter in the halo of the Milky Way should produce gamma-rays at a level that may soon be observable. Previous work has argued that the annihilation signal will be dominated by emission from very small clumps (perhaps smaller even than the Earth), which would be most easily detected where they cluster together in the dark matter haloes of dwarf satellite galaxies. Here we report that such small-scale structure will, in fact, have a negligible impact on dark matter detectability. Rather, the dominant and probably most easily detectable signal will be produced by diffuse dark matter in the main halo of the Milky Way. If the main halo is strongly detected, then small dark matter clumps should also be visible, but may well contain no stars, thereby confirming a key prediction of the cold dark matter model.

Dark matter annihilation at the galactic center

NASA Astrophysics Data System (ADS)

Linden, Tim

Observations by the WMAP and PLANCK satellites have provided extraordinarily accurate observations on the densities of baryonic matter, dark matter, and dark energy in the universe. These observations indicate that our universe is composed of approximately five times as much dark matter as baryonic matter. However, efforts to detect a particle responsible for the energy density of dark matter have been unsuccessful. Theoretical models have indicated that a leading candidate for the dark matter is the lightest supersymmetric particle, which may be stable due to a conserved R-parity. This dark matter particle would still be capable of interacting with baryons via weak-force interactions in the early universe, a process which was found to naturally explain the observed relic abundance of dark matter today. These residual annihilations can persist, albeit at a much lower rate, in the present universe, providing a detectable signal from dark matter annihilation events which occur throughout the universe. Simulations calculating the distribution of dark matter in our galaxy almost universally predict the galactic center of the Milky Way Galaxy (GC) to provide the brightest signal from dark matter annihilation due to its relative proximity and large simulated dark matter density. Recent advances in telescope technology have allowed for the first multiwavelength analysis of the GC, with suitable effective exposure, angular resolution, and energy resolution in order to detect dark matter particles with properties similar to those predicted by the WIMP miracle. In this work, I describe ongoing efforts which have successfully detected an excess in gamma-ray emission from the region immediately surrounding the GC, which is difficult to describe in terms of standard diffuse emission predicted in the GC region. While the jury is still out on any dark matter interpretation of this excess, I describe several related observations which may indicate a dark matter origin. Finally, I discuss the role of future telescopes in differentiating a dark matter model from astrophysical emission.

Doppler effect on indirect detection of dark matter using dark matter only simulations

DOE PAGES

Powell, Devon; Laha, Ranjan; Ng, Kenny C. Y.; ...

2017-03-15

Indirect detection of dark matter is a major avenue for discovery. However, baryonic backgrounds are diverse enough to mimic many possible signatures of dark matter. In this work, we study the newly proposed technique of dark matter velocity spectroscopy. The nonrotating dark matter halo and the Solar motion produce a distinct longitudinal dependence of the signal which is opposite in direction to that produced by baryons. Using collisionless dark matter only simulations of Milky Way like halos, we show that this new signature is robust and holds great promise. We develop mock observations by a high energy resolution x-ray spectrometermore » on a sounding rocket, the Micro-X experiment, to our test case, the 3.5 keV line. We show that by using six different pointings, Micro-X can exclude a constant line energy over various longitudes at ≥ 3σ. As a result, the halo triaxiality is an important effect, and it will typically reduce the significance of this signal. We emphasize that this new smoking gun in motion signature of dark matter is general and is applicable to any dark matter candidate which produces a sharp photon feature in annihilation or decay.« less

Doppler effect on indirect detection of dark matter using dark matter only simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Devon; Laha, Ranjan; Ng, Kenny C. Y.

Indirect detection of dark matter is a major avenue for discovery. However, baryonic backgrounds are diverse enough to mimic many possible signatures of dark matter. In this work, we study the newly proposed technique of dark matter velocity spectroscopy. The nonrotating dark matter halo and the Solar motion produce a distinct longitudinal dependence of the signal which is opposite in direction to that produced by baryons. Using collisionless dark matter only simulations of Milky Way like halos, we show that this new signature is robust and holds great promise. We develop mock observations by a high energy resolution x-ray spectrometermore » on a sounding rocket, the Micro-X experiment, to our test case, the 3.5 keV line. We show that by using six different pointings, Micro-X can exclude a constant line energy over various longitudes at ≥ 3σ. As a result, the halo triaxiality is an important effect, and it will typically reduce the significance of this signal. We emphasize that this new smoking gun in motion signature of dark matter is general and is applicable to any dark matter candidate which produces a sharp photon feature in annihilation or decay.« less

Search for neutrinos from dark matter self-annihilations in the center of the Milky Way with 3 years of IceCube/DeepCore

NASA Astrophysics Data System (ADS)

Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Al Samarai, I.; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Argüelles, C.; Auffenberg, J.; Axani, S.; Bagherpour, H.; Bai, X.; Barron, J. P.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Tjus, J. Becker; Becker, K.-H.; BenZvi, S.; Berley, D.; Bernardini, E.; Besson, D. Z.; Binder, G.; Bindig, D.; Blaufuss, E.; Blot, S.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Bourbeau, J.; Bradascio, F.; Braun, J.; Brayeur, L.; Brenzke, M.; Bretz, H.-P.; Bron, S.; Burgman, A.; Carver, T.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cross, R.; Day, M.; de André, J. P. A. M.; De Clercq, C.; DeLaunay, J. J.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Eller, P.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Franckowiak, A.; Friedman, E.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Giang, W.; Glauch, T.; Glüsenkamp, T.; Goldschmidt, A.; Gonzalez, J. G.; Grant, D.; Griffith, Z.; Haack, C.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Hokanson-Fasig, B.; Hoshina, K.; Huang, F.; Huber, M.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Kalacynski, P.; Kang, W.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kheirandish, A.; Kim, J.; Kim, M.; Kintscher, T.; Kiryluk, J.; Kittler, T.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koschinsky, J. P.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Kyriacou, A.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lauber, F.; Lennarz, D.; Lesiak-Bzdak, M.; Leuermann, M.; Liu, Q. R.; Lu, L.; Lünemann, J.; Luszczak, W.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Maruyama, R.; Mase, K.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Micallef, J.; Momenté, G.; Montaruli, T.; Moore, R. W.; Moulai, M.; Nahnhauer, R.; Nakarmi, P.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Pollmann, A. Obertacke; Olivas, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Peiffer, P.; Pepper, J. A.; de los Heros, C. Pérez; Pieloth, D.; Pinat, E.; Plum, M.; Price, P. B.; Przybylski, G. T.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relethford, B.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Rysewyk, D.; Sälzer, T.; Sanchez Herrera, S. E.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Sarkar, S.; Satalecka, K.; Schlunder, P.; Schmidt, T.; Schneider, A.; Schoenen, S.; Schöneberg, S.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stachurska, J.; Stanev, T.; Stasik, A.; Stettner, J.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taboada, I.; Tatar, J.; Tenholt, F.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Tung, C. F.; Turcati, A.; Turley, C. F.; Ty, B.; Unger, E.; Usner, M.; Vandenbroucke, J.; Driessche, W. Van; Eijndhoven, N. van; Vanheule, S.; Santen, J. van; Vehring, M.; Vogel, E.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandler, F. D.; Wandkowsky, N.; Waza, A.; Weaver, C.; Weiss, M. J.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wickmann, S.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wolf, M.; Wood, J.; Wood, T. R.; Woolsey, E.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Yuan, T.; Zoll, M.

2017-09-01

We present a search for a neutrino signal from dark matter self-annihilations in the Milky Way using the IceCube Neutrino Observatory (IceCube). In 1005 days of data we found no significant excess of neutrinos over the background of neutrinos produced in atmospheric air showers from cosmic ray interactions. We derive upper limits on the velocity averaged product of the dark matter self-annihilation cross section and the relative velocity of the dark matter particles < σ _{ {A}}v> . Upper limits are set for dark matter particle candidate masses ranging from 10 GeV up to 1 TeV while considering annihilation through multiple channels. This work sets the most stringent limit on a neutrino signal from dark matter with mass between 10 and 100 GeV, with a limit of 1.18\\cdot 10^{-23} { cm}^3 {s}^{-1} for 100 GeV dark matter particles self-annihilating via τ ^+τ ^- to neutrinos (assuming the Navarro-Frenk-White dark matter halo profile).

DEPFET detectors for direct detection of MeV Dark Matter particles

NASA Astrophysics Data System (ADS)

Bähr, A.; Kluck, H.; Ninkovic, J.; Schieck, J.; Treis, J.

2017-12-01

The existence of dark matter is undisputed, while the nature of it is still unknown. Explaining dark matter with the existence of a new unobserved particle is among the most promising possible solutions. Recently dark matter candidates in the MeV mass region received more and more interest. In comparison to the mass region between a few GeV to several TeV, this region is experimentally largely unexplored. We discuss the application of a RNDR DEPFET semiconductor detector for direct searches for dark matter in the MeV mass region. We present the working principle of the RNDR DEPFET devices and review the performance obtained by previously performed prototype measurements. The future potential of the technology as dark matter detector is discussed and the sensitivity for MeV dark matter detection with RNDR DEPFET sensors is presented. Under the assumption of six background events in the region of interest and an exposure of 1 kg year a sensitivity of about \\overline{σ }e = 10^{-41} {cm}^2 for dark matter particles with a mass of 10 MeV can be reached.

Revisiting the direct detection of dark matter in simplified models

NASA Astrophysics Data System (ADS)

Li, Tong

2018-07-01

In this work we numerically re-examine the loop-induced WIMP-nucleon scattering cross section for the simplified dark matter models and the constraint set by the latest direct detection experiment. We consider a fermion, scalar or vector dark matter component from five simplified models with leptophobic spin-0 mediators coupled only to Standard Model quarks and dark matter particles. The tree-level WIMP-nucleon cross sections in these models are all momentum-suppressed. We calculate the non-suppressed spin-independent WIMP-nucleon cross sections from loop diagrams and investigate the constrained space of dark matter mass and mediator mass by Xenon1T. The constraints from indirect detection and collider search are also discussed.

Dark matter from a classically scale-invariant S U (3 )X

NASA Astrophysics Data System (ADS)

Karam, Alexandros; Tamvakis, Kyriakos

2016-09-01

In this work we study a classically scale-invariant extension of the Standard Model in which the dark matter and electroweak scales are generated through the Coleman-Weinberg mechanism. The extra S U (3 )X gauge factor gets completely broken by the vacuum expectation values of two scalar triplets. Out of the eight resulting massive vector bosons the three lightest are stable due to an intrinsic Z2×Z2' discrete symmetry and can constitute dark matter candidates. We analyze the phenomenological viability of the predicted multi-Higgs sector imposing theoretical and experimental constraints. We perform a comprehensive analysis of the dark matter predictions of the model solving numerically the set of coupled Boltzmann equations involving all relevant dark matter processes and explore the direct detection prospects of the dark matter candidates.

Modeling the Dark Matter of Galaxy Clusters Using the Tensor-Vector-Scalar Theory of Alternate Gravity

NASA Astrophysics Data System (ADS)

Ragozzine, Brett

The invocation of dark matter in the universe is predicated upon gravitational observations that cannot be explained by the amount of luminous matter that we detect. There is an ongoing debate over which gravitational model is correct. The work herein tests a prescription of gravity theory known as Tensor-Vector-Scalar and is based upon the work of Angus et al. (2007). We add upon this work by extending the sample of galaxy clusters to five and testing the accepted Navarro, Frenk & White (NFW) dark matter potential (Navarro et al., 1996). Our independent implementation of this method includes weak gravitational lensing analysis to determine the amount of dark matter in these galaxy clusters by calculating the gas fraction ƒgas = Mgas=Mtot. The ability of the Tensor-Vector-Scalar theory to predict a consistent ƒgas across all galaxy clusters is a measure of its liklihood of being the correct gravity model.

Dipolar dark matter with massive bigravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blanchet, Luc; Heisenberg, Lavinia; Department of Physics & The Oskar Klein Centre, AlbaNova University Centre,Roslagstullsbacken 21, 10691 Stockholm

2015-12-14

Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the twomore » metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because of the particular couplings of the matter fields and vector field to the metrics, a ghost in the decoupling limit is present in the dark matter sector. However, it might be possible to push the mass of the ghost beyond the strong coupling scale by an appropriate choice of the parameters of the model. Crucial questions to address in future work are the exact mass of the ghost, and the cosmological implications of the model.« less

Dipolar dark matter with massive bigravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blanchet, Luc; Heisenberg, Lavinia, E-mail: blanchet@iap.fr, E-mail: laviniah@kth.se

2015-12-01

Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the twomore » metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because of the particular couplings of the matter fields and vector field to the metrics, a ghost in the decoupling limit is present in the dark matter sector. However, it might be possible to push the mass of the ghost beyond the strong coupling scale by an appropriate choice of the parameters of the model. Crucial questions to address in future work are the exact mass of the ghost, and the cosmological implications of the model.« less

EDITORIAL: Focus on Dark Matter and Particle Physics

NASA Astrophysics Data System (ADS)

Aprile, Elena; Profumo, Stefano

2009-10-01

The quest for the nature of dark matter has reached a historical point in time, with several different and complementary experiments on the verge of conclusively exploring large portions of the parameter space of the most theoretically compelling particle dark matter models. This focus issue on dark matter and particle physics brings together a broad selection of invited articles from the leading experimental and theoretical groups in the field. The leitmotif of the collection is the need for a multi-faceted search strategy that includes complementary experimental and theoretical techniques with the common goal of a sound understanding of the fundamental particle physical nature of dark matter. These include theoretical modelling, high-energy colliders and direct and indirect searches. We are confident that the works collected here present the state of the art of this rapidly changing field and will be of interest to both experts in the topic of dark matter as well as to those new to this exciting field. Focus on Dark Matter and Particle Physics Contents DARK MATTER AND ASTROPHYSICS Scintillator-based detectors for dark matter searches I S K Kim, H J Kim and Y D Kim Cosmology: small-scale issues Joel R Primack Big Bang nucleosynthesis and particle dark matter Karsten Jedamzik and Maxim Pospelov Particle models and the small-scale structure of dark matter Torsten Bringmann DARK MATTER AND COLLIDERS Dark matter in the MSSM R C Cotta, J S Gainer, J L Hewett and T G Rizzo The role of an e+e- linear collider in the study of cosmic dark matter M Battaglia Collider, direct and indirect detection of supersymmetric dark matter Howard Baer, Eun-Kyung Park and Xerxes Tata INDIRECT PARTICLE DARK MATTER SEARCHES:EXPERIMENTS PAMELA and indirect dark matter searches M Boezio et al An indirect search for dark matter using antideuterons: the GAPS experiment C J Hailey Perspectives for indirect dark matter search with AMS-2 using cosmic-ray electrons and positrons B Beischer, P von Doetinchem, H Gast, T Kirn and S Schael Axion searches with helioscopes and astrophysical signatures for axion(-like) particles K Zioutas, M Tsagri, Y Semertzidis, T Papaevangelou, T Dafni and V Anastassopoulos The indirect search for dark matter with IceCube Francis Halzen and Dan Hooper DIRECT DARK MATTER SEARCHES:EXPERIMENTS Gaseous dark matter detectors G Sciolla and C J Martoff Search for dark matter with CRESST Rafael F Lang and Wolfgang Seidel DIRECT AND INDIRECT PARTICLE DARK MATTER SEARCHES:THEORY Dark matter annihilation around intermediate mass black holes: an update Gianfranco Bertone, Mattia Fornasa, Marco Taoso and Andrew R Zentner Update on the direct detection of dark matter in MSSM models with non-universal Higgs masses John Ellis, Keith A Olive and Pearl Sandick Dark stars: a new study of the first stars in the Universe Katherine Freese, Peter Bodenheimer, Paolo Gondolo and Douglas Spolyar Determining the mass of dark matter particles with direct detection experiments Chung-Lin Shan The detection of subsolar mass dark matter halos Savvas M Koushiappas Neutrino coherent scattering rates at direct dark matter detectors Louis E Strigari Gamma rays from dark matter annihilation in the central region of the Galaxy Pasquale Dario Serpico and Dan Hooper DARK MATTER MODELS The dark matter interpretation of the 511 keV line Céline Boehm Axions as dark matter particles Leanne D Duffy and Karl van Bibber Sterile neutrinos Alexander Kusenko Dark matter candidates Lars Bergström Minimal dark matter: model and results Marco Cirelli and Alessandro Strumia Shedding light on the dark sector with direct WIMP production Partha Konar, Kyoungchul Kong, Konstantin T Matchev and Maxim Perelstein Axinos as dark matter particles Laura Covi and Jihn E Kim

Dynamical system analysis for DBI dark energy interacting with dark matter

NASA Astrophysics Data System (ADS)

Mahata, Nilanjana; Chakraborty, Subenoy

2015-01-01

A dynamical system analysis related to Dirac-Born-Infeld (DBI) cosmological model has been investigated in this present work. For spatially flat FRW spacetime, the Einstein field equation for DBI scenario has been used to study the dynamics of DBI dark energy interacting with dark matter. The DBI dark energy model is considered as a scalar field with a nonstandard kinetic energy term. An interaction between the DBI dark energy and dark matter is considered through a phenomenological interaction between DBI scalar field and the dark matter fluid. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables. The potential of the DBI scalar field is assumed to be exponential. Finally, critical points are determined, their nature have been analyzed and corresponding cosmological scenario has been discussed.

Comprehensive asymmetric dark matter model

NASA Astrophysics Data System (ADS)

Lonsdale, Stephen J.; Volkas, Raymond R.

2018-05-01

Asymmetric dark matter (ADM) is motivated by the similar cosmological mass densities measured for ordinary and dark matter. We present a comprehensive theory for ADM that addresses the mass density similarity, going beyond the usual ADM explanations of similar number densities. It features an explicit matter-antimatter asymmetry generation mechanism, has one fully worked out thermal history and suggestions for other possibilities, and meets all phenomenological, cosmological and astrophysical constraints. Importantly, it incorporates a deep reason for why the dark matter mass scale is related to the proton mass, a key consideration in ADM models. Our starting point is the idea of mirror matter, which offers an explanation for dark matter by duplicating the standard model with a dark sector related by a Z2 parity symmetry. However, the dark sector need not manifest as a symmetric copy of the standard model in the present day. By utilizing the mechanism of "asymmetric symmetry breaking" with two Higgs doublets in each sector, we develop a model of ADM where the mirror symmetry is spontaneously broken, leading to an electroweak scale in the dark sector that is significantly larger than that of the visible sector. The weak sensitivity of the ordinary and dark QCD confinement scales to their respective electroweak scales leads to the necessary connection between the dark matter and proton masses. The dark matter is composed of either dark neutrons or a mixture of dark neutrons and metastable dark hydrogen atoms. Lepton asymmetries are generated by the C P -violating decays of heavy Majorana neutrinos in both sectors. These are then converted by sphaleron processes to produce the observed ratio of visible to dark matter in the universe. The dynamics responsible for the kinetic decoupling of the two sectors emerges as an important issue that we only partially solve.

Search for neutrinos from dark matter self-annihilations in the center of the Milky Way with 3 years of IceCube/DeepCore: IceCube Collaboration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aartsen, M. G.; Ackermann, M.; Adams, J.

Here, we present a search for a neutrino signal from dark matter self-annihilations in the Milky Way using the IceCube Neutrino Observatory (IceCube). In 1005 days of data we found no significant excess of neutrinos over the background of neutrinos produced in atmospheric air showers from cosmic ray interactions. We derive upper limits on the velocity averaged product of the dark matter self-annihilation cross section and the relative velocity of the dark matter particles < σ A v>. We then set the upper limits for dark matter particle candidate masses ranging from 10 GeV up to 1 TeV while considering annihilation throughmore » multiple channels. This work sets the most stringent limit on a neutrino signal from dark matter with mass between 10 and 100 GeV, with a limit of 1.18·10 -23cm 3s -1 for 100 GeV dark matter particles self-annihilating via τ + τ - to neutrinos (assuming the Navarro–Frenk–White dark matter halo profile).« less

AMS-02 fits dark matter

NASA Astrophysics Data System (ADS)

Balázs, Csaba; Li, Tong

2016-05-01

In this work we perform a comprehensive statistical analysis of the AMS-02 electron, positron fluxes and the antiproton-to-proton ratio in the context of a simplified dark matter model. We include known, standard astrophysical sources and a dark matter component in the cosmic ray injection spectra. To predict the AMS-02 observables we use propagation parameters extracted from observed fluxes of heavier nuclei and the low energy part of the AMS-02 data. We assume that the dark matter particle is a Majorana fermion coupling to third generation fermions via a spin-0 mediator, and annihilating to multiple channels at once. The simultaneous presence of various annihilation channels provides the dark matter model with additional flexibility, and this enables us to simultaneously fit all cosmic ray spectra using a simple particle physics model and coherent astrophysical assumptions. Our results indicate that AMS-02 observations are not only consistent with the dark matter hypothesis within the uncertainties, but adding a dark matter contribution improves the fit to the data. Assuming, however, that dark matter is solely responsible for this improvement of the fit, it is difficult to evade the latest CMB limits in this model.

The dark matter of galaxy voids

NASA Astrophysics Data System (ADS)

Sutter, P. M.; Lavaux, Guilhem; Wandelt, Benjamin D.; Weinberg, David H.; Warren, Michael S.

2014-03-01

How do observed voids relate to the underlying dark matter distribution? To examine the spatial distribution of dark matter contained within voids identified in galaxy surveys, we apply Halo Occupation Distribution models representing sparsely and densely sampled galaxy surveys to a high-resolution N-body simulation. We compare these galaxy voids to voids found in the halo distribution, low-resolution dark matter and high-resolution dark matter. We find that voids at all scales in densely sampled surveys - and medium- to large-scale voids in sparse surveys - trace the same underdensities as dark matter, but they are larger in radius by ˜20 per cent, they have somewhat shallower density profiles and they have centres offset by ˜ 0.4Rv rms. However, in void-to-void comparison we find that shape estimators are less robust to sampling, and the largest voids in sparsely sampled surveys suffer fragmentation at their edges. We find that voids in galaxy surveys always correspond to underdensities in the dark matter, though the centres may be offset. When this offset is taken into account, we recover almost identical radial density profiles between galaxies and dark matter. All mock catalogues used in this work are available at http://www.cosmicvoids.net.

Search for neutrinos from dark matter self-annihilations in the center of the Milky Way with 3 years of IceCube/DeepCore: IceCube Collaboration

DOE PAGES

Aartsen, M. G.; Ackermann, M.; Adams, J.; ...

2017-09-20

Here, we present a search for a neutrino signal from dark matter self-annihilations in the Milky Way using the IceCube Neutrino Observatory (IceCube). In 1005 days of data we found no significant excess of neutrinos over the background of neutrinos produced in atmospheric air showers from cosmic ray interactions. We derive upper limits on the velocity averaged product of the dark matter self-annihilation cross section and the relative velocity of the dark matter particles < σ A v>. We then set the upper limits for dark matter particle candidate masses ranging from 10 GeV up to 1 TeV while considering annihilation throughmore » multiple channels. This work sets the most stringent limit on a neutrino signal from dark matter with mass between 10 and 100 GeV, with a limit of 1.18·10 -23cm 3s -1 for 100 GeV dark matter particles self-annihilating via τ + τ - to neutrinos (assuming the Navarro–Frenk–White dark matter halo profile).« less

Interacting dark sector and precision cosmology

NASA Astrophysics Data System (ADS)

Buen-Abad, Manuel A.; Schmaltz, Martin; Lesgourgues, Julien; Brinckmann, Thejs

2018-01-01

We consider a recently proposed model in which dark matter interacts with a thermal background of dark radiation. Dark radiation consists of relativistic degrees of freedom which allow larger values of the expansion rate of the universe today to be consistent with CMB data (H0-problem). Scattering between dark matter and radiation suppresses the matter power spectrum at small scales and can explain the apparent discrepancies between ΛCDM predictions of the matter power spectrum and direct measurements of Large Scale Structure LSS (σ8-problem). We go beyond previous work in two ways: 1. we enlarge the parameter space of our previous model and allow for an arbitrary fraction of the dark matter to be interacting and 2. we update the data sets used in our fits, most importantly we include LSS data with full k-dependence to explore the sensitivity of current data to the shape of the matter power spectrum. We find that LSS data prefer models with overall suppressed matter clustering due to dark matter - dark radiation interactions over ΛCDM at 3–4 σ. However recent weak lensing measurements of the power spectrum are not yet precise enough to clearly distinguish two limits of the model with different predicted shapes for the linear matter power spectrum. In two appendices we give a derivation of the coupled dark matter and dark radiation perturbation equations from the Boltzmann equation in order to clarify a confusion in the recent literature, and we derive analytic approximations to the solutions of the perturbation equations in the two physically interesting limits of all dark matter weakly interacting or a small fraction of dark matter strongly interacting.

A SQUID-Based RF Cavity Search for Dark Matter Axions

NASA Astrophysics Data System (ADS)

Hotz, Michael T.

The axion is a hypothetical elementary particle resulting from a solution to the "Strong-CP" problem. This serious problem in the standard model of particle physics is manifested as a 1010 discrepancy between the measured upper limit and the calculated value of the neutron's electric dipole moment. Furthermore, a light (~mueV) axion is an ideal dark matter candidate: axions would have been copiously produced during the Big Bang and would be the primary component of the dark matter in the universe. The resolution of the Strong-CP problem and the discovery of the composition of dark matter are two of the most pressing problems in physics. The observation of a light, dark-matter axion would resolve both of these problems. The Axion Dark Matter eXperiment (ADMX) is the most sensitive search for dark-matter axions. Axions in our Milky Way Galaxy may scatter off a magnetic field and convert into microwave photons. ADMX consists of a tunable high-Q RF cavity within the bore of a large, 8.5 Tesla superconducting solenoidal magnet. When the cavity's resonant frequency matches the axion's total energy, the probability of axion-to-photon conversion is enhanced. The cavity's narrow bandwidth requires ADMX to slowly scan possible axion masses. A receiver amplifies, mixes, and digitizes the power developed in the cavity from possible axion-to-photon conversions. This is the most sensitive spectral receiver of microwave radiation in the world. The resulting data is scrutinized for an axion signal above the thermal background. ADMX first operated from 1995-2005 and produced exclusion limits on the energy of dark-matter axions from 1.9 mueV to 3.3 mueV. In order to improve on these limits and continue the search for plausible dark-matter axions, the system was considerably upgraded from 2005 until 2008. In the upgrade, the key technical advance was the use of a dc Superconducting QUantum Interference Device (SQUID) as a microwave amplifier. The SQUID amplifier's noise level is near the allowed minimum from quantum mechanics, allowing ADMX to reduce its thermal noise background by up to 100x. However, SQUIDs are extremely sensitive to magnetic fields, such as those within in ADMX. Integrating a SQUID amplifier into ADMX presented a serious technical challenge. Commissioning the SQUID amplifier was a major focus of my thesis work. This work demonstrates the successful use of a SQUID amplifier in ADMX during operations from 2008-2010. Compared to other dark-matter candidates, the axion's mass and the axion's coupling strength to normal matter and radiation are rather tightly constrained. This allows for the near-definitive elimination or detection of dark-matter axions. A successful detection in ADMX would immediately lead to a determination of the axion's spectral line shape. This shape encodes the history of the Milky Way's formation and is therefore of high scientific importance. The imperfectly-constrained Milky Way dark-matter halo, however, produces remnant uncertainties of the axion signal in both its spectral line-shape and its total intensity, complicating the ADMX search. This work investigates proposed features of dark-matter halo models which enhance ADMX's sensitivity. From these models, this work presents the corresponding exclusion limits for both the local axion density and axion-to-photon coupling strength for axions with mass in the 3.36 mueV to 3.69 mueV region.

Results from the DarkSide-50 Dark Matter Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Alden

2016-01-01

While there is tremendous astrophysical and cosmological evidence for dark matter, its precise nature is one of the most significant open questions in modern physics. Weakly interacting massive particles (WIMPs) are a particularly compelling class of dark matter candidates with masses of the order 100 GeV and couplings to ordinary matter at the weak scale. Direct detection experiments are aiming to observe the low energy (<100 keV) scattering of dark matter off normal matter. With the liquid noble technology leading the way in WIMP sensitivity, no conclusive signals have been observed yet. The DarkSide experiment is looking for WIMP darkmore » matter using a liquid argon target in a dual-phase time projection chamber located deep underground at Gran Sasso National Laboratory (LNGS) in Italy. Currently filled with argon obtained from underground sources, which is greatly reduced in radioactive 39Ar, DarkSide-50 recently made the most sensitive measurement of the 39Ar activity in underground argon and used it to set the strongest WIMP dark matter limit using liquid argon to date. This work describes the full chain of analysis used to produce the recent dark matter limit, from reconstruction of raw data to evaluation of the final exclusion curve. The DarkSide- 50 apparatus is described in detail, followed by discussion of the low level reconstruction algorithms. The algorithms are then used to arrive at three broad analysis results: The electroluminescence signals in DarkSide-50 are used to perform a precision measurement of ii longitudinal electron diffusion in liquid argon. A search is performed on the underground argon data to identify the delayed coincidence signature of 85Kr decays to the 85mRb state, a crucial ingredient in the measurement of the 39Ar activity in the underground argon. Finally, a full description of the WIMP search is given, including development of cuts, efficiencies, energy scale, and exclusion curve in the WIMP mass vs. spin-independent WIMP-nucleon scattering cross section plane. This work was supervised by Hanguo Wang and was completed in collaboration with members of the DarkSide collaboration.« less

Dark matter searches for monoenergetic neutrinos arising from stopped meson decay in the Sun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rott, Carsten; In, Seongjin; Kumar, Jason

Dark matter can be gravitationally captured by the Sun after scattering off solar nuclei. Annihilations of the dark matter trapped and accumulated in the centre of the Sun could result in one of the most detectable and recognizable signals for dark matter. Searches for high-energy neutrinos produced in the decay of annihilation products have yielded extremely competitive constraints on the spin-dependent scattering cross sections of dark matter with nuclei. Recently, the low energy neutrino signal arising from dark-matter annihilation to quarks which then hadronize and shower has been suggested as a competitive and complementary search strategy. These high-multiplicity hadronic showersmore » give rise to a large amount of pions which will come to rest in the Sun and decay, leading to a unique sub-GeV neutrino signal. We here improve on previous works by considering the monoenergetic neutrino signal arising from both pion and kaon decay. We consider searches at liquid scintillation, liquid argon, and water Cherenkov detectors and find very competitive sensitivities for few-GeV dark matter masses.« less

Beyond vanilla dark matter: New channels in the multifaceted search for dark matter

NASA Astrophysics Data System (ADS)

Yaylali, David E.

Though we are extremely confident that non-baryonic dark matter exists in our universe, very little is known about its fundamental nature or its relationship with the Standard Model. Guided by theoretical motivations, a desire for generality in our experimental strategies, and a certain amount of hopeful optimism, we have established a basic framework and set of assumptions about the dark sector which we are now actively testing. After years of probing the parameter spaces of these vanilla dark-matter scenarios, through a variety of different search channels, a conclusive direct (non-gravitational) discovery of dark matter eludes us. This very well may suggest that our first-order expectations of the dark sector are too simplistic. This work describes two ways in which we can expand the experimental reach of vanilla dark-matter scenarios while maintaining the model-independent generality which is at this point still warranted. One way in which this is done is to consider coupling structures between the SM and the dark sector other than the two canonical types --- scalar and axial-vector --- leading to spin dependent and independent interactions at direct-detection experiments. The second way we generalize the vanilla scenarios is to consider multi-component dark sectors. We find that both of these generalizations lead to new and interesting phenomenology, and provide a richer complementarity structure between the different experimental probes we are using to search for dark matter.

Antimatter cosmic rays from dark matter annihilation: First results from an N-body experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lavalle, J.; Nezri, E.; Athanassoula, E.

2008-11-15

While the particle hypothesis for dark matter may be very soon investigated at the LHC, and as the PAMELA and GLAST satellites are currently taking new data on charged and gamma cosmic rays, the need of controlling the theoretical uncertainties affecting the possible indirect signatures of dark matter annihilation is of paramount importance. The uncertainties which originate from the dark matter distribution are difficult to estimate because current astrophysical observations provide rather weak dynamical constraints and because, according to cosmological N-body simulations, dark matter is neither smoothly nor spherically distributed in galactic halos. Some previous studies made use of N-bodymore » simulations to compute the {gamma}-ray flux from dark matter annihilation, but such a work has never been performed for the antimatter (positron and antiproton) primary fluxes, for which transport processes complicate the calculations. We take advantage of the galaxylike 3D dark matter map extracted from the Horizon Project results to calculate the positron and antiproton fluxes from dark matter annihilation, in a model-independent approach as well as for dark matter particle benchmarks relevant at the LHC scale (from supersymmetric and extradimensional theories). We find that the flux uncertainties arise mainly from fluctuations of the local dark matter density, and are of {approx}1 order of magnitude. We compare our results to analytic descriptions of the dark matter halo, showing how the latter can well reproduce the former. The overall antimatter predictions associated with our benchmark models are shown to lie far below the existing measurements and, in particular, that of the positron fraction recently reported by PAMELA, and far below the background predictions as well. Finally, we stress the limits of the use of an N-body framework in this context.« less

Collider Signal II:. Missing ET Signatures and Dark Matter Connection

NASA Astrophysics Data System (ADS)

Baer, Howard

2010-08-01

These lectures give an overview of aspects of missing ET signatures from new physics at the LHC, along with their important connection to dark matter physics. Mostly, I will concentrate on supersymmetric (SUSY) sources of ɆT, but will also mention Little Higgs models with T-parity (LHT) and universal extra dimensions (UED) models with KK-parity. Lecture 1 covers SUSY basics, model building and spectra computation. Lecture 2 addresses sparticle production and decay mechanisms at hadron colliders and event generation. Lecture 3 covers SUSY signatures at LHC, along with LHT and UED signatures for comparison. In Lecture 4, I address the dark matter connection, and how direct and indirect dark matter searches, along with LHC collider searches, may allow us to both discover and characterize dark matter in the next several years. Finally, the interesting scenario of Yukawa-unified SUSY is examined; this case works best if the dark matter turns out to be a mixture of axion/axino states, rather than neutralinos.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rott, Carsten; In, Seongjin; Kumar, Jason

Dark matter can be gravitationally captured by the Sun after scattering off solar nuclei. Annihilations of the dark matter trapped and accumulated in the centre of the Sun could result in one of the most detectable and recognizable signals for dark matter. Searches for high-energy neutrinos produced in the decay of annihilation products have yielded extremely competitive constraints on the spin-dependent scattering cross sections of dark matter with nuclei. Recently, the low energy neutrino signal arising from dark-matter annihilation to quarks which then hadronize and shower has been suggested as a competitive and complementary search strategy. These high-multiplicity hadronic showersmore » give rise to a large amount of pions which will come to rest in the Sun and decay, leading to a unique sub-GeV neutrino signal. We here improve on previous works by considering the monoenergetic neutrino signal arising from both pion and kaon decay. We consider searches at liquid scintillation, liquid argon, and water Cherenkov detectors and find very competitive sensitivities for few-GeV dark matter masses.« less

Ratcheting Up The Search for Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDermott, Samuel Dylan

2014-01-01

The last several years have included remarkable advances in two of the primary areas of fundamental particle physics: the search for dark matter and the discovery of the Higgs boson. This dissertation will highlight some contributions made on the forefront of these exciting fields. Although the circumstantial evidence supporting the dark matter hypothesis is now almost undeniably significant, indisputable direct proof is still lacking. As the direct searches for dark matter continue, we can maximize our prospects of discovery by using theoretical techniques complementary to the observational searches to rule out additional, otherwise accessible parameter space. In this dissertation, Imore » report bounds on a wide range of dark matter theories. The models considered here cover the spectrum from the canonical case of self-conjugate dark matter with weak-scale interactions, to electrically charged dark matter, to non-annihilating, non-fermionic dark matter. These bounds are obtained from considerations of astrophysical and cosmological data, including, respectively: diffuse gamma ray photon observations; structure formation considerations, along with an explication of the novel local dark matter structure due to galactic astrophysics; and the existence of old pulsars in dark-matter-rich environments. I also consider the prospects for a model of neutrino dark matter which has been motivated by a wide set of seemingly contradictory experimental results. In addition, I include a study that provides the tools to begin solving the speculative ``inverse'' problem of extracting dark matter properties solely from hypothetical nuclear energy spectra, which we may face if dark matter is discovered with multiple direct detection experiments. In contrast to the null searches for dark matter, we have the example of the recent discovery of the Higgs boson. The Higgs boson is the first fundamental scalar particle ever observed, and precision measurements of the production and decay of the Higgs boson represent a unique entry p! oint to searches for new kinds of physics. Continuing to refine our understanding of the Higgs boson will also allow us to learn about a vast array of possible new physics. This dissertation includes work parameterizing some of the scenarios that are most likely to be discovered with future Higgs data.« less

Probing sub-GeV dark matter-baryon scattering with cosmological observables

NASA Astrophysics Data System (ADS)

Xu, Weishuang Linda; Dvorkin, Cora; Chael, Andrew

2018-05-01

We derive new limits on the elastic scattering cross section between baryons and dark matter using cosmic microwave background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form σ ∝vn , where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-ℓ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of ˜MeV . We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.

Ruling out dark matter interpretation of the galactic GeV excess by gamma-ray data of galaxy clusters.

PubMed

Chan, Man Ho; Leung, Chung Hei

2017-11-02

Recently, some very tight constraints of annihilating dark matter have been obtained from gamma-ray data of the Milky Way and Milky Way dwarf spheroidal satellite galaxies. In this article, we report that there are two excellent galaxy clusters (A2877 and Fornax) which can provide interesting constraints for annihilating dark matter. The lower limits of the dark matter mass for the thermal relic annihilation cross section are 25 GeV, 6 GeV, 130 GeV and 100 GeV respectively for the e + e - , μ + μ - , τ + τ - and [Formula: see text] channels. For some configuration of our working assumptions, our results improve the Fermi-LAT upper limits of annihilation cross sections by a factor of 1.3 - 1.8 for wide ranges of dark matter mass for e + e - , μ + μ - and [Formula: see text] channels, and a factor of 1.2-1.8 for τ + τ - channel with dark matter mass ≤100 GeV. These limits basically rule out most of the existing popular dark matter interpretation of the GeV excess in the Milky Way.

Mapping all the mass in the universe (with weak gravitational lensing) - Oral Presentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Everett, Spencer

Recent discoveries have shown that most of the universe is made of an exotic dark matter that behaves much differently than the normal matter that we experience in everyday life. As we cannot detect dark matter directly, we must infer its location in the universe by indirect effects, such as the distortion of light from distant galaxies as it travels through large clouds of dark matter. While the degree of distortion should be proportional to the amount of dark matter present, we don't know the original shape of the galaxy so the distortion is difficult to quantify. If we hadmore » a model of how dark matter is linked to galaxies, and thus be able predict the amount of distortion that should occur, we could apply the model to galaxy surveys to map out the dark matter in our universe. In this research, I attach a spherical 'halo' of dark matter to each galaxy in a simulated universe to approximate its known complex dark matter structure. I then predict how the halos distort the light from distant galaxies generated behind the halos. As the data is simulated, the true distortion of the light is known which is compared to the halo-predicted distortion. I find that, on average, the model under-predicts the degree of distortion on all scales and fails to capture distortions from large-scale dark matter structure. These issues are likely due to missing features in the model, as the halo model is a greatly simplified version of the actual distribution of dark matter. Potential improvements to the model for future work are discussed.« less

Gravitational wave signals of electroweak phase transition triggered by dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, Wei; Guo, Huai-Ke; Shu, Jing, E-mail: chaowei@bnu.edu.cn, E-mail: ghk@itp.ac.cn, E-mail: jshu@itp.ac.cn

We study in this work a scenario that the universe undergoes a two step phase transition with the first step happened to the dark matter sector and the second step being the transition between the dark matter and the electroweak vacuums, where the barrier between the two vacuums, that is necessary for a strongly first order electroweak phase transition (EWPT) as required by the electroweak baryogenesis mechanism, arises at the tree-level. We illustrate this idea by working with the standard model (SM) augmented by a scalar singlet dark matter and an extra scalar singlet which mixes with the SM Higgsmore » boson. We study the conditions for such pattern of phase transition to occur and especially for the strongly first order EWPT to take place, as well as its compatibility with the basic requirements of a successful dark matter, such as observed relic density and constraints of direct detections. We further explore the discovery possibility of this pattern EWPT by searching for the gravitational waves generated during this process in spaced based interferometer, by showing a representative benchmark point of the parameter space that the generated gravitational waves fall within the sensitivity of eLISA, DECIGO and BBO.« less

Gravitational wave signals of electroweak phase transition triggered by dark matter

NASA Astrophysics Data System (ADS)

Chao, Wei; Guo, Huai-Ke; Shu, Jing

2017-09-01

We study in this work a scenario that the universe undergoes a two step phase transition with the first step happened to the dark matter sector and the second step being the transition between the dark matter and the electroweak vacuums, where the barrier between the two vacuums, that is necessary for a strongly first order electroweak phase transition (EWPT) as required by the electroweak baryogenesis mechanism, arises at the tree-level. We illustrate this idea by working with the standard model (SM) augmented by a scalar singlet dark matter and an extra scalar singlet which mixes with the SM Higgs boson. We study the conditions for such pattern of phase transition to occur and especially for the strongly first order EWPT to take place, as well as its compatibility with the basic requirements of a successful dark matter, such as observed relic density and constraints of direct detections. We further explore the discovery possibility of this pattern EWPT by searching for the gravitational waves generated during this process in spaced based interferometer, by showing a representative benchmark point of the parameter space that the generated gravitational waves fall within the sensitivity of eLISA, DECIGO and BBO.

Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

NASA Astrophysics Data System (ADS)

Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora

2017-09-01

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2Δ ln L=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2Δ ln L=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ Nfluid, will be improved by an order of magnitude compared to current bounds.

Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora, E-mail: rkrall@physics.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: dvorkin@physics.harvard.edu

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide nomore » support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N {sub fluid}, will be improved by an order of magnitude compared to current bounds.« less

ASSESSING ASTROPHYSICAL UNCERTAINTIES IN DIRECT DETECTION WITH GALAXY SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sloane, Jonathan D.; Buckley, Matthew R.; Brooks, Alyson M.

2016-11-01

We study the local dark matter velocity distribution in simulated Milky Way-mass galaxies, generated at high resolution with both dark matter and baryons. We find that the dark matter in the solar neighborhood is influenced appreciably by the inclusion of baryons, increasing the speed of dark matter particles compared to dark matter-only simulations. The gravitational potential due to the presence of a baryonic disk increases the amount of high velocity dark matter, resulting in velocity distributions that are more similar to the Maxwellian Standard Halo Model than predicted from dark matter-only simulations. Furthermore, the velocity structures present in baryonic simulationsmore » possess a greater diversity than expected from dark matter-only simulations. We show that the impact on the direct detection experiments LUX, DAMA/Libra, and CoGeNT using our simulated velocity distributions, and explore how resolution and halo mass within the Milky Way’s estimated mass range impact the results. A Maxwellian fit to the velocity distribution tends to overpredict the amount of dark matter in the high velocity tail, even with baryons, and thus leads to overly optimistic direct detection bounds on models that are dependent on this region of phase space for an experimental signal. Our work further demonstrates that it is critical to transform simulated velocity distributions to the lab frame of reference, due to the fact that velocity structure in the solar neighborhood appears when baryons are included. There is more velocity structure present when baryons are included than in dark matter-only simulations. Even when baryons are included, the importance of the velocity structure is not as apparent in the Galactic frame of reference as in the Earth frame.« less

Identifying WIMP dark matter from particle and astroparticle data

NASA Astrophysics Data System (ADS)

Bertone, Gianfranco; Bozorgnia, Nassim; Kim, Jong Soo; Liem, Sebastian; McCabe, Christopher; Otten, Sydney; Ruiz de Austri, Roberto

2018-03-01

One of the most promising strategies to identify the nature of dark matter consists in the search for new particles at accelerators and with so-called direct detection experiments. Working within the framework of simplified models, and making use of machine learning tools to speed up statistical inference, we address the question of what we can learn about dark matter from a detection at the LHC and a forthcoming direct detection experiment. We show that with a combination of accelerator and direct detection data, it is possible to identify newly discovered particles as dark matter, by reconstructing their relic density assuming they are weakly interacting massive particles (WIMPs) thermally produced in the early Universe, and demonstrating that it is consistent with the measured dark matter abundance. An inconsistency between these two quantities would instead point either towards additional physics in the dark sector, or towards a non-standard cosmology, with a thermal history substantially different from that of the standard cosmological model.

A History of Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertone, Gianfranco; Hooper, Dan

Although dark matter is a central element of modern cosmology, the history of how it became accepted as part of the dominant paradigm is often ignored or condensed into a brief anecdotical account focused around the work of a few pioneering scientists. The aim of this review is to provide the reader with a broader historical perspective on the observational discoveries and the theoretical arguments that led the scientific community to adopt dark matter as an essential part of the standard cosmological model.

Tully-Fisher relation, galactic rotation curves and dissipative mirror dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foot, R., E-mail: rfoot@unimelb.edu.au

2014-12-01

If dark matter is dissipative then the distribution of dark matter within galactic halos can be governed by dissipation, heating and hydrostatic equilibrium. Previous work has shown that a specific model, in the framework of mirror dark matter, can explain several empirical galactic scaling relations. It is shown here that this dynamical halo model implies a quasi-isothermal dark matter density, ρ(r) ≅ ρ{sub 0}r{sub 0}{sup 2}/(r{sup 2}+r{sub 0}{sup 2}), where the core radius, r{sub 0}, scales with disk scale length, r{sub D}, via r{sub 0}/kpc ≈ 1.4(r{sub D}/kpc). Additionally, the product ρ{sub 0}r{sub 0} is roughly constant, i.e. independent ofmore » galaxy size (the constant is set by the parameters of the model). The derived dark matter density profile implies that the galactic rotation velocity satisfies the Tully-Fisher relation, L{sub B}∝v{sup 3}{sub max}, where v{sub max} is the maximal rotational velocity. Examples of rotation curves resulting from this dynamics are given.« less

Cornering pseudoscalar-mediated dark matter with the LHC and cosmology

NASA Astrophysics Data System (ADS)

Banerjee, Shankha; Barducci, Daniele; Bélanger, Geneviève; Fuks, Benjamin; Goudelis, Andreas; Zaldivar, Bryan

2017-07-01

Models in which dark matter particles communicate with the visible sector through a pseudoscalar mediator are well-motivated both from a theoretical and from a phenomenological standpoint. With direct detection bounds being typically subleading in such scenarios, the main constraints stem either from collider searches for dark matter, or from indirect detection experiments. However, LHC searches for the mediator particles themselves can not only compete with — or even supersede — the reach of direct collider dark matter probes, but they can also test scenarios in which traditional monojet searches become irrelevant, especially when the mediator cannot decay on-shell into dark matter particles or its decay is suppressed. In this work we perform a detailed analysis of a pseudoscalar-mediated dark matter simplified model, taking into account a large set of collider constraints and concentrating on the parameter space regions favoured by cos-mological and astrophysical data. We find that mediator masses above 100-200 GeV are essentially excluded by LHC searches in the case of large couplings to the top quark, while forthcoming collider and astrophysical measurements will further constrain the available parameter space.

Effect of electromagnetic dipole dark matter on energy transport in the solar interior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geytenbeek, Ben; Rao, Soumya; White, Martin

In recent years, a revised set of solar abundances has led to a discrepancy in the sound-speed profile between helioseismology and theoretical solar models. Conventional solutions require additional mechanisms for energy transport within the Sun. Vincent et al. have recently suggested that dark matter with a momentum or velocity dependent cross section could provide a solution. In this work, we consider three models of dark matter with such cross sections and their effect on the stellar structure. In particular, the three models incorporate dark matter particles interacting through an electromagnetic dipole moment: an electric dipole, a magnetic dipole or anmore » anapole. Each model is implemented in the DarkStec stellar evolution program, which incorporates the effects of dark matter capture and heat transport within the solar interior. We show that dark matter with an anapole moment of ∼ 1 GeV{sup −2} or magnetic dipole moment of ∼ 10{sup −3}μ {sub p} can improve the sound-speed profile, small frequency separations and convective zone radius with respect to the Standard Solar Model. However, the required dipole moments are strongly excluded by direct detection experiments.« less

Universal clustering of dark matter in phase space

NASA Astrophysics Data System (ADS)

Zavala, Jesús; Afshordi, Niayesh

2016-03-01

We have recently introduced a novel statistical measure of dark matter clustering in phase space, the particle phase-space average density (P2SAD). In a two-paper series, we studied the structure of P2SAD in the Milky Way-size Aquarius haloes, constructed a physically motivated model to describe it, and illustrated its potential as a powerful tool to predict signals sensitive to the nanostructure of dark matter haloes. In this work, we report a remarkable universality of the clustering of dark matter in phase space as measured by P2SAD within the subhaloes of host haloes across different environments covering a range from dwarf-size to cluster-size haloes (1010-1015 M⊙). Simulations show that the universality of P2SAD holds for more than seven orders of magnitude, over a 2D phase space, covering over three orders of magnitude in distance/velocity, with a simple functional form that can be described by our model. Invoking the universality of P2SAD, we can accurately predict the non-linear power spectrum of dark matter at small scales all the way down to the decoupling mass limit of cold dark matter particles. As an application, we compute the subhalo boost to the annihilation of dark matter in a wide range of host halo masses.

The Dark Matter of Lab Work: Illuminating the Negotiation of Disciplined Perception in Mechanics

ERIC Educational Resources Information Center

Lindwall, Oskar; Lymer, Gustav

2008-01-01

This study examines the practical work of a pair of students and an instructor using probeware in a mechanics lab. The aim of the study is to describe and discuss a type of interactional sequence that we refer to as "dark matter", the ordinary backdrop to the extraordinary sequences that are easily recognizable as clear-cut instances of learning.…

Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry

NASA Astrophysics Data System (ADS)

Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Ansseau, I.; Anton, G.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; Beiser, E.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cruz Silva, A. H.; Danninger, M.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Edsjö, J.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Fösig, C.-C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gier, D.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kiryluk, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, G.; Kroll, M.; Krückl, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mandelartz, M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Richter, S.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Sabbatini, L.; Sander, H.-G.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Savage, C.; Schatto, K.; Schimp, M.; Schlunder, P.; Schmidt, T.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schulte, L.; Schumacher, L.; Scott, P.; Seckel, D.; Seunarine, S.; Silverwood, H.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Te{š}ić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.

2016-04-01

We present an improved event-level likelihood formalism for including neutrino telescope data in global fits to new physics. We derive limits on spin-dependent dark matter-proton scattering by employing the new formalism in a re-analysis of data from the 79-string IceCube search for dark matter annihilation in the Sun, including explicit energy information for each event. The new analysis excludes a number of models in the weak-scale minimal supersymmetric standard model (MSSM) for the first time. This work is accompanied by the public release of the 79-string IceCube data, as well as an associated computer code for applying the new likelihood to arbitrary dark matter models.

Prospects for indirect dark matter searches with MeV photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartels, Richard; Gaggero, Daniele; Weniger, Christoph, E-mail: r.t.bartels@uva.nl, E-mail: d.gaggero@uva.nl, E-mail: c.weniger@uva.nl

2017-05-01

Over the past decade, extensive studies have been undertaken to search for photon signals from dark matter annihilation or decay for dark matter particle masses above ∼1 GeV. However, due to the lacking sensitivity of current experiments at MeV–GeV energies, sometimes dubbed the 'MeV gap', dark matter models with MeV to sub-GeV particle masses have received little attention so far. Various proposed MeV missions (like, e.g., e-ASTROGAM or AMEGO) are aimed at closing this gap in the mid- or long-term future. This, and the absence of clear dark matter signals in the GeV–TeV range, makes it relevant to carefully reconsidermore » the expected experimental instrumental sensitivities in this mass range. The most common two-body annihilation channels for sub-GeV dark matter are to neutrinos, electrons, pions or directly to photons. Among these, only the electron channel has been extensively studied, and almost exclusively in the context of the 511 keV line. In this work, we study the prospects for detecting MeV dark matter annihilation in general in future MeV missions, using e-ASTROGAM as reference, and focusing on dark matter masses in the range 1 MeV–3 GeV. In the case of leptonic annihilation, we emphasise the importance of the often overlooked bremsstrahlung and in-flight annihilation spectral features, which in many cases provide the dominant gamma-ray signal in this regime.« less

Dynamic field theory and equations of motion in cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopeikin, Sergei M., E-mail: kopeikins@missouri.edu; Petrov, Alexander N., E-mail: alex.petrov55@gmail.com

2014-11-15

We discuss a field-theoretical approach based on general-relativistic variational principle to derive the covariant field equations and hydrodynamic equations of motion of baryonic matter governed by cosmological perturbations of dark matter and dark energy. The action depends on the gravitational and matter Lagrangian. The gravitational Lagrangian depends on the metric tensor and its first and second derivatives. The matter Lagrangian includes dark matter, dark energy and the ordinary baryonic matter which plays the role of a bare perturbation. The total Lagrangian is expanded in an asymptotic Taylor series around the background cosmological manifold defined as a solution of Einstein’s equationsmore » in the form of the Friedmann–Lemaître–Robertson–Walker (FLRW) metric tensor. The small parameter of the decomposition is the magnitude of the metric tensor perturbation. Each term of the series expansion is gauge-invariant and all of them together form a basis for the successive post-Friedmannian approximations around the background metric. The approximation scheme is covariant and the asymptotic nature of the Lagrangian decomposition does not require the post-Friedmannian perturbations to be small though computationally it works the most effectively when the perturbed metric is close enough to the background FLRW metric. The temporal evolution of the background metric is governed by dark matter and dark energy and we associate the large scale inhomogeneities in these two components as those generated by the primordial cosmological perturbations with an effective matter density contrast δρ/ρ≤1. The small scale inhomogeneities are generated by the condensations of baryonic matter considered as the bare perturbations of the background manifold that admits δρ/ρ≫1. Mathematically, the large scale perturbations are given by the homogeneous solution of the linearized field equations while the small scale perturbations are described by a particular solution of these equations with the bare stress–energy tensor of the baryonic matter. We explicitly work out the covariant field equations of the successive post-Friedmannian approximations of Einstein’s equations in cosmology and derive equations of motion of large and small scale inhomogeneities of dark matter and dark energy. We apply these equations to derive the post-Friedmannian equations of motion of baryonic matter comprising stars, galaxies and their clusters.« less

Constraining Elko dark matter at the LHC with monophoton events

NASA Astrophysics Data System (ADS)

Alves, Alexandre; Dias, M.; de Campos, F.; Duarte, L.; Hoff da Silva, J. M.

2018-02-01

A mass-dimension-one fermion, also known as Elko, constitutes a dark-matter candidate which might interact with photons at the tree level in a specific fashion. In this work, we investigate the constraints imposed by unitarity and LHC data on this type of interactions using the search for new physics in monophoton events. We found that Elkos which can explain the dark matter relic abundance mainly through electromagnetic interactions are excluded at the 95% CL by the 8 TeV LHC data for masses up to 1 TeV.

On the Evolution of Dark Matter Halo Properties Following Major and Minor Mergers

NASA Astrophysics Data System (ADS)

Wu, Peter; Zhang, Shawn; Lee, Christoph; Primack, Joel

2018-01-01

We conducted an analysis on dark matter halo properties following major and minor mergers to advance our understanding of halo evolution. In this work, we analyzed ~80,000 dark matter halos from the Bolshoi-Planck cosmological simulation and studied halo evolution during relaxation after major mergers. We then applied a Gaussian filter to the property evolutions and characterized peak distributions, frequencies, and variabilities for several halo properties, including centering, spin, shape (prolateness), scale radius, and virial ratio. However, there were also halos that experienced relaxation without the presence of major mergers. We hypothesized that this was due to minor mergers unrecorded by the simulation analysis. By using property peaks to create a novel merger detection algorithm, we attempted to find minor mergers and match them to the unaccounted relaxed halos. Not only did we find evidence that minor mergers were the causes, but we also found similarities between major and minor merger effects, showing the significance of minor mergers for future studies. Through our dark matter merger statistics, we expect our work to ultimately serve as vital parameters towards better understanding galaxy formation and evolution. Most of this work was carried out by high school students working under the auspices of the Science Internship Program (SIP) at UC Santa Cruz.

Gravitational waves from SU( N) glueball dark matter

DOE PAGES

Soni, Amarjit; Zhang, Yue

2017-05-30

Here, a hidden sector with pure non-abelian gauge symmetry is an elegant and just about the simplest model of dark matter. In this model the dark matter candidate is the lightest bound state made of the confined gauge fields, the dark glueball. In spite of its simplicity, the model has been shown to have several interesting non-standard implications in cosmology. In this work, we explore the gravitational waves from binary boson stars made of self-gravitating dark glueball fields as a natural and important consequence. We derive the dark SU(N) star mass and radius as functions of the only two fundamentalmore » parameters in the model, the glueball mass m and the number of colors N, and identify the regions that could be probed by the LIGO and future gravitational wave observatories.« less

Search for gamma-ray emission from dark matter annihilation in the Small Magellanic Cloud with the Fermi Large Area Telescope

DOE PAGES

Caputo, Regina; Buckley, Matthew R.; Martin, Pierrick; ...

2016-03-22

The Small Magellanic Cloud (SMC) is the second-largest satellite galaxy of the Milky Way and is only 60 kpc away. As a nearby, massive, and dense object with relatively low astrophysical backgrounds, it is a natural target for dark matter indirect detection searches. In this work, we use six years of Pass 8 data from the Fermi Large Area Telescope to search for gamma-ray signals of dark matter annihilation in the SMC. Using data-driven fits to the gamma-ray backgrounds, and a combination of N-body simulations and direct measurements of rotation curves to estimate the SMC DM density profile, we found that themore » SMC was well described by standard astrophysical sources, and no signal from dark matter annihilation was detected. We set conservative upper limits on the dark matter annihilation cross section. Furthermore, these constraints are in agreement with stronger constraints set by searches in the Large Magellanic Cloud and approach the canonical thermal relic cross section at dark matter masses lower than 10 GeV in the bb¯ and τ +τ - channels.« less

Dark Matter Profiles in Dwarf Galaxies: A Statistical Sample Using High-Resolution Hα Velocity Fields from PCWI

NASA Astrophysics Data System (ADS)

Relatores, Nicole C.; Newman, Andrew B.; Simon, Joshua D.; Ellis, Richard; Truong, Phuongmai N.; Blitz, Leo

2018-01-01

We present high quality Hα velocity fields for a sample of nearby dwarf galaxies (log M/M⊙ = 8.4-9.8) obtained as part of the Dark Matter in Dwarf Galaxies survey. The purpose of the survey is to investigate the cusp-core discrepancy by quantifying the variation of the inner slope of the dark matter distributions of 26 dwarf galaxies, which were selected as likely to have regular kinematics. The data were obtained with the Palomar Cosmic Web Imager, located on the Hale 5m telescope. We extract rotation curves from the velocity fields and use optical and infrared photometry to model the stellar mass distribution. We model the total mass distribution as the sum of a generalized Navarro-Frenk-White dark matter halo along with the stellar and gaseous components. We present the distribution of inner dark matter density profile slopes derived from this analysis. For a subset of galaxies, we compare our results to an independent analysis based on CO observations. In future work, we will compare the scatter in inner density slopes, as well as their correlations with galaxy properties, to theoretical predictions for dark matter core creation via supernovae feedback.

What the Milky Way's dwarfs tell us about the Galactic Center extended gamma-ray excess

NASA Astrophysics Data System (ADS)

Keeley, Ryan E.; Abazajian, Kevork N.; Kwa, Anna; Rodd, Nicholas L.; Safdi, Benjamin R.

2018-05-01

The Milky Way's Galactic Center harbors a gamma-ray excess that is a candidate signal of annihilating dark matter. Dwarf galaxies remain predominantly dark in their expected commensurate emission. In this work we quantify the degree of consistency between these two observations through a joint likelihood analysis. In doing so we incorporate Milky Way dark matter halo profile uncertainties, as well as an accounting of diffuse gamma-ray emission uncertainties in dark matter annihilation models for the Galactic Center extended gamma-ray excess (GCE) detected by the Fermi Gamma-Ray Space Telescope. The preferred range of annihilation rates and masses expands when including these unknowns. Even so, using two recent determinations of the Milky Way halo's local density leaves the GCE preferred region of single-channel dark matter annihilation models to be in strong tension with annihilation searches in combined dwarf galaxy analyses. A third, higher Milky Way density determination, alleviates this tension. Our joint likelihood analysis allows us to quantify this inconsistency. We provide a set of tools for testing dark matter annihilation models' consistency within this combined data set. As an example, we test a representative inverse Compton sourced self-interacting dark matter model, which is consistent with both the GCE and dwarfs.

SABRE: A search for dark matter and a test of the DAMA/LIBRA annual-modulation result using thallium-doped sodium-iodide scintillation detectors

NASA Astrophysics Data System (ADS)

Shields, Emily Kathryn

Ample evidence has been gathered demonstrating that the majority of the mass in the universe is composed of non-luminous, non-baryonic matter. Though the evidence for dark matter is unassailable, its nature and properties remain unknown. A broad effort has been undertaken by the physics community to detect dark-matter particles through direct-detection techniques. For over a decade, the DAMA/LIBRA experiment has observed a highly significant (9.3sigma) modulation in the scintillation event rate in their highly pure NaI(Tl) detectors, which they use as the basis of a claim for the discovery of dark-matter particles. However, the dark-matter interpretation of the DAMA/LIBRA modulation remains unverified. While there have been some recent hints of dark matter in the form of a light Weakly-Interacting Massive Particle (WIMP) from the CoGeNT and CDMS-Si experiments, when assuming a WIMP dark-matter model, several other experiments, including the LUX and XENON noble-liquid experiments, the KIMS CsI(Tl) experiment, and several bubble chamber experiments, conflict with DAMA/LIBRA. However, these experiments use different dark-matter targets and cannot be compared with DAMA/LIBRA in a model-independent way. The uncertainty surrounding the dark-matter model, astrophysical model, and nuclear-physics effects makes it necessary for a new NaI(Tl) experiment to directly test the DAMA/LIBRA result. The Sodium-iodide with Active Background REjection (SABRE) experiment seeks to provide a much-needed model-independent test of the DAMA/LIBRA modulation by developing highly pure crystal detectors with very low radioactivity and deploying them in an active veto detector that can reject key backgrounds in a dark-matter measurement. This work focuses on the efforts put forward by the SABRE collaboration in developing low-background, low-threshold crystal detectors, designing and fabricating a liquid-scintillator veto detector, and simulating the predicted background spectrum for a dark-matter measurement. In addition, recent controversy surrounding the value of an important parameter for direct detection---the nuclear quenching factor---prompted SABRE to perform a measurement of the quenching factor in sodium. The measurement, its results, and the implications for DAMA/LIBRA and dark matter are also described.

A three-dimensional hydrodynamic treatment of the hot dark matter cosmological scenario

NASA Technical Reports Server (NTRS)

Cen, Renyue; Ostriker, Jeremiah P.

1992-01-01

The study computes the evolution of the hot dark matter (HDM) model containing both baryonic matter and dark matter for a post recombination Friedmann-Robertson-Walker universe. A locally valid Newtonian approximation is used to model a representative piece of the universe with size much less than the horizon. For the HDM model with the present chosen normalization, the hard X-ray (1-10 keV) radiation intensity is less than that in the observations (Wu et al., 1991) by a factor of 30. In agreement with other work, it is found that baryonic matter is slightly antibiased over dark matter on the cell scale, 0.5/h Mpc = 667 kpc. The HDM model with the present chosen parameters does not overproduce X-ray-luminous clusters, and there is a negative evolution in the late epochs in the sense that the number density of X-ray clusters was higher at 0.5 redshift than at 0 redshift at the brightest end.

Early Career: The search for weakly interacting dark matter with liquid xenon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, Carter

2017-02-08

We report results from a search for weakly interacting dark matter particles obtained with the LUX experiment. LUX was located at a depth of 4850 feet at the Sanford Underground Research Facility in Lead, South Dakota from 2013 through 2016. It found no evidence for dark matter particle interactions and set new constraints on the properties of such particles for masses between 6 GeV and 100 TeV. The work reported here also characterized the performance of such experiments by developing a new calibration technique based upon a tritium beta decay source.

Numerical Convergence in the Dark Matter Halos Properties Using Cosmological Simulations

NASA Astrophysics Data System (ADS)

Mosquera-Escobar, X. E.; Muñoz-Cuartas, J. C.

2017-07-01

Nowadays, the accepted cosmological model is the so called -Cold Dark Matter (CDM). In such model, the universe is considered to be homogeneous and isotropic, composed of diverse components as the dark matter and dark energy, where the latter is the most abundant one. Dark matter plays an important role because it is responsible for the generation of gravitational potential wells, commonly called dark matter halos. At the end, dark matter halos are characterized by a set of parameters (mass, radius, concentration, spin parameter), these parameters provide valuable information for different studies, such as galaxy formation, gravitational lensing, etc. In this work we use the publicly available code Gadget2 to perform cosmological simulations to find to what extent the numerical parameters of the simu- lations, such as gravitational softening, integration time step and force calculation accuracy affect the physical properties of the dark matter halos. We ran a suite of simulations where these parameters were varied in a systematic way in order to explore accurately their impact on the structural parameters of dark matter halos. We show that the variations on the numerical parameters affect the structural pa- rameters of dark matter halos, such as concentration, virial radius, and concentration. We show that these modifications emerged when structures become non- linear (at redshift 2) for the scale of our simulations, such that these variations affected the formation and evolution structure of halos mainly at later cosmic times. As a quantitative result, we propose which would be the most appropriate values for the numerical parameters of the simulations, such that they do not affect the halo properties that are formed. For force calculation accuracy we suggest values smaller or equal to 0.0001, integration time step smaller o equal to 0.005 and for gravitational softening we propose equal to 1/60th of the mean interparticle distance, these values, correspond to the smaller values in the numerical parameters variations. This is an important numerical exercise, since for instance, it is believed that galaxy structural parameters are strongly dependent on dark matter halo structural parameters.

Lyman-α forest constraints on decaying dark matter

NASA Astrophysics Data System (ADS)

Wang, Mei-Yu; Croft, Rupert A. C.; Peter, Annika H. G.; Zentner, Andrew R.; Purcell, Chris W.

2013-12-01

We present an analysis of high-resolution N-body simulations of decaying dark matter cosmologies focusing on the statistical properties of the transmitted Lyman-α (Lyα) forest flux in the high-redshift intergalactic medium (IGM). In this type of model a dark matter particle decays into a slightly less massive stable dark matter daughter particle and a comparably light particle. The small mass splitting provides a nonrelativistic kick velocity Vk=cΔM/M to the daughter particle resulting in free-streaming and subsequent damping of small-scale density fluctuations. Current Lyα forest power spectrum measurements probe comoving scales up to ˜2-3h-1Mpc at redshifts z˜2-4, providing one of the most robust ways to probe cosmological density fluctuations on relatively small scales. The suppression of structure growth due to the free-streaming of dark matter daughter particles also has a significant impact on the neutral hydrogen cloud distribution, which traces the underlying dark matter distribution well at high redshift. We exploit Lyα forest power spectrum measurements to constrain the amount of free-streaming of dark matter in such models and thereby place limits on decaying dark matter based only on the dynamics of cosmological perturbations without any assumptions about the interactions of the decay products. We use a suite of dark-matter-only simulations together with the fluctuating Gunn-Peterson approximation to derive the Lyα flux distribution. We argue that this approach should be sufficient for our main purpose, which is to demonstrate the power of the Lyα forest to constrain decaying dark matter models. We find that Sloan Digital Sky Survey 1D Lyα forest power spectrum data place a lifetime-dependent upper limit Vk≲30-70km/s for decay lifetimes ≲10Gyr. This is the most stringent model-independent bound on invisible dark matter decays with small mass splittings. For larger mass splittings (large Vk), Lyα forest data restrict the dark matter lifetime to Γ-1≳40Gyr. We leave the calibration of IGM properties using high-resolution hydrodynamic simulations for future work, which might become necessary if we consider data with higher precision such as the Baryon Oscillation and Spectroscopic Survey (BOSS) Lyα data. Forthcoming BOSS data should be able to provide more stringent constraints on exotic dark matter, mainly because the larger BOSS quasar spectrum sample will significantly reduce statistical errors.

Dark degeneracy and interacting cosmic components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aviles, Alejandro; Cervantes-Cota, Jorge L.

2011-10-15

We study some properties of the dark degeneracy, which is the fact that what we measure in gravitational experiments is the energy-momentum tensor of the total dark sector, and any split into components (as in dark matter and dark energy) is arbitrary. In fact, just one dark fluid is necessary to obtain exactly the same cosmological and astrophysical phenomenology as the {Lambda}CDM model. We work explicitly the first-order perturbation theory and show that beyond the linear order the dark degeneracy is preserved under some general assumptions. Then we construct the dark fluid from a collection of interacting fluids. Finally, wemore » try to break the degeneracy with a general class of couplings to baryonic matter. Nonetheless, we show that these interactions can also be understood in the context of the {Lambda}CDM model as between dark matter and baryons. For this last investigation we choose two independent parametrizations for the interactions, one inspired by electromagnetism and the other by chameleon theories. Then, we constrain them with a joint analysis of CMB and supernovae observational data.« less

Hierarchy of N-point functions in the ΛCDM and ReBEL cosmologies

NASA Astrophysics Data System (ADS)

Hellwing, Wojciech A.; Juszkiewicz, Roman; van de Weygaert, Rien

2010-11-01

In this work we investigate higher-order statistics for the ΛCDM and ReBEL scalar-interacting dark matter models by analyzing 180h-1Mpc dark matter N-body simulation ensembles. The N-point correlation functions and the related hierarchical amplitudes, such as skewness and kurtosis, are computed using the counts-in-cells method. Our studies demonstrate that the hierarchical amplitudes Sn of the scalar-interacting dark matter model significantly deviate from the values in the ΛCDM cosmology on scales comparable and smaller than the screening length rs of a given scalar-interacting model. The corresponding additional forces that enhance the total attractive force exerted on dark matter particles at galaxy scales lower the values of the hierarchical amplitudes Sn. We conclude that hypothetical additional exotic interactions in the dark matter sector should leave detectable markers in the higher-order correlation statistics of the density field. We focused in detail on the redshift evolution of the dark matter field’s skewness and kurtosis. From this investigation we find that the deviations from the canonical ΛCDM model introduced by the presence of the “fifth” force attain a maximum value at redshifts 0.5

Around the Way: Testing ΛCDM with Milky Way Stellar Stream Constraints

NASA Astrophysics Data System (ADS)

Dai, Biwei; Robertson, Brant E.; Madau, Piero

2018-05-01

Recent analyses of the Pal 5 and GD-1 tidal streams suggest that the inner dark matter halo of the Milky Way is close to spherical, in tension with predictions from collisionless N-body simulations of cosmological structure formation. We use the Eris simulation to test whether the combination of dissipative physics and hierarchical structure formation can produce Milky Way–like galaxies whose dark matter halos match the tidal stream constraints from the GD-1 and Pal 5 clusters. We use a dynamical model of the simulated Eris galaxy to generate many realizations of the GD-1 and Pal 5 tidal streams, marginalize over observational uncertainties in the cluster galactocentric positions and velocities, and compare with the observational constraints. We find that the total density and potential of Eris contributed by baryons and dark matter satisfies constraints from the existing Milky Way stellar stream data, as the baryons both round and redistribute the dark matter during the dissipative formation of the galaxy, and provide a centrally concentrated mass distribution that rounds the inner potential. The Eris dark matter halo or a spherical Navarro–Frenk–White dark matter work comparably well in modeling the stream data. In contrast, the equivalent dark matter–only ErisDark simulation produces a prolate halo that cannot reproduce the observed stream data. The ongoing Gaia mission will provide decisive tests of the consistency between {{Λ }}{CDM} and Milky Way streams, and should distinguish between models like Eris and more spherical halos.

Gravitational collapse of dark matter interacting with dark energy: Black hole formation

NASA Astrophysics Data System (ADS)

Shah, Hasrat Hussain; Iqbal, Quaid

In this work, we study the gravitational collapsing process of a spherically symmetric star constitute of Dark Matter (DM), ρM, and Dark Energy (DE) ρ. In this model, we use anisotropic pressure with Equation of State (EoS) pt = λρ and pr = lρ, (l + 2λ < -1). It reveals that gravitational collapse of DM and DE with interaction leads to the formation of the black hole. When l + 2λ < -3 (phantoms), dust and phantoms could be ejected from the death of white hole. This emitted matter again undergoes to collapsing process and becomes the black hole. This study gives the generalization for isotropy of pressure in the fluid to anisotropy when there will be interaction between DM and DE.

Dark stars in Starobinsky's model

NASA Astrophysics Data System (ADS)

Panotopoulos, Grigoris; Lopes, Ilídio

2018-01-01

In the present work we study non-rotating dark stars in f (R ) modified theory of gravity. In particular, we have considered bosonic self-interacting dark matter modeled inside the star as a Bose-Einstein condensate, while as far as the modified theory of gravity is concerned we have assumed Starobinsky's model R +a R2. We solve the generalized structure equations numerically, and we obtain the mass-to-ratio relation for several different values of the parameter a , and for two different dark matter equation-of-states. Our results show that the dark matter stars become more compact in the R-squared gravity compared to general relativity, while at the same time the highest star mass is slightly increased in the modified gravitational theory. The numerical value of the highest star mass for each case has been reported.

Calculation of momentum distribution function of a non-thermal fermionic dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, Anirban; Gupta, Aritra, E-mail: anirbanbiswas@hri.res.in, E-mail: aritra@hri.res.in

The most widely studied scenario in dark matter phenomenology is the thermal WIMP scenario. Inspite of numerous efforts to detect WIMP, till now we have no direct evidence for it. A possible explanation for this non-observation of dark matter could be because of its very feeble interaction strength and hence, failing to thermalise with the rest of the cosmic soup. In other words, the dark matter might be of non-thermal origin where the relic density is obtained by the so-called freeze-in mechanism. Furthermore, if this non-thermal dark matter is itself produced substantially from the decay of another non-thermal mother particle,more » then their distribution functions may differ in both size and shape from the usual equilibrium distribution function. In this work, we have studied such a non-thermal (fermionic) dark matter scenario in the light of a new type of U(1){sub B−L} model. The U(1){sub B−L} model is interesting, since, besides being anomaly free, it can give rise to neutrino mass by Type II see-saw mechanism. Moreover, as we will show, it can accommodate a non-thermal fermionic dark matter as well. Starting from the collision terms, we have calculated the momentum distribution function for the dark matter by solving a coupled system of Boltzmann equations. We then used it to calculate the final relic abundance, as well as other relevant physical quantities. We have also compared our result with that obtained from solving the usual Boltzmann (or rate) equations directly in terms of comoving number density, Y . Our findings suggest that the latter approximation is valid only in cases where the system under study is close to equilibrium, and hence should be used with caution.« less

Calculation of momentum distribution function of a non-thermal fermionic dark matter

NASA Astrophysics Data System (ADS)

Biswas, Anirban; Gupta, Aritra

2017-03-01

The most widely studied scenario in dark matter phenomenology is the thermal WIMP scenario. Inspite of numerous efforts to detect WIMP, till now we have no direct evidence for it. A possible explanation for this non-observation of dark matter could be because of its very feeble interaction strength and hence, failing to thermalise with the rest of the cosmic soup. In other words, the dark matter might be of non-thermal origin where the relic density is obtained by the so-called freeze-in mechanism. Furthermore, if this non-thermal dark matter is itself produced substantially from the decay of another non-thermal mother particle, then their distribution functions may differ in both size and shape from the usual equilibrium distribution function. In this work, we have studied such a non-thermal (fermionic) dark matter scenario in the light of a new type of U(1)B-L model. The U(1)B-L model is interesting, since, besides being anomaly free, it can give rise to neutrino mass by Type II see-saw mechanism. Moreover, as we will show, it can accommodate a non-thermal fermionic dark matter as well. Starting from the collision terms, we have calculated the momentum distribution function for the dark matter by solving a coupled system of Boltzmann equations. We then used it to calculate the final relic abundance, as well as other relevant physical quantities. We have also compared our result with that obtained from solving the usual Boltzmann (or rate) equations directly in terms of comoving number density, Y. Our findings suggest that the latter approximation is valid only in cases where the system under study is close to equilibrium, and hence should be used with caution.

Strong gravitational lensing probes of the particle nature of dark matter

NASA Astrophysics Data System (ADS)

Moustakas, Leonidas A.; Abazajian, Kevork; Benson, Andrew; Bolton, Adam S.; Bullock, James S.; Chen, Jacqueline; Cheng, Edward; Coe, Dan; Congdon, Arthur B.; Dalal, Neal; Diemand, Juerg; Dobke, Benjamin M.; Dobler, Greg; Dore, Olivier; Dutton, Aaron; Ellis, Richard; Fassnacht, Chris D.; Ferguson, Henry; Finkbeiner, Douglas; Gavassi, Raphael; High, Fredrick William; Jeltema, Telsa; Jullo, Eric; Kaplinghat, Manoj; Keeton, Charles R.; Kneib, Jean-Paul; Koopmans, Leon V.E.; Koishiappas, Savvas M.; Kuhlen, Michael; Kusenko, Alexander; Lawrence, Charles R.; Loeb, Avi; Madae, Piero; Marshall, Phil; Metcalf, R. Ben; Natarajan, Priya; Primack, Joel R.; Profumo, Stefano; Seiffert, Michael D.; Simon, Josh; Stern, Daniel; Strigari, Louis; Taylor, James E.; Wayth, Randall; Wambsganss, Joachim; Wechsler, Risa; Zentner, Andrew

There is a vast menagerie of plausible candidates for the constituents of dark matter, both within and beyond extensions of the Standard Model of particle physics. Each of these candidates may have scattering (and other) cross section properties that are consistent with the dark matter abundance, BBN, and the most scales in the matter power spectrum; but which may have vastly different behavior at sub-galactic "cutoff" scales, below which dark matter density fluctuations are smoothed out. The only way to quantitatively measure the power spectrum behavior at sub-galactic scales at distances beyond the local universe, and indeed over cosmic time, is through probes available in multiply imaged strong gravitational lenses. Gravitational potential perturbations by dark matter substructure encode information in the observed relative magnifications, positions, and time delays in a strong lens. Each of these is sensitive to a different moment of the substructure mass function and to different effective mass ranges of the substructure. The time delay perturbations, in particular, are proving to be largely immune to the degeneracies and systematic uncertainties that have impacted exploitation of strong lenses for such studies. There is great potential for a coordinated theoretical and observational effort to enable a sophisticated exploitation of strong gravitational lenses as direct probes of dark matter properties. This opportunity motivates this white paper, and drives the need for: a) strong support of the theoretical work necessary to understand all astrophysical consequences for different dark matter candidates; and b) tailored observational campaigns, and even a fully dedicated mission, to obtain the requisite data.

Comparison between two scalar field models using rotation curves of spiral galaxies

NASA Astrophysics Data System (ADS)

Fernández-Hernández, Lizbeth M.; Rodríguez-Meza, Mario A.; Matos, Tonatiuh

2018-04-01

Scalar fields have been used as candidates for dark matter in the universe, from axions with masses ∼ 10-5eV until ultra-light scalar fields with masses ∼ Axions behave as cold dark matter while the ultra-light scalar fields galaxies are Bose-Einstein condensate drops. The ultra-light scalar fields are also called scalar field dark matter model. In this work we study rotation curves for low surface brightness spiral galaxies using two scalar field models: the Gross-Pitaevskii Bose-Einstein condensate in the Thomas-Fermi approximation and a scalar field solution of the Klein-Gordon equation. We also used the zero disk approximation galaxy model where photometric data is not considered, only the scalar field dark matter model contribution to rotation curve is taken into account. From the best-fitting analysis of the galaxy catalog we use, we found the range of values of the fitting parameters: the length scale and the central density. The worst fitting results (values of χ red2 much greater than 1, on the average) were for the Thomas-Fermi models, i.e., the scalar field dark matter is better than the Thomas- Fermi approximation model to fit the rotation curves of the analysed galaxies. To complete our analysis we compute from the fitting parameters the mass of the scalar field models and two astrophysical quantities of interest, the dynamical dark matter mass within 300 pc and the characteristic central surface density of the dark matter models. We found that the value of the central mass within 300 pc is in agreement with previous reported results, that this mass is ≈ 107 M ⊙/pc2, independent of the dark matter model. And, on the contrary, the value of the characteristic central surface density do depend on the dark matter model.

Annihilation cross section of Kaluza Klien dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Rakesh, E-mail: rakesh-sharma-ujn@yahoo.co.in; Upadhyaya, G. K., E-mail: gopalujjain@yahoo.co.in; Sharma, S.

2015-07-31

The question as to how this universe came into being and as to how it has evolved to its present stage, is an old question. The answer to this question unfolds many secrets regarding fundamental particles and forces between them. Theodor Kaluza proposed the concept that the universe is composed of more than four space-time dimensions. In his work, electromagnetism is united with gravity. Various extra dimension formulations have been proposed to solve a variety of problems. Recently, the idea of more than four space time dimensions is applied to the search for particle identity of dark matter (DM). Signaturemore » of dark matter can be revealed by analysis of very high energy electrons which are coming from outer space. We investigate recent advancement in the field of dark matter search with reference to very high energy electrons from outer space [1-8].« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aartsen, M.G.; Abraham, K.; Ackermann, M.

We present an improved event-level likelihood formalism for including neutrino telescope data in global fits to new physics. We derive limits on spin-dependent dark matter-proton scattering by employing the new formalism in a re-analysis of data from the 79-string IceCube search for dark matter annihilation in the Sun, including explicit energy information for each event. The new analysis excludes a number of models in the weak-scale minimal supersymmetric standard model (MSSM) for the first time. This work is accompanied by the public release of the 79-string IceCube data, as well as an associated computer code for applying the new likelihoodmore » to arbitrary dark matter models.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jesus, J.F.; Pereira, S.H., E-mail: jfjesus@itapeva.unesp.br, E-mail: shpereira@gmail.com

In this work the results from the quantum process of matter creation have been used in order to constrain the mass of the dark matter particles in an accelerated Cold Dark Matter model (Creation Cold Dark Matter, CCDM). In order to take into account a back reaction effect due to the particle creation phenomenon, it has been assumed a small deviation ε for the scale factor in the matter dominated era of the form t{sup 2/3+ε}. Based on recent H(z) data, the best fit values for the mass of dark matter created particles and the ε parameter have been foundmore » as m = 1.6× 10{sup 3} GeV, restricted to a 68.3% c.l. interval of 1.5 < m < 6.3× 10{sup 7}) GeV and ε = -0.250{sup +0.15}{sub -0.096} at 68.3% c.l. For these best fit values the model correctly recovers a transition from decelerated to accelerated expansion and admits a positive creation rate near the present era. Contrary to recent works in CCDM models where the creation rate was phenomenologically derived, here we have used a quantum mechanical result for the creation rate of real massive scalar particles, given a self consistent justification for the physical process. This method also indicates a possible solution to the so called ''dark degeneracy'', where one can not distinguish if it is the quantum vacuum contribution or quantum particle creation which accelerates the Universe expansion.« less

How does the Structure of Spherical Dark Matter Halos Affect the Types of Orbits in Disk Galaxies?

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.

The main objective of this work is to determine the character of orbits of stars moving in the meridional (R,z) plane of an axially symmetric time-independent disk galaxy model with a central massive nucleus and an additional spherical dark matter halo component. In particular, we try to reveal the influence of the scale length of the dark matter halo on the different families of orbits of stars, by monitoring how the percentage of chaotic orbits, as well as the percentages of orbits of the main regular resonant families evolve when this parameter varies. The smaller alignment index (SALI) was computed by numerically integrating the equations of motion as well as the variational equations to extensive samples of orbits in order to distinguish safely bet ween ordered and chaotic motion. In addition, a method based on the concept of spectral dynamics that utilizes the Fourier transform of the time series of each coordinate is used to identify the various families of regular orbits and also to recognize the secondary resonances that bifurcate from them. Our numerical computations reveal that when the dark matter halo is highly concentrated, that is when the scale length has low values the vast majority of star orbits move in regular orbits, while on the oth er hand in less concentrated dark matter halos the percentage of chaos increases significantly. We also compared our results with early related work.

A question of separation: disentangling tracer bias and gravitational non-linearity with counts-in-cells statistics

NASA Astrophysics Data System (ADS)

Uhlemann, C.; Feix, M.; Codis, S.; Pichon, C.; Bernardeau, F.; L'Huillier, B.; Kim, J.; Hong, S. E.; Laigle, C.; Park, C.; Shin, J.; Pogosyan, D.

2018-02-01

Starting from a very accurate model for density-in-cells statistics of dark matter based on large deviation theory, a bias model for the tracer density in spheres is formulated. It adopts a mean bias relation based on a quadratic bias model to relate the log-densities of dark matter to those of mass-weighted dark haloes in real and redshift space. The validity of the parametrized bias model is established using a parametrization-independent extraction of the bias function. This average bias model is then combined with the dark matter PDF, neglecting any scatter around it: it nevertheless yields an excellent model for densities-in-cells statistics of mass tracers that is parametrized in terms of the underlying dark matter variance and three bias parameters. The procedure is validated on measurements of both the one- and two-point statistics of subhalo densities in the state-of-the-art Horizon Run 4 simulation showing excellent agreement for measured dark matter variance and bias parameters. Finally, it is demonstrated that this formalism allows for a joint estimation of the non-linear dark matter variance and the bias parameters using solely the statistics of subhaloes. Having verified that galaxy counts in hydrodynamical simulations sampled on a scale of 10 Mpc h-1 closely resemble those of subhaloes, this work provides important steps towards making theoretical predictions for density-in-cells statistics applicable to upcoming galaxy surveys like Euclid or WFIRST.

Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope

DOE PAGES

Ackermann, M.; Ajello, M.; Allafort, A.; ...

2010-05-20

Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~ 200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits excludemore » large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~ 5 over a smooth-halo assumption. Here, we also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. Finally, in this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.« less

MATTER IN THE BEAM: WEAK LENSING, SUBSTRUCTURES, AND THE TEMPERATURE OF DARK MATTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahdi, Hareth S.; Elahi, Pascal J.; Lewis, Geraint F.

2016-08-01

Warm dark matter (WDM) models offer an attractive alternative to the current cold dark matter (CDM) cosmological model. We present a novel method to differentiate between WDM and CDM cosmologies, namely, using weak lensing; this provides a unique probe as it is sensitive to all of the “matter in the beam,” not just dark matter haloes and the galaxies that reside in them, but also the diffuse material between haloes. We compare the weak lensing maps of CDM clusters to those in a WDM model corresponding to a thermally produced 0.5 keV dark matter particle. Our analysis clearly shows thatmore » the weak lensing magnification, convergence, and shear distributions can be used to distinguish between CDM and WDM models. WDM models increase the probability of weak magnifications, with the differences being significant to ≳5 σ , while leaving no significant imprint on the shear distribution. WDM clusters analyzed in this work are more homogeneous than CDM ones, and the fractional decrease in the amount of material in haloes is proportional to the average increase in the magnification. This difference arises from matter that would be bound in compact haloes in CDM being smoothly distributed over much larger volumes at lower densities in WDM. Moreover, the signature does not solely lie in the probability distribution function but in the full spatial distribution of the convergence field.« less

The dark-baryonic matter mass relation for observational verification in Verlinde's emergent gravity

NASA Astrophysics Data System (ADS)

Shen, Jian Qi

2018-06-01

Recently, a new interesting idea of origin of gravity has been developed by Verlinde. In this scheme of emergent gravity, where horizon entropy, microscopic de Sitter states and relevant contribution to gravity are involved, an entropy displacement resulting from matter behaves as a memory effect and can be exhibited at sub-Hubble scales, namely, the entropy displacement and its "elastic" response would lead to emergent gravity, which gives rise to an extra gravitational force. Then galactic dark matter effects may origin from such extra emergent gravity. We discuss some concepts in Verlinde's theory of emergent gravity and point out some possible problems or issues, e.g., the gravitational potential caused by Verlinde's emergent apparent dark matter may no longer be continuous in spatial distribution at ordinary matter boundary (such as a massive sphere surface). In order to avoid the unnatural discontinuity of the extra emergent gravity of Verlinde's apparent dark matter, we suggest a modified dark-baryonic mass relation (a formula relating Verlinde's apparent dark matter mass to ordinary baryonic matter mass) within this framework of emergent gravity. The modified mass relation is consistent with Verlinde's result at relatively small scales (e.g., R<3h_{70}^{-1} Mpc). However, it seems that, compared with Verlinde's relation, at large scales (e.g., gravitating systems with R>3h_{70}^{-1} Mpc), the modified dark-baryonic mass relation presented here might be in better agreement with the experimental curves of weak lensing analysis in the recent work of Brouwer et al. Galactic rotation curves are compared between Verlinde's emergent gravity and McGaugh's recent model of MOND (Modified Newtonian Dynamics established based on recent galaxy observations). It can be found that Verlinde rotational curves deviate far from those of McGaugh MOND model when the MOND effect (or emergent dark matter) dominates. Some applications of the modified dark-baryonic mass relation inspired by Verlinde's emergent gravity will be addressed for galactic and solar scales. Potential possibilities to test this dark-baryonic mass relation as well as apparent dark matter effects, e.g., planetary perihelion precession at Solar System scale, will be considered. This may enable to place some constraints on the magnitudes of the MOND characteristic acceleration at the small solar scale.

Particle creation and non-equilibrium thermodynamical prescription of dark fluids for universe bounded by an event horizon

NASA Astrophysics Data System (ADS)

Saha, Subhajit; Biswas, Atreyee; Chakraborty, Subenoy

2015-03-01

In the present work, flat FRW model of the universe is considered to be an isolated open thermodynamical system where non-equilibrium prescription has been studied using the mechanism of particle creation. In the perspective of recent observational evidences, the matter distribution in the universe is assumed to be dominated by dark matter and dark energy. The dark matter is chosen as dust while for dark energy, the following choices are considered: (i) Perfect fluid with constant equation of state and (ii) Holographic dark energy. In both the cases, the validity of generalized second law of thermodynamics (GSLT) which states that the total entropy of the fluid as well as that of the horizon should not decrease with the evolution of the universe, has been examined graphically for universe bounded by the event horizon. It is found that GSLT holds in both the cases with some restrictions on the interacting coupling parameter.

Dark matter subhalos and unidentified sources in the Fermi 3FGL source catalog

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoonenberg, Djoeke; Gaskins, Jennifer; Bertone, Gianfranco

2016-05-01

If dark matter consists of weakly interacting massive particles (WIMPs), dark matter subhalos in the Milky Way could be detectable as gamma-ray point sources due to WIMP annihilation. In this work, we perform an updated study of the detectability of dark matter subhalos as gamma-ray sources with the Fermi Large Area Telescope (Fermi LAT). We use the results of the Via Lactea II simulation, scaled to the Planck 2015 cosmological parameters, to predict the local dark matter subhalo distribution. Under optimistic assumptions for the WIMP parameters—a 40 GeV particle annihilating to b b-bar with a thermal cross-section, as required tomore » explain the Galactic center GeV excess—we predict that at most ∼ 10 subhalos might be present in the third Fermi LAT source catalog (3FGL). This is a smaller number than has been predicted by prior studies, and we discuss the origin of this difference. We also compare our predictions for the detectability of subhalos with the number of subhalo candidate sources in 3FGL, and derive upper limits on the WIMP annihilation cross-section as a function of the particle mass. If a dark matter interpretation could be excluded for all 3FGL sources, our constraints would be competitive with those found by indirect searches using other targets, such as known Milky Way satellite galaxies.« less

Prospects for distinguishing dark matter models using annual modulation

DOE PAGES

Witte, Samuel J.; Gluscevic, Vera; McDermott, Samuel D.

2017-02-24

It has recently been demonstrated that, in the event of a putative signal in dark matter direct detection experiments, properly identifying the underlying dark matter-nuclei interaction promises to be a challenging task. Given the most optimistic expectations for the number counts of recoil events in the forthcoming Generation 2 experiments, differentiating between interactions that produce distinct features in the recoil energy spectra will only be possible if a strong signal is observed simultaneously on a variety of complementary targets. However, there is a wide range of viable theories that give rise to virtually identical energy spectra, and may only differmore » by the dependence of the recoil rate on the dark matter velocity. In this work, we investigate how degeneracy between such competing models may be broken by analyzing the time dependence of nuclear recoils, i.e. the annual modulation of the rate. For this purpose, we simulate dark matter events for a variety of interactions and experiments, and perform a Bayesian model-selection analysis on all simulated data sets, evaluating the chance of correctly identifying the input model for a given experimental setup. Lastly, we find that including information on the annual modulation of the rate may significantly enhance the ability of a single target to distinguish dark matter models with nearly degenerate recoil spectra, but only with exposures beyond the expectations of Generation 2 experiments.« less

Synchrotron Emission from Dark Matter Annihilation: Predictions for Constraints from Non-detections of Galaxy Clusters with New Radio Surveys

NASA Astrophysics Data System (ADS)

Storm, Emma; Jeltema, Tesla E.; Splettstoesser, Megan; Profumo, Stefano

2017-04-01

The annihilation of dark matter particles is expected to yield a broad radiation spectrum via the production of Standard Model particles in astrophysical environments. In particular, electrons and positrons from dark matter annihilation produce synchrotron radiation in the presence of magnetic fields. Galaxy clusters are the most massive collapsed structures in the universe, and are known to host ˜μG-scale magnetic fields. They are therefore ideal targets to search for, or to constrain the synchrotron signal from dark matter annihilation. In this work, we use the expected sensitivities of several planned surveys from the next generation of radio telescopes to predict the constraints on dark matter annihilation models which will be achieved in the case of non-detections of diffuse radio emission from galaxy clusters. Specifically, we consider the Tier 1 survey planned for the Low Frequency Array (LOFAR) at 120 MHz, the Evolutionary Map of the Universe (EMU) survey planned for the Australian Square Kilometre Array Pathfinder (ASKAP) at 1.4 GHz, and planned surveys for Aperture Tile in Focus (APERTIF) at 1.4 GHz. We find that, for massive clusters and dark matter masses ≲ 100 {GeV}, the predicted limits on the annihilation cross section would rule out vanilla thermal relic models for even the shallow LOFAR Tier 1, ASKAP, and APERTIF surveys.

Fermionic dark matter and neutrino masses in a B - L model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sánchez-Vega, B. L.; Schmitz, E. R.

2015-09-01

In this work we present a common framework for neutrino masses and dark matter. Specifically, we work with a local B - L extension of the standard model which has three right-handed neutrinos, n(Ri), and some extra scalars, Phi, phi(i), besides the standard model fields. The n(Ri)'s have nonstandard B - L quantum numbers and thus these couple to different scalars. This model has the attractive property that an almost automatic Z(2) symmetry acting only on a fermionic field, n(R3), is present. Taking advantage of this Z(2) symmetry, we study both the neutrino mass generation via a natural seesaw mechanismmore » at low energy and the possibility of n(R3) being a dark matter candidate. For this last purpose, we study its relic abundance and its compatibility with the current direct detection experiments.« less

Fermi Bubbles under Dark Matter Scrutiny Part II: Particle Physics Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Wei-Chih; Urbano, Alfredo; Xue, Wei, E-mail: whuang@sissa.it, E-mail: alfredo.urbano@sissa.it, E-mail: wxue@sissa.it

2014-04-01

The analysis of the gamma-ray photons collected by the Fermi Large Area Telescope reveals, after removal of astrophysical background, the existence of an excess towards the Galactic center. This excess peaks around few GeV, and its origin is compatible with the gamma-ray flux originating from Dark Matter annihilation. In this work we take a closer look on this interpretation; we investigate which kind of Dark Matter, and which type of interactions with the Standard Model fields are able to reproduce the observed signal. The structure of the paper is twofold. In the first part, we follow an effective field theorymore » approach considering both fermionic and scalar Dark Matter. The computation of the relic density, the constraint imposed from the null result of direct searches, and the reliability of the effective field theory description allow us to single out only two viable dim-6 operators in the case of fermionic Dark Matter. In the second part, we analyze some concrete models. In particular, we find that the scalar Higgs portal can provide a simple, concrete and realistic scenario able to explain the GeV excess under scrutiny.« less

The role of the dark matter haloes on the cosmic star formation rate

NASA Astrophysics Data System (ADS)

Pereira, Eduardo S.; Miranda, Oswaldo D.

2015-11-01

The cosmic star formation rate (CSFR) represents the fraction of gas that is converted into stars within a certain comoving volume and at a given time t. However the evolution of the dark matter haloes and its relationship with the CSFR is not yet clear. In this context, we have investigated the role of the dark halo mass function - DHMF - in the process of gas conversion into stars. We observed a strong dependence between the fraction of baryons in structures, fb, and the specific mass function used for describing the dark matter haloes. In some cases, we have obtained fb greater than one at redshift z = 0 . This result indicates that the evolution of dark matter, described by the specific DHMF, could not trace the baryonic matter without a bias parameter. We also observed that the characteristic time-scale for star formation, τ, is strongly dependent on the considered DHMF, when the model is confronted against the observational data. Also, as part of this work it was released, under GNU general public license, a Python package called 'pycosmicstar' to study the CSFR and its relationship with the DHMF.

Finite Inflation, Holography, and Dark Matter Annihilation

NASA Astrophysics Data System (ADS)

Scacco, Andrew Joseph

This thesis covers work on theoretical cosmology relating to inflation, de Sitter space, dark matter annihilation, and holography. A unifying feature of all these topics is that all of them occur in de Sitter space or focus on epochs of the Universe when the spacetime was close to de Sitter and that all of them have some connection to holography. Chapter 1 provides a pedagogical introduction to the fundamentals of cosmology, inflation, de Sitter space, dark matter annihilation and entanglement entropy. Chapter 2 covers the impact on the causal entropic principle of dark matter annihilation that we find to have the greatest relevance at late times in the future when the dark energy has driven the universe to be asymptotically de Sitter. In this chapter we estimate holographically preferred dark matter properties for a range of assumptions. Chapter 3 covers holographic bounds in models of finite inflation, specifically the Banks-Fischler bound and de Sitter equilibrium. The assumptions in each of these models are explored in detail and some interesting new connections are presented. Chapter 4 tests models of inflation with a fast-roll start that happen to satisfy the holographic bounds in Chapter 3 against cosmic microwave background data from Planck. We find a slight preference for a feature at the scale predicted by the Banks-Fischler bound though this preference is not found to be statistically significant. Chapter 5 contains a numerical computation of the holographic mutual information for an annular configuration of regions on a conformal field theory in de Sitter space using the AdS/CFT correspondence. This computation shows that the de Sitter space CFT entanglement entropy matches what would be expected from a Minkowski CFT and shows that the HRT conjecture works for this case.

A Two-Step Integrated Theory of Everything (TOE)

NASA Astrophysics Data System (ADS)

Colella, Antonio

2017-01-01

Two opposing TOE visions are my Two-Step (physics/math) and Hawking's single math step. My Two-Step should replace the single step because of the latter's near zero results after a century of attempts. My physics step had 3 goals. First ``Everything'' was defined as 20 interrelated amplified theories (e.g. string, Higgs forces, spontaneous symmetry breaking, particle decays, dark matter, dark energy, stellar black holes) and their intimate physical interrelationships. Amplifications of Higgs forces theory (e.g. matter particles and their associated Higgs forces were one and inseparable, spontaneous symmetry breaking was bidirectional and caused by high temperatures not Higgs forces, and sum of 8 Higgs forces of 8 permanent matter particles was dark energy) were key to my Two-Step TOE. The second goal answered all outstanding physics questions: what were Higgs forces, dark energy, dark matter, stellar black holes, our universe's creation, etc.? The third goal provided correct inputs for the two part second math step, an E8 Lie algebra for particles and an N-body cosmology simulation (work in progress). Scientific advancement occurs only if the two opposing TOEs are openly discussed/debated.

Viscous self interacting dark matter and cosmic acceleration

NASA Astrophysics Data System (ADS)

Atreya, Abhishek; Bhatt, Jitesh R.; Mishra, Arvind

2018-02-01

Self interacting dark matter (SIDM) provides us with a consistent solution to certain astrophysical observations in conflict with collision-less cold DM paradigm. In this work we estimate the shear viscosity (η) and bulk viscosity (ζ) of SIDM, within kinetic theory formalism, for galactic and cluster size SIDM halos. To that extent we make use of the recent constraints on SIDM cross-section for the dwarf galaxies, LSB galaxies and clusters. We also estimate the change in solution of Einstein's equation due to these viscous effects and find that σ/m constraints on SIDM from astrophysical data provide us with sufficient viscosity to account for the observed cosmic acceleration at present epoch, without the need of any additional dark energy component. Using the estimates of dark matter density for galactic and cluster size halo we find that the mean free path of dark matter ~ few Mpc. Thus the smallest scale at which the viscous effect start playing the role is cluster scale. Astrophysical data for dwarf, LSB galaxies and clusters also seems to suggest the same. The entire analysis is independent of any specific particle physics motivated model for SIDM.

Impeded Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopp, Joachim; Liu, Jia; Slatyer, Tracy

Here, we consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario \\Impeded Dark Matter". We also demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may evenmore » be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. Furthermore, for positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.« less

Impeded Dark Matter

DOE PAGES

Kopp, Joachim; Liu, Jia; Slatyer, Tracy; ...

2016-12-12

Here, we consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario \\Impeded Dark Matter". We also demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may evenmore » be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. Furthermore, for positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.« less

On Dark Peaks and Missing Mass: A Weak-Lensing Mass Reconstruction of the Merging Cluster System A520

NASA Technical Reports Server (NTRS)

Clowe, Douglas; Markevitch, Maxim; Bradac, Marusa; Gonzalez, Anthony H.; Chung, Sun Mi

2012-01-01

Merging clusters of galaxies are unique in their power to directly probe and place limits on the self-interaction cross-section of dark matter. Detailed observations of several merging clusters have shown the intracluster gas to be displaced from the centroids of dark matter and galaxy density by ram pressure, while the latter components are spatially coincident, consistent with collisionless dark matter. This has been used to place upper limits on the dark matter particle self-interaction cross-section of order 1 sq cm/g. The cluster A520 has been seen as a possible exception. We revisit A520 presenting new Hubble Space Telescope Advanced Camera for Surveys mosaic images and a Magellan image set. We perform a detailed weak-lensing analysis and show that the weak-lensing mass measurements and morphologies of the core galaxy-filled structures are mostly in good agreement with previous works. There is, however, one significant difference: We do not detect the previously claimed "dark core" that contains excess mass with no significant galaxy overdensity at the location of the X-ray plasma. This peak has been suggested to be indicative of a large self-interaction cross-section for dark matter (at least approx 5alpha larger than the upper limit of 0.7 sq cm/g determined by observations of the Bullet Cluster). We find no such indication and instead find that the mass distribution of A520, after subtraction of the X-ray plasma mass, is in good agreement with the luminosity distribution of the cluster galaxies.We conclude that A520 shows no evidence to contradict the collisionless dark matter scenario.

q -deformed statistics and the role of light fermionic dark matter in SN1987A cooling

NASA Astrophysics Data System (ADS)

Guha, Atanu; J, Selvaganapathy; Das, Prasanta Kumar

2017-01-01

The light dark matter (≃1 - 30 MeV ) particles pair produced in electron-positron annihilation e-e+→ γ χ χ ¯ inside the supernova core can take away the energy released in the supernova SN1987A explosion. Working within the formalism of q -deformed statistics [with the average value of the supernovae core temperature (fluctuating) being TS N=30 MeV ] and using the Raffelt's criterion on the emissivity for any new channel ɛ ˙ (e+e-→χ χ ¯ )≤1 019 erg g-1 s-1 , we find that as the deformation parameter q changes from 1.0 (undeformed scenario) to 1.1 (deformed scenario), the lower bound on the scale Λ of the dark matter effective theory varies from 3.3 ×1 06 TeV to 3.2 ×1 07 TeV for a dark matter fermion of mass mχ=30 MeV . Using the optical depth criteria on the free streaming of the dark matter fermion, we find the lower bound on Λ ˜1 08 TeV for mχ=30 MeV . In a scenario, where the dark matter fermions are pair produced in the outermost sector of the supernova core [with radius 0.9 Rc≤r ≤Rc , Rc(=10 km ) being the supernova core radius or the radius of protoneutron star], we find that the bound on Λ (˜3 ×1 07 TeV ) obtained from SN cooling criteria (Raffelt's criteria) is comparable with the bound obtained from free streaming (optical depth criterion) for light fermion dark matter of mass mχ=10 - 30 MeV .

Hierarchical phase space structure of dark matter haloes: Tidal debris, caustics, and dark matter annihilation

NASA Astrophysics Data System (ADS)

Afshordi, Niayesh; Mohayaee, Roya; Bertschinger, Edmund

2009-04-01

Most of the mass content of dark matter haloes is expected to be in the form of tidal debris. The density of debris is not constant, but rather can grow due to formation of caustics at the apocenters and pericenters of the orbit, or decay as a result of phase mixing. In the phase space, the debris assemble in a hierarchy that is truncated by the primordial temperature of dark matter. Understanding this phase structure can be of significant importance for the interpretation of many astrophysical observations and, in particular, dark matter detection experiments. With this purpose in mind, we develop a general theoretical framework to describe the hierarchical structure of the phase space of cold dark matter haloes. We do not make any assumption of spherical symmetry and/or smooth and continuous accretion. Instead, working with correlation functions in the action-angle space, we can fully account for the hierarchical structure (predicting a two-point correlation function ∝ΔJ-1.6 in the action space), as well as the primordial discreteness of the phase space. As an application, we estimate the boost to the dark matter annihilation signal due to the structure of the phase space within virial radius: the boost due to the hierarchical tidal debris is of order unity, whereas the primordial discreteness of the phase structure can boost the total annihilation signal by up to an order of magnitude. The latter is dominated by the regions beyond 20% of the virial radius, and is largest for the recently formed haloes with the least degree of phase mixing. Nevertheless, as we argue in a companion paper, the boost due to small gravitationally-bound substructure can dominate this effect at low redshifts.

The pursuit of dark matter at colliders—an overview

NASA Astrophysics Data System (ADS)

Penning, Björn

2018-06-01

Dark matter is one of the main puzzles in fundamental physics and the goal of a diverse, multi-pronged research programme. Underground and astrophysical searches look for dark matter particles in the cosmos, either by interacting directly or by searching for dark matter annihilation. Particle colliders, in contrast, might produce dark matter in the laboratory and are able to probe most basic dark-matter–matter interactions. They are sensitive to low dark matter masses, provide complementary information at higher masses and are subject to different systematic uncertainties. Collider searches are therefore an important part of an inter-disciplinary dark matter search strategy. This article highlights the experimental and phenomenological development in collider dark matter searches of recent years and their connection with the wider field.

A precision search for WIMPs with charged cosmic rays

NASA Astrophysics Data System (ADS)

Reinert, Annika; Winkler, Martin Wolfgang

2018-01-01

AMS-02 has reached the sensitivity to probe canonical thermal WIMPs by their annihilation into antiprotons. Due to the high precision of the data, uncertainties in the astrophysical background have become the most limiting factor for indirect dark matter detection. In this work we systematically quantify and—where possible—reduce uncertainties in the antiproton background. We constrain the propagation of charged cosmic rays through the combination of antiproton, B/C and positron data. Cross section uncertainties are determined from a wide collection of accelerator data and are—for the first time ever—fully taken into account. This allows us to robustly constrain even subdominant dark matter signals through their spectral properties. For a standard NFW dark matter profile we are able to exclude thermal WIMPs with masses up to 570 GeV which annihilate into bottom quarks. While we confirm a reported excess compatible with dark matter of mass around 80 GeV, its local (global) significance only reaches 2.2 σ (1.1 σ) in our analysis.

Effect of dark matter halo on global spiral modes in a collisionless galactic disk

NASA Astrophysics Data System (ADS)

Ghosh, Soumavo; Saini, Tarun Deep; Jog, Chanda J.

2017-07-01

Low surface brightness (LSB) galaxies are dominated by dark matter halo from the innermost radii; hence they are ideal candidates to investigate the influence of dark matter on different dynamical aspects of spiral galaxies. Here, we study the effect of dark matter halo on grand-design, m = 2 , spiral modes in a galactic disk, treated as a collisionless system, by carrying out a global modal analysis within the WKB approximation. First, we study a superthin, LSB galaxy UGC 7321 and show that it does not support discrete global spiral modes when modeled as a disk-alone system or as a disk plus dark matter system. Even a moderate increase in the stellar central surface density does not yield any global spiral modes. This naturally explains the observed lack of strong large-scale spiral structure in LSBs. An earlier work (Ghosh et al., 2016) where the galactic disk was treated as a fluid system for simplicity had shown that the dominant halo could not arrest global modes. We found that this difference arises due to the different dispersion relation used in the two cases and which plays a crucial role in the search for global spiral modes. Thus the correct treatment of stars as a collisionless system as done here results in the suppression of global spiral modes, in agreement with the observations. We performed a similar modal analysis for the Galaxy, and found that the dark matter halo has a negligible effect on large-scale spiral structure.

Direct and Indirect Dark Matter Detection in Gauge Theories (in Portuguese)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Queiroz, Farinaldo

The Dark matter (DM) problem constitutes a key question at the interface among Particle Physics, Astrophysics and Cosmology. The observational data which have been accumulated in the last years point to an existence of non baryonic amount of DM. Since the Standard Model (SM) does not provide any candidate for such non-baryonic DM, the evidence of DM is a major indication for new physics beyond the SM. We will study in this work one of the most popular DM candidates, the so called WIMPs (Weakly Interacting Massive Particles) from a direct and indirect detection perspective. In order to approach themore » direct and indirect dection of DM in the context of Particle Physics in a more pedagogic way, we will begin our discussion talking about a minimal extension of the SM. Later we will work on the subject in a 3-3-1 model. Next, we will study the role of WIMPs in the Big Bang Nucleosynthesis. Lastly, we will look for indirect DM signals in the center of our galaxy using the NASA Satellite, called Fermi-LAT. Through a comprehensive analysis of the data events observed by Fermi-LAT and some background models, we will constrain the dark matter annihilation cross section for several annihilation channels and dark matter halo profiles.« less

Gravitational wave from dark sector with dark pion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsumura, Koji; Yamada, Masatoshi; Yamaguchi, Yuya, E-mail: ko2@gauge.scphys.kyoto-u.ac.jp, E-mail: m.yamada@thphys.uni-heidelberg.de, E-mail: yy@particle.sci.hokudai.ac.jp

In this work, we investigate the spectra of gravitational waves produced by chiral symmetry breaking in dark quantum chromodynamics (dQCD) sector. The dark pion (π) can be a dark matter candidate as weakly interacting massive particle (WIMP) or strongly interacting massive particle (SIMP). For a WIMP scenario, we introduce the dQCD sector coupled to the standard model (SM) sector with classical scale invariance and investigate the annihilation process of the dark pion via the 2π → 2 SM process. For a SIMP scenario, we investigate the 3π → 2π annihilation process of the dark pion as a SIMP using chiralmore » perturbation theory. We find that in the WIMP scenario the gravitational wave background spectra can be observed by future space gravitational wave antennas. On the other hand, when the dark pion is the SIMP dark matter with the constraints for the chiral perturbative limit and pion-pion scattering cross section, the chiral phase transition becomes crossover and then the gravitational waves are not produced.« less

Microbial control of the dark end of the biological pump

PubMed Central

2014-01-01

A fraction of the carbon captured by phytoplankton in the sunlit surface ocean sinks to depth as dead organic matter and faecal material. The microbial breakdown of this material in the subsurface ocean generates carbon dioxide. Collectively, this microbially mediated flux of carbon from the atmosphere to the ocean interior is termed the biological pump. In recent decades it has become clear that the composition of the phytoplankton community in the surface ocean largely determines the quantity and quality of organic matter that sinks to depth. This settling organic matter, however, is not sufficient to meet the energy demands of microbes in the dark ocean. Two additional sources of organic matter have been identified: non-sinking organic particles of debated origin that escape capture by sediment traps and exhibit stable concentrations throughout the dark ocean, and microbes that convert inorganic carbon into organic matter. Whether these two sources can together account for the significant mismatch between organic matter consumption and supply in the dark ocean remains to be seen. It is clear, however, that the microbial community of the deep ocean works in a fundamentally different way from surface water communities. PMID:24707320

Codecaying Dark Matter.

PubMed

Dror, Jeff Asaf; Kuflik, Eric; Ng, Wee Hao

2016-11-18

We propose a new mechanism for thermal dark matter freeze-out, called codecaying dark matter. Multicomponent dark sectors with degenerate particles and out-of-equilibrium decays can codecay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross section, which is predicted to be boosted, and the decay rate of the dark sector particles. The mechanism is viable in a broad range of dark matter parameter space, with a robust prediction of an enhanced indirect detection signal. Finally, we present a simple model that realizes codecaying dark matter.

Can particle-creation phenomena replace dark energy?

NASA Astrophysics Data System (ADS)

Debnath, Subhra; Sanyal, Abhik Kumar

2011-07-01

Particle creation at the expense of the gravitational field might be sufficient to explain the cosmic evolution history, without the need of dark energy at all. This phenomena has been investigated in a recent work by Lima et al (Class. Quantum Grav. 2008 25 205006) assuming particle creation at the cost of gravitational energy in the late Universe. However, the model does not satisfy the WMAP constraint on the matter-radiation equality (Steigman et al 2009 J. Cosmol. Astropart. Phys. JCAP06(2009)033). Here, we have suggested a model, in the same framework, which fits perfectly with SNIa data at low redshift as well as an early integrated Sachs-Wolfe effect on the matter-radiation equality determined by WMAP at high redshift. Such a model requires the presence of nearly 26% primeval matter in the form of baryons and cold dark matter.

Gravitational collapse and the vacuum energy

NASA Astrophysics Data System (ADS)

Campos, M.

2014-03-01

To explain the accelerated expansion of the universe, models with interacting dark components (dark energy and dark matter) have been considered recently in the literature. Generally, the dark energy component is physically interpreted as the vacuum energy of the all fields that fill the universe. As the other side of the same coin, the influence of the vacuum energy on the gravitational collapse is of great interest. We study such collapse adopting different parameterizations for the evolution of the vacuum energy. We discuss the homogeneous collapsing star fluid, that interacts with a vacuum energy component, using the stiff matter case as example. We conclude this work with a discussion of the Cahill-McVittie mass for the collapsed object.

Detecting dark matter with imploding pulsars in the galactic center.

PubMed

Bramante, Joseph; Linden, Tim

2014-11-07

The paucity of old millisecond pulsars observed at the galactic center of the Milky Way could be the result of dark matter accumulating in and destroying neutron stars. In regions of high dark matter density, dark matter clumped in a pulsar can exceed the Schwarzschild limit and collapse into a natal black hole which destroys the pulsar. We examine what dark matter models are consistent with this hypothesis and find regions of parameter space where dark matter accumulation can significantly degrade the neutron star population within the galactic center while remaining consistent with observations of old millisecond pulsars in globular clusters and near the solar position. We identify what dark matter couplings and masses might cause a young pulsar at the galactic center to unexpectedly extinguish. Finally, we find that pulsar collapse age scales inversely with the dark matter density and linearly with the dark matter velocity dispersion. This implies that maximum pulsar age is spatially dependent on position within the dark matter halo of the Milky Way. In turn, this pulsar age spatial dependence will be dark matter model dependent.

Cosmological perturbations during the Bose-Einstein condensation of dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freitas, R.C.; Gonçalves, S.V.B., E-mail: rodolfo.camargo@pq.cnpq.br, E-mail: sergio.vitorino@pq.cnpq.br

In the present work, we analyze the evolution of the scalar and tensorial perturbations and the quantities relevant for the physical description of the Universe, as the density contrast of the scalar perturbations and the gravitational waves energy density during the Bose-Einstein condensation of dark matter. The behavior of these parameters during the Bose-Einstein phase transition of dark matter is analyzed in details. To study the cosmological dynamics and evolution of scalar and tensorial perturbations in a Universe with and without cosmological constant we use both analytical and numerical methods. The Bose-Einstein phase transition modifies the evolution of gravitational wavesmore » of cosmological origin, as well as the process of large-scale structure formation.« less

Global constraints on vector-like WIMP effective interactions

DOE PAGES

Blennow, Mattias; Coloma, Pilar; Fernandez-Martinez, Enrique; ...

2016-04-07

In this work we combine information from relic abundance, direct detection, cosmic microwave background, positron fraction, gamma rays, and colliders to explore the existing constraints on couplings between Dark Matter and Standard Model constituents when no underlying model or correlation is assumed. For definiteness, we include independent vector-like effective interactions for each Standard Model fermion. Our results show that low Dark Matter masses below 20 GeV are disfavoured at the 3 σ  level with respect to higher masses, due to the tension between the relic abundance requirement and upper constraints on the Dark Matter couplings. Lastly, large couplings are typically onlymore » allowed in combinations which avoid effective couplings to the nuclei used in direct detection experiments.« less

Sensitivity of Atom Interferometry to Ultralight Scalar Field Dark Matter.

PubMed

Geraci, Andrew A; Derevianko, Andrei

2016-12-23

We discuss the use of atom interferometry as a tool to search for dark matter (DM) composed of virialized ultralight fields (VULFs). Previous work on VULF DM detection using accelerometers has considered the possibility of equivalence-principle-violating effects whereby gradients in the dark matter field can directly produce relative accelerations between media of differing composition. In atom interferometers, we find that time-varying phase signals induced by coherent oscillations of DM fields can also arise due to changes in the atom rest mass that can occur between light pulses throughout the interferometer sequence as well as changes in Earth's gravitational field. We estimate that several orders of magnitude of unexplored phase space for VULF DM couplings can be probed due to these new effects.

Quark seesaw mechanism, dark U (1 ) symmetry, and the baryon-dark matter coincidence

NASA Astrophysics Data System (ADS)

Gu, Pei-Hong; Mohapatra, Rabindra N.

2017-09-01

We attempt to understand the baryon-dark matter coincidence problem within the quark seesaw extension of the standard model where parity invariance is used to solve the strong C P problem. The S U (2 )L×S U (2 )R×U (1 )B -L gauge symmetry of this model is extended by a dark U (1 )X group plus inclusion of a heavy neutral vector-like fermion χL ,R charged under the dark group which plays the role of dark matter. All fermions are Dirac type in this model. Decay of heavy scalars charged under U (1 )X leads to simultaneous asymmetry generation of the dark matter and baryons after sphaleron effects are included. The U (1 )X group not only helps to stabilize the dark matter but also helps in the elimination of the symmetric part of the dark matter via χ -χ ¯ annihilation. For dark matter mass near the proton mass, it explains why the baryon and dark matter abundances are of similar magnitude (the baryon-dark matter coincidence problem). This model is testable in low threshold (sub-keV) direct dark matter search experiments.

Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Jonathan H., E-mail: jonathan.h.m.davis@gmail.com

2015-03-01

Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments are said to run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable throughmore » a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that, using only spectral information, the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions it can still be surpassed using timing information, and so the neutrino floor is not an absolute limit on the sensitivity of Direct Detection experiments.« less

Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Jonathan H.

2015-03-09

Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments are said to run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable throughmore » a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that, using only spectral information, the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions it can still be surpassed using timing information, and so the neutrino floor is not an absolute limit on the sensitivity of Direct Detection experiments.« less

REVIEWS OF TOPICAL PROBLEMS: The search for dark matter particles

NASA Astrophysics Data System (ADS)

Ryabov, Vladimir A.; Tsarev, Vladimir A.; Tskhovrebov, Andrei M.

2008-11-01

Evidence of dark matter in the Universe is discussed and the most popular candidates for dark matter particles are reviewed. The review is mainly devoted to numerous experiments, both underway and planned, on the search for dark matter particles. Various experimental methods are discussed, including those involving direct registration of dark matter particles with the detector and those where the products of dark matter decay and annihilation are registered.

[Dark matter and dark energy of the universe].

PubMed

Aguilar Peris, José

2005-01-01

At the turn of the 20th Century, the Universe was thought to consist of our solar system, the Sun, planets, satellites and comets, floating under the Milky Way. The astronomers were ignorant of the existence of galaxies, clusters, quasars and black holes. Over the last ten years the Cosmology has made remarkable progress in our understanding of the composition of the Universe: 23 per cent is in an unknown form called dark matter; 73 per cent in another form called dark energy; 3 per cent is made of free hydrogen and helium atoms; 0.5 per cent makes up all the light we see in the night including the stars, clusters and superclusters; 0.3 per cent is in free neutrino particles; and finally, 0.03 per cent is in the heavier nuclei of which the Sun, the Earth and ourselves are made. In this work we study specially the dark matter and the dark energy. The first one appears to be attached to galaxies, and astronomers agree that it is cold, meaning that the particles that make up that matter are not moving fast. Very recently astronomers discovered that a tremendous amount of the so-cahled dark energy exists and that it is pushing and accelerating the expansion of the Universe. Should this expansion continue for another 14,000 million years, the sky will darken with only a handful of galaxies remaining visible.

Measuring the Value Added of Management: A Knowledge Value Added Approach

DTIC Science & Technology

2006-12-31

Dark Matter ” ................................................................3 Difficult-to-track Dark Matter Outputs .................................................5 Computing Metaphor..........................................................................6 Dark Matter Correlates with Market Performance ..............................8 Outputs of Dark Matter .......................................................................9 Operationalizing: The Measurement of Dark

Asymmetric capture of Dirac dark matter by the Sun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blennow, Mattias; Clementz, Stefan

2015-08-18

Current problems with the solar model may be alleviated if a significant amount of dark matter from the galactic halo is captured in the Sun. We discuss the capture process in the case where the dark matter is a Dirac fermion and the background halo consists of equal amounts of dark matter and anti-dark matter. By considering the case where dark matter and anti-dark matter have different cross sections on solar nuclei as well as the case where the capture process is considered to be a Poisson process, we find that a significant asymmetry between the captured dark particles andmore » anti-particles is possible even for an annihilation cross section in the range expected for thermal relic dark matter. Since the captured number of particles are competitive with asymmetric dark matter models in a large range of parameter space, one may expect solar physics to be altered by the capture of Dirac dark matter. It is thus possible that solutions to the solar composition problem may be searched for in these type of models.« less

Cosmological bounds on non-Abelian dark forces

NASA Astrophysics Data System (ADS)

Forestell, Lindsay; Morrissey, David E.; Sigurdson, Kris

2018-04-01

Non-Abelian dark gauge forces that do not couple directly to ordinary matter may be realized in nature. The minimal form of such a dark force is a pure Yang-Mills theory. If the dark sector is reheated in the early Universe, it will be realized as a set of dark gluons at high temperatures and as a collection of dark glueballs at lower temperatures, with a cosmological phase transition from one form to the other. Despite being dark, the gauge fields of the new force can connect indirectly to the standard model through nonrenormalizable operators. These operators will transfer energy between the dark and visible sectors, and they allow some or all of the dark glueballs to decay. In this work we investigate the cosmological evolution and decays of dark glueballs in the presence of connector operators to the standard model. Dark glueball decays can modify cosmological and astrophysical observables, and we use these considerations to put very strong limits on the existence of pure non-Abelian dark forces. On the other hand, if one or more of the dark glueballs are stable, we find that they can potentially make up the dark matter of the Universe.

Galaxy formation through hierarchical clustering

NASA Astrophysics Data System (ADS)

White, Simon D. M.; Frenk, Carlos S.

1991-09-01

Analytic methods for studying the formation of galaxies by gas condensation within massive dark halos are presented. The present scheme applies to cosmogonies where structure grows through hierarchical clustering of a mixture of gas and dissipationless dark matter. The simplest models consistent with the current understanding of N-body work on dissipationless clustering, and that of numerical and analytic work on gas evolution and cooling are adopted. Standard models for the evolution of the stellar population are also employed, and new models for the way star formation heats and enriches the surrounding gas are constructed. Detailed results are presented for a cold dark matter universe with Omega = 1 and H(0) = 50 km/s/Mpc, but the present methods are applicable to other models. The present luminosity functions contain significantly more faint galaxies than are observed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

König, Johannes; Merle, Alexander; Totzauer, Maximilian

We investigate the early Universe production of sterile neutrino Dark Matter by the decays of singlet scalars. All previous studies applied simplifying assumptions and/or studied the process only on the level of number densities, which makes it impossible to give statements about cosmic structure formation. We overcome these issues by dropping all simplifying assumptions (except for one we showed earlier to work perfectly) and by computing the full course of Dark Matter production on the level of non-thermal momentum distribution functions. We are thus in the position to study a broad range of aspects of the resulting settings and applymore » a broad set of bounds in a reliable manner. We have a particular focus on how to incorporate bounds from structure formation on the level of the linear power spectrum, since the simplistic estimate using the free-streaming horizon clearly fails for highly non-thermal distributions. Our work comprises the most detailed and comprehensive study of sterile neutrino Dark Matter production by scalar decays presented so far.« less

A dark matter scaling relation from mirror dark matter

NASA Astrophysics Data System (ADS)

Foot, R.

2014-12-01

Mirror dark matter, and other similar dissipative dark matter candidates, need an energy source to stabilize dark matter halos around spiral galaxies. It has been suggested previously that ordinary supernovae can potentially supply the required energy. By matching the energy supplied to the halo from supernovae to that lost due to radiative cooling, we here derive a rough scaling relation, RSN ∝ρ0r02 (RSN is the supernova rate and ρ0 ,r0 the dark matter central density and core radius). Such a relation is consistent with dark matter properties inferred from studies of spiral galaxies with halo masses larger than 3 ×1011M⊙. We speculate that other observed galaxy regularities might be explained within the framework of such dissipative dark matter.

Tying dark matter to baryons with self-interactions.

PubMed

Kaplinghat, Manoj; Keeley, Ryan E; Linden, Tim; Yu, Hai-Bo

2014-07-11

Self-interacting dark matter (SIDM) models have been proposed to solve the small-scale issues with the collisionless cold dark matter paradigm. We derive equilibrium solutions in these SIDM models for the dark matter halo density profile including the gravitational potential of both baryons and dark matter. Self-interactions drive dark matter to be isothermal and this ties the core sizes and shapes of dark matter halos to the spatial distribution of the stars, a radical departure from previous expectations and from cold dark matter predictions. Compared to predictions of SIDM-only simulations, the core sizes are smaller and the core densities are higher, with the largest effects in baryon-dominated galaxies. As an example, we find a core size around 0.3 kpc for dark matter in the Milky Way, more than an order of magnitude smaller than the core size from SIDM-only simulations, which has important implications for indirect searches of SIDM candidates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozorgnia, Nassim; Gelmini, Graciela B.; Gondolo, Paolo, E-mail: n.bozorgnia@uva.nl, E-mail: gelmini@physics.ucla.edu, E-mail: paolo@physics.utah.edu

Directional dark matter detection attempts to measure the direction of motion of nuclei recoiling after having interacted with dark matter particles in the halo of our Galaxy. Due to Earth's motion with respect to the Galaxy, the dark matter flux is concentrated around a preferential direction. An anisotropy in the recoil direction rate is expected as an unmistakable signature of dark matter. The average nuclear recoil direction is expected to coincide with the average direction of dark matter particles arriving to Earth. Here we point out that for a particular type of dark matter, inelastic exothermic dark matter, the meanmore » recoil direction as well as a secondary feature, a ring of maximum recoil rate around the mean recoil direction, could instead be opposite to the average dark matter arrival direction. Thus, the detection of an average nuclear recoil direction opposite to the usually expected direction would constitute a spectacular experimental confirmation of this type of dark matter.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blennow, Mattias; Clementz, Stefan, E-mail: emb@kth.se, E-mail: scl@kth.se

Current problems with the solar model may be alleviated if a significant amount of dark matter from the galactic halo is captured in the Sun. We discuss the capture process in the case where the dark matter is a Dirac fermion and the background halo consists of equal amounts of dark matter and anti-dark matter. By considering the case where dark matter and anti-dark matter have different cross sections on solar nuclei as well as the case where the capture process is considered to be a Poisson process, we find that a significant asymmetry between the captured dark particles andmore » anti-particles is possible even for an annihilation cross section in the range expected for thermal relic dark matter. Since the captured number of particles are competitive with asymmetric dark matter models in a large range of parameter space, one may expect solar physics to be altered by the capture of Dirac dark matter. It is thus possible that solutions to the solar composition problem may be searched for in these type of models.« less

The DarkSide-50 Experiment: Electron Recoil Calibrations and A Global Energy Variable

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hackett, Brianne Rae

2017-01-01

Over the course of decades, there has been mounting astronomical evidence for non-baryonic dark matter, yet its precise nature remains elusive. A favored candidate for dark matter is the Weakly Interacting Massive Particle (WIMP) which arises naturally out of extensions to the Standard Model. WIMPs are expected to occasionally interact with particles of normal matter through nuclear recoils. DarkSide-50 aims to detect this type of particle through the use of a two-phase liquid argon time projection chamber. To make a claim of discovery, an accurate understanding of the background and WIMP search region is imperative. Knowledge of the backgrounds ismore » done through extensive studies of DarkSide-50's response to electron and nuclear recoils. The CALibration Insertion System (CALIS) was designed and built for the purpose of introduc- ing radioactive sources into or near the detector in a joint eort between Fermi National Laboratory (FNAL) and the University of Hawai'i at Manoa. This work describes the testing, installation, and commissioning of CALIS at the Laboratori Nazionali del Gran Sasso. CALIS has been used in mul- tiple calibration campaigns with both neutron and sources. In this work, DarkSide-50's response to electron recoils, which are important for background estimations, was studied through the use of calibration sources by constructing a global energy variable which takes into account the anti- correlation between scintillation and ionization signals produced by interactions in the liquid argon. Accurately reconstructing the event energy correlates directly with quantitatively understanding the WIMP sensitivity in DarkSide-50. This work also validates the theoretically predicted decay spectrum of 39Ar against 39Ar decay data collected in the early days of DarkSide-50 while it was lled with atmospheric argon; a validation of this type is not readily found in the literature. Finally, we show how well the constructed energy variable can predict energy spectra for the calibration sources and for 39Ar.« less

Secretly asymmetric dark matter

NASA Astrophysics Data System (ADS)

Agrawal, Prateek; Kilic, Can; Swaminathan, Sivaramakrishnan; Trendafilova, Cynthia

2017-01-01

We study a mechanism where the dark matter number density today arises from asymmetries generated in the dark sector in the early Universe, even though the total dark matter number remains zero throughout the history of the Universe. The dark matter population today can be completely symmetric, with annihilation rates above those expected from thermal weakly interacting massive particles. We give a simple example of this mechanism using a benchmark model of flavored dark matter. We discuss the experimental signatures of this setup, which arise mainly from the sector that annihilates the symmetric component of dark matter.

Dark Matter Halos with VIRUS-P

NASA Astrophysics Data System (ADS)

Murphy, Jeremy; Gebhardt, K.

2010-05-01

We present new, two-dimensional stellar kinematic data on several of the most massive galaxies in the local universe. These data were taken with the integral field spectrograph, VIRUS-P, and extend to unprecedented radial distances. Once robust stellar kinematics are in hand, we run orbit-based axisymmetric dynamical models in order to constrain the stellar mass-to-light ratio and dark matter halo parameters. We have run a large set of dynamical models on the second rank galaxy in the Virgo cluster, M87, and find clear evidence for a massive dark matter halo. The two-dimensional stellar kinematics for several of our other targets, all first and second rank galaxies, are also presented. Dark matter halos are known to dominate the mass profile of elliptical galaxies somewhere between one to two effective radii, yet due to the low surface brightness at these radial distances, determining stellar dynamics is technologically challenging. To overcome this, constraints on the dark matter halo are often made with planetary nebulae or globular clusters at large radii. However, as results from different groups have returned contradictory results, it remains unclear whether different dynamical tracers always follow the stellar kinematics. Due to VIRUS-P's large field of view and on-sky fiber diameter, we are able to determine stellar kinematics at radial distances that overlap with other dynamical tracers. Understanding what the dynamics of stars, planetary nebula and globular clusters tell us about both the extent of the dark matter halo profile and the formation histories of the largest elliptical galaxies is a primary science driver for this work.

Dilaton-assisted dark matter.

PubMed

Bai, Yang; Carena, Marcela; Lykken, Joseph

2009-12-31

A dilaton could be the dominant messenger between standard model fields and dark matter. The measured dark matter relic abundance relates the dark matter mass and spin to the conformal breaking scale. The dark matter-nucleon spin-independent cross section is predicted in terms of the dilaton mass. We compute the current constraints on the dilaton from LEP and Tevatron experiments, and the gamma-ray signal from dark matter annihilation to dilatons that could be observed by Fermi Large Area Telescope.

Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud

NASA Technical Reports Server (NTRS)

Drlica-Wagner, Alex; Gomez-Vargas, German A.; Hewitt, John W.; Linden, Tim; Tibaldo, Luigi

2014-01-01

Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use gamma-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant gamma-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (approximately 3 x 10 (sup -26) cubic centimeters per second) for dark matter masses less than or approximately 30 gigaelectronvolts annihilating via the B/B- bar oscillation or tau/antitau channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

Searching For Dark Matter Annihilation In The Smith High-Velocity Cloud

DOE PAGES

Drlica-Wagner, Alex; Gómez-Vargas, Germán A.; Hewitt, John W.; ...

2014-06-27

Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use γ-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant γ-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation crossmore » section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (~3 × 10 -26 cm3 s -1) for dark matter masses . 30 GeV annihilating via the b¯b or τ⁺τ⁻ channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.« less

Implications of two-component dark matter induced by forbidden channels and thermal freeze-out

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aoki, Mayumi; Toma, Takashi, E-mail: mayumi@hep.s.kanazawa-u.ac.jp, E-mail: takashi.toma@tum.de

2017-01-01

We consider a model of two-component dark matter based on a hidden U(1) {sub D} symmetry, in which relic densities of the dark matter are determined by forbidden channels and thermal freeze-out. The hidden U(1) {sub D} symmetry is spontaneously broken to a residual Z{sub 4} symmetry, and the lightest Z{sub 4} charged particle can be a dark matter candidate. Moreover, depending on the mass hierarchy in the dark sector, we have two-component dark matter. We show that the relic density of the lighter dark matter component can be determined by forbidden annihilation channels which require larger couplings compared tomore » the normal freeze-out mechanism. As a result, a large self-interaction of the lighter dark matter component can be induced, which may solve small scale problems of ΛCDM model. On the other hand, the heavier dark matter component is produced by normal freeze-out mechanism. We find that interesting implications emerge between the two dark matter components in this framework. We explore detectabilities of these dark matter particles and show some parameter space can be tested by the SHiP experiment.« less

Cold dark matter: Controversies on small scales.

PubMed

Weinberg, David H; Bullock, James S; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H G

2015-10-06

The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way's dwarf galaxy satellites. We review the current observational and theoretical status of these "small-scale controversies." Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years.

Secluded WIMPs, Dark QED with Massive Photons, and the Galactic Center Gamma-Ray Excess

NASA Technical Reports Server (NTRS)

Fortes, E. C. F. S.; Pleitez, V.; Stecker, F. W.

2015-01-01

We discuss a particular secluded WIMP dark matter model consisting of neutral fermions as the dark matter candidate and a Proca-Wentzel (PW) field as a mediator. In the model that we consider here, dark matter WIMPs interact with standard model (SM) particles only through the PW field of approximately MeV-multi-GeV mass particles. The interactions occur via a U(1)' mediator, V'(sub mu), which couples to the SM by kinetic mixing with U(1) hypercharge bosons, B'(sub mu). One important difference between our model and other such models in the literature is the absence of an extra singlet scalar, so that the parameter with dimension of mass M(sup 2, sub V) is not related to a spontaneous symmetry breaking. This QED based model is also renormalizable. The mass scale of the mediator and the absence of the singlet scalar can lead to interesting astrophysical signatures. The dominant annihilation channels are different from those usually considered in previous work. We show that the GeV energy gamma-ray excess in the galactic center region, as derived from Fermi-LAT Gamma-ray Space Telescope data, can be attributed to such secluded dark matter WIMPs, given parameters of the model that are consistent with both the cosmological dark matter density and the upper limits on WIMP spin-independent elastic scattering. Secluded WIMP models are also consistent with suggested upper limits on a DM contribution to the cosmic-ray antiproton flux.

Collapsed Dark Matter Structures

NASA Astrophysics Data System (ADS)

Buckley, Matthew R.; DiFranzo, Anthony

2018-02-01

The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

Collapsed Dark Matter Structures.

PubMed

Buckley, Matthew R; DiFranzo, Anthony

2018-02-02

The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

The Evolving Search for the Nature of Dark Energy | Berkeley Lab

Science.gov Websites

percent of its contents is ordinary matter, 24 percent is dark matter, and all the rest is dark energy ordinary matter, 24 percent is dark matter, and all the rest is dark energy - unless there's a flaw in our Universe, and it's pushing all the rest - ordinary matter and dark matter - farther apart at an ever

Interacting dark energy models as an approach for solving Cosmic Coincidence Problem

NASA Astrophysics Data System (ADS)

Shojaei, Hamed

Understanding the dark side of the Universe is one of the main tasks of physicists. As there is no thorough understanding of nature of the dark energy, this area is full of new ideas and there may be several discoveries, theoretical or experimental, in the near future. We know that dark energy, though not detected directly, exists and it is not just an exotic idea. The presence of dark energy is required by the observation of the acceleration of the universe. There are several questions regarding dark energy. What is the nature of dark energy? How does it interact with matter, baryonic or dark? Why is the density of dark energy so tiny, i.e. why rhoΛ ≈ 10--120 M4Pl ? And finally why does its density have the same order of magnitude as the density of matter does at the present time? The last question is one form of what is known as the "Cosmic Coincidence Problem" and in this work, I have been investigating one way to resolve this issue. Observations of Type Ia supernovae indicate that we are in an accelerating universe. A matter-dominated universe cannot be accelerating. A good fit is obtained if we assume that energy density parameters are O Λ = 0.7 and Om = 0.3. Here O Λ is related to dark energy, or cosmological constant in ΛCDM model. At the same time data from Wilkinson Microwave Anisotropy Probe (WMAP) satellite and supernova surveys have placed a constraint on w, the equation of state for dark energy, which is actually the ratio of pressure and energy density. Any good theory needs to explain this coincidence problem and yields a value for w between -1.1 and -0.9. I have employed an interesting approach to solve this problem by assuming that there exists an interaction between dark energy and matter in the context of holographic dark energy. This interaction converts dark energy to matter or vice versa without violating the local conservation of energy in the universe. Holographic dark energy by itself indicates that the value of dark energy is related to the surface of a horizon. In this work, interacting dark energy models are considered in flat and curved spacetime, and their properties have been explored. Adding interaction to the equations of motion, creates new equilibrium solutions for the evolution of the universe. Adjusting parameters in the theory yields equilibrium solutions which are very close to the universe at the present time. In this sense, being in a universe where dark energy density and matter density are comparable is not a coincidence anymore. We don't just happen to be in this era. This situation is the equilibrium situation which the universe had been driven toward and there is no coincidence at all. I believe these models are not just for resolving the cosmic coincidence problem. They are capable of explaining the universe in all of its evolutionary stages. Upon finding the correct interaction, a task which is still under investigation, one is able to have a whole picture for the universe from the beginning, before inflation, until now. Finding that interaction also will help to discover the fundamental theory which explains the nature of dark energy.

A global fit of the γ-ray galactic center excess within the scalar singlet Higgs portal model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuoco, Alessandro; Eiteneuer, Benedikt; Heisig, Jan

2016-06-28

We analyse the excess in the γ-ray emission from the center of our galaxy observed by Fermi-LAT in terms of dark matter annihilation within the scalar Higgs portal model. In particular, we include the astrophysical uncertainties from the dark matter distribution and allow for unspecified additional dark matter components. We demonstrate through a detailed numerical fit that the strength and shape of the γ-ray spectrum can indeed be described by the model in various regions of dark matter masses and couplings. Constraints from invisible Higgs decays, direct dark matter searches, indirect searches in dwarf galaxies and for γ-ray lines, andmore » constraints from the dark matter relic density reduce the parameter space to dark matter masses near the Higgs resonance. We find two viable regions: one where the Higgs-dark matter coupling is of O(10{sup −2}), and an additional dark matter component beyond the scalar WIMP of our model is preferred, and one region where the Higgs-dark matter coupling may be significantly smaller, but where the scalar WIMP constitutes a significant fraction or even all of dark matter. Both viable regions are hard to probe in future direct detection and collider experiments.« less

Massive graviton dark matter with environment dependent mass: A natural explanation of the dark matter-baryon ratio

NASA Astrophysics Data System (ADS)

Aoki, Katsuki; Mukohyama, Shinji

2017-11-01

We propose a scenario that can naturally explain the observed dark matter-baryon ratio in the context of bimetric theory with a chameleon field. We introduce two additional gravitational degrees of freedom, the massive graviton and the chameleon field, corresponding to dark matter and dark energy, respectively. The chameleon field is assumed to be nonminimally coupled to dark matter, i.e., the massive graviton, through the graviton mass terms. We find that the dark matter-baryon ratio is dynamically adjusted to the observed value due to the energy transfer by the chameleon field. As a result, the model can explain the observed dark matter-baryon ratio independently from the initial abundance of them.

Dark sequential Z ' portal: Collider and direct detection experiments

NASA Astrophysics Data System (ADS)

Arcadi, Giorgio; Campos, Miguel D.; Lindner, Manfred; Masiero, Antonio; Queiroz, Farinaldo S.

2018-02-01

We revisit the status of a Majorana fermion as a dark matter candidate when a sequential Z' gauge boson dictates the dark matter phenomenology. Direct dark matter detection signatures rise from dark matter-nucleus scatterings at bubble chamber and liquid xenon detectors, and from the flux of neutrinos from the Sun measured by the IceCube experiment, which is governed by the spin-dependent dark matter-nucleus scattering. On the collider side, LHC searches for dilepton and monojet + missing energy signals play an important role. The relic density and perturbativity requirements are also addressed. By exploiting the dark matter complementarity we outline the region of parameter space where one can successfully have a Majorana dark matter particle in light of current and planned experimental sensitivities.

Antiproton signatures from astrophysical and dark matter sources at the galactic center

NASA Astrophysics Data System (ADS)

Cembranos, J. A. R.; Gammaldi, V.; Maroto, A. L.

2015-03-01

The center of our Galaxy is a complex region characterized by extreme phenomena. The presence of the supermassive Sagittarius A* black hole, a high dark matter density and an even higher baryonic density are able to produce very energetic processes. Indeed, high energetic gamma-rays have been observed by different telescopes, although their origin is not clear. In this work, we estimate the possible antiproton flux component associated with this signal. The expected secondary astrophysical antiproton background already saturates the observed data. It implies that any other important astrophysical source leads to an inconsistent excess. We estimate the sensitivity of PAMELA to this new primary antiproton source, which depends on the diffusion model and its spectral features. In particular, we consider antiproton spectra described by a power-law, a monochromatic signal and a Standard Model particle-antiparticle channel production. This latter spectrum is typical in the production from annihilating or decaying dark matter. We pay particular attention to the case of a heavy dark matter candidate, which could be associated with the High Energy Stereoscopic System (HESS) data observed from the J1745-290 source.

Dark matter at DeepCore and IceCube

NASA Astrophysics Data System (ADS)

Barger, V.; Gao, Y.; Marfatia, D.

2011-03-01

With the augmentation of IceCube by DeepCore, the prospect for detecting dark matter annihilation in the Sun is much improved. To complement this experimental development, we provide a thorough template analysis of the particle physics issues that are necessary to precisely interpret the data. Our study is about nitty-gritty and is intended as a framework for detailed work on a variety of dark matter candidates. To accurately predict the source neutrino spectrum, we account for spin-correlations of the final state particles and the helicity-dependence of their decays, and absorption effects at production. We fully treat the propagation of neutrinos through the Sun, including neutrino oscillations, energy losses and tau regeneration. We simulate the survival probability of muons produced in the Earth by using the Muon Monte Carlo program, reproduce the published IceCube effective area, and update the parameters in the differential equation that approximates muon energy losses. To evaluate the zenith-angle dependent atmospheric background event rate, we track the Sun and determine the time it spends at each zenith-angle. Throughout, we employ neutralino dark matter as our example.

Updated search for spectral lines from Galactic dark matter interactions with pass 8 data from the Fermi Large Area Telescope

DOE PAGES

Ackermann, M.; Ajello, M.; Albert, A.; ...

2015-06-15

Dark matter in the Milky Way may annihilate directly into γ rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV–500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increasemore » exposure of the Galactic center region. Furthermore, we search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.« less

Flavored dark matter beyond Minimal Flavor Violation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agrawal, Prateek; Blanke, Monika; Gemmler, Katrin

We study the interplay of flavor and dark matter phenomenology for models of flavored dark matter interacting with quarks. We allow an arbitrary flavor structure in the coupling of dark matter with quarks. This coupling is assumed to be the only new source of violation of the Standard Model flavor symmetry extended by a U(3) χ associated with the dark matter. We call this ansatz Dark Minimal Flavor Violation (DMFV) and highlight its various implications, including an unbroken discrete symmetry that can stabilize the dark matter. As an illustration we study a Dirac fermionic dark matter χ which transforms asmore » triplet under U(3) χ , and is a singlet under the Standard Model. The dark matter couples to right-handed down-type quarks via a colored scalar mediator Φ with a coupling λ. We identify a number of “flavor-safe” scenarios for the structure of λ which are beyond Minimal Flavor Violation. Also, for dark matter and collider phenomenology we focus on the well-motivated case of b-flavored dark matter. Furthermore, the combined flavor and dark matter constraints on the parameter space of λ turn out to be interesting intersections of the individual ones. LHC constraints on simplified models of squarks and sbottoms can be adapted to our case, and monojet searches can be relevant if the spectrum is compressed.« less

Flavored dark matter beyond Minimal Flavor Violation

DOE PAGES

Agrawal, Prateek; Blanke, Monika; Gemmler, Katrin

2014-10-13

We study the interplay of flavor and dark matter phenomenology for models of flavored dark matter interacting with quarks. We allow an arbitrary flavor structure in the coupling of dark matter with quarks. This coupling is assumed to be the only new source of violation of the Standard Model flavor symmetry extended by a U(3) χ associated with the dark matter. We call this ansatz Dark Minimal Flavor Violation (DMFV) and highlight its various implications, including an unbroken discrete symmetry that can stabilize the dark matter. As an illustration we study a Dirac fermionic dark matter χ which transforms asmore » triplet under U(3) χ , and is a singlet under the Standard Model. The dark matter couples to right-handed down-type quarks via a colored scalar mediator Φ with a coupling λ. We identify a number of “flavor-safe” scenarios for the structure of λ which are beyond Minimal Flavor Violation. Also, for dark matter and collider phenomenology we focus on the well-motivated case of b-flavored dark matter. Furthermore, the combined flavor and dark matter constraints on the parameter space of λ turn out to be interesting intersections of the individual ones. LHC constraints on simplified models of squarks and sbottoms can be adapted to our case, and monojet searches can be relevant if the spectrum is compressed.« less

LHC - a "Why" Facility

ScienceCinema

Gordon Kane

2017-12-09

The Standard Models of particle physics and cosmology describe the world we see, and how it works, very well. But we want to understand (not just accommodate) much more – how does the Higgs mechanism work, what is the dark matter, why is the universe matter and not antimatter, why is parity violated, why are the particles (quarks and leptons) what they are, and why are the forces that act on them to make our world what they are, and more. Today is an exciting time to be doing particle physics – on the experimental side we have data coming from LHC and dark matter experiments that will provide clues to these questions, and on the theoretical side we have a framework (string theory) that addresses all these “why” questions. LHC data will not qualitatively improve our description – rather, it may provide the data that will allow us to learn about the dark matter, the Higgs physics, the matter asymmetry, etc, to test underlying theories such as string theory, and begin to answer the “why” questions. Supersymmetry is the best motivated discovery, and it would also open a window to the underlying theory near the Planck scale.

Theoretical Comparison Between Candidates for Dark Matter

NASA Astrophysics Data System (ADS)

McKeough, James; Hira, Ajit; Valdez, Alexandra

2017-01-01

Since the generally-accepted view among astrophysicists is that the matter component of the universe is mostly dark matter, the search for dark matter particles continues unabated. The Large Underground Xenon (LUX) improvements, aided by advanced computer simulations at the U.S. Department of Energy's Lawrence Berkeley National Laboratory's (Berkeley Lab) National Energy Research Scientific Computing Center (NERSC) and Brown University's Center for Computation and Visualization (CCV), can potentially eliminate some particle models of dark matter. Generally, the proposed candidates can be put in three categories: baryonic dark matter, hot dark matter, and cold dark matter. The Lightest Supersymmetric Particle(LSP) of supersymmetric models is a dark matter candidate, and is classified as a Weakly Interacting Massive Particle (WIMP). Similar to the cosmic microwave background radiation left over from the Big Bang, there is a background of low-energy neutrinos in our Universe. According to some researchers, these may be the explanation for the dark matter. One advantage of the Neutrino Model is that they are known to exist. Dark matter made from neutrinos is termed ``hot dark matter''. We formulate a novel empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function adequately treats both void size and redshift, and describes the scale radius and the central density of voids. We started with a five-parameter model. Our research is mainly on LSP and Neutrino models.

Mystery of the Hidden Cosmos [Complex Dark Matter

DOE PAGES

Dobrescu, Bogdan A.; Lincoln, Don

2015-06-16

Scientists know there must be more matter in the universe than what is visible. Searches for this dark matter have focused on a single unseen particle, but decades of experiments have been unsuccessful at finding it. Exotic possibilities for dark matter are looking increasingly plausible. Rather than just one particle, dark matter could contain an entire world of particles and forces that barely interact with normal matter. Complex dark matter could form dark atoms and molecules and even clump together to make hidden galactic disks that overlap with the spiral arms of the Milky Way and other galaxies. Experiments aremore » under way to search for evidence of such a dark sector.« less

Dark Matter Decay between Phase Transitions at the Weak Scale.

PubMed

Baker, Michael J; Kopp, Joachim

2017-08-11

We propose a new alternative to the weakly interacting massive particle paradigm for dark matter. Rather than being determined by thermal freeze-out, the dark matter abundance in this scenario is set by dark matter decay, which is allowed for a limited amount of time just before the electroweak phase transition. More specifically, we consider fermionic singlet dark matter particles coupled weakly to a scalar mediator S_{3} and to auxiliary dark sector fields, charged under the standard model gauge groups. Dark matter freezes out while still relativistic, so its abundance is initially very large. As the Universe cools down, the scalar mediator develops a vacuum expectation value (VEV), which breaks the symmetry that stabilizes dark matter. This allows dark matter to mix with charged fermions and decay. During this epoch, the dark matter abundance is reduced to give the value observed today. Later, the SM Higgs field also develops a VEV, which feeds back into the S_{3} potential and restores the dark sector symmetry. In a concrete model we show that this "VEV flip-flop" scenario is phenomenologically successful in the most interesting regions of its parameter space. We also comment on detection prospects at the LHC and elsewhere.

Dark Matter Decay between Phase Transitions at the Weak Scale

NASA Astrophysics Data System (ADS)

Baker, Michael J.; Kopp, Joachim

2017-08-01

We propose a new alternative to the weakly interacting massive particle paradigm for dark matter. Rather than being determined by thermal freeze-out, the dark matter abundance in this scenario is set by dark matter decay, which is allowed for a limited amount of time just before the electroweak phase transition. More specifically, we consider fermionic singlet dark matter particles coupled weakly to a scalar mediator S3 and to auxiliary dark sector fields, charged under the standard model gauge groups. Dark matter freezes out while still relativistic, so its abundance is initially very large. As the Universe cools down, the scalar mediator develops a vacuum expectation value (VEV), which breaks the symmetry that stabilizes dark matter. This allows dark matter to mix with charged fermions and decay. During this epoch, the dark matter abundance is reduced to give the value observed today. Later, the SM Higgs field also develops a VEV, which feeds back into the S3 potential and restores the dark sector symmetry. In a concrete model we show that this "VEV flip-flop" scenario is phenomenologically successful in the most interesting regions of its parameter space. We also comment on detection prospects at the LHC and elsewhere.

Sourcing dark matter and dark energy from α-attractors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Swagat S.; Sahni, Varun; Shtanov, Yuri, E-mail: swagat@iucaa.in, E-mail: varun@iucaa.in, E-mail: shtanov@bitp.kiev.ua

In [1], Kallosh and Linde drew attention to a new family of superconformal inflationary potentials, subsequently called α-attractors [2]. The α-attractor family can interpolate between a large class of inflationary models. It also has an important theoretical underpinning within the framework of supergravity. We demonstrate that the α-attractors have an even wider appeal since they may describe dark matter and perhaps even dark energy. The dark matter associated with the α-attractors, which we call α-dark matter (αDM), shares many of the attractive features of fuzzy dark matter, with V (φ) = ½ m {sup 2}φ{sup 2}, while having none ofmore » its drawbacks. Like fuzzy dark matter, αDM can have a large Jeans length which could resolve the cusp-core and substructure problems faced by standard cold dark matter. αDM also has an appealing tracker property which enables it to converge to the late-time dark matter asymptote, ( w ) ≅ 0, from a wide range of initial conditions. It thus avoids the enormous fine-tuning problems faced by the m {sup 2}φ{sup 2} potential in describing dark matter.« less

Radial oscillations of strange quark stars admixed with condensed dark matter

NASA Astrophysics Data System (ADS)

Panotopoulos, G.; Lopes, Ilídio

2017-10-01

We compute the 20 lowest frequency radial oscillation modes of strange stars admixed with condensed dark matter. We assume a self-interacting bosonic dark matter, and we model dark matter inside the star as a Bose-Einstein condensate. In this case the equation of state is a polytropic one with index 1 +1 /n =2 and a constant K that is computed in terms of the mass of the dark matter particle and the scattering length. Assuming a mass and a scattering length compatible with current observational bounds for self-interacting dark matter, we have integrated numerically first the Tolman-Oppenheimer-Volkoff equations for the hydrostatic equilibrium, and then the equations for the perturbations ξ =Δ r /r and η =Δ P /P . For a compact object with certain mass and radius we have considered here three cases, namely no dark matter at all and two different dark matter scenarios. Our results show that (i) the separation between consecutive modes increases with the amount of dark matter, and (ii) the effect is more pronounced for higher order modes. These effects are relevant even for a strange star made of 5% dark matter.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witte, Samuel J.; Gluscevic, Vera; McDermott, Samuel D.

It has recently been demonstrated that, in the event of a putative signal in dark matter direct detection experiments, properly identifying the underlying dark matter-nuclei interaction promises to be a challenging task. Given the most optimistic expectations for the number counts of recoil events in the forthcoming Generation 2 experiments, differentiating between interactions that produce distinct features in the recoil energy spectra will only be possible if a strong signal is observed simultaneously on a variety of complementary targets. However, there is a wide range of viable theories that give rise to virtually identical energy spectra, and may only differmore » by the dependence of the recoil rate on the dark matter velocity. In this work, we investigate how degeneracy between such competing models may be broken by analyzing the time dependence of nuclear recoils, i.e. the annual modulation of the rate. For this purpose, we simulate dark matter events for a variety of interactions and experiments, and perform a Bayesian model-selection analysis on all simulated data sets, evaluating the chance of correctly identifying the input model for a given experimental setup. Lastly, we find that including information on the annual modulation of the rate may significantly enhance the ability of a single target to distinguish dark matter models with nearly degenerate recoil spectra, but only with exposures beyond the expectations of Generation 2 experiments.« less

Dark Matter Search in Space: Combined Analysis of Cosmic-Ray Antiproton-to-proton Flux Ratio and Positron Flux Measured by AMS-02

NASA Astrophysics Data System (ADS)

Feng, Jie; Zhang, Hong-Hao

2018-05-01

Dark matter searches in space have been carried out for many years. Measurements of cosmic-ray (CR) photons, charged antiparticles, and neutrinos are useful tools for dark matter indirect searches. The antiparticle energy spectra of CRs have several exciting features, such as the unexpected positron excess at E ∼ 10–500 GeV and the remarkably flattening antiproton/proton at E ∼ 60–450 GeV precisely measured by the AMS-02 experiment, which cannot be explained simultaneously by secondary production in the interstellar medium. In this work, we report a combined analysis of CR antiproton and positron spectra arising from dark matter on the top of a secondary production in a spatial-dependent propagation model. We discuss the systematic uncertainties from the antiproton production cross section using the two latest Monte Carlo generators, i.e., EPOS LHC and QGSJET-II-04m. We compare their results. In the case of EPOS LHC, we find that the dark matter pair annihilating into τ leptons channel with a 100% branching ratio and the p-wave annihilation cross section assumption is the only possible one-channel scenario to explain the data. On the other hand, there is not a single possible channel in the case of QGSJET-II-04m. We also propose possible two-channel scenarios based on these two Monte Carlo generators.

Dark revelations of the [SU(3)]3 and [SU(3)]4 gauge extensions of the standard model

NASA Astrophysics Data System (ADS)

Kownacki, Corey; Ma, Ernest; Pollard, Nicholas; Popov, Oleg; Zakeri, Mohammadreza

2018-02-01

Two theoretically well-motivated gauge extensions of the standard model are SU(3)C × SU(3)L × SU(3)R and SU(3)q × SU(3)L × SU(3)l × SU(3)R, where SU(3)q is the same as SU(3)C and SU(3)l is its color leptonic counterpart. Each has three variations, according to how SU(3)R is broken. It is shown here for the first time that a built-in dark U(1)D gauge symmetry exists in all six versions. However, the corresponding symmetry breaking pattern does not reduce properly to that of the standard model, unless an additional Z2‧ symmetry is defined, so that U(1)D ×Z2‧ is broken to Z2 dark parity. The available dark matter candidates in each case include fermions, scalars, as well as vector gauge bosons. This work points to the possible unity of matter with dark matter, the origin of which may not be ad hoc.

Testing the Bose-Einstein Condensate dark matter model at galactic cluster scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harko, Tiberiu; Liang, Pengxiang; Liang, Shi-Dong

The possibility that dark matter may be in the form of a Bose-Einstein Condensate (BEC) has been extensively explored at galactic scale. In particular, good fits for the galactic rotations curves have been obtained, and upper limits for the dark matter particle mass and scattering length have been estimated. In the present paper we extend the investigation of the properties of the BEC dark matter to the galactic cluster scale, involving dark matter dominated astrophysical systems formed of thousands of galaxies each. By considering that one of the major components of a galactic cluster, the intra-cluster hot gas, is describedmore » by King's β-model, and that both intra-cluster gas and dark matter are in hydrostatic equilibrium, bound by the same total mass profile, we derive the mass and density profiles of the BEC dark matter. In our analysis we consider several theoretical models, corresponding to isothermal hot gas and zero temperature BEC dark matter, non-isothermal gas and zero temperature dark matter, and isothermal gas and finite temperature BEC, respectively. The properties of the finite temperature BEC dark matter cluster are investigated in detail numerically. We compare our theoretical results with the observational data of 106 galactic clusters. Using a least-squares fitting, as well as the observational results for the dark matter self-interaction cross section, we obtain some upper bounds for the mass and scattering length of the dark matter particle. Our results suggest that the mass of the dark matter particle is of the order of μ eV, while the scattering length has values in the range of 10{sup −7} fm.« less

Static structure of chameleon dark matter as an explanation of dwarf spheroidal galaxy cores

NASA Astrophysics Data System (ADS)

Chanda, Prolay Krishna; Das, Subinoy

2017-04-01

We propose a novel mechanism that explains the cored dark matter density profile in recently observed dark matter rich dwarf spheroidal galaxies. In our scenario, dark matter particle mass decreases gradually as a function of distance towards the center of a dwarf galaxy due to its interaction with a chameleon scalar. At closer distance towards the Galactic center the strength of attractive scalar fifth force becomes much stronger than gravity and is balanced by the Fermi pressure of the dark matter cloud; thus, an equilibrium static configuration of the dark matter halo is obtained. Like the case of soliton star or fermion Q-star, the stability of the dark matter halo is obtained as the scalar achieves a static profile and reaches an asymptotic value away from the Galactic center. For simple scalar-dark matter interaction and quadratic scalar self-interaction potential, we show that dark matter behaves exactly like cold dark matter (CDM) beyond a few kpc away from the Galactic center but at closer distance it becomes lighter and Fermi pressure cannot be ignored anymore. Using Thomas-Fermi approximation, we numerically solve the radial static profile of the scalar field, fermion mass and dark matter energy density as a function of distance. We find that for fifth force mediated by an ultralight scalar, it is possible to obtain a flattened dark matter density profile towards the Galactic center. In our scenario, the fifth force can be neglected at distance r ≥1 kpc from the Galactic center and dark matter can be simply treated as heavy nonrelativistic particles beyond this distance, thus reproducing the success of CDM at large scales.

Cold dark matter plus not-so-clumpy dark relics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diamanti, Roberta; Ando, Shin'ichiro; Weniger, Christoph

Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions,more » covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction f {sub ncdm} of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2σ limits for non-cold dark matter particles with masses in the range 1–10 keV are f {sub ncdm}≤0.29 (0.23) for fermions (bosons), and for masses in the 10–100 keV range they are f {sub ncdm}≤0.43 (0.45), respectively.« less

Superconducting Detectors for Superlight Dark Matter.

PubMed

Hochberg, Yonit; Zhao, Yue; Zurek, Kathryn M

2016-01-08

We propose and study a new class of superconducting detectors that are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark-matter limit, m(X)≳1  keV. We compute the rate of dark-matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological or astrophysical constraints could be detected by such detectors with a moderate size exposure.

Superconducting Detectors for Superlight Dark Matter

NASA Astrophysics Data System (ADS)

Hochberg, Yonit; Zhao, Yue; Zurek, Kathryn M.

2016-01-01

We propose and study a new class of superconducting detectors that are sensitive to O (meV ) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark-matter limit, mX≳1 keV . We compute the rate of dark-matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological or astrophysical constraints could be detected by such detectors with a moderate size exposure.

Holographic vortices in the presence of dark matter sector

NASA Astrophysics Data System (ADS)

Rogatko, Marek; Wysokinski, Karol I.

2015-12-01

The dark matter seem to be an inevitable ingredient of the total matter configuration in the Universe and the knowledge how the dark matter affects the properties of superconductors is of vital importance for the experiments aimed at its direct detection. The homogeneous magnetic field acting perpendicularly to the surface of (2+1) dimensional s-wave holographic superconductor in the theory with dark matter sector has been modeled by the additional U(1)-gauge field representing dark matter and coupled to the Maxwell one. As expected the free energy for the vortex configuration turns out to be negative. Importantly its value is lower in the presence of dark matter sector. This feature can explain why in the Early Universe first the web of dark matter appeared and next on these gratings the ordinary matter forming cluster of galaxies has formed.

Dissipative dark matter halos: The steady state solution

NASA Astrophysics Data System (ADS)

Foot, R.

2018-02-01

Dissipative dark matter, where dark matter particle properties closely resemble familiar baryonic matter, is considered. Mirror dark matter, which arises from an isomorphic hidden sector, is a specific and theoretically constrained scenario. Other possibilities include models with more generic hidden sectors that contain massless dark photons [unbroken U (1 ) gauge interactions]. Such dark matter not only features dissipative cooling processes but also is assumed to have nontrivial heating sourced by ordinary supernovae (facilitated by the kinetic mixing interaction). The dynamics of dissipative dark matter halos around rotationally supported galaxies, influenced by heating as well as cooling processes, can be modeled by fluid equations. For a sufficiently isolated galaxy with a stable star formation rate, the dissipative dark matter halos are expected to evolve to a steady state configuration which is in hydrostatic equilibrium and where heating and cooling rates locally balance. Here, we take into account the major cooling and heating processes, and numerically solve for the steady state solution under the assumptions of spherical symmetry, negligible dark magnetic fields, and that supernova sourced energy is transported to the halo via dark radiation. For the parameters considered, and assumptions made, we were unable to find a physically realistic solution for the constrained case of mirror dark matter halos. Halo cooling generally exceeds heating at realistic halo mass densities. This problem can be rectified in more generic dissipative dark matter models, and we discuss a specific example in some detail.

Direct dark matter detection with the DarkSide-50 experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagani, Luca

2017-01-01

The existence of dark matter is known because of its gravitational effects, and although its nature remains undisclosed, there is a growing indication that the galactic halo could be permeated by weakly interacting massive particles (WIMPs) with mass of the order ofmore » $100$$\\,GeV/c$$^2$ and coupling with ordinary matter at or below the weak scale. In this context, DarkSide-50 aims to direct observe WIMP-nucleon collisions in a liquid argon dual phase time-projection chamber located deep underground at Gran Sasso National Laboratory, in Italy. In this work a re-analysis of the data that led to the best limit on WIMP-nucleon cross section with an argon target is done. As starting point of the new approach, the energy reconstruction of events is considered: a new energy variable is developed where anti-correlation between ionization and scintillation produced by an interaction is taken into account. As first result, a better energy resolution is achieved. In this new energy framewor k, access is granted to micro-physics parameters fundamental to argon scintillation such as the recombination and quenching as a function of the energy. The improved knowledge of recombination and quenching allows to develop a new model for distinguish between events possibly due to WIMPs and backgrounds. In light of the new model, the final result of this work is a more stringent limit on spin independent WIMP-nucleon cross section with an argon target. This work was supervised by Marco Pallavicini and was completed in collaboration with members of the DarkSide collaboration.« less

The segregation of baryons and dark matter during halo assembly

NASA Astrophysics Data System (ADS)

Liao, Shihong; Gao, Liang; Frenk, Carlos S.; Guo, Qi; Wang, Jie

2017-09-01

The standard galaxy formation theory assumes that baryons and dark matter are initially well mixed before becoming segregated due to radiative cooling. We use non-radiative hydrodynamical simulations to explicitly examine this assumption and find that baryons and dark matter can also be segregated due to different characteristics of gas and dark matter during the buildup of the halo. As a result, baryons in many haloes do not originate from the same Lagrangian region as the dark matter. When using the fraction of corresponding dark matter and gas particles in the initial conditions (the 'paired fraction') as a proxy of the dark matter and gas segregation strength of a halo, on average about 25 per cent of the baryonic and dark matter of the final halo are segregated in the initial conditions. This is at odds with the assumption of the standard galaxy formation model. A consequence of this effect is that the baryons and dark matter of the same halo initially experience different tidal torques and thus their angular momentum vectors are often misaligned. The degree of the misalignment is largely preserved during later halo assembly and can be understood with the tidal torque theory. The result challenges the precision of some semi-analytical approaches that utilize dark matter halo merger trees to infer properties of gas associated with dark matter haloes.

Observational constraints on variable equation of state parameters of dark matter and dark energy after Planck

NASA Astrophysics Data System (ADS)

Kumar, Suresh; Xu, Lixin

2014-10-01

In this paper, we study a cosmological model in general relativity within the framework of spatially flat Friedmann-Robertson-Walker space-time filled with ordinary matter (baryonic), radiation, dark matter and dark energy, where the latter two components are described by Chevallier-Polarski-Linder equation of state parameters. We utilize the observational data sets from SNLS3, BAO and Planck + WMAP9 + WiggleZ measurements of matter power spectrum to constrain the model parameters. We find that the current observational data offer tight constraints on the equation of state parameter of dark matter. We consider the perturbations and study the behavior of dark matter by observing its effects on CMB and matter power spectra. We find that the current observational data favor the cold dark matter scenario with the cosmological constant type dark energy at the present epoch.

Hypercharged dark matter and direct detection as a probe of reheating.

PubMed

Feldstein, Brian; Ibe, Masahiro; Yanagida, Tsutomu T

2014-03-14

The lack of new physics at the LHC so far weakens the argument for TeV scale thermal dark matter. On the other hand, heavier, nonthermal dark matter is generally difficult to test experimentally. Here we consider the interesting and generic case of hypercharged dark matter, which can allow for heavy dark matter masses without spoiling testability. Planned direct detection experiments will be able to see a signal for masses up to an incredible 1010  GeV, and this can further serve to probe the reheating temperature up to about 109  GeV, as determined by the nonthermal dark matter relic abundance. The Z-mediated nature of the dark matter scattering may be determined in principle by comparing scattering rates on different detector nuclei, which in turn can reveal the dark matter mass. We will discuss the extent to which future experiments may be able to make such a determination.

Flooded Dark Matter and S level rise

NASA Astrophysics Data System (ADS)

Randall, Lisa; Scholtz, Jakub; Unwin, James

2016-03-01

Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as "Maximum Baroqueness". We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant non-thermal leptogenesis implementation in which decays of a heavy right-handed neutrino lead to late time reheating of the Standard Model degrees of freedom and provide suitable conditions for creation of a lepton asymmetry.

Correlation Analysis between Spin, Velocity Shear, and Vorticity of Baryonic and Dark Matter Halos

NASA Astrophysics Data System (ADS)

Liu, Li-li

2017-04-01

Based on the cosmological hydrodynamic simulations, we investigate the correlations between the spin, velocity shear and vorticity in dark matter halos, as well as the relationship between the baryonic matter and the dark matter. We find that (1) the difference between the vorticity of baryonic matter and that of dark matter is evident on the scales of < 0.2 h-1 Mpc; (2) the vorticity of baryonic matter exhibits a stronger correlation with the tensor of velocity shear than the vorticity of dark matter does; and (3) the spinning direction of small-mass dark matter halos tends to be parallel to the direction of their host filaments, while the spinning direction of massive dark matter halos tends to be perpendicular to the direction of their host filaments, and the intensity of this kind correlation depends on the size of simulation box, and the simulation accuracy. These factors may cause the relationship between the the spins of dark matter halos and those of galaxies to be complicated, and affect the correlation between the galaxy spins and the nearby large-scale structures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boehm, Celine; Ascasibar, Yago

In a previous work, it was found that the light dark matter scenario could be a possible explanation to the 511 keV emission line detected at the center of our galaxy. Here, we show that hints of this scenario may also have been discovered in particle physics experiments. This could explain the discrepancy between the measurement of the fine structure constant and the value referenced in the CODATA. Finally, our results indicate that some of the light dark matter features could be tested in accelerators. Their discovery might favor N=2 supersymmetry.

The phenomenology of maverick dark matter

NASA Astrophysics Data System (ADS)

Krusberg, Zosia Anna Celina

Astrophysical observations from galactic to cosmological scales point to a substantial non-baryonic component to the universe's total matter density. Although very little is presently known about the physical properties of dark matter, its existence offers some of the most compelling evidence for physics beyond the standard model (BSM). In the weakly interacting massive particle (WIMP) scenario, the dark matter consists of particles that possess weak-scale interactions with the particles of the standard model, offering a compelling theoretical framework that allows us to understand the relic abundance of dark matter as a natural consequence of the thermal history of the early universe. From the perspective of particle physics phenomenology, the WIMP scenario is appealing for two additional reasons. First, many theories of BSM physics contain attractive WIMP candidates. Second, the weak-scale interactions between WIMPs and standard model particles imply the possibility of detecting scatterings between relic WIMPs and detector nuclei in direct detection experiments, products of WIMP annihilations at locations throughout the galaxy in indirect detection programs, and WIMP production signals at high-energy particle colliders. In this work, we use an effective field theory approach to study model-independent dark matter phenomenology in direct detection and collider experiments. The maverick dark matter scenario is defined by an effective field theory in which the WIMP is the only new particle within the energy range accessible to the Large Hadron Collider (LHC). Although certain assumptions are necessary to keep the problem tractable, we describe our WIMP candidate generically by specifying only its spin and dominant interaction form with standard model particles. Constraints are placed on the masses and coupling constants of the maverick WIMPs using the Wilkinson Microwave Anisotropy Probe (WMAP) relic density measurement and direct detection exclusion data from both spin-independent (XENON100 and SuperCDMS) and spin-dependent (COUPP) experiments. We further study the distinguishability of maverick WIMP production signals at the Tevatron and the LHC---at its early and nominal configurations---using standard simulation packages, place constraints on maverick WIMP properties using existing collider data, and determine projected mass reaches in future data from both colliders. We find ourselves in a unique era of theoretically-motivated, high-precision dark matter searches that hold the potential to give us important insights, not only into the nature of dark matter, but also into the physics that lies beyond the standard model.

Concentrated dark matter: Enhanced small-scale structure from codecaying dark matter

NASA Astrophysics Data System (ADS)

Dror, Jeff A.; Kuflik, Eric; Melcher, Brandon; Watson, Scott

2018-03-01

We study the cosmological consequences of codecaying dark matter—a recently proposed mechanism for depleting the density of dark matter through the decay of nearly degenerate particles. A generic prediction of this framework is an early dark matter dominated phase in the history of the Universe, that results in the enhanced growth of dark matter perturbations on small scales. We compute the duration of the early matter dominated phase and show that the perturbations are robust against washout from free streaming. The enhanced small-scale structure is expected to survive today in the form of compact microhalos and can lead to significant boost factors for indirect-detection experiments, such as FERMI, where dark matter would appear as point sources.

Search for 100 MeV to 10 GeV γ-ray lines in the Fermi-LAT data and implications for gravitino dark matter in the μνSSM

DOE PAGES

Albert, Andrea; Gómez-Vargas, Germán A.; Grefe, Michael; ...

2014-10-13

We present that dark matter decay or annihilation may produce monochromatic signals in the γ-ray energy range. In this work we argue that there are strong theoretical motivations for studying these signals in the framework of gravitino dark matter decay and we perform a search for γ-ray spectral lines from 100 MeV to 10 GeV with Fermi-LAT data. In contrast to previous line searches at higher energies, the sensitivity of the present search is dominated by systematic uncertainties across most of the energy range considered. We estimate the size of systematic effects by analysing the flux from a number ofmore » control regions, and include the systematic uncertainties consistently in our fitting procedure. We have not observed any significant signals and present model-independent limits on γ-ray line emission from decaying and annihilating dark matter. We apply the former limits to the case of the gravitino, a well-known dark matter candidate in supersymmetric scenarios. In particular, the R-parity violating ''μ from ν'' Supersymmetric Standard Model μνSSM) is an attractive scenario in which including right-handed neutrinos solves the μ problem of the Minimal Supersymmetric Standard Model while simultaneously explaining the origin of neutrino masses. At the same time, the violation of R-parity renders the gravitino unstable and subject to decay into a photon and a neutrino. Finally, as a consequence of the limits on line emission, μνSSM gravitinos with masses larger than about 5 GeV, or lifetimes smaller than about 1028 s, are excluded at 95% confidence level as dark matter candidates.« less

Pressure from dark matter annihilation and the rotation curve of spiral galaxies

NASA Astrophysics Data System (ADS)

Wechakama, M.; Ascasibar, Y.

2011-05-01

The rotation curves of spiral galaxies are one of the basic predictions of the cold dark matter paradigm, and their shape in the innermost regions has been hotly debated over the last decades. The present work shows that dark matter annihilation into electron-positron pairs may affect the observed rotation curve by a significant amount. We adopt a model-independent approach, where all the electrons and positrons are injected with the same initial energy E0˜mdmc2 in the range from 1 MeV to 1 TeV and the injection rate is constrained by INTEGRAL, Fermi and HESS data. The pressure of the relativistic electron-positron gas is determined by solving the diffusion-loss equation, considering inverse Compton scattering, synchrotron radiation, Coulomb collisions, bremsstrahlung and ionization. For values of the gas density and magnetic field that are representative of the Milky Way, it is estimated that pressure gradients are strong enough to balance gravity in the central parts if E0 < 1 GeV. The exact value depends somewhat on the astrophysical parameters, and it changes dramatically with the slope of the dark matter density profile. For very steep slopes, as those expected from adiabatic contraction, the rotation curves of spiral galaxies would be affected on ˜kpc scales for most values of E0. By comparing the predicted rotation curves with observations of dwarf and low surface brightness galaxies, we show that the pressure from dark matter annihilation may improve the agreement between theory and observations in some cases, but it also imposes severe constraints on the model parameters (most notably, the inner slope of halo density profile, as well as the mass and the annihilation cross-section of dark matter particles into electron-positron pairs).

Probes for dark matter physics

NASA Astrophysics Data System (ADS)

Khlopov, Maxim Yu.

The existence of cosmological dark matter is in the bedrock of the modern cosmology. The dark matter is assumed to be nonbaryonic and consists of new stable particles. Weakly Interacting Massive Particle (WIMP) miracle appeals to search for neutral stable weakly interacting particles in underground experiments by their nuclear recoil and at colliders by missing energy and momentum, which they carry out. However, the lack of WIMP effects in their direct underground searches and at colliders can appeal to other forms of dark matter candidates. These candidates may be weakly interacting slim particles, superweakly interacting particles, or composite dark matter, in which new particles are bound. Their existence should lead to cosmological effects that can find probes in the astrophysical data. However, if composite dark matter contains stable electrically charged leptons and quarks bound by ordinary Coulomb interaction in elusive dark atoms, these charged constituents of dark atoms can be the subject of direct experimental test at the colliders. The models, predicting stable particles with charge ‑ 2 without stable particles with charges + 1 and ‑ 1 can avoid severe constraints on anomalous isotopes of light elements and provide solution for the puzzles of dark matter searches. In such models, the excessive ‑ 2 charged particles are bound with primordial helium in O-helium atoms, maintaining specific nuclear-interacting form of the dark matter. The successful development of composite dark matter scenarios appeals for experimental search for doubly charged constituents of dark atoms, making experimental search for exotic stable double charged particles experimentum crucis for dark atoms of composite dark matter.

Warm dark matter effects in a spherical collapse model with shear and angular momentum

NASA Astrophysics Data System (ADS)

Marciu, Mihai

2016-03-01

This paper investigates the nonlinear structure formation in a spherical top-hat collapse model based on the pseudo-Newtonian approximation. The system is composed of warm dark matter and dark energy and the dynamical properties of the collapsing region are analyzed for various parametrizations of the dark matter equation of state which are in agreement with current observations. Concerning dark energy, observational constraints of the Chevallier-Polarski-Linder model and the Jassal-Bagla-Padmanabhan equation of state have been considered. During the collapse, the positive dark matter pressure leads to an increase of growth for dark matter and dark energy perturbations and an accelerated expansion for the spherical region. Hence, in the warm dark matter hypothesis, the structure formation is accelerated and the inconsistencies of the Λ CDM model at the galactic scales could be solved. The results obtained are applicable only to adiabatic warm dark matter physical models which are compatible with the pseudo-Newtonian approach.

Capture and decay of electroweak WIMPonium

NASA Astrophysics Data System (ADS)

Asadi, Pouya; Baumgart, Matthew; Fitzpatrick, Patrick J.; Krupczak, Emmett; Slatyer, Tracy R.

2017-02-01

The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. The presence of these bound states enhances the annihilation rate via resonances in the Sommerfeld enhancement, but they can also be produced directly with the emission of a low-energy photon. In this work we compute the rate for SU(2) triplet dark matter (the wino) to bind into WIMPonium—which is possible via single-photon emission for wino masses above 5 TeV for relative velocity v < O(10-2) —and study the subsequent decays of these bound states. We present results with applications beyond the wino case, e.g. for dark matter inhabiting a nonabelian dark sector; these include analytic capture and transition rates for general dark sectors in the limit of vanishing force carrier mass, efficient numerical routines for calculating positive and negative-energy eigenstates of a Hamiltonian containing interactions with both massive and massless force carriers, and a study of the scaling of bound state formation in the short-range Hulth&apos{e}n potential. In the specific case of the wino, we find that the rate for bound state formation is suppressed relative to direct annihilation, and so provides only a small correction to the overall annihilation rate. The soft photons radiated by the capture process and by bound state transitions could permit measurement of the dark matter's quantum numbers; for wino-like dark matter, such photons are rare, but might be observable by a future ground-based gamma-ray telescope combining large effective area and a low energy threshold.

Warm and cold fermionic dark matter via freeze-in

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klasen, Michael; Yaguna, Carlos E., E-mail: michael.klasen@uni-muenster.de, E-mail: carlos.yaguna@uni-muenster.de

2013-11-01

The freeze-in mechanism of dark matter production provides a simple and intriguing alternative to the WIMP paradigm. In this paper, we analyze whether freeze-in can be used to account for the dark matter in the so-called singlet fermionic model. In it, the SM is extended with only two additional fields, a singlet scalar that mixes with the Higgs boson, and the dark matter particle, a fermion assumed to be odd under a Z{sub 2} symmetry. After numerically studying the generation of dark matter, we analyze the dependence of the relic density with respect to all the free parameters of themore » model. These results are then used to obtain the regions of the parameter space that are compatible with the dark matter constraint. We demonstrate that the observed dark matter abundance can be explained via freeze-in over a wide range of masses extending down to the keV range. As a result, warm and cold dark matter can be obtained in this model. It is also possible to have dark matter masses well above the unitarity bound for WIMPs.« less

Natural implementation of neutralino dark matter

NASA Astrophysics Data System (ADS)

King, Steve F.; Roberts, Jonathan P.

2006-09-01

The prediction of neutralino dark matter is generally regarded as one of the successes of the Minimal Supersymmetric Standard Model (MSSM). However the successful regions of parameter space allowed by WMAP and collider constraints are quite restricted. We discuss fine-tuning with respect to both dark matter and Electroweak Symmetry Breaking (EWSB) and explore regions of MSSM parameter space with non-universal gaugino and third family scalar masses in which neutralino dark matter may be implemented naturally. In particular allowing non-universal gauginos opens up the bulk region that allows Bino annihilation via t-channel slepton exchange, leading to ``supernatural dark matter'' corresponding to no fine-tuning at all with respect to dark matter. By contrast we find that the recently proposed ``well tempered neutralino'' regions involve substantial fine-tuning of MSSM parameters in order to satisfy the dark matter constraints, although the fine tuning may be ameliorated if several annihilation channels act simultaneously. Although we have identified regions of ``supernatural dark matter'' in which there is no fine tuning to achieve successful dark matter, the usual MSSM fine tuning to achieve EWSB always remains.

Dark Matter Decays from Nonminimal Coupling to Gravity.

PubMed

Catà, Oscar; Ibarra, Alejandro; Ingenhütt, Sebastian

2016-07-08

We consider the standard model extended with a dark matter particle in curved spacetime, motivated by the fact that the only current evidence for dark matter is through its gravitational interactions, and we investigate the impact on the dark matter stability of terms in the Lagrangian linear in the dark matter field and proportional to the Ricci scalar. We show that this "gravity portal" induces decay even if the dark matter particle only has gravitational interactions, and that the decay branching ratios into standard model particles only depend on one free parameter: the dark matter mass. We study in detail the case of a singlet scalar as a dark matter candidate, which is assumed to be absolutely stable in flat spacetime due to a discrete Z_{2} symmetry, but which may decay in curved spacetimes due to a Z_{2}-breaking nonminimal coupling to gravity. We calculate the dark matter decay widths and we set conservative limits on the nonminimal coupling parameter from experiments. The limits are very stringent and suggest that there must exist an additional mechanism protecting the singlet scalar from decaying via this gravity portal.

Cores in Dwarf Galaxies from Fermi Repulsion

NASA Astrophysics Data System (ADS)

Randall, Lisa; Scholtz, Jakub; Unwin, James

2017-05-01

We show that Fermi repulsion can lead to cored density profiles in dwarf galaxies for sub-keV fermionic dark matter. We treat the dark matter as a quasi-degenerate self-gravitating Fermi gas and calculate its density profile assuming hydrostatic equilibrium. We find that suitable dwarf galaxy cores of size ≳130 pc can be achieved for fermion dark matter with mass in the range of 70-400 eV. While in conventional dark matter scenarios such sub-keV thermal dark matter would be excluded by free streaming bounds, the constraints are ameliorated in models with dark matter at a lower temperature than conventional thermal scenarios, such as the Flooded Dark Matter model that we have previously considered. Modifying the arguments of Tremaine and Gunn, we derive a conservative lower bound on the mass of fermionic dark matter of 70 eV and a stronger lower bound from Lymanα clouds of about 470 eV, leading to slightly smaller cores than have been observed. We comment on this result and how the tension is relaxed in dark matter scenarios with non-thermal momentum distributions.

The Darkside-50 Experiment: Electron Recoil Calibrations and a Global Energy Variable

NASA Astrophysics Data System (ADS)

Hackett, Brianne R.

Over the course of decades, there has been mounting astronomical evidence for non-baryonic dark matter, yet its precise nature remains elusive. A favored candidate for dark matter is the Weakly Interacting Massive Particle (WIMP) which arises naturally out of extensions to the Standard Model. WIMPs are expected to occasionally interact with particles of normal matter through nuclear recoils. DarkSide-50 aims to detect this type of particle through the use of a two-phase liquid argon time projection chamber. To make a claim of discovery, an accurate understanding of the background and WIMP search region is imperative. Knowledge of the backgrounds is done through extensive studies of DarkSide-50's response to electron and nuclear recoils. The CALibration Insertion System (CALIS) was designed and built for the purpose of introducing radioactive sources into or near the detector in a joint effort between Fermi National Laboratory (FNAL) and the University of Hawai'i at Manoa. This work describes the testing, installation, and commissioning of CALIS at the Laboratori Nazionali del Gran Sasso. CALIS has been used in multiple calibration campaigns with both neutron and gamma sources. In this work, DarkSide-50's response to electron recoils, which are important for background estimations, was studied through the use of gamma calibration sources by constructing a global energy variable which takes into account the anti-correlation between scintillation and ionization signals produced by interactions in the liquid argon. Accurately reconstructing the event energy correlates directly with quantitatively understanding the WIMP sensitivity in DarkSide-50. This work also validates the theoretically predicted beta decay spectrum of 39Ar against 39Ar beta decay data collected in the early days of DarkSide-50 while it was filled with atmospheric argon; a validation of this type is not readily found in the literature. Finally, we show how well the constructed energy variable can predict energy spectra for the calibration sources and for 39Ar.

Large Synoptic Survey Telescope: From Science Drivers to Reference Design

DTIC Science & Technology

2008-01-01

faint time domain. The LSST design is driven by four main science themes: constraining dark energy and dark matter , taking an inventory of the Solar...Energy and Dark Matter (2) Taking an Inventory of the Solar System (3) Exploring the Transient Optical Sky (4) Mapping the Milky Way Each of these four...Constraining Dark Energy and Dark Matter Current models of cosmology require the exis- tence of both dark matter and dark energy to match observational

Detection of sub-MeV dark matter with three-dimensional Dirac materials

NASA Astrophysics Data System (ADS)

Hochberg, Yonit; Kahn, Yonatan; Lisanti, Mariangela; Zurek, Kathryn M.; Grushin, Adolfo G.; Ilan, Roni; Griffin, Sinéad M.; Liu, Zhen-Fei; Weber, Sophie F.; Neaton, Jeffrey B.

2018-01-01

We propose the use of three-dimensional Dirac materials as targets for direct detection of sub-MeV dark matter. Dirac materials are characterized by a linear dispersion for low-energy electronic excitations, with a small band gap of O (meV ) if lattice symmetries are broken. Dark matter at the keV scale carrying kinetic energy as small as a few meV can scatter and excite an electron across the gap. Alternatively, bosonic dark matter as light as a few meV can be absorbed by the electrons in the target. We develop the formalism for dark matter scattering and absorption in Dirac materials and calculate the experimental reach of these target materials. We find that Dirac materials can play a crucial role in detecting dark matter in the keV to MeV mass range that scatters with electrons via a kinetically mixed dark photon, as the dark photon does not develop an in-medium effective mass. The same target materials provide excellent sensitivity to absorption of light bosonic dark matter in the meV to hundreds of meV mass range, superior to all other existing proposals when the dark matter is a kinetically mixed dark photon.

The next phase of the Axion Dark Matter eXperiment

NASA Astrophysics Data System (ADS)

Carosi, Gianpaolo; Asztalos, S.; Hagmann, C.; Kinion, D.; van Bibber, K.; Hotz, M.; Lyapustin, D.; Rosenberg, L.; Rybka, G.; Wagner, A.; Hoskins, J.; Martin, C.; Sikivie, P.; Sullivan, N.; Tanner, D.; Bradley, R.; Clarke, J.; ADMX Collaboration

2011-04-01

Axions are a well motivated dark matter candidate which may be detected by their resonant conversion to photons in the presence of a large static magnetic field. The Axion Dark Matter eXperiment recently finished a search for DM axions using a new ultralow noise microwave receiver based on a SQUID amplifier. The success of this precursor experiment has paved the way for a definitive axion search which will see the system noise temperature lowered from 1.8 K to 100 mK, dramatically increasing sensitivity to even pessimistic axion models as well as increasing scan speed. Here we discuss the implementation of this next experimental phase. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Security, LLC, Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Dark-matter particles without weak-scale masses or weak interactions.

PubMed

Feng, Jonathan L; Kumar, Jason

2008-12-05

We propose that dark matter is composed of particles that naturally have the correct thermal relic density, but have neither weak-scale masses nor weak interactions. These models emerge naturally from gauge-mediated supersymmetry breaking, where they elegantly solve the dark-matter problem. The framework accommodates single or multiple component dark matter, dark-matter masses from 10 MeV to 10 TeV, and interaction strengths from gravitational to strong. These candidates enhance many direct and indirect signals relative to weakly interacting massive particles and have qualitatively new implications for dark-matter searches and cosmological implications for colliders.

General calculation of the cross section for dark matter annihilations into two photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Cely, Camilo; Rivera, Andres, E-mail: Camilo.Alfredo.Garcia.Cely@ulb.ac.be, E-mail: afelipe.rivera@udea.edu.co

2017-03-01

Assuming that the underlying model satisfies some general requirements such as renormalizability and CP conservation, we calculate the non-relativistic one-loop cross section for any self-conjugate dark matter particle annihilating into two photons. We accomplish this by carefully classifying all possible one-loop diagrams and, from them, reading off the dark matter interactions with the particles running in the loop. Our approach is general and leads to the same results found in the literature for popular dark matter candidates such as the neutralinos of the MSSM, minimal dark matter, inert Higgs and Kaluza-Klein dark matter.

Detecting superlight dark matter with Fermi-degenerate materials

DOE PAGES

Hochberg, Yonit; Pyle, Matt; Zhao, Yue; ...

2016-08-08

We examine in greater detail the recent proposal of using superconductors for detecting dark matter as light as the warm dark matter limit of O(keV). Detection of suc light dark matter is possible if the entire kinetic energy of the dark matter is extracted in the scattering, and if the experiment is sensitive to O(meV) energy depositions. This is the case for Fermi-degenerate materials in which the Fermi velocity exceeds the dark matter velocity dispersion in the Milky Way of ~10 –3. We focus on a concrete experimental proposal using a superconducting target with a transition edge sensor in ordermore » to detect the small energy deposits from the dark matter scatterings. Considering a wide variety of constraints, from dark matter self-interactions to the cosmic microwave background, we show that models consistent with cosmological/astrophysical and terrestrial constraints are observable with such detectors. A wider range of viable models with dark matter mass below an MeV is available if dark matter or mediator properties (such as couplings or masses) differ at BBN epoch or in stellar interiors from those in superconductors. We also show that metal targets pay a strong in-medium suppression for kinetically mixed mediators; this suppression is alleviated with insulating targets.« less

One dark matter mystery: halos in the cosmic web

NASA Astrophysics Data System (ADS)

Gaite, Jose

2015-01-01

The current cold dark matter cosmological model explains the large scale cosmic web structure but is challenged by the observation of a relatively smooth distribution of matter in galactic clusters. We consider various aspects of modeling the dark matter around galaxies as distributed in smooth halos and, especially, the smoothness of the dark matter halos seen in N-body cosmological simulations. We conclude that the problems of the cold dark matter cosmology on small scales are more serious than normally admitted.

Dark Kinetic Heating of Neutron Stars and an Infrared Window on WIMPs, SIMPs, and Pure Higgsinos

NASA Astrophysics Data System (ADS)

Baryakhtar, Masha; Bramante, Joseph; Li, Shirley Weishi; Linden, Tim; Raj, Nirmal

2017-09-01

We identify a largely model-independent signature of dark matter (DM) interactions with nucleons and electrons. DM in the local galactic halo, gravitationally accelerated to over half the speed of light, scatters against and deposits kinetic energy into neutron stars, heating them to infrared blackbody temperatures. The resulting radiation could potentially be detected by the James Webb Space Telescope, the Thirty Meter Telescope, or the European Extremely Large Telescope. This mechanism also produces optical emission from neutron stars in the galactic bulge, and x-ray emission near the galactic center because dark matter is denser in these regions. For GeV-PeV mass dark matter, dark kinetic heating would initially unmask any spin-independent or spin-dependent dark matter-nucleon cross sections exceeding 2 ×10-45 cm2, with improved sensitivity after more telescope exposure. For lighter-than-GeV dark matter, cross-section sensitivity scales inversely with dark matter mass because of Pauli blocking; for heavier-than-PeV dark matter, it scales linearly with mass as a result of needing multiple scatters for capture. Future observations of dark sector-warmed neutron stars could determine whether dark matter annihilates in or only kinetically heats neutron stars. Because inelastic interstate transitions of up to a few GeV would occur in relativistic scattering against nucleons, elusive inelastic dark matter like pure Higgsinos can also be discovered.

Dark Kinetic Heating of Neutron Stars and an Infrared Window on WIMPs, SIMPs, and Pure Higgsinos.

PubMed

Baryakhtar, Masha; Bramante, Joseph; Li, Shirley Weishi; Linden, Tim; Raj, Nirmal

2017-09-29

We identify a largely model-independent signature of dark matter (DM) interactions with nucleons and electrons. DM in the local galactic halo, gravitationally accelerated to over half the speed of light, scatters against and deposits kinetic energy into neutron stars, heating them to infrared blackbody temperatures. The resulting radiation could potentially be detected by the James Webb Space Telescope, the Thirty Meter Telescope, or the European Extremely Large Telescope. This mechanism also produces optical emission from neutron stars in the galactic bulge, and x-ray emission near the galactic center because dark matter is denser in these regions. For GeV-PeV mass dark matter, dark kinetic heating would initially unmask any spin-independent or spin-dependent dark matter-nucleon cross sections exceeding 2×10^{-45}  cm^{2}, with improved sensitivity after more telescope exposure. For lighter-than-GeV dark matter, cross-section sensitivity scales inversely with dark matter mass because of Pauli blocking; for heavier-than-PeV dark matter, it scales linearly with mass as a result of needing multiple scatters for capture. Future observations of dark sector-warmed neutron stars could determine whether dark matter annihilates in or only kinetically heats neutron stars. Because inelastic interstate transitions of up to a few GeV would occur in relativistic scattering against nucleons, elusive inelastic dark matter like pure Higgsinos can also be discovered.

Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baldes, Iason; Petraki, Kalliopi, E-mail: iason.baldes@desy.de, E-mail: kpetraki@lpthe.jussieu.fr

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of themore » annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.« less

Cold dark matter: Controversies on small scales

PubMed Central

Weinberg, David H.; Bullock, James S.; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H. G.

2015-01-01

The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way’s dwarf galaxy satellites. We review the current observational and theoretical status of these “small-scale controversies.” Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years. PMID:25646464

Constraints on the coupling between dark energy and dark matter from CMB data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murgia, R.; Gariazzo, S.; Fornengo, N., E-mail: riccardo.murgia@sissa.it, E-mail: gariazzo@to.infn.it, E-mail: fornengo@to.infn.it

2016-04-01

We investigate a phenomenological non-gravitational coupling between dark energy and dark matter, where the interaction in the dark sector is parameterized as an energy transfer either from dark matter to dark energy or the opposite. The models are constrained by a whole host of updated cosmological data: cosmic microwave background temperature anisotropies and polarization, high-redshift supernovae, baryon acoustic oscillations, redshift space distortions and gravitational lensing. Both models are found to be compatible with all cosmological observables, but in the case where dark matter decays into dark energy, the tension with the independent determinations of H{sub 0} and σ{sub 8}, alreadymore » present for standard cosmology, increases: this model in fact predicts lower H{sub 0} and higher σ{sub 8}, mostly as a consequence of the higher amount of dark matter at early times, leading to a stronger clustering during the evolution. Instead, when dark matter is fed by dark energy, the reconstructed values of H{sub 0} and σ{sub 8} nicely agree with their local determinations, with a full reconciliation between high- and low-redshift observations. A non-zero coupling between dark energy and dark matter, with an energy flow from the former to the latter, appears therefore to be in better agreement with cosmological data.« less

Light dark matter through assisted annihilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dey, Ujjal Kumar; Maity, Tarak Nath; Ray, Tirtha Sankar, E-mail: ujjal@cts.iitkgp.ernet.in, E-mail: tarak.maity.physics@gmail.com, E-mail: tirthasankar.ray@gmail.com

2017-03-01

In this paper we investigate light dark matter scenarios where annihilation to Standard Model particles at tree-level is kinematically forbidden. In such cases annihilation can be aided by massive Standard Model-like species, called assisters , in the initial state that enhances the available phase space opening up novel tree-level processes. We investigate the feasibility of such non-standard assisted annihilation processes to reproduce the observed relic density of dark matter. We present a simple scalar dark matter-scalar assister model where this is realised. We find that if the dark matter and assister are relatively degenerate the required relic density can bemore » achieved for a keV-MeV scale dark matter. We briefly discuss the cosmological constraints on such dark matter scenarios.« less

Probing Sub-GeV Dark Matter with Conventional Detectors.

PubMed

Kouvaris, Chris; Pradler, Josef

2017-01-20

The direct detection of dark matter particles with mass below the GeV scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic dark matter nucleus scattering sets a principal limit on detectability. Here, we propose to bypass the kinematic limitations by considering the inelastic channel of photon emission from bremsstrahlung in the nuclear recoil. Our proposed method allows us to set the first limits on dark matter below 500 MeV in the plane of dark matter mass and cross section with nucleons. In situations where a dark-matter-electron coupling is suppressed, bremsstrahlung may constitute the only path to probe low-mass dark matter awaiting new detector technologies with lowered recoil energy thresholds.

Asymmetric dark matter models in SO(10)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagata, Natsumi; Olive, Keith A.; Zheng, Jiaming, E-mail: natsumi@hep-th.phys.s.u-tokyo.ac.jp, E-mail: olive@physics.umn.edu, E-mail: zheng@physics.umn.edu

2017-02-01

We systematically study the possibilities for asymmetric dark matter in the context of non-supersymmetric SO(10) models of grand unification. Dark matter stability in SO(10) is guaranteed by a remnant Z{sub 2} symmetry which is preserved when the intermediate scale gauge subgroup of SO(10) is broken by a (\\bf 126) dimensional representation. The asymmetry in the dark matter states is directly generated through the out-of-equilibrium decay of particles around the intermediate scale, or transferred from the baryon/lepton asymmetry generated in the Standard Model sector by leptogenesis. We systematically classify possible asymmetric dark matter candidates in terms of their quantum numbers, andmore » derive the conditions for each case that the observed dark matter density is (mostly) explained by the asymmetry of dark matter particles.« less

Analysis of interacting entropy-corrected holographic and new agegraphic dark energies

NASA Astrophysics Data System (ADS)

Ranjit, Chayan; Debnath, Ujjal

In the present work, we assume the flat FRW model of the universe is filled with dark matter and dark energy where they are interacting. For dark energy model, we consider the entropy-corrected HDE (ECHDE) model and the entropy-corrected NADE (ECNADE). For entropy-corrected models, we assume logarithmic correction and power law correction. For ECHDE model, length scale L is assumed to be Hubble horizon and future event horizon. The ωde-ωde‧ analysis for our different horizons are discussed.

DaMaSCUS: the impact of underground scatterings on direct detection of light dark matter

NASA Astrophysics Data System (ADS)

Emken, Timon; Kouvaris, Chris

2017-10-01

Conventional dark matter direct detection experiments set stringent constraints on dark matter by looking for elastic scattering events between dark matter particles and nuclei in underground detectors. However these constraints weaken significantly in the sub-GeV mass region, simply because light dark matter does not have enough energy to trigger detectors regardless of the dark matter-nucleon scattering cross section. Even if future experiments lower their energy thresholds, they will still be blind to parameter space where dark matter particles interact with nuclei strongly enough that they lose enough energy and become unable to cause a signal above the experimental threshold by the time they reach the underground detector. Therefore in case dark matter is in the sub-GeV region and strongly interacting, possible underground scatterings of dark matter with terrestrial nuclei must be taken into account because they affect significantly the recoil spectra and event rates, regardless of whether the experiment probes DM via DM-nucleus or DM-electron interaction. To quantify this effect we present the publicly available Dark Matter Simulation Code for Underground Scatterings (DaMaSCUS), a Monte Carlo simulator of DM trajectories through the Earth taking underground scatterings into account. Our simulation allows the precise calculation of the density and velocity distribution of dark matter at any detector of given depth and location on Earth. The simulation can also provide the accurate recoil spectrum in underground detectors as well as the phase and amplitude of the diurnal modulation caused by this shadowing effect of the Earth, ultimately relating the modulations expected in different detectors, which is important to decisively conclude if a diurnal modulation is due to dark matter or an irrelevant background.

DaMaSCUS: the impact of underground scatterings on direct detection of light dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emken, Timon; Kouvaris, Chris, E-mail: emken@cp3.sdu.dk, E-mail: kouvaris@cp3.sdu.dk

Conventional dark matter direct detection experiments set stringent constraints on dark matter by looking for elastic scattering events between dark matter particles and nuclei in underground detectors. However these constraints weaken significantly in the sub-GeV mass region, simply because light dark matter does not have enough energy to trigger detectors regardless of the dark matter-nucleon scattering cross section. Even if future experiments lower their energy thresholds, they will still be blind to parameter space where dark matter particles interact with nuclei strongly enough that they lose enough energy and become unable to cause a signal above the experimental threshold bymore » the time they reach the underground detector. Therefore in case dark matter is in the sub-GeV region and strongly interacting, possible underground scatterings of dark matter with terrestrial nuclei must be taken into account because they affect significantly the recoil spectra and event rates, regardless of whether the experiment probes DM via DM-nucleus or DM-electron interaction. To quantify this effect we present the publicly available Dark Matter Simulation Code for Underground Scatterings (DaMaSCUS), a Monte Carlo simulator of DM trajectories through the Earth taking underground scatterings into account. Our simulation allows the precise calculation of the density and velocity distribution of dark matter at any detector of given depth and location on Earth. The simulation can also provide the accurate recoil spectrum in underground detectors as well as the phase and amplitude of the diurnal modulation caused by this shadowing effect of the Earth, ultimately relating the modulations expected in different detectors, which is important to decisively conclude if a diurnal modulation is due to dark matter or an irrelevant background.« less

Effect of hydrodynamical-simulation–inspired dark matter velocity profile on directional detection of dark matter

DOE PAGES

Laha, Ranjan

2018-02-01

Directional detection is an important way to detect dark matter. An input for these experiments is the dark matter velocity distribution. Recent hydrodynamical simulations have shown that the dark matter velocity distribution differs substantially from the Standard Halo Model. We study the impact of some of these updated velocity distributions in dark matter directional detection experiments. Here, we calculate the ratio of events required to confirm the forward-backward asymmetry and the existence of the ring of maximum recoil rate using different dark matter velocity distributions for 19F and Xe targets. We show that with the use of updated dark mattermore » velocity profiles, the forward-backward asymmetry and the ring of maximum recoil rate can be confirmed using a factor of ~ 2– 3 less events when compared to that using the Standard Halo Model.« less

Dissipative dark matter and the Andromeda plane of satellites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randall, Lisa; Scholtz, Jakub, E-mail: randall@physics.harvard.edu, E-mail: jscholtz@physics.harvard.edu

We show that dissipative dark matter can potentially explain the large observed mass to light ratio of the dwarf satellite galaxies that have been observed in the recently identified planar structure around Andromeda, which are thought to result from tidal forces during a galaxy merger. Whereas dwarf galaxies created from ordinary disks would be dark matter poor, dark matter inside the galactic plane not only provides a source of dark matter, but one that is more readily bound due to the dark matter's lower velocity. This initial N-body study shows that with a thin disk of dark matter inside themore » baryonic disk, mass-to-light ratios as high as O(90) can be generated when tidal forces pull out patches of sizes similar to the scales of Toomre instabilities of the dark disk. A full simulation will be needed to confirm this result.« less

Effect of hydrodynamical-simulation–inspired dark matter velocity profile on directional detection of dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laha, Ranjan

Directional detection is an important way to detect dark matter. An input for these experiments is the dark matter velocity distribution. Recent hydrodynamical simulations have shown that the dark matter velocity distribution differs substantially from the Standard Halo Model. We study the impact of some of these updated velocity distributions in dark matter directional detection experiments. Here, we calculate the ratio of events required to confirm the forward-backward asymmetry and the existence of the ring of maximum recoil rate using different dark matter velocity distributions for 19F and Xe targets. We show that with the use of updated dark mattermore » velocity profiles, the forward-backward asymmetry and the ring of maximum recoil rate can be confirmed using a factor of ~ 2– 3 less events when compared to that using the Standard Halo Model.« less

Dark matter repulsion could thwart direct detection

DOE PAGES

Davoudiasl, Hooman

2017-11-20

We consider a feeble repulsive interaction between ordinary matter and dark matter, with a range similar to or larger than the size of the Earth. Dark matter can thus be repelled from the Earth, leading to null results in direct detection experiments, regardless of the strength of the short-distance interactions of dark matter with atoms. Generically, such a repulsive force would not allow trapping of dark matter inside astronomical bodies. In this scenario, accelerator-based experiments may furnish the only robust signals of asymmetric dark matter models, which typically lack indirect signals from self-annihilation. Finally, some of the variants of ourmore » hypothesis are also briefly discussed.« less

Dark matter repulsion could thwart direct detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davoudiasl, Hooman

We consider a feeble repulsive interaction between ordinary matter and dark matter, with a range similar to or larger than the size of the Earth. Dark matter can thus be repelled from the Earth, leading to null results in direct detection experiments, regardless of the strength of the short-distance interactions of dark matter with atoms. Generically, such a repulsive force would not allow trapping of dark matter inside astronomical bodies. In this scenario, accelerator-based experiments may furnish the only robust signals of asymmetric dark matter models, which typically lack indirect signals from self-annihilation. Finally, some of the variants of ourmore » hypothesis are also briefly discussed.« less

Make dark matter charged again

NASA Astrophysics Data System (ADS)

Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa; Scholtz, Jakub

2017-05-01

We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large, a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model.

Multi-Messenger Astronomy and Dark Matter

NASA Astrophysics Data System (ADS)

Bergström, Lars

This chapter presents the elaborated lecture notes on Multi-Messenger Astronomy and Dark Matter given by Lars Bergström at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". One of the main problems of astrophysics and astro-particle physics is that the nature of dark matter remains unsolved. There are basically three complementary approaches to try to solve this problem. One is the detection of new particles with accelerators, the second is the observation of various types of messengers from radio waves to gamma-ray photons and neutrinos, and the third is the use of ingenious experiments for direct detection of dark matter particles. After giving an introduction to the particle universe, the author discusses the relic density of particles, basic cross sections for neutrinos and gamma-rays, supersymmetric dark matter, detection methods for neutralino dark matter, particular dark matter candidates, the status of dark matter detection, a detailled calculation on an hypothetical "Saas-Fee Wimp", primordial black holes, and gravitational waves.

Alphas and surface backgrounds in liquid argon dark matter detectors

NASA Astrophysics Data System (ADS)

Stanford, Christopher J.

Current observations from astrophysics indicate the presence of dark matter, an invisible form of matter that makes up a large part of the mass of the universe. One of the leading theories for dark matter is that it is made up of Weakly Interacting Massive Particles (WIMPs). One of the ways we try to discover WIMPs is by directly detecting their interaction with regular matter. This can be done using a scintillator such as liquid argon, which gives off light when a particle interacts with it. Liquid argon (LAr) is a favorable means of detecting WIMPs because it has an inherent property that enables a technique called pulse-shape discrimination (PSD). PSD can distinguish a WIMP signal from the constant background of electromagnetic signals from other sources, like gamma rays. However, there are other background signals that PSD is not as capable of rejecting, such as those caused by alpha decays on the interior surfaces of the detector. Radioactive elements that undergo alpha decay are introduced to detector surfaces during construction by radon gas that is naturally present in the air, as well as other means. When these surface isotopes undergo alpha decay, they can produce WIMP-like signals in the detector. We present here two LAr experiments. The first (RaDOSE) discovered a property of an organic compound that led to a technique for rejecting surface alpha decays in LAr detectors with high efficiency. The second (DarkSide-50) is a dark matter experiment operated at LNGS in Italy and is the work of an international collaboration. A detailed look is given into alpha decays and surface backgrounds present in the detector, and projections are made of alpha-related backgrounds for 500 live days of data. The technique developed with RaDOSE is applied to DarkSide-50 to determine its effectiveness in practice. It is projected to suppress the surface background in DarkSide-50 by more than a factor of 1000.

The dark matter distribution of M87 and NGC 1399

NASA Technical Reports Server (NTRS)

Tsai, John C.

1993-01-01

Recent X-ray observations of clusters of galaxies indicate that, outside the innermost about 100 kpc region, the ratio of dark matter density to baryonic matter density declines with radius. We show that this result is consistent with a cold dark matter simulation, suggesting the presence of dissipationless dark matter in the observed clusters. This is contrary to previous suggestions that dissipational baryonic dark matter is required to explain the decline in the density ratio. The simulation further shows that, in the inner 100 kpc region, the density ratio should rise with radius. We confirm this property in M87 and NGC 1399, which are close enough to allow the determination of the density ratio in the required inner region. X-ray mappings of the dark matter distribution in clusters of galaxies are therefore consistent with the presence of dissipationless dark matter.

Constraints on Leptophilic Dark Matter from the AMS-02 Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavasonza, Leila Ali; Gast, Henning; Schael, Stefan

2017-04-10

The annihilation of dark matter particles in the Galactic halo of the Milky Way may lead to cosmic ray signatures that can be probed by the AMS-02 experiment, which has measured the composition and fluxes of charged cosmic rays with unprecedented precision. Given the absence of characteristic spectral features in the electron and positron fluxes measured by AMS-02, we derive upper limits on the dark matter annihilation cross section for leptophilic dark matter models. Our limits are based on a new background model that describes all recent measurements of the energy spectra of cosmic-ray positrons and electrons. For thermal darkmore » matter relics, we can exclude dark matter masses below about 100 GeV. We include the radiation of electroweak gauge bosons in the dark matter annihilation process and compute the antiproton signal that can be expected within leptophilic dark matter models.« less

Mimicking dark matter in Horndeski gravity

NASA Astrophysics Data System (ADS)

Rinaldi, Massimiliano

2017-06-01

Since the rediscovery of Horndeski gravity, a lot of work has been devoted to the exploration of its properties, especially in the context of dark energy. However, one sector of this theory, namely the one containing the coupling of the Einstein tensor to the kinetic term of the scalar field, shows some surprising features in the construction of black holes and neutron stars. Motivated by these new results, I explore the possibility that this sector of Horndeski gravity can mimic cold dark matter at cosmological level and also explain the flattening of galactic rotation curves. I will show that, in principle, it is possible to achieve both goals with at least two scalar fields and a minimal set of assumptions.

Mapping extragalactic dark matter annihilation with galaxy surveys: A systematic study of stacked group searches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lisanti, Mariangela; Mishra-Sharma, Siddharth; Rodd, Nicholas L.

Dark matter in the halos surrounding galaxy groups and clusters can annihilate to high-energy photons. Recent advancements in the construction of galaxy group catalogs provide many thousands of potential extragalactic targets for dark matter. In this paper, we outline a procedure to infer the dark matter signal associated with a given galaxy group. Applying this procedure to a catalog of sources, one can create a full-sky map of the brightest extragalactic dark matter targets in the nearby Universe (z≲0.03), supplementing sources of dark matter annihilation from within the local group. As with searches for dark matter in dwarf galaxies, thesemore » extragalactic targets can be stacked together to enhance the signals associated with dark matter. We validate this procedure on mock Fermi gamma-ray data sets using a galaxy catalog constructed from the DarkSky N-body cosmological simulation and demonstrate that the limits are robust, at O(1) levels, to systematic uncertainties on halo mass and concentration. We also quantify other sources of systematic uncertainty arising from the analysis and modeling assumptions. Lastly, our results suggest that a stacking analysis using galaxy group catalogs provides a powerful opportunity to discover extragalactic dark matter and complements existing studies of Milky Way dwarf galaxies.« less

Mapping extragalactic dark matter annihilation with galaxy surveys: A systematic study of stacked group searches

NASA Astrophysics Data System (ADS)

Lisanti, Mariangela; Mishra-Sharma, Siddharth; Rodd, Nicholas L.; Safdi, Benjamin R.; Wechsler, Risa H.

2018-03-01

Dark matter in the halos surrounding galaxy groups and clusters can annihilate to high-energy photons. Recent advancements in the construction of galaxy group catalogs provide many thousands of potential extragalactic targets for dark matter. In this paper, we outline a procedure to infer the dark matter signal associated with a given galaxy group. Applying this procedure to a catalog of sources, one can create a full-sky map of the brightest extragalactic dark matter targets in the nearby Universe (z ≲0.03 ), supplementing sources of dark matter annihilation from within the local group. As with searches for dark matter in dwarf galaxies, these extragalactic targets can be stacked together to enhance the signals associated with dark matter. We validate this procedure on mock Fermi gamma-ray data sets using a galaxy catalog constructed from the DarkSky N -body cosmological simulation and demonstrate that the limits are robust, at O (1 ) levels, to systematic uncertainties on halo mass and concentration. We also quantify other sources of systematic uncertainty arising from the analysis and modeling assumptions. Our results suggest that a stacking analysis using galaxy group catalogs provides a powerful opportunity to discover extragalactic dark matter and complements existing studies of Milky Way dwarf galaxies.

Mapping extragalactic dark matter annihilation with galaxy surveys: A systematic study of stacked group searches

DOE PAGES

Lisanti, Mariangela; Mishra-Sharma, Siddharth; Rodd, Nicholas L.; ...

2018-03-09

Dark matter in the halos surrounding galaxy groups and clusters can annihilate to high-energy photons. Recent advancements in the construction of galaxy group catalogs provide many thousands of potential extragalactic targets for dark matter. In this paper, we outline a procedure to infer the dark matter signal associated with a given galaxy group. Applying this procedure to a catalog of sources, one can create a full-sky map of the brightest extragalactic dark matter targets in the nearby Universe (z≲0.03), supplementing sources of dark matter annihilation from within the local group. As with searches for dark matter in dwarf galaxies, thesemore » extragalactic targets can be stacked together to enhance the signals associated with dark matter. We validate this procedure on mock Fermi gamma-ray data sets using a galaxy catalog constructed from the DarkSky N-body cosmological simulation and demonstrate that the limits are robust, at O(1) levels, to systematic uncertainties on halo mass and concentration. We also quantify other sources of systematic uncertainty arising from the analysis and modeling assumptions. Lastly, our results suggest that a stacking analysis using galaxy group catalogs provides a powerful opportunity to discover extragalactic dark matter and complements existing studies of Milky Way dwarf galaxies.« less

Quantum field theory of interacting dark matter and dark energy: Dark monodromies

DOE PAGES

D’Amico, Guido; Hamill, Teresa; Kaloper, Nemanja

2016-11-28

We discuss how to formulate a quantum field theory of dark energy interacting with dark matter. We show that the proposals based on the assumption that dark matter is made up of heavy particles with masses which are very sensitive to the value of dark energy are strongly constrained. Quintessence-generated long-range forces and radiative stability of the quintessence potential require that such dark matter and dark energy are completely decoupled. However, if dark energy and a fraction of dark matter are very light axions, they can have significant mixings which are radiatively stable and perfectly consistent with quantum field theory.more » Such models can naturally occur in multi-axion realizations of monodromies. The mixings yield interesting signatures which are observable and are within current cosmological limits but could be constrained further by future observations« less

Quantum field theory of interacting dark matter and dark energy: Dark monodromies

DOE Office of Scientific and Technical Information (OSTI.GOV)

D’Amico, Guido; Hamill, Teresa; Kaloper, Nemanja

We discuss how to formulate a quantum field theory of dark energy interacting with dark matter. We show that the proposals based on the assumption that dark matter is made up of heavy particles with masses which are very sensitive to the value of dark energy are strongly constrained. Quintessence-generated long-range forces and radiative stability of the quintessence potential require that such dark matter and dark energy are completely decoupled. However, if dark energy and a fraction of dark matter are very light axions, they can have significant mixings which are radiatively stable and perfectly consistent with quantum field theory.more » Such models can naturally occur in multi-axion realizations of monodromies. The mixings yield interesting signatures which are observable and are within current cosmological limits but could be constrained further by future observations« less

Detection of sub-MeV dark matter with three-dimensional Dirac materials

DOE PAGES

Hochberg, Yonit; Kahn, Yonatan; Lisanti, Mariangela; ...

2018-01-08

Here, we propose the use of three-dimensional Dirac materials as targets for direct detection of sub-MeV dark matter. Dirac materials are characterized by a linear dispersion for low-energy electronic excitations, with a small band gap of Ο(meV) if lattice symmetries are broken. Dark matter at the keV scale carrying kinetic energy as small as a few meV can scatter and excite an electron across the gap. Alternatively, bosonic dark matter as light as a few meV can be absorbed by the electrons in the target. We develop the formalism for dark matter scattering and absorption in Dirac materials and calculatemore » the experimental reach of these target materials. We find that Dirac materials can play a crucial role in detecting dark matter in the keV to MeV mass range that scatters with electrons via a kinetically mixed dark photon, as the dark photon does not develop an in-medium effective mass. The same target materials provide excellent sensitivity to absorption of light bosonic dark matter in the meV to hundreds of meV mass range, superior to all other existing proposals when the dark matter is a kinetically mixed dark photon.« less

Detection of sub-MeV dark matter with three-dimensional Dirac materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hochberg, Yonit; Kahn, Yonatan; Lisanti, Mariangela

Here, we propose the use of three-dimensional Dirac materials as targets for direct detection of sub-MeV dark matter. Dirac materials are characterized by a linear dispersion for low-energy electronic excitations, with a small band gap of Ο(meV) if lattice symmetries are broken. Dark matter at the keV scale carrying kinetic energy as small as a few meV can scatter and excite an electron across the gap. Alternatively, bosonic dark matter as light as a few meV can be absorbed by the electrons in the target. We develop the formalism for dark matter scattering and absorption in Dirac materials and calculatemore » the experimental reach of these target materials. We find that Dirac materials can play a crucial role in detecting dark matter in the keV to MeV mass range that scatters with electrons via a kinetically mixed dark photon, as the dark photon does not develop an in-medium effective mass. The same target materials provide excellent sensitivity to absorption of light bosonic dark matter in the meV to hundreds of meV mass range, superior to all other existing proposals when the dark matter is a kinetically mixed dark photon.« less

Dark matter freeze-out in a nonrelativistic sector

NASA Astrophysics Data System (ADS)

Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele

2016-08-01

A thermally decoupled hidden sector of particles, with a mass gap, generically enters a phase of cannibalism in the early Universe. The Standard Model sector becomes exponentially colder than the hidden sector. We propose the cannibal dark matter framework, where dark matter resides in a cannibalizing sector with a relic density set by 2-to-2 annihilations. Observable signals of cannibal dark matter include a boosted rate for indirect detection, new relativistic degrees of freedom, and warm dark matter.

Xenon Purification Research and Development for the LZ Dark Matter Experiment

NASA Astrophysics Data System (ADS)

Pech, Katherin

2013-04-01

The LZ Experiment is a next generation dark matter detector based on the current LUX detector design, with a 7-ton active volume. Although many research and development breakthroughs were achieved for the 350 kg LUX detector, the large volume scaling required for LZ presents a new set of design challenges that need to be overcome. Because the search for WIMP-like dark matter requires ultra low background experiments, the xenon target material in the LZ detector must meet purity specifications beyond what is commercially available. This challenge is two-fold. The xenon must contain extremely low amounts of electronegative impurities such as oxygen, which attenuate the charge signal. Additionally, it must also have very little of the inert isotope Kr-85, a beta-emitter that can obscure the dark matter signal in the detector volume. The purity requirements for the LUX experiment have been achieved, but the factor of 20 scaling in volume for LZ and increased demands for sensitivity mean that new research and development work must be done to increase our xenon purification capabilities. This talk will focus on the efforts being done at Case Western Reserve University to meet these strict purity requirements for the LZ Experiment.

Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators.

PubMed

Backović, Mihailo; Krämer, Michael; Maltoni, Fabio; Martini, Antony; Mawatari, Kentarou; Pellen, Mathieu

Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In this work, we consider various simplified models with s -channel mediators. We implement such models in the FeynRules/MadGraph5_aMC@NLO framework, which allows to include higher-order QCD corrections in realistic simulations and to study their effect systematically. As a first phenomenological application, we present predictions for dark matter production in association with jets and with a top-quark pair at the LHC, at next-to-leading order accuracy in QCD, including matching/merging to parton showers. Our study shows that higher-order QCD corrections to dark matter production via s -channel mediators have a significant impact not only on total production rates, but also on shapes of distributions. We also show that the inclusion of next-to-leading order effects results in a sizeable reduction of the theoretical uncertainties.

Measuring the power spectrum of dark matter substructure using strong gravitational lensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hezaveh, Yashar; Dalal, Neal; Holder, Gilbert

2016-11-01

In recent years, it has become possible to detect individual dark matter subhalos near images of strongly lensed extended background galaxies. Typically, only the most massive subhalos in the strong lensing region may be detected this way. In this work, we show that strong lenses may also be used to constrain the much more numerous population of lower mass subhalos that are too small to be detected individually. In particular, we show that the power spectrum of projected density fluctuations in galaxy halos can be measured using strong gravitational lensing. We develop the mathematical framework of power spectrum estimation, andmore » test our method on mock observations. We use our results to determine the types of observations required to measure the substructure power spectrum with high significance. We predict that deep observations (∼10 hours on a single target) with current facilities can measure this power spectrum at the 3σ level, with no apparent degeneracy with unknown clumpiness in the background source structure or fluctuations from detector noise. Upcoming ALMA measurements of strong lenses are capable of placing strong constraints on the abundance of dark matter subhalos and the underlying particle nature of dark matter.« less

Antiproton signatures from astrophysical and dark matter sources at the galactic center

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cembranos, J.A.R.; Gammaldi, V.; Maroto, A.L., E-mail: cembra@ucm.es, E-mail: vivigamm@ucm.es, E-mail: maroto@fis.ucm.es

2015-03-01

The center of our Galaxy is a complex region characterized by extreme phenomena. The presence of the supermassive Sagittarius A* black hole, a high dark matter density and an even higher baryonic density are able to produce very energetic processes. Indeed, high energetic gamma-rays have been observed by different telescopes, although their origin is not clear. In this work, we estimate the possible antiproton flux component associated with this signal. The expected secondary astrophysical antiproton background already saturates the observed data. It implies that any other important astrophysical source leads to an inconsistent excess. We estimate the sensitivity of PAMELAmore » to this new primary antiproton source, which depends on the diffusion model and its spectral features. In particular, we consider antiproton spectra described by a power-law, a monochromatic signal and a Standard Model particle-antiparticle channel production. This latter spectrum is typical in the production from annihilating or decaying dark matter. We pay particular attention to the case of a heavy dark matter candidate, which could be associated with the High Energy Stereoscopic System (HESS) data observed from the J1745-290 source.« less

Constraints on Dark Matter Annihilation by Synchrotron Emission based on Planck Data

NASA Astrophysics Data System (ADS)

Muanglay, Chalit; Wechakama, Maneenate; Cantlay, Brandon K.

2017-09-01

Synchrotron emission can be a good probe for dark matter particles in the Milky Way. We have investigated the production of electrons and positrons in the Milky Way within the context of dark matter annihilation. Upper limits on the relevant cross-section are obtained by comparing synchrotron emission in the microwave bands with Planck data. According to our results, the dark matter annihilation cross-section into electron-positron pairs should not be higher than the canonical value for a thermal relic if the mass of the dark matter candidate is smaller than a few GeV. In addition, we also look for constraints on the inner slope of dark matter density profile in the Milky Way. Our results indicate that the inner slope of dark matter profile is between 1 to 1.5.

Novel dark matter phenomenology at colliders

NASA Astrophysics Data System (ADS)

Wardlow, Kyle Patrick

While a suitable candidate particle for dark matter (DM) has yet to be discovered, it is possible one will be found by experiments currently investigating physics on the weak scale. If discovered on that energy scale, the dark matter will likely be producible in significant quantities at colliders like the LHC, allowing the properties of and underlying physical model characterizing the dark matter to be precisely determined. I assume that the dark matter will be produced as one of the decay products of a new massive resonance related to physics beyond the Standard Model, and using the energy distributions of the associated visible decay products, develop techniques for determining the symmetry protecting these potential dark matter candidates from decaying into lighter Standard Model (SM) particles and to simultaneously measure the masses of both the dark matter candidate and the particle from which it decays.

Constraining heavy dark matter with cosmic-ray antiprotons

NASA Astrophysics Data System (ADS)

Cuoco, Alessandro; Heisig, Jan; Korsmeier, Michael; Krämer, Michael

2018-04-01

Cosmic-ray observations provide a powerful probe of dark matter annihilation in the Galaxy. In this paper we derive constraints on heavy dark matter from the recent precise AMS-02 antiproton data. We consider all possible annihilation channels into pairs of standard model particles. Furthermore, we interpret our results in the context of minimal dark matter, including higgsino, wino and quintuplet dark matter. We compare the cosmic-ray antiproton limits to limits from γ-ray observations of dwarf spheroidal galaxies and to limits from γ-ray and γ-line observations towards the Galactic center. While the latter limits are highly dependent on the dark matter density distribution and only exclude a thermal wino for cuspy profiles, the cosmic-ray limits are more robust, strongly disfavoring the thermal wino dark matter scenario even for a conservative estimate of systematic uncertainties.

Probing dark matter physics with galaxy clusters

NASA Astrophysics Data System (ADS)

Dalal, Neal

2016-10-01

We propose a theoretical investigation of the effects of a class of dark matter (DM) self-interactions on the properties of galaxy clusters and their host dark matter halos. Recent work using HST has claimed the detection of a particular form of DM self-interaction, which can lead to observable displacements between satellite galaxies within clusters and the DM subhalos hosting them. This form of self-interaction is highly anisotropic, favoring forward scattering with low momentum transfer, unlike isotropically scattering self-interacting dark matter (SIDM) models. This class of models has not been simulated numerically, clouding the interpretation of the claimed offsets between galaxies and lensing peaks observed by HST. We propose to perform high resolution simulations of cosmological structure formation for this class of SIDM model, focusing on three observables accessible to existing HST observations of clusters. First, we will quantify the extent to which offsets between baryons and DM can arise in these models, as a function of the cross section. Secondly, we will also quantify the effects of this type of DM self-interaction on halo concentrations, to determine the range of cross-sections allowed by existing stringent constraints from HST. Finally we will compute the so-called splashback feature in clusters, specifically focusing on whether SIDM can resolve the current discrepancy between observed values of splashback radii in clusters compared to theoretical predictions for CDM. The proposed investigations will add value to all existing deep HST observations of galaxy clusters by allowing them to probe dark matter physics in three independent ways.

Direct dark matter search by annual modulation with 2.7 years of XMASS-I data

NASA Astrophysics Data System (ADS)

Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakahata, M.; Norita, T.; Ogawa, H.; Sato, K.; Sekiya, H.; Takachio, O.; Takeda, A.; Tasaka, S.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Itow, Y.; Kanzawa, K.; Kegasa, R.; Masuda, K.; Takiya, H.; Fushimi, K.; Kanzaki, G.; Martens, K.; Suzuki, Y.; Xu, B. D.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Oka, N.; Takeuchi, Y.; Kim, Y. H.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Miyasaka, M.; Nishijima, K.; Nakamura, S.; Xmass Collaboration

2018-05-01

An annual modulation signal due to the Earth orbiting around the Sun would be one of the strongest indications of the direct detection of dark matter. In 2016, we reported a search for dark matter by looking for this annual modulation with our single-phase liquid xenon XMASS-I detector. That analysis resulted in a slightly negative modulation amplitude at low energy. In this work, we included more than one year of additional data, which more than doubles the exposure to 800 live days with the same 832 kg target mass. When we assume weakly interacting massive particle (WIMP) dark matter elastically scattering on the xenon target, the exclusion upper limit for the WIMP-nucleon cross section was improved by a factor of 2 to 1.9 ×10-41 cm2 at 8 GeV /c2 at 90% confidence level with our newly implemented data selection through a likelihood method. For the model-independent case, without assuming any specific dark matter model, we obtained more consistency with the null hypothesis than before with a p -value of 0.11 in the 1-20 keV energy region. This search probed this region with an exposure that was larger than that of DAMA/LIBRA. We also did not find any significant amplitude in the data for periodicity with periods between 50 and 600 days in the energy region between 1 to 6 keV.

Triplets of galaxies: Their dynamics, evolution, and the origin of chaos in them

NASA Technical Reports Server (NTRS)

Chernin, Arthur D.; Ivanov, Alexei V.

1990-01-01

Recently Karachentsev's group at The Smithsonian Astrophysical Observatory (SAO) (6-meter Telescope Observatory) published a list of 84 triple systems of galaxies with their distances, radial (line of sight) velocities, and angular sizes (Karachentseva et al., 1988). This gives a new ground for studies of the dark matter problem which fills the gap between the large cosmic scales (White, 1987; Dekel and Rees, 1987, and Einasto et al., 1977) and the scale of individual galaxies (Erickson et al., 1987). The data on the typical velocity dispersions and linear dimension of the triplets indicate that they contain considerable amounts of dark matter (see also earlier work of Karachentseva et al., 1979). Numerical simulations show that the statistical characteristics of the Karachentsev triplets can be imitated by model ensembles of triple systems with dark matter masses M sub d = (1-3 x 10(exp 12) M sub O, which is almost ten times greater than the typical mass of stellar galaxies estimated by the standard mass-to-luminosity ration (Kiseleva and Chernin, 1988). Here, the authors report that important information can be drawn from the data on the visible configurations of these systems. The statistics of configurations provide an independent evidence for dark matter in the triplets; moreover, it enables one to argue that dark matter seems to be distributed over the whole volume of the typical triplet forming its common corona rather than concentrated within individual coronae (or haloes) of the member galaxies.

Cosmological simulations of decaying dark matter: implications for small-scale structure of dark matter haloes

NASA Astrophysics Data System (ADS)

Wang, Mei-Yu; Peter, Annika H. G.; Strigari, Louis E.; Zentner, Andrew R.; Arant, Bryan; Garrison-Kimmel, Shea; Rocha, Miguel

2014-11-01

We present a set of N-body simulations of a class of models in which an unstable dark matter particle decays into a stable dark matter particle and a non-interacting light particle with decay lifetime comparable to the Hubble time. We study the effects of the recoil kick velocity (Vk) received by the stable dark matter on the structures of dark matter haloes ranging from galaxy-cluster to Milky Way-mass scales. For Milky Way-mass haloes, we use high-resolution, zoom-in simulations to explore the effects of decays on Galactic substructure. In general, haloes with circular velocities comparable to the magnitude of kick velocity are most strongly affected by decays. We show that models with lifetimes Γ-1 ˜ H_0^{-1} and recoil speeds Vk ˜ 20-40 km s-1 can significantly reduce both the abundance of Galactic subhaloes and their internal densities. We find that decaying dark matter models that do not violate current astrophysical constraints can significantly mitigate both the `missing satellites problem' and the more recent `too big to fail problem'. These decaying models predict significant time evolution of haloes, and this implies that at high redshifts decaying models exhibit the similar sequence of structure formation as cold dark matter. Thus, decaying dark matter models are significantly less constrained by high-redshift phenomena than warm dark matter models. We conclude that models of decaying dark matter make predictions that are relevant for the interpretation of small galaxies observations in the Local Group and can be tested as well as by forthcoming large-scale surveys.

Stellar Velocity Dispersion: Linking Quiescent Galaxies to Their Dark Matter Halos

NASA Astrophysics Data System (ADS)

Zahid, H. Jabran; Sohn, Jubee; Geller, Margaret J.

2018-06-01

We analyze the Illustris-1 hydrodynamical cosmological simulation to explore the stellar velocity dispersion of quiescent galaxies as an observational probe of dark matter halo velocity dispersion and mass. Stellar velocity dispersion is proportional to dark matter halo velocity dispersion for both central and satellite galaxies. The dark matter halos of central galaxies are in virial equilibrium and thus the stellar velocity dispersion is also proportional to dark matter halo mass. This proportionality holds even when a line-of-sight aperture dispersion is calculated in analogy to observations. In contrast, at a given stellar velocity dispersion, the dark matter halo mass of satellite galaxies is smaller than virial equilibrium expectations. This deviation from virial equilibrium probably results from tidal stripping of the outer dark matter halo. Stellar velocity dispersion appears insensitive to tidal effects and thus reflects the correlation between stellar velocity dispersion and dark matter halo mass prior to infall. There is a tight relation (≲0.2 dex scatter) between line-of-sight aperture stellar velocity dispersion and dark matter halo mass suggesting that the dark matter halo mass may be estimated from the measured stellar velocity dispersion for both central and satellite galaxies. We evaluate the impact of treating all objects as central galaxies if the relation we derive is applied to a statistical ensemble. A large fraction (≳2/3) of massive quiescent galaxies are central galaxies and systematic uncertainty in the inferred dark matter halo mass is ≲0.1 dex thus simplifying application of the simulation results to currently available observations.

Origin of ΔN{sub eff} as a result of an interaction between dark radiation and dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bjaelde, Ole Eggers; Das, Subinoy; Moss, Adam, E-mail: oeb@phys.au.dk, E-mail: subinoy@physik.rwth-aachen.de, E-mail: Adam.Moss@nottingham.ac.uk

2012-10-01

Results from the Wilkinson Microwave Anisotropy Probe (WMAP), Atacama Cosmology Telescope (ACT) and recently from the South Pole Telescope (SPT) have indicated the possible existence of an extra radiation component in addition to the well known three neutrino species predicted by the Standard Model of particle physics. In this paper, we explore the possibility of the apparent extra dark radiation being linked directly to the physics of cold dark matter (CDM). In particular, we consider a generic scenario where dark radiation, as a result of an interaction, is produced directly by a fraction of the dark matter density effectively decayingmore » into dark radiation. At an early epoch when the dark matter density is negligible, as an obvious consequence, the density of dark radiation is also very small. As the Universe approaches matter radiation equality, the dark matter density starts to dominate thereby increasing the content of dark radiation and changing the expansion rate of the Universe. As this increase in dark radiation content happens naturally after Big Bang Nucleosynthesis (BBN), it can relax the possible tension with lower values of radiation degrees of freedom measured from light element abundances compared to that of the CMB. We numerically confront this scenario with WMAP+ACT and WMAP+SPT data and derive an upper limit on the allowed fraction of dark matter decaying into dark radiation.« less

Dark matter as a trigger for periodic comet impacts.

PubMed

Randall, Lisa; Reece, Matthew

2014-04-25

Although statistical evidence is not overwhelming, possible support for an approximately 35×106  yr periodicity in the crater record on Earth could indicate a nonrandom underlying enhancement of meteorite impacts at regular intervals. A proposed explanation in terms of tidal effects on Oort cloud comet perturbations as the Solar System passes through the galactic midplane is hampered by lack of an underlying cause for sufficiently enhanced gravitational effects over a sufficiently short time interval and by the time frame between such possible enhancements. We show that a smooth dark disk in the galactic midplane would address both these issues and create a periodic enhancement of the sort that has potentially been observed. Such a disk is motivated by a novel dark matter component with dissipative cooling that we considered in earlier work. We show how to evaluate the statistical evidence for periodicity by input of appropriate measured priors from the galactic model, justifying or ruling out periodic cratering with more confidence than by evaluating the data without an underlying model. We find that, marginalizing over astrophysical uncertainties, the likelihood ratio for such a model relative to one with a constant cratering rate is 3.0, which moderately favors the dark disk model. Our analysis furthermore yields a posterior distribution that, based on current crater data, singles out a dark matter disk surface density of approximately 10M⊙/pc2. The geological record thereby motivates a particular model of dark matter that will be probed in the near future.

QCD Axion Dark Matter with a Small Decay Constant

NASA Astrophysics Data System (ADS)

Co, Raymond T.; Hall, Lawrence J.; Harigaya, Keisuke

2018-05-01

The QCD axion is a good dark matter candidate. The observed dark matter abundance can arise from misalignment or defect mechanisms, which generically require an axion decay constant fa˜O (1011) GeV (or higher). We introduce a new cosmological origin for axion dark matter, parametric resonance from oscillations of the Peccei-Quinn symmetry breaking field, that requires fa˜(108- 1011) GeV . The axions may be warm enough to give deviations from cold dark matter in large scale structure.

Dark energy and the structure of the Coma cluster of galaxies

NASA Astrophysics Data System (ADS)

Chernin, A. D.; Bisnovatyi-Kogan, G. S.; Teerikorpi, P.; Valtonen, M. J.; Byrd, G. G.; Merafina, M.

2013-05-01

Context. We consider the Coma cluster of galaxies as a gravitationally bound physical system embedded in the perfectly uniform static dark energy background as implied by ΛCDM cosmology. Aims: We ask if the density of dark energy is high enough to affect the structure of a large and rich cluster of galaxies. Methods: We base our work on recent observational data on the Coma cluster, and apply our theory of local dynamical effects of dark energy, including the zero-gravity radius RZG of the local force field as the key parameter. Results: 1) Three masses are defined that characterize the structure of a regular cluster: the matter mass MM, the dark-energy effective mass MDE (<0), and the gravitating mass MG (=MM + MDE). 2) A new matter-density profile is suggested that reproduces the observational data well for the Coma cluster in the radius range from 1.4 Mpc to 14 Mpc and takes the dark energy background into account. 3) Using this profile, we calculate upper limits for the total size of the Coma cluster, R ≤ RZG ≈ 20 Mpc, and its total matter mass, MM ≲ MM(RZG) = 6.2 × 1015 M⊙. Conclusions: The dark energy antigravity affects the structure of the Coma cluster strongly at large radii R ≳ 14 Mpc and should be considered when its total mass is derived.

Dark-matter decay as a complementary probe of multicomponent dark sectors.

PubMed

Dienes, Keith R; Kumar, Jason; Thomas, Brooks; Yaylali, David

2015-02-06

In single-component theories of dark matter, the 2→2 amplitudes for dark-matter production, annihilation, and scattering can be related to each other through various crossing symmetries. The detection techniques based on these processes are thus complementary. However, multicomponent theories exhibit an additional direction for dark-matter complementarity: the possibility of dark-matter decay from heavier to lighter components. We discuss how this new detection channel may be correlated with the others, and demonstrate that the enhanced complementarity which emerges can be an important ingredient in probing and constraining the parameter spaces of such models.

Distinguishing dark matter from unresolved point sources in the Inner Galaxy with photon statistics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Samuel K.; Lisanti, Mariangela; Safdi, Benjamin R., E-mail: samuelkl@princeton.edu, E-mail: mlisanti@princeton.edu, E-mail: bsafdi@princeton.edu

2015-05-01

Data from the Fermi Large Area Telescope suggests that there is an extended excess of GeV gamma-ray photons in the Inner Galaxy. Identifying potential astrophysical sources that contribute to this excess is an important step in verifying whether the signal originates from annihilating dark matter. In this paper, we focus on the potential contribution of unresolved point sources, such as millisecond pulsars (MSPs). We propose that the statistics of the photons—in particular, the flux probability density function (PDF) of the photon counts below the point-source detection threshold—can potentially distinguish between the dark-matter and point-source interpretations. We calculate the flux PDFmore » via the method of generating functions for these two models of the excess. Working in the framework of Bayesian model comparison, we then demonstrate that the flux PDF can potentially provide evidence for an unresolved MSP-like point-source population.« less

A possible formation scenario for dwarf spheroidal galaxies - III. Adding star formation histories to the fiducial model

NASA Astrophysics Data System (ADS)

Alarcón Jara, A. G.; Fellhauer, M.; Matus Carrillo, D. R.; Assmann, P.; Urrutia Zapata, F.; Hazeldine, J.; Aravena, C. A.

2018-02-01

Dwarf spheroidal galaxies are regarded as the basic building blocks in the formation of larger galaxies and are the most dark matter dominated systems in the Universe, known so far. There are several models that attempt to explain their formation and evolution, but they have problems modelling the formation of isolated dwarf spheroidal galaxies. Here, we will explain a possible formation scenario in which star clusters form inside the dark matter halo of a dwarf spheroidal galaxy. These star clusters suffer from low star formation efficiency and dissolve while orbiting inside the dark matter halo. Thereby, they build the faint luminous components that we observe in dwarf spheroidal galaxies. In this paper, we study this model by adding different star formation histories to the simulations and compare the results with our previous work and observational data to show that we can explain the formation of dwarf spheroidal galaxies.

NASA Finds Direct Proof of Dark Matter

NASA Astrophysics Data System (ADS)

2006-08-01

Dark matter and normal matter have been wrenched apart by the tremendous collision of two large clusters of galaxies. The discovery, using NASA's Chandra X-ray Observatory and other telescopes, gives direct evidence for the existence of dark matter. "This is the most energetic cosmic event, besides the Big Bang, which we know about," said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Lensing Illustration Gravitational Lensing Explanation These observations provide the strongest evidence yet that most of the matter in the universe is dark. Despite considerable evidence for dark matter, some scientists have proposed alternative theories for gravity where it is stronger on intergalactic scales than predicted by Newton and Einstein, removing the need for dark matter. However, such theories cannot explain the observed effects of this collision. "A universe that's dominated by dark stuff seems preposterous, so we wanted to test whether there were any basic flaws in our thinking," said Doug Clowe of the University of Arizona at Tucson, and leader of the study. "These results are direct proof that dark matter exists." Animation of Cluster Collision Animation of Cluster Collision In galaxy clusters, the normal matter, like the atoms that make up the stars, planets, and everything on Earth, is primarily in the form of hot gas and stars. The mass of the hot gas between the galaxies is far greater than the mass of the stars in all of the galaxies. This normal matter is bound in the cluster by the gravity of an even greater mass of dark matter. Without dark matter, which is invisible and can only be detected through its gravity, the fast-moving galaxies and the hot gas would quickly fly apart. The team was granted more than 100 hours on the Chandra telescope to observe the galaxy cluster 1E0657-56. The cluster is also known as the bullet cluster, because it contains a spectacular bullet-shaped cloud of hundred-million-degree gas. The X-ray image shows the bullet shape is due to a wind produced by the high-speed collision of a smaller cluster with a larger one. 4-Panel Illustrations of Cluster Collision 4-Panel Illustrations of Cluster Collision In addition to the Chandra observation, the Hubble Space Telescope, the European Southern Observatory's Very Large Telescope and the Magellan optical telescopes were used to determine the location of the mass in the clusters. This was done by measuring the effect of gravitational lensing, where gravity from the clusters distorts light from background galaxies as predicted by Einstein's theory of general relativity. The hot gas in this collision was slowed by a drag force, similar to air resistance. In contrast, the dark matter was not slowed by the impact, because it does not interact directly with itself or the gas except through gravity. This produced the separation of the dark and normal matter seen in the data. If hot gas was the most massive component in the clusters, as proposed by alternative gravity theories, such a separation would not have been seen. Instead, dark matter is required. Animation: Galaxy Cluster in Perspective Animation: Galaxy Cluster in Perspective "This is the type of result that future theories will have to take into account," said Sean Carroll, a cosmologist at the University of Chicago, who was not involved with the study. "As we move forward to understand the true nature of dark matter, this new result will be impossible to ignore." This result also gives scientists more confidence that the Newtonian gravity familiar on Earth and in the solar system also works on the huge scales of galaxy clusters. "We've closed this loophole about gravity, and we've come closer than ever to seeing this invisible matter," Clowe said. These results are being published in an upcoming issue of The Astrophysical Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center, Cambridge, Mass. Additional information and images can be found at: http://chandra.harvard.edu and http://chandra.nasa.gov

Thermal Dark Matter Below a MeV

DOE PAGES

Berlin, Asher; Blinov, Nikita

2018-01-08

We consider a class of models in which thermal dark matter is lighter than a MeV. If dark matter thermalizes with the standard model below the temperature of neutrino-photon decoupling, equilibration and freeze-out cool and heat the standard model bath comparably, alleviating constraints from measurements of the effective number of neutrino species. We demonstrate this mechanism in a model consisting of fermionic dark matter coupled to a light scalar mediator. Thermal dark matter can be as light as a few keV, while remaining compatible with existing cosmological and astrophysical observations. This framework motivates new experiments in the direct search formore » sub-MeV thermal dark matter and light force carriers.« less

Thermal Dark Matter Below a MeV

NASA Astrophysics Data System (ADS)

Berlin, Asher; Blinov, Nikita

2018-01-01

We consider a class of models in which thermal dark matter is lighter than a MeV. If dark matter thermalizes with the standard model below the temperature of neutrino-photon decoupling, equilibration and freeze-out cool and heat the standard model bath comparably, alleviating constraints from measurements of the effective number of neutrino species. We demonstrate this mechanism in a model consisting of fermionic dark matter coupled to a light scalar mediator. Thermal dark matter can be as light as a few keV, while remaining compatible with existing cosmological and astrophysical observations. This framework motivates new experiments in the direct search for sub-MeV thermal dark matter and light force carriers.

New LUX result constrains exotic quark mediators with the vector dark matter

NASA Astrophysics Data System (ADS)

Chen, Chuan-Ren; Li, Ming-Jie

2016-12-01

The scenario of the compressed mass spectrum between heavy quark and dark matter is a challenge for LHC searches. However, the elastic scattering cross-section between dark matter and nuclei in dark matter direct detection experiments can be enhanced with nearly degenerate masses between heavy quarks and dark matter. In this paper, we illustrate such scenario with a vector dark matter, using the latest result from LUX 2016. The mass constraints on heavy quarks can be more stringent than current limits from LHC, unless the coupling strength is very small. However, the compress mass spectrum with allowed tiny coupling strength makes the decay lifetime of heavy quarks longer than the timescale of QCD hadronization.

Inelastic Boosted Dark Matter at direct detection experiments

NASA Astrophysics Data System (ADS)

Giudice, Gian F.; Kim, Doojin; Park, Jong-Chul; Shin, Seodong

2018-05-01

We explore a novel class of multi-particle dark sectors, called Inelastic Boosted Dark Matter (iBDM). These models are constructed by combining properties of particles that scatter off matter by making transitions to heavier states (Inelastic Dark Matter) with properties of particles that are produced with a large Lorentz boost in annihilation processes in the galactic halo (Boosted Dark Matter). This combination leads to new signals that can be observed at ordinary direct detection experiments, but require unconventional searches for energetic recoil electrons in coincidence with displaced multi-track events. Related experimental strategies can also be used to probe MeV-range boosted dark matter via their interactions with electrons inside the target material.

Cosmological simulations of multicomponent cold dark matter.

PubMed

Medvedev, Mikhail V

2014-08-15

The nature of dark matter is unknown. A number of dark matter candidates are quantum flavor-mixed particles but this property has never been accounted for in cosmology. Here we explore this possibility from the first principles via extensive N-body cosmological simulations and demonstrate that the two-component dark matter model agrees with observational data at all scales. Substantial reduction of substructure and flattening of density profiles in the centers of dark matter halos found in simulations can simultaneously resolve several outstanding puzzles of modern cosmology. The model shares the "why now?" fine-tuning caveat pertinent to all self-interacting models. Predictions for direct and indirect detection dark matter experiments are made.

Thermal Dark Matter Below a MeV.

PubMed

Berlin, Asher; Blinov, Nikita

2018-01-12

We consider a class of models in which thermal dark matter is lighter than a MeV. If dark matter thermalizes with the standard model below the temperature of neutrino-photon decoupling, equilibration and freeze-out cool and heat the standard model bath comparably, alleviating constraints from measurements of the effective number of neutrino species. We demonstrate this mechanism in a model consisting of fermionic dark matter coupled to a light scalar mediator. Thermal dark matter can be as light as a few keV, while remaining compatible with existing cosmological and astrophysical observations. This framework motivates new experiments in the direct search for sub-MeV thermal dark matter and light force carriers.

Thermal Dark Matter Below a MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berlin, Asher; Blinov, Nikita

We consider a class of models in which thermal dark matter is lighter than a MeV. If dark matter thermalizes with the standard model below the temperature of neutrino-photon decoupling, equilibration and freeze-out cool and heat the standard model bath comparably, alleviating constraints from measurements of the effective number of neutrino species. We demonstrate this mechanism in a model consisting of fermionic dark matter coupled to a light scalar mediator. Thermal dark matter can be as light as a few keV, while remaining compatible with existing cosmological and astrophysical observations. This framework motivates new experiments in the direct search formore » sub-MeV thermal dark matter and light force carriers.« less

A dark energy model alternative to generalized Chaplygin gas

NASA Astrophysics Data System (ADS)

Hova, Hoavo; Yang, Huanxiong

By proposing a new cosmic fluid model of ‑ 1 ≤ ω ≤ 0 as an alternative to the generalized Chaplygin gas, we reexamine the role of Chaplygin gaslike fluid models in understanding dark energy and dark matter. Instead of as a unified dark matter, the fluid is suggested to be a mixture of unclustered dark energy and pressureless dark matter. Within such a scenario, the sub-horizon fluctuations of matter are stable and scale invariant, similar to those in standard ΛCDM model.

Dark matter and cosmological nucleosynthesis

NASA Technical Reports Server (NTRS)

Schramm, D. N.

1986-01-01

Existing dark matter problems, i.e., dynamics, galaxy formation and inflation, are considered, along with a model which proposes dark baryons as the bulk of missing matter in a fractal universe. It is shown that no combination of dark, nonbaryonic matter can either provide a cosmological density parameter value near unity or, as in the case of high energy neutrinos, allow formation of condensed matter at epochs when quasars already existed. The possibility that correlations among galactic clusters are scale-free is discussed. Such a distribution of matter would yield a fractal of 1.2, close to a one-dimensional universe. Biasing, cosmic superstrings, and percolated explosions and hot dark matter are theoretical approaches that would satisfy the D = 1.2 fractal model of the large-scale structure of the universe and which would also allow sufficient dark matter in halos to close the universe.

Absorption of light dark matter in semiconductors

DOE PAGES

Hochberg, Yonit; Lin, Tongyan; Zurek, Kathryn M.

2017-01-01

Semiconductors are by now well-established targets for direct detection of MeV to GeV dark matter via scattering off electrons. We show that semiconductor targets can also detect significantly lighter dark matter via an absorption process. When the dark matter mass is above the band gap of the semiconductor (around an eV), absorption proceeds by excitation of an electron into the conduction band. Below the band gap, multiphonon excitations enable absorption of dark matter in the 0.01 eV to eV mass range. Energetic dark matter particles emitted from the sun can also be probed for masses below an eV. We derivemore » the reach for absorption of a relic kinetically mixed dark photon or pseudoscalar in germanium and silicon, and show that existing direct detection results already probe new parameter space. Finally, with only a moderate exposure, low-threshold semiconductor target experiments can exceed current astrophysical and terrestrial constraints on sub-keV bosonic dark matter.« less

Bright gamma-ray Galactic Center excess and dark dwarfs: Strong tension for dark matter annihilation despite Milky Way halo profile and diffuse emission uncertainties

NASA Astrophysics Data System (ADS)

Abazajian, Kevork N.; Keeley, Ryan E.

2016-04-01

We incorporate Milky Way dark matter halo profile uncertainties, as well as an accounting of diffuse gamma-ray emission uncertainties in dark matter annihilation models for the Galactic Center Extended gamma-ray excess (GCE) detected by the Fermi Gamma Ray Space Telescope. The range of particle annihilation rate and masses expand when including these unknowns. However, two of the most precise empirical determinations of the Milky Way halo's local density and density profile leave the signal region to be in considerable tension with dark matter annihilation searches from combined dwarf galaxy analyses for single-channel dark matter annihilation models. The GCE and dwarf tension can be alleviated if: one, the halo is very highly concentrated or strongly contracted; two, the dark matter annihilation signal differentiates between dwarfs and the GC; or, three, local stellar density measures are found to be significantly lower, like that from recent stellar counts, increasing the local dark matter density.

The Structure of Dark Matter Halos in Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Burkert, A.

1995-07-01

Recent observations indicate that dark matter halos have flat central density profiles. Cosmological simulations with nonbaryonic dark matter, however, predict self-similar halos with central density cusps. This contradiction has lead to the conclusion that dark matter must be baryonic. Here it is shown that the dark matter halos of dwarf spiral galaxies represent a one-parameter family with self-similar density profiles. The observed global halo parameters are coupled with each other through simple scaling relations which can be explained by the standard cold dark matter model if one assumes that all the halos formed from density fluctuations with the same primordial amplitude. We find that the finite central halo densities correlate with the other global parameters. This result rules out scenarios where the flat halo cores formed subsequently through violent dynamical processes in the baryonic component. These cores instead provide important information on the origin and nature of dark matter in dwarf galaxies.

ASTROPHYSICS. Exclusion of leptophilic dark matter models using XENON100 electronic recoil data.

PubMed

2015-08-21

Laboratory experiments searching for galactic dark matter particles scattering off nuclei have so far not been able to establish a discovery. We use data from the XENON100 experiment to search for dark matter interacting with electrons. With no evidence for a signal above the low background of our experiment, we exclude a variety of representative dark matter models that would induce electronic recoils. For axial-vector couplings to electrons, we exclude cross sections above 6 × 10(-35) cm(2) for particle masses of m(χ) = 2 GeV/c(2). Independent of the dark matter halo, we exclude leptophilic models as an explanation for the long-standing DAMA/LIBRA signal, such as couplings to electrons through axial-vector interactions at a 4.4σ confidence level, mirror dark matter at 3.6σ, and luminous dark matter at 4.6σ. Copyright © 2015, American Association for the Advancement of Science.

Prospects for detecting a net photon circular polarization produced by decaying dark matter

NASA Astrophysics Data System (ADS)

Elagin, Andrey; Kumar, Jason; Sandick, Pearl; Teng, Fei

2017-11-01

If dark matter interactions with Standard Model particles are C P violating, then dark matter annihilation/decay can produce photons with a net circular polarization. We consider the prospects for experimentally detecting evidence for such a circular polarization. We identify optimal models for dark matter interactions with the Standard Model, from the point of view of detectability of the net polarization, for the case of either symmetric or asymmetric dark matter. We find that, for symmetric dark matter, evidence for net polarization could be found by a search of the Galactic center by an instrument sensitive to circular polarization with an efficiency-weighted exposure of at least 50 ,000 cm2 yr , provided the systematic detector uncertainties are constrained at the 1% level. Better sensitivity can be obtained in the case of asymmetric dark matter. We discuss the prospects for achieving the needed level of performance using possible detector technologies.

Directional detection of dark matter in universal bound states

DOE PAGES

Laha, Ranjan

2015-10-06

It has been suggested that several small-scale structure anomalies in Λ CDM cosmology can be solved by strong self-interaction between dark matter particles. It was shown in Ref. [1] that the presence of a near threshold S-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. This can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). Ref. [2] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. Here we study the angularmore » recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. Furthermore, observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics.« less

The fraternal WIMP miracle

DOE PAGES

Craig, Nathaniel; Katz, Andrey

2015-10-27

We identify and analyze thermal dark matter candidates in the fraternal twin Higgs model and its generalizations. The relic abundance of fraternal twin dark matter is set by twin weak interactions, with a scale tightly tied to the weak scale of the Standard Model by naturalness considerations. As such, the dark matter candidates benefit from a "fraternal WIMP miracle'', reproducing the observed dark matter abundance for dark matter masses between 50 and 150 GeV . However, the couplings dominantly responsible for dark matter annihilation do not lead to interactions with the visible sector. The direct detection rate is instead setmore » via fermionic Higgs portal interactions, which are likewise constrained by naturalness considerations but parametrically weaker than those leading to dark matter annihilation. Finally, the predicted direct detection cross section is close to current LUX bounds and presents an opportunity for the next generation of direct detection experiments.« less

Statistical analyses of Higgs- and Z -portal dark matter models

NASA Astrophysics Data System (ADS)

Ellis, John; Fowlie, Andrew; Marzola, Luca; Raidal, Martti

2018-06-01

We perform frequentist and Bayesian statistical analyses of Higgs- and Z -portal models of dark matter particles with spin 0, 1 /2 , and 1. Our analyses incorporate data from direct detection and indirect detection experiments, as well as LHC searches for monojet and monophoton events, and we also analyze the potential impacts of future direct detection experiments. We find acceptable regions of the parameter spaces for Higgs-portal models with real scalar, neutral vector, Majorana, or Dirac fermion dark matter particles, and Z -portal models with Majorana or Dirac fermion dark matter particles. In many of these cases, there are interesting prospects for discovering dark matter particles in Higgs or Z decays, as well as dark matter particles weighing ≳100 GeV . Negative results from planned direct detection experiments would still allow acceptable regions for Higgs- and Z -portal models with Majorana or Dirac fermion dark matter particles.

Probing the stability of superheavy dark matter particles with high-energy neutrinos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esmaili, Arman; Peres, Orlando L.G.; Ibarra, Alejandro, E-mail: aesmaili@ifi.unicamp.br, E-mail: ibarra@tum.de, E-mail: orlando@ifi.unicamp.br

2012-11-01

Two of the most fundamental properties of the dark matter particle, the mass and the lifetime, are only weakly constrained by the astronomical and cosmological evidence of dark matter. We derive in this paper lower limits on the lifetime of dark matter particles with masses in the range 10TeV−10{sup 15}TeV from the non-observation of ultrahigh energy neutrinos in the AMANDA, IceCube, Auger and ANITA experiments. For dark matter particles which produce neutrinos in a two body or a three body leptonic decay, we find that the dark matter lifetime must be longer than O(10{sup 26}−10{sup 28})s for masses between 10more » TeV and the Grand Unification scale. Finally, we also calculate, for concrete particle physics scenarios, the limits on the strength of the interactions that induce the dark matter decay.« less

Towards understanding thermal history of the Universe through direct and indirect detection of dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roszkowski, Leszek; Trojanowski, Sebastian; Turzyński, Krzysztof, E-mail: leszek.roszkowski@ncbj.gov.pl, E-mail: sebastian.trojanowski@uci.edu, E-mail: Krzysztof-Jan.Turzynski@fuw.edu.pl

We examine the question to what extent prospective detection of dark matter by direct and indirect- detection experiments could shed light on what fraction of dark matter was generated thermally via the freeze-out process in the early Universe. By simulating putative signals that could be seen in the near future and using them to reconstruct WIMP dark matter properties, we show that, in a model- independent approach this could only be achieved in a thin sliver of the parameter space. However, with additional theoretical input the hypothesis about the thermal freeze-out as the dominant mechanism for generating dark matter canmore » potentially be verified. We illustrate this with two examples: an effective field theory of dark matter with a vector messenger and a higgsino or wino dark matter within the MSSM.« less

Multicomponent Dark Matter in Radiative Seesaw Models

NASA Astrophysics Data System (ADS)

Aoki, Mayumi; Kaneko, Daiki; Kubo, Jisuke

2017-11-01

We discuss radiative seesaw models, in which an exact Z_2¥times Z_2' symmetry is imposed. Due to the exact Z_2¥times Z_2' symmetry, neutrino masses are generated at a two-loop level and at least two extra stable electrically neutral particles are predicted. We consider two models: one has a multi-component dark matter system and the other one has a dark radiation in addition to a dark matter. In the multi-component dark matter system, non-standard dark matter annihilation processes exist. We find that they play important roles in determining the relic abundance and also responsible for the monochromatic neutrino lines resulting from the dark matter annihilation process. In the model with the dark radiation, the structure of the Yukawa coupling is considerably constrained and gives an interesting relationship among cosmology, lepton flavor violating decay of the charged leptons and the decay of the inert Higgs bosons.

Make dark matter charged again

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa

2017-05-01

We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large,more » a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model.« less

Nonthermal Supermassive Dark Matter

NASA Technical Reports Server (NTRS)

Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio

1999-01-01

We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may he elementary particles of mass much greater than the weak scale. Searches for dark matter should ma be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well.

Towards an understanding of dark matter: Precise gravitational lensing analysis complemented by robust photometric redshifts

NASA Astrophysics Data System (ADS)

Coe, Daniel Aaron

The goal of thesis is to help scientists resolve one of the great mysteries of our time: the nature of Dark Matter. Dark Matter is currently believed to make up over 80% of the material in our universe, yet we have so far inferred but a few of its basic properties. Here we study the Dark Matter surrounding a galaxy cluster, Abell 1689, via the most direct method currently available--gravitational lensing. Abell 1689 is a "strong" gravitational lens, meaning it produces multiple images of more distant galaxies. The observed positions of these images can be measured very precisely and act as a blueprint allowing us to reconstruct the Dark Matter distribution of the lens. Until now, such mass models of Abell 1689 have reproduced the observed multiple images well but with significant positional offsets. Using a new method we develop here, we obtain a new mass model which perfectly reproduces the observed positions of 168 knots identified within 135 multiple images of 42 galaxies. An important ingredient to our mass model is the accurate measurement of distances to the lensed galaxies via their photometric redshifts. Here we develop tools which improve the accuracy of these measurements based on our study of the Hubble Ultra Deep Field, the only image yet taken to comparable depth as the magnified regions of Abell 1689. We present results both for objects in the Hubble Ultra Deep Field and for galaxies gravitationally lensed by Abell 1689. As part of this thesis, we also provide reviews of Dark Matter and Gravitational Lensing, including a chapter devoted to the mass profiles of Dark Matter halos realized in simulations. The original work presented here was performed primarily by myself under the guidance of Narciso Benítez and Holland Ford as a member of the Advanced Camera for Surveys GTO Science Team at Johns Hopkins University and the Instituto de Astrofisica de Andalucfa. My advisors served on my thesis committee along with Rick White, Gabor Domokos, and Steve Zelditch.

Dark matter vs. astrophysics in the interpretation of AMS-02 electron and positron data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mauro, Mattia Di; Donato, Fiorenza; Fornengo, Nicolao

We perform a detailed quantitative analysis of the recent AMS-02 electron and positron data. We investigate the interplay between the emission from primary astrophysical sources, namely Supernova Remnants and Pulsar Wind Nebulae, and the contribution from a dark matter annihilation or decay signal. Our aim is to assess the information that can be derived on dark matter properties when both dark matter and primary astrophysical sources are assumed to jointly contribute to the leptonic observables measured by the AMS-02 experiment. We investigate both the possibility to set robust constraints on the dark matter annihilation/decay rate and the possibility to lookmore » for dark matter signals within realistic models that take into account the full complexity of the astrophysical background. Our results show that AMS-02 data enable to probe efficiently vast regions of the dark matter parameter space and, in some cases, to set constraints on the dark matter annihilation/decay rate that are comparable or even stronger than the ones derived from other indirect detection channels.« less

Condensation of galactic cold dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Visinelli, Luca

2016-07-07

We consider the steady-state regime describing the density profile of a dark matter halo, if dark matter is treated as a Bose-Einstein condensate. We first solve the fluid equation for “canonical” cold dark matter, obtaining a class of density profiles which includes the Navarro-Frenk-White profile, and which diverge at the halo core. We then solve numerically the equation obtained when an additional “quantum pressure” term is included in the computation of the density profile. The solution to this latter case is finite at the halo core, possibly avoiding the “cuspy halo problem” present in some cold dark matter theories. Withinmore » the model proposed, we predict the mass of the cold dark matter particle to be of the order of M{sub χ}c{sup 2}≈10{sup −24} eV, which is of the same order of magnitude as that predicted in ultra-light scalar cold dark matter models. Finally, we derive the differential equation describing perturbations in the density and the pressure of the dark matter fluid.« less

Explaining dark matter and B decay anomalies with an L μ - L τ model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altmannshofer, Wolfgang; Gori, Stefania; Profumo, Stefano

We present a dark sector model based on gauging the L μ - L τ symmetry that addresses anomalies in b→ sμ +μ - decays and that features a particle dark matter candidate. The dark matter particle candidate is a vector-like Dirac fermion coupled to the Z' gauge boson of the L μ - L τ symmetry. We compute the dark matter thermal relic density, its pair-annihilation cross section, and the loop-suppressed dark matter-nucleon scattering cross section, and compare our predictions with current and future experimental results. We demonstrate that after taking into account bounds from Bs meson oscillations, darkmore » matter direct detection, and the CMB, the model is highly predictive: B physics anomalies and a viable particle dark matter candidate, with a mass of ~ (5 - 23) GeV, can be accommodated only in a tightly-constrained region of parameter space, with sharp predictions for future experimental tests. The viable region of parameter space expands if the dark matter is allowed to have L μ - L τ charges that are smaller than those of the SM leptons.« less

Explaining dark matter and B decay anomalies with an L μ - L τ model

DOE PAGES

Altmannshofer, Wolfgang; Gori, Stefania; Profumo, Stefano; ...

2016-12-20

We present a dark sector model based on gauging the L μ - L τ symmetry that addresses anomalies in b→ sμ +μ - decays and that features a particle dark matter candidate. The dark matter particle candidate is a vector-like Dirac fermion coupled to the Z' gauge boson of the L μ - L τ symmetry. We compute the dark matter thermal relic density, its pair-annihilation cross section, and the loop-suppressed dark matter-nucleon scattering cross section, and compare our predictions with current and future experimental results. We demonstrate that after taking into account bounds from Bs meson oscillations, darkmore » matter direct detection, and the CMB, the model is highly predictive: B physics anomalies and a viable particle dark matter candidate, with a mass of ~ (5 - 23) GeV, can be accommodated only in a tightly-constrained region of parameter space, with sharp predictions for future experimental tests. The viable region of parameter space expands if the dark matter is allowed to have L μ - L τ charges that are smaller than those of the SM leptons.« less

Search for gamma-ray emission from dark matter annihilation in the large magellanic cloud with the fermi large area telescope

DOE PAGES

Buckley, Matthew R.; Charles, Eric; Gaskins, Jennifer M.; ...

2015-05-05

At a distance of 50 kpc and with a dark matter mass of ~10 10 M ⊙, the large magellanic cloud (LMC) is a natural target for indirect dark matter searches. We use five years of data from the Fermi Large Area Telescope (LAT) and updated models of the gamma-ray emission from standard astrophysical components to search for a dark matter annihilation signal from the LMC. We perform a rotation curve analysis to determine the dark matter distribution, setting a robust minimum on the amount of dark matter in the LMC, which we use to set conservative bounds on the annihilationmore » cross section. The LMC emission is generally very well described by the standard astrophysical sources, with at most a 1–2σ excess identified near the kinematic center of the LMC once systematic uncertainties are taken into account. As a result, we place competitive bounds on the dark matter annihilation cross section as a function of dark matter particle mass and annihilation channel.« less

Revisiting simplified dark matter models in terms of AMS-02 and Fermi-LAT

NASA Astrophysics Data System (ADS)

Li, Tong

2018-01-01

We perform an analysis of the simplified dark matter models in the light of cosmic ray observables by AMS-02 and Fermi-LAT. We assume fermion, scalar or vector dark matter particle with a leptophobic spin-0 mediator that couples only to Standard Model quarks and dark matter via scalar and/or pseudo-scalar bilinear. The propagation and injection parameters of cosmic rays are determined by the observed fluxes of nuclei from AMS-02. We find that the AMS-02 observations are consistent with the dark matter framework within the uncertainties. The AMS-02 antiproton data prefer 30 (50) GeV - 5 TeV dark matter mass and require an effective annihilation cross section in the region of 4 × 10-27 (7 × 10-27) - 4 × 10-24 cm3/s for the simplified fermion (scalar and vector) dark matter models. The cross sections below 2 × 10-26 cm3/s can evade the constraint from Fermi-LAT dwarf galaxies for about 100 GeV dark matter mass.

A search for dark matter in the Galactic halo with HAWC

NASA Astrophysics Data System (ADS)

Abeysekara, A. U.; Albert, A.; Alfaro, R.; Alvarez, C.; Arceo, R.; Arteaga-Velázquez, J. C.; Avila Rojas, D.; Ayala Solares, H. A.; Becerril, A.; Belmont-Moreno, E.; BenZvi, S. Y.; Bernal, A.; Brisbois, C.; Caballero-Mora, K. S.; Capistrán, T.; Carramiñana, A.; Casanova, S.; Castillo, M.; Cotti, U.; Cotzomi, J.; De León, C.; De la Fuente, E.; Diaz Hernandez, R.; Dingus, B. L.; DuVernois, M. A.; Díaz-Vélez, J. C.; Engel, K.; Enríquez-Rivera, O.; Fiorino, D. W.; Fleischhack, H.; Fraija, N.; García-González, J. A.; Garfias, F.; González Muñoz, A.; González, M. M.; Goodman, J. A.; Hampel-Arias, Z.; Harding, J. P.; Hernandez, S.; Hernandez-Almada, A.; Hueyotl-Zahuantitla, F.; Hüntemeyer, P.; Iriarte, A.; Jardin-Blicq, A.; Joshi, V.; Kaufmann, S.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linnemann, J. T.; Longinotti, A. L.; Luis-Raya, G.; Luna-García, R.; López-Coto, R.; Malone, K.; Marinelli, S. S.; Martinez, O.; Martinez-Castellanos, I.; Martínez-Castro, J.; Matthews, J. A.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nellen, L.; Newbold, M.; Nisa, M. U.; Noriega-Papaqui, R.; Pelayo, R.; Pretz, J.; Pérez-Pérez, E. G.; Ren, Z.; Rho, C. D.; Rodd, N. L.; Rosa-González, D.; Rosenberg, M.; Ruiz-Velasco, E.; Safdi, B. R.; Salazar, H.; Salesa Greus, F.; Sandoval, A.; Schneider, M.; Sinnis, G.; Smith, A. J.; Springer, R. W.; Surajbali, P.; Taboada, I.; Tibolla, O.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Vianello, G.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wisher, I. G.; Wood, J.; Yapici, T.; Yodh, G. B.; Younk, P. W.; Zepeda, A.; Zhou, H.; Álvarez, J. D.

2018-02-01

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 500 GeV – 100 TeV gamma rays and cosmic rays. With its observations over 2/3 of the sky every day, the HAWC observatory is sensitive to a wide variety of astrophysical sources, including possible gamma rays from dark matter. Dark matter annihilation and decay in the Milky Way Galaxy should produce gamma-ray signals across many degrees on the sky. The HAWC instantaneous field-of-view of 2 sr enables observations of extended regions on the sky, such as those from dark matter in the Galactic halo. Here we show limits on the dark matter annihilation cross-section and decay lifetime from HAWC observations of the Galactic halo with 15 months of data. These are some of the most robust limits on TeV and PeV dark matter, largely insensitive to the dark matter morphology. These limits begin to constrain models in which PeV IceCube neutrinos are explained by dark matter which primarily decays into hadrons.

Exothermic dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graham, Peter W.; Saraswat, Prashant; Harnik, Roni

2010-09-15

We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10. The dark matter consists of at least two light states with mass {approx}few GeV and splittings {approx}5 keV. It is natural for the heavier states to be cosmologically long-lived and to make up an O(1) fraction of the dark matter. Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state downscatters off of a nucleus, becoming a lower energy state.more » In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.« less

Phases of cannibal dark matter

NASA Astrophysics Data System (ADS)

Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele

2016-12-01

A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector is cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.

Dark Matter Freeze-in Production in Fast-Expanding Universes

NASA Astrophysics Data System (ADS)

D'Eramo, Francesco; Fernandez, Nicolas; Profumo, Stefano

2018-02-01

If the dark matter is produced in the early universe prior to Big Bang nucleosynthesis, a modified cosmological history can drastically affect the abundance of relic dark matter particles. Here, we assume that an additional species to radiation dominates at early times, causing the expansion rate at a given temperature to be larger than in the standard radiation-dominated case. We demonstrate that, if this is the case, dark matter production via freeze-in (a scenario when dark matter interacts very weakly, and is dumped in the early universe out of equilibrium by decay or scattering processes involving particles in the thermal bath) is dramatically suppressed. We illustrate and quantitatively and analytically study this phenomenon for three different paradigmatic classes of freeze-in scenarios. For the frozen-in dark matter abundance to be as large as observations, couplings between the dark matter and visible-sector particles must be enhanced by several orders of magnitude. This sheds some optimistic prospects for the otherwise dire experimental and observational outlook of detecting dark matter produced by freeze-in.

A search for dark matter in the Galactic halo with HAWC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abeysekara, A. U.; Albert, A.; Alfaro, R.

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 500 GeV – 100 TeV gamma rays and cosmic rays. With its observations over 2/3 of the sky every day, the HAWC observatory is sensitive to a wide variety of astrophysical sources, including possible gamma rays from dark matter. Dark matter annihilation and decay in the Milky Way Galaxy should produce gamma-ray signals across many degrees on the sky. The HAWC instantaneous field-of-view of 2 sr enables observations of extended regions on the sky, such as those from dark matter in the Galactic halo. Heremore » we show limits on the dark matter annihilation cross-section and decay lifetime from HAWC observations of the Galactic halo with 15 months of data. These are some of the most robust limits on TeV and PeV dark matter, largely insensitive to the dark matter morphology. These limits begin to constrain models in which PeV IceCube neutrinos are explained by dark matter which primarily decays into hadrons.« less

Phases of cannibal dark matter

DOE PAGES

Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.; ...

2016-12-13

A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector ismore » cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.« less

A search for dark matter in the Galactic halo with HAWC

DOE PAGES

Abeysekara, A. U.; Albert, A.; Alfaro, R.; ...

2018-02-23

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 500 GeV – 100 TeV gamma rays and cosmic rays. With its observations over 2/3 of the sky every day, the HAWC observatory is sensitive to a wide variety of astrophysical sources, including possible gamma rays from dark matter. Dark matter annihilation and decay in the Milky Way Galaxy should produce gamma-ray signals across many degrees on the sky. The HAWC instantaneous field-of-view of 2 sr enables observations of extended regions on the sky, such as those from dark matter in the Galactic halo. Heremore » we show limits on the dark matter annihilation cross-section and decay lifetime from HAWC observations of the Galactic halo with 15 months of data. These are some of the most robust limits on TeV and PeV dark matter, largely insensitive to the dark matter morphology. These limits begin to constrain models in which PeV IceCube neutrinos are explained by dark matter which primarily decays into hadrons.« less

Dark Matters

ScienceCinema

Joseph Silk

2018-04-17

One of the greatest mysteries in the cosmos is that it is mostly dark.  Astronomers and particle physicists today are seeking to unravel the nature of this mysterious, but pervasive dark matter which has profoundly influenced the formation of structure in the universe.  I will describe the complex interplay between galaxy formation and dark matter detectability and review recent attempts to measure particle dark matter by direct and indirect means.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hochberg, Yonit; Pyle, Matt; Zhao, Yue

We examine in greater detail the recent proposal of using superconductors for detecting dark matter as light as the warm dark matter limit of O(keV). Detection of suc light dark matter is possible if the entire kinetic energy of the dark matter is extracted in the scattering, and if the experiment is sensitive to O(meV) energy depositions. This is the case for Fermi-degenerate materials in which the Fermi velocity exceeds the dark matter velocity dispersion in the Milky Way of ~10 –3. We focus on a concrete experimental proposal using a superconducting target with a transition edge sensor in ordermore » to detect the small energy deposits from the dark matter scatterings. Considering a wide variety of constraints, from dark matter self-interactions to the cosmic microwave background, we show that models consistent with cosmological/astrophysical and terrestrial constraints are observable with such detectors. A wider range of viable models with dark matter mass below an MeV is available if dark matter or mediator properties (such as couplings or masses) differ at BBN epoch or in stellar interiors from those in superconductors. We also show that metal targets pay a strong in-medium suppression for kinetically mixed mediators; this suppression is alleviated with insulating targets.« less

Baryonic impact on the dark matter orbital properties of Milky Way-sized haloes

NASA Astrophysics Data System (ADS)

Zhu, Qirong; Hernquist, Lars; Marinacci, Federico; Springel, Volker; Li, Yuexing

2017-04-01

We study the orbital properties of dark matter haloes by combining a spectral method and cosmological simulations of Milky Way-sized Galaxies. We compare the dynamics and orbits of individual dark matter particles from both hydrodynamic and N-body simulations, and find that the fraction of box, tube and resonant orbits of the dark matter halo decreases significantly due to the effects of baryons. In particular, the central region of the dark matter halo in the hydrodynamic simulation is dominated by regular, short-axis tube orbits, in contrast to the chaotic, box and thin orbits dominant in the N-body run. This leads to a more spherical dark matter halo in the hydrodynamic run compared to a prolate one as commonly seen in the N-body simulations. Furthermore, by using a kernel-based density estimator, we compare the coarse-grained phase-space densities of dark matter haloes in both simulations and find that it is lower by ˜0.5 dex in the hydrodynamic run due to changes in the angular momentum distribution, which indicates that the baryonic process that affects the dark matter is irreversible. Our results imply that baryons play an important role in determining the shape, kinematics and phase-space density of dark matter haloes in galaxies.

Non-thermal production of minimal dark matter via right-handed neutrino decay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aoki, Mayumi; Toma, Takashi; Vicente, Avelino

2015-09-29

Minimal Dark Matter (MDM) stands as one of the simplest dark matter scenarios. In MDM models, annihilation and co-annihilation processes among the members of the MDM multiplet are usually very efficient, pushing the dark matter mass above O(10) TeV in order to reproduce the observed dark matter relic density. Motivated by this little drawback, in this paper we consider an extension of the MDM scenario by three right-handed neutrinos. Two specific choices for the MDM multiplet are studied: a fermionic SU(2){sub L} quintuplet and a scalar SU(2){sub L} septuplet. The lightest right-handed neutrino, with tiny Yukawa couplings, never reaches thermalmore » equilibrium in the early universe and is produced by freeze-in. This creates a link between dark matter and neutrino physics: dark matter can be non-thermally produced by the decay of the lightest right-handed neutrino after freeze-out, allowing to lower significantly the dark matter mass. We discuss the phenomenology of the non-thermally produced MDM and, taking into account significant Sommerfeld corrections, we find that the dark matter mass must have some specific values in order not to be in conflict with the current bounds from gamma-ray observations.« less

Non-thermal production of minimal dark matter via right-handed neutrino decay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aoki, Mayumi; Toma, Takashi; Vicente, Avelino, E-mail: mayumi@hep.s.kanazawa-u.ac.jp, E-mail: takashi.toma@th.u-psud.fr, E-mail: Avelino.Vicente@ulg.ac.be

2015-09-01

Minimal Dark Matter (MDM) stands as one of the simplest dark matter scenarios. In MDM models, annihilation and co-annihilation processes among the members of the MDM multiplet are usually very efficient, pushing the dark matter mass above O(10) TeV in order to reproduce the observed dark matter relic density. Motivated by this little drawback, in this paper we consider an extension of the MDM scenario by three right-handed neutrinos. Two specific choices for the MDM multiplet are studied: a fermionic SU(2){sub L} quintuplet and a scalar SU(2){sub L} septuplet. The lightest right-handed neutrino, with tiny Yukawa couplings, never reaches thermalmore » equilibrium in the early universe and is produced by freeze-in. This creates a link between dark matter and neutrino physics: dark matter can be non-thermally produced by the decay of the lightest right-handed neutrino after freeze-out, allowing to lower significantly the dark matter mass. We discuss the phenomenology of the non-thermally produced MDM and, taking into account significant Sommerfeld corrections, we find that the dark matter mass must have some specific values in order not to be in conflict with the current bounds from gamma-ray observations.« less

Form factors for dark matter capture by the Sun in effective theories

NASA Astrophysics Data System (ADS)

Catena, Riccardo; Schwabe, Bodo

2015-04-01

In the effective theory of isoscalar and isovector dark matter-nucleon interactions mediated by a heavy spin-1 or spin-0 particle, 8 isotope-dependent nuclear response functions can be generated in the dark matter scattering by nuclei. We compute the 8 nuclear response functions for the 16 most abundant elements in the Sun, i.e. H, 3He, 4He, 12C, 14N, 16O, 20Ne, 23Na, 24Mg, 27Al, 28Si, 32S, 40Ar, 40Ca, 56Fe, and 59Ni, through numerical shell model calculations. We use our response functions to compute the rate of dark matter capture by the Sun for all isoscalar and isovector dark matter-nucleon effective interactions, including several operators previously considered for dark matter direct detection only. We study in detail the dependence of the capture rate on specific dark matter-nucleon interaction operators, and on the different elements in the Sun. We find that a so far neglected momentum dependent dark matter coupling to the nuclear vector charge gives a larger contribution to the capture rate than the constant spin-dependent interaction commonly included in dark matter searches at neutrino telescopes. Our investigation lays the foundations for model independent analyses of dark matter induced neutrino signals from the Sun. The nuclear response functions obtained in this study are listed in analytic form in an appendix, ready to be used in other projects.

Dark energy and modified gravity in the Effective Field Theory of Large-Scale Structure

NASA Astrophysics Data System (ADS)

Cusin, Giulia; Lewandowski, Matthew; Vernizzi, Filippo

2018-04-01

We develop an approach to compute observables beyond the linear regime of dark matter perturbations for general dark energy and modified gravity models. We do so by combining the Effective Field Theory of Dark Energy and Effective Field Theory of Large-Scale Structure approaches. In particular, we parametrize the linear and nonlinear effects of dark energy on dark matter clustering in terms of the Lagrangian terms introduced in a companion paper [1], focusing on Horndeski theories and assuming the quasi-static approximation. The Euler equation for dark matter is sourced, via the Newtonian potential, by new nonlinear vertices due to modified gravity and, as in the pure dark matter case, by the effects of short-scale physics in the form of the divergence of an effective stress tensor. The effective fluid introduces a counterterm in the solution to the matter continuity and Euler equations, which allows a controlled expansion of clustering statistics on mildly nonlinear scales. We use this setup to compute the one-loop dark-matter power spectrum.

Skew-flavored dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agrawal, Prateek; Chacko, Zackaria; Fortes, Elaine C. F. S.

We explore a novel flavor structure in the interactions of dark matter with the Standard Model. We consider theories in which both the dark matter candidate, and the particles that mediate its interactions with the Standard Model fields, carry flavor quantum numbers. The interactions are skewed in flavor space, so that a dark matter particle does not directly couple to the Standard Model matter fields of the same flavor, but only to the other two flavors. This framework respects minimal flavor violation and is, therefore, naturally consistent with flavor constraints. We study the phenomenology of a benchmark model in whichmore » dark matter couples to right-handed charged leptons. In large regions of parameter space, the dark matter can emerge as a thermal relic, while remaining consistent with the constraints from direct and indirect detection. The collider signatures of this scenario include events with multiple leptons and missing energy. In conclusion, these events exhibit a characteristic flavor pattern that may allow this class of models to be distinguished from other theories of dark matter.« less

Skew-flavored dark matter

DOE PAGES

Agrawal, Prateek; Chacko, Zackaria; Fortes, Elaine C. F. S.; ...

2016-05-10

We explore a novel flavor structure in the interactions of dark matter with the Standard Model. We consider theories in which both the dark matter candidate, and the particles that mediate its interactions with the Standard Model fields, carry flavor quantum numbers. The interactions are skewed in flavor space, so that a dark matter particle does not directly couple to the Standard Model matter fields of the same flavor, but only to the other two flavors. This framework respects minimal flavor violation and is, therefore, naturally consistent with flavor constraints. We study the phenomenology of a benchmark model in whichmore » dark matter couples to right-handed charged leptons. In large regions of parameter space, the dark matter can emerge as a thermal relic, while remaining consistent with the constraints from direct and indirect detection. The collider signatures of this scenario include events with multiple leptons and missing energy. In conclusion, these events exhibit a characteristic flavor pattern that may allow this class of models to be distinguished from other theories of dark matter.« less

The cryogenic dark matter search low ionization-threshold experiment

NASA Astrophysics Data System (ADS)

Basu Thakur, Ritoban

Over 80 years ago we discovered the presence of Dark Matter in our universe. Endeavors in astronomy and cosmology are in consensus with ever improving precision that Dark Matter constitutes an essential 27% of our universe. The Standard Model of Particle Physics does not provide any answers to the Dark Matter problem. It is imperative that we understand Dark Matter and discover its fundamental nature. This is because, alongside other important factors, Dark Matter is responsible for formation of structure in our universe. The very construct in which we sit is defined by its abundance. The Milky Way galaxy, hence life, wouldn't have formed if small over densities of Dark Matter had not caused sufficient accretion of stellar material. Marvelous experiments have been designed based on basic notions to directly and indirectly study Dark Matter, and the Cryogenic Dark Matter Search (CDMS) experiment has been a pioneer and forerunner in the direct detection field. Generations of the CDMS experiment were designed with advanced scientific upgrades to detect Dark Matter particles of mass O(100) GeV/c2. This mass-scale was set primarily by predictions from Super Symmetry. Around 2013 the canonical SUSY predictions were losing some ground and several observations (rather hints of signals) from various experiments indicated to the possibility of lighter Dark Matter of mass O(10) GeV/c2. While the SuperCDMS experiment was probing the regular parameter space, the CDMSlite experiment was conceived to dedicatedly search for light Dark Matter using a novel technology. "CDMSlite" stands for CDMS - low ionization threshold experiment. Here we utilize a unique electron phonon coupling mechanism to measure ionization generated by scattering of light particles. Typically signals from such low energy recoils would be washed under instrumental noise.In CDMSlite via generation of Luke-Neganov phonons we can detect the small ionization energies, amplified in phonon modes during charge transport. This technology allows us to reach very low thresholds and reliably measure and investigate low energy recoils from light Dark Matter particles. This thesis describes the physics behind CDMSlite, the experimenta design and the first science results from CDMSlite operated at the Soudan Underground Laboratory.

The Cryogenic Dark Matter Search low ionization-threshold experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basu Thakur, Ritoban

2014-01-01

Over 80 years ago we discovered the presence of Dark Matter in our universe. Endeavors in astronomy and cosmology are in consensus with ever improving precision that Dark Matter constitutes an essential 27% of our universe. The Standard Model of Particle Physics does not provide any answers to the Dark Matter problem. It is imperative that we understand Dark Matter and discover its fundamental nature. This is because, alongside other important factors, Dark Matter is responsible for formation of structure in our universe. The very construct in which we sit is defined by its abundance. The Milky Way galaxy, hencemore » life, wouldn't have formed if small over densities of Dark Matter had not caused sufficient accretion of stellar material. Marvelous experiments have been designed based on basic notions to directly and in-directly study Dark Matter, and the Cryogenic Dark Matter Search (CDMS) experiment has been a pioneer and forerunner in the direct detection field. Generations of the CDMS experiment were designed with advanced scientific upgrades to detect Dark Matter particles of mass O(100) GeV/c 2. This mass-scale was set primarily by predictions from Super Symmetry. Around 2013 the canonical SUSY predictions were losing some ground and several observations (rather hints of signals) from various experiments indicated to the possibility of lighter Dark Matter of mass O(10) GeV/c 2. While the SuperCDMS experiment was probing the regular parameter space, the CDMSlite experiment was conceived to dedicatedly search for light Dark Matter using a novel technology. "CDMSlite" stands for CDMS - low ionization threshold experiment. Here we utilize a unique electron phonon coupling mechanism to measure ionization generated by scattering of light particles. Typically signals from such low energy recoils would be washed under instrumental noise. In CDMSlite via generation of Luke-Neganov phonons we can detect the small ionization energies, amplified in phonon modes during charge transport. This technology allows us to reach very low thresholds and reliably measure and investigate low energy recoils from light Dark Matter particles. This thesis describes the physics behind CDMSlite, the experimental design and the first science results from CDMSlite operated at the Soudan Underground Laboratory.« less

Self-interacting dark matter constraints in a thick dark disk scenario

NASA Astrophysics Data System (ADS)

Vattis, Kyriakos; Koushiappas, Savvas M.

2018-05-01

A thick dark matter disk is predicted in cold dark matter simulations as the outcome of the interaction between accreted satellites and the stellar disk in Milky Way-sized halos. We study the effects of a self-interacting thick dark disk on the energetic neutrino flux from the Sun. We find that for particle masses between 100 GeV and 1 TeV and dark matter annihilation to τ+τ-, either the self-interaction may not be strong enough to solve the small-scale structure motivation or a dark disk cannot be present in the Milky Way.

Vector Dark Matter through a radiative Higgs portal

DOE PAGES

DiFranzo, Anthony; Fox, Patrick J.; Tait, Tim M. P.

2016-04-21

We study a model of spin-1 dark matter which interacts with the Standard Model predominantly via exchange of Higgs bosons. We propose an alternative UV completion to the usual Vector Dark Matter Higgs Portal, in which vector-like fermions charged under SU(2)more » $$_W \\times$$ U(1)$$_Y$$ and under the dark gauge group, U(1)$$^\\prime$$, generate an effective interaction between the Higgs and the dark matter at one loop. Furthermore, we explore the resulting phenomenology and show that this dark matter candidate is a viable thermal relic and satisfies Higgs invisible width constraints as well as direct detection bounds.« less

On wave dark matter in spiral and barred galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez-Medina, Luis A.; Matos, Tonatiuh; Bray, Hubert L., E-mail: lmedina@fis.cinvestav.mx, E-mail: bray@math.duke.edu, E-mail: tmatos@fis.cinvestav.mx

2015-12-01

We recover spiral and barred spiral patterns in disk galaxy simulations with a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter (SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC) dark matter). Here we show how the interaction between a baryonic disk and its Dark Matter Halo triggers the formation of spiral structures when the halo is allowed to have a triaxial shape and angular momentum. This is a more realistic picture within the WDM model since a non-spherical rotating halo seems to be more natural. By performing hydrodynamic simulations, along with earlier test particlesmore » simulations, we demonstrate another important way in which wave dark matter is consistent with observations. The common existence of bars in these simulations is particularly noteworthy. This may have consequences when trying to obtain information about the dark matter distribution in a galaxy, the mere presence of spiral arms or a bar usually indicates that baryonic matter dominates the central region and therefore observations, like rotation curves, may not tell us what the DM distribution is at the halo center. But here we show that spiral arms and bars can develop in DM dominated galaxies with a central density core without supposing its origin on mechanisms intrinsic to the baryonic matter.« less

Light higgsino dark matter from non-thermal cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aparicio, Luis; Cicoli, Michele; Dutta, Bhaskar

We study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter domination prior to Big Bang nucleosynthesis. Matter domination changes the dark matter relic abundance if it ends via reheating to a temperature below the higgsino thermal freeze-out temperature. We perform a model independent analysis of the higgsino dark matter production in such scenario. We show that light higgsino-type dark matter is possible for reheating temperatures close to 1 GeV. We study the impact of dark matter indirect detection and collider physics in this context. We show that Fermi-LAT data rulemore » out non-thermal higgsinos with masses below 300 GeV. A future indirect dark matter searches from Fermi-LAT and CTA will be able to cover essentially the full parameter space. Contrary to the thermal case, collider signals from a 100 TeV collider could fully test the non-thermal higgsino scenario. In the second part of the paper we discuss the motivation of such non-thermal cosmology from the perspective of string theory with late-time decaying moduli for both KKLT and LVS moduli stabilisation mechanisms. Finally, we describe the impact of embedding higgsino dark matter in these scenarios.« less

Light higgsino dark matter from non-thermal cosmology

DOE PAGES

Aparicio, Luis; Cicoli, Michele; Dutta, Bhaskar; ...

2016-11-01

We study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter domination prior to Big Bang nucleosynthesis. Matter domination changes the dark matter relic abundance if it ends via reheating to a temperature below the higgsino thermal freeze-out temperature. We perform a model independent analysis of the higgsino dark matter production in such scenario. We show that light higgsino-type dark matter is possible for reheating temperatures close to 1 GeV. We study the impact of dark matter indirect detection and collider physics in this context. We show that Fermi-LAT data rulemore » out non-thermal higgsinos with masses below 300 GeV. A future indirect dark matter searches from Fermi-LAT and CTA will be able to cover essentially the full parameter space. Contrary to the thermal case, collider signals from a 100 TeV collider could fully test the non-thermal higgsino scenario. In the second part of the paper we discuss the motivation of such non-thermal cosmology from the perspective of string theory with late-time decaying moduli for both KKLT and LVS moduli stabilisation mechanisms. Finally, we describe the impact of embedding higgsino dark matter in these scenarios.« less

Dark Matter Coannihilation with a Lighter Species

NASA Astrophysics Data System (ADS)

Berlin, Asher

2017-09-01

We propose a new thermal freeze-out mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very long-lived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, MGUT˜1016 GeV .

WIMP-less dark matter and meson decays with missing energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKeen, David

2009-06-01

WIMP-less dark matter [J. L. Feng and J. Kumar, Phys. Rev. Lett. 101, 231301 (2008).] offers an attractive framework in which dark matter can be very light. We investigate the implications of such scenarios on invisible decays of bottomonium states for dark matter with a mass less than around 5 GeV. We relate these decays to measurements of nucleon-dark matter elastic scattering. We also investigate the effect that a coupling to s quarks has on flavor changing b{yields}s processes involving missing energy.

QCD Axion Dark Matter with a Small Decay Constant.

PubMed

Co, Raymond T; Hall, Lawrence J; Harigaya, Keisuke

2018-05-25

The QCD axion is a good dark matter candidate. The observed dark matter abundance can arise from misalignment or defect mechanisms, which generically require an axion decay constant f_{a}∼O(10^{11})  GeV (or higher). We introduce a new cosmological origin for axion dark matter, parametric resonance from oscillations of the Peccei-Quinn symmetry breaking field, that requires f_{a}∼(10^{8}-10^{11})  GeV. The axions may be warm enough to give deviations from cold dark matter in large scale structure.

Dark Matter Coannihilation with a Lighter Species.

PubMed

Berlin, Asher

2017-09-22

We propose a new thermal freeze-out mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very long-lived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, M_{GUT}∼10^{16}  GeV.

Intermediate-mass Black Holes and Dark Matter at the Galactic Center

NASA Astrophysics Data System (ADS)

Lacroix, Thomas; Silk, Joseph

2018-01-01

Could there be a large population of intermediate-mass black holes (IMBHs) formed in the early universe? Whether primordial or formed in Population III, these are likely to be very subdominant compared to the dark matter density, but could seed early dwarf galaxy/globular cluster and supermassive black hole formation. Via survival of dark matter density spikes, we show here that a centrally concentrated relic population of IMBHs, along with ambient dark matter, could account for the Fermi gamma-ray “excess” in the Galactic center because of dark matter particle annihilations.

Geometric compatibility of IceCube TeV-PeV neutrino excess and its galactic dark matter origin

DOE PAGES

Bai, Yang; Lu, Ran; Salvado, Jordi

2016-01-27

Here, we perform a geometric analysis for the sky map of the IceCube TeV-PeV neutrino excess and test its compatibility with the sky map of decaying dark matter signals in our galaxy. Furthermore, we have found that a galactic decaying dark matter component in general improve the goodness of the fit of our model, although the pure isotropic hypothesis has a better fit than the pure dark matter one. Finally, we also consider several representative decaying dark matter, which can provide a good t to the observed spectrum at IceCube with a dark matter lifetime of around 12 orders ofmore » magnitude longer than the age of the universe.« less

Lepton flavor violation induced by dark matter

NASA Astrophysics Data System (ADS)

Arcadi, Giorgio; Ferreira, C. P.; Goertz, Florian; Guzzo, M. M.; Queiroz, Farinaldo S.; Santos, A. C. O.

2018-04-01

Guided by gauge principles we discuss a predictive and falsifiable UV complete model where the Dirac fermion that accounts for the cold dark matter abundance in our Universe induces the lepton flavor violation (LFV) decays μ →e γ and μ →e e e as well as μ -e conversion. We explore the interplay between direct dark matter detection, relic density, collider probes and lepton flavor violation to conclusively show that one may have a viable dark matter candidate yielding flavor violation signatures that can be probed in the upcoming experiments. In fact, keeping the dark matter mass at the TeV scale, a sizable LFV signal is possible, while reproducing the correct dark matter relic density and meeting limits from direct-detection experiments.

Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande.

PubMed

Kachulis, C; Abe, K; Bronner, C; Hayato, Y; Ikeda, M; Iyogi, K; Kameda, J; Kato, Y; Kishimoto, Y; Marti, Ll; Miura, M; Moriyama, S; Nakahata, M; Nakano, Y; Nakayama, S; Okajima, Y; Orii, A; Pronost, G; Sekiya, H; Shiozawa, M; Sonoda, Y; Takeda, A; Takenaka, A; Tanaka, H; Tasaka, S; Tomura, T; Akutsu, R; Kajita, T; Kaneyuki, K; Nishimura, Y; Okumura, K; Tsui, K M; Labarga, L; Fernandez, P; Blaszczyk, F D M; Gustafson, J; Kearns, E; Raaf, J L; Stone, J L; Sulak, L R; Berkman, S; Tobayama, S; Goldhaber, M; Elnimr, M; Kropp, W R; Mine, S; Locke, S; Weatherly, P; Smy, M B; Sobel, H W; Takhistov, V; Ganezer, K S; Hill, J; Kim, J Y; Lim, I T; Park, R G; Himmel, A; Li, Z; O'Sullivan, E; Scholberg, K; Walter, C W; Ishizuka, T; Nakamura, T; Jang, J S; Choi, K; Learned, J G; Matsuno, S; Smith, S N; Amey, J; Litchfield, R P; Ma, W Y; Uchida, Y; Wascko, M O; Cao, S; Friend, M; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Abe, K E; Hasegawa, M; Suzuki, A T; Takeuchi, Y; Yano, T; Hayashino, T; Hiraki, T; Hirota, S; Huang, K; Jiang, M; Nakamura, K E; Nakaya, T; Quilain, B; Patel, N D; Wendell, R A; Anthony, L H V; McCauley, N; Pritchard, A; Fukuda, Y; Itow, Y; Murase, M; Muto, F; Mijakowski, P; Frankiewicz, K; Jung, C K; Li, X; Palomino, J L; Santucci, G; Vilela, C; Wilking, M J; Yanagisawa, C; Ito, S; Fukuda, D; Ishino, H; Kibayashi, A; Koshio, Y; Nagata, H; Sakuda, M; Xu, C; Kuno, Y; Wark, D; Di Lodovico, F; Richards, B; Tacik, R; Kim, S B; Cole, A; Thompson, L; Okazawa, H; Choi, Y; Ito, K; Nishijima, K; Koshiba, M; Totsuka, Y; Suda, Y; Yokoyama, M; Calland, R G; Hartz, M; Martens, K; Simpson, C; Suzuki, Y; Vagins, M R; Hamabe, D; Kuze, M; Yoshida, T; Ishitsuka, M; Martin, J F; Nantais, C M; Tanaka, H A; Konaka, A; Chen, S; Wan, L; Zhang, Y; Wilkes, R J; Minamino, A

2018-06-01

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector.

Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande

NASA Astrophysics Data System (ADS)

Kachulis, C.; Abe, K.; Bronner, C.; Hayato, Y.; Ikeda, M.; Iyogi, K.; Kameda, J.; Kato, Y.; Kishimoto, Y.; Marti, Ll.; Miura, M.; Moriyama, S.; Nakahata, M.; Nakano, Y.; Nakayama, S.; Okajima, Y.; Orii, A.; Pronost, G.; Sekiya, H.; Shiozawa, M.; Sonoda, Y.; Takeda, A.; Takenaka, A.; Tanaka, H.; Tasaka, S.; Tomura, T.; Akutsu, R.; Kajita, T.; Kaneyuki, K.; Nishimura, Y.; Okumura, K.; Tsui, K. M.; Labarga, L.; Fernandez, P.; Blaszczyk, F. d. M.; Gustafson, J.; Kearns, E.; Raaf, J. L.; Stone, J. L.; Sulak, L. R.; Berkman, S.; Tobayama, S.; Goldhaber, M.; Elnimr, M.; Kropp, W. R.; Mine, S.; Locke, S.; Weatherly, P.; Smy, M. B.; Sobel, H. W.; Takhistov, V.; Ganezer, K. S.; Hill, J.; Kim, J. Y.; Lim, I. T.; Park, R. G.; Himmel, A.; Li, Z.; O'Sullivan, E.; Scholberg, K.; Walter, C. W.; Ishizuka, T.; Nakamura, T.; Jang, J. S.; Choi, K.; Learned, J. G.; Matsuno, S.; Smith, S. N.; Amey, J.; Litchfield, R. P.; Ma, W. Y.; Uchida, Y.; Wascko, M. O.; Cao, S.; Friend, M.; Hasegawa, T.; Ishida, T.; Ishii, T.; Kobayashi, T.; Nakadaira, T.; Nakamura, K.; Oyama, Y.; Sakashita, K.; Sekiguchi, T.; Tsukamoto, T.; Abe, KE.; Hasegawa, M.; Suzuki, A. T.; Takeuchi, Y.; Yano, T.; Hayashino, T.; Hiraki, T.; Hirota, S.; Huang, K.; Jiang, M.; Nakamura, KE.; Nakaya, T.; Quilain, B.; Patel, N. D.; Wendell, R. A.; Anthony, L. H. V.; McCauley, N.; Pritchard, A.; Fukuda, Y.; Itow, Y.; Murase, M.; Muto, F.; Mijakowski, P.; Frankiewicz, K.; Jung, C. K.; Li, X.; Palomino, J. L.; Santucci, G.; Vilela, C.; Wilking, M. J.; Yanagisawa, C.; Ito, S.; Fukuda, D.; Ishino, H.; Kibayashi, A.; Koshio, Y.; Nagata, H.; Sakuda, M.; Xu, C.; Kuno, Y.; Wark, D.; Di Lodovico, F.; Richards, B.; Tacik, R.; Kim, S. B.; Cole, A.; Thompson, L.; Okazawa, H.; Choi, Y.; Ito, K.; Nishijima, K.; Koshiba, M.; Totsuka, Y.; Suda, Y.; Yokoyama, M.; Calland, R. G.; Hartz, M.; Martens, K.; Simpson, C.; Suzuki, Y.; Vagins, M. R.; Hamabe, D.; Kuze, M.; Yoshida, T.; Ishitsuka, M.; Martin, J. F.; Nantais, C. M.; Tanaka, H. A.; Konaka, A.; Chen, S.; Wan, L.; Zhang, Y.; Wilkes, R. J.; Minamino, A.; Super-Kamiokande Collaboration

2018-06-01

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector.

Very heavy dark Skyrmions

NASA Astrophysics Data System (ADS)

Dick, Rainer

2017-12-01

A dark sector with a solitonic component provides a means to circumvent the problem of generically low annihilation cross sections of very heavy dark matter particles. At the same time, enhanced annihilation cross sections are necessary for indirect detection of very heavy dark matter components beyond 100 TeV. Non-thermally produced dark matter in this mass range could therefore contribute to the cosmic γ -ray and neutrino flux above 100 TeV, and massive Skyrmions provide an interesting framework for the discussion of these scenarios. Therefore a Higgs portal and a neutrino portal for very heavy Skyrmion dark matter are discussed. The Higgs portal model demonstrates a dark mediator bottleneck, where limitations on particle annihilation cross sections will prevent a signal from the potentially large soliton annihilation cross sections. This problem can be avoided in models where the dark mediator decays. This is illustrated by the neutrino portal for Skyrmion dark matter.

Directly detecting isospin-violating dark matter

NASA Astrophysics Data System (ADS)

Kelso, Chris; Kumar, Jason; Marfatia, Danny; Sandick, Pearl

2018-03-01

We consider the prospects for multiple dark matter direct detection experiments to determine if the interactions of a dark matter candidate are isospin-violating. We focus on theoretically well-motivated examples of isospin-violating dark matter (IVDM), including models in which dark matter interactions with nuclei are mediated by a dark photon, a Z , or a squark. We determine that the best prospects for distinguishing IVDM from the isospin-invariant scenario arise in the cases of dark photon-or Z -mediated interactions, and that the ideal experimental scenario would consist of large exposure xenon- and neon-based detectors. If such models just evade current direct detection limits, then one could distinguish such models from the standard isospin-invariant case with two detectors with of order 100 ton-year exposure.

Observing Primeval Galaxies and Dark Matter with LAIRTS

DTIC Science & Technology

1988-12-05

in the form of black holes. Previously, we had argued that the dark matter in the halo of spiral galaxies is not baryonic . Now we have extended those...consider each type of barvonic matter and show the contradictions that would exist if the dark matter were made up of each form of baryonic matter . A topic...Classification) Observing Primeval Galaxies and Dark Matter with LAIRTS 12. PERSONAL AUTHOR(S) 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year

Charting the Unknown: A Hunt in the Dark

NASA Astrophysics Data System (ADS)

Mohlabeng, Gopolang Mokoka

Astrophysical and cosmological observations have pointed strongly to the existence of dark matter in the Universe, yet its nature remains elusive. It may be hidden in a vast unknown parameter space in which exhaustively searching for a signal is not feasible. We are, therefore, compelled to consider a robust program based on a wide range of new theoretical ideas and complementary strategies for detection. The aim of this dissertation is to investigate the phenomenology of diverse dark sectors with the objective of understanding and characterizing dark matter. We do so by exploring dark matter phenomenology under three main frameworks of study: (I) the model dependent approach, (II) model independent approach and (III) considering simplified models. In each framework we focus on unexplored and well motivated dark matter scenarios as well as their prospects of detection at current and future experiments. First, we concentrate on the model dependent method where we consider minimal dark matter in the form of mixed fermionic stable states in a gauge extension of the standard model. In particular, we incorporate the fermion mixings governed by gauge invariant interactions with the heavier degrees of freedom. We find that the manner of mixing has an impact on the detectability of the dark matter at experiments. Pursuing this model dependent direction, we explore a space-time extension of the standard model which houses a vector dark matter candidate. We incorporate boundary terms arising from the topology of the model and find that these control the way dark matter may interact with baryonic matter. Next we investigate the model independent approach in which we examine a non-minimal dark sector in the form of boosted dark matter. In this study, we consider an effective field theory involving two stable fermionic states. We probe the sensitivity of this type of dark matter coming from the galactic center and the center of the Sun, and investigate its detection prospects at current and future large volume experiments. Finally, we explore an intermediate approach in the form of a simplified model. Here we analyze a different non-minimal dark sector in which its interactions with the standard model sector are mediated primarily by the Higgs Boson. We discuss for the first time a vector and fermion dark matter preserved under the same stabilization symmetry. We find that the presence of both species in the early Universe results in rare processes contributing to the dark matter relic abundance. We conclude that connecting these three frameworks under one main dark matter program, instead of concentrating on them individually, could help us understand what we are missing, and may assist us to produce ground breaking ideas which lead to the discovery of a signal in the near future.

Alternative to particle dark matter

NASA Astrophysics Data System (ADS)

Khoury, Justin

2015-01-01

We propose an alternative to particle dark matter that borrows ingredients of modified Newtonian dynamics (MOND) while adding new key components. The first new feature is a dark matter fluid, in the form of a scalar field with small equation of state and sound speed. This component is critical in reproducing the success of cold dark matter for the expansion history and the growth of linear perturbations, but does not cluster significantly on nonlinear scales. Instead, the missing mass problem on nonlinear scales is addressed by a modification of the gravitational force law. The force law approximates MOND at large and intermediate accelerations, and therefore reproduces the empirical success of MOND at fitting galactic rotation curves. At ultralow accelerations, the force law reverts to an inverse-square law, albeit with a larger Newton's constant. This latter regime is important in galaxy clusters and is consistent with their observed isothermal profiles, provided the characteristic acceleration scale of MOND is mildly varying with scale or mass, such that it is 12 times higher in clusters than in galaxies. We present an explicit relativistic theory in terms of two scalar fields. The first scalar field is governed by a Dirac-Born-Infeld action and behaves as a dark matter fluid on large scales. The second scalar field also has single-derivative interactions and mediates a fifth force that modifies gravity on nonlinear scales. Both scalars are coupled to matter via an effective metric that depends locally on the fields. The form of this effective metric implies the equality of the two scalar gravitational potentials, which ensures that lensing and dynamical mass estimates agree. Further work is needed in order to make both the acceleration scale of MOND and the fraction at which gravity reverts to an inverse-square law explicitly dynamical quantities, varying with scale or mass.

Low-Mass Dark Matter Search Results and Radiogenic Backgrounds for the Cryogenic Dark Matter Search

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pepin, Mark David

An ever-increasing amount of evidence suggests that approximately one quarter of the energy in the universe is composed of some non-luminous, and hitherto unknown, “dark matter”. Physicists from numerous sub-fields have been working on and trying to solve the dark matter problem for decades. The common solution is the existence of some new type of elementary particle with particular focus on weakly interacting massive particles (WIMPs). One avenue of dark matter research is to create an extremely sensitive particle detector with the goal of directly observing the interaction of WIMPs with standard matter. The Cryogenic Dark Matter Search (CDMS) projectmore » operated at the Soudan Underground Laboratory from 2003–2015, under the CDMS II and SuperCDMS Soudan experiments, with this goal of directly detecting dark matter. The next installation, SuperCDMS SNOLAB, is planned for near-future operation. The reason the dark-matter particle has not yet been observed in traditional particle physics experiments is that it must have very small cross sections, thus making such interactions extremely rare. In order to identify these rare events in the presence of a background of known particles and interactions, direct detection experiments employ various types and amounts of shielding to prevent known backgrounds from reaching the instrumented detector(s). CDMS utilized various gamma and neutron shielding to such an effect that the shielding, and other experimental components, themselves were sources of background. These radiogenic backgrounds must be understood to have confidence in any WIMP-search result. For this dissertation, radiogenic background studies and estimates were performed for various analyses covering CDMS II, SuperCDMS Soudan, and SuperCDMS SNOLAB. Lower-mass dark matter t c2 inent in the past few years. The CDMS detectors can be operated in an alternative, higher-biased, mode v to decrease their energy thresholds and correspondingly increase their sensitivity to low-mass WIMPs. This is the CDMS low ionization threshold experiment (CDMSlite), which has pushed the frontier at lower WIMP masses. This dissertation describes the second run of CDMSlite at Soudan: its hardware, operations, analysis, and results. The results include new WIMP mass-cross section upper limits on the spin-independent and spin-dependent WIMP-nucleon interactions. Thanks to the lower background and threshold in this run compared to the first CDMSlite run, these limits are the most sensitive in the world below WIMP masses of ~4 GeV/c 2. This demonstrates also the great promise and utility of the high-voltage operating mode in the SuperCDMS SNOLAB experiment.« less

DAEδALUS and dark matter detection

DOE PAGES

Kahn, Yonatan; Krnjaic, Gordan; Thaler, Jesse; ...

2015-03-05

Among laboratory probes of dark matter, fixed-target neutrino experiments are particularly well suited to search for light weakly coupled dark sectors. Here in this paper, we show that the DAEδALUS source setup$-$an 800 MeV proton beam impinging on a target of graphite and copper$-$can improve the present LSND bound on dark photon models by an order of magnitude over much of the accessible parameter space for light dark matter when paired with a suitable neutrino detector such as LENA. Interestingly, both DAEδALUS and LSND are sensitive to dark matter produced from off-shell dark photons. We show for the first timemore » that LSND can be competitive with searches for visible dark photon decays and that fixed-target experiments have sensitivity to a much larger range of heavy dark photon masses than previously thought. We review the mechanism for dark matter production and detection through a dark photon mediator, discuss the beam-off and beam-on backgrounds, and present the sensitivity in dark photon kinetic mixing for both the DAEδALUS/LENA setup and LSND in both the on- and off-shell regimes.« less

Toward electroweak scale cold dark matter with local dark gauge symmetry and beyond the DM EFT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ko, Pyungwon, E-mail: pko@kias.re.kr

2016-06-21

In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singletmore » portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for DM.« less

New fermionic dark matters, extended Standard Model and cosmic rays

NASA Astrophysics Data System (ADS)

Hwang, Jae-Kwang

2017-08-01

Three generations of leptons and quarks correspond to the lepton charges (LCs) in this work. Then, the leptons have the electric charges (ECs) and LCs. The quarks have the ECs, LCs and color charges (CCs). Three heavy leptons and three heavy quarks are introduced to make the missing third flavor of EC. Then the three new particles which have the ECs are proposed as the bastons (dark matters) with the rest masses of 26.121 eV/c2, 42.7 GeV/c2 and 1.9 × 1015 eV/c2. These new particles are applied to explain the origins of the astrophysical observations like the ultra-high energy cosmic rays and supernova 1987A anti-neutrino data. It is concluded that the 3.5 keV X-ray peak observed from the cosmic X-ray background spectra is originated not from the pair annihilations of the dark matters but from the X-ray emission of the Q1 baryon atoms which are similar in the atomic structure to the hydrogen atom. The presence of the 3.5 keV cosmic X-ray supports the presence of the Q1 quark with the EC of -4/3. New particles can be indirectly seen from the astrophysical observations like the cosmic ray and cosmic gamma ray. In this work, the systematic quantized charges of EC, LC and CC for the elementary particles are used to consistently explain the decay and reaction schemes of the elementary particles. Also, the strong, weak and dark matter forces are consistently explained.

Dark matter and the equivalence principle

NASA Technical Reports Server (NTRS)

Frieman, Joshua A.; Gradwohl, Ben-Ami

1993-01-01

A survey is presented of the current understanding of dark matter invoked by astrophysical theory and cosmology. Einstein's equivalence principle asserts that local measurements cannot distinguish a system at rest in a gravitational field from one that is in uniform acceleration in empty space. Recent test-methods for the equivalence principle are presently discussed as bases for testing of dark matter scenarios involving the long-range forces between either baryonic or nonbaryonic dark matter and ordinary matter.

Can tonne-scale direct detection experiments discover nuclear dark matter?

NASA Astrophysics Data System (ADS)

Butcher, Alistair; Kirk, Russell; Monroe, Jocelyn; West, Stephen M.

2017-10-01

Models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to Standard Model nuclei. We examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. We calculate the number of events required to distinguish these spectra from those of a standard point-like WIMP state with a decaying exponential recoil spectrum. In the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from WIMPs at the 3 σ level in a single experiment. Given the total exposure time of DEAP-3600 and XENON1T we find that at best a 2 σ distinction is possible by these experiments individually, while 3 σ sensitivity is reached for a range of parameters by the combination of the two experiments. We show that future upgrades of these experiments have potential to distinguish a large range of nuclear dark matter models from that of a WIMP at greater than 3 σ.

Can tonne-scale direct detection experiments discover nuclear dark matter?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butcher, Alistair; Kirk, Russell; Monroe, Jocelyn

Models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to Standard Model nuclei. We examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. We calculate the number of events required to distinguish these spectra from those of a standard point-like WIMP state with amore » decaying exponential recoil spectrum. In the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from WIMPs at the 3 σ level in a single experiment. Given the total exposure time of DEAP-3600 and XENON1T we find that at best a 2 σ distinction is possible by these experiments individually, while 3 σ sensitivity is reached for a range of parameters by the combination of the two experiments. We show that future upgrades of these experiments have potential to distinguish a large range of nuclear dark matter models from that of a WIMP at greater than 3 σ .« less

Manifestations of Dark matter and variation of the fundamental constants in atomic and astrophysical phenomena

NASA Astrophysics Data System (ADS)

Flambaum, Victor

2016-05-01

Low-mass boson dark matter particles produced after Big Bang form classical field and/or topological defects. In contrast to traditional dark matter searches, effects produced by interaction of an ordinary matter with this field and defects may be first power in the underlying interaction strength rather than the second or fourth power (which appears in a traditional search for the dark matter). This may give a huge advantage since the dark matter interaction constant is extremely small. Interaction between the density of the dark matter particles and ordinary matter produces both `slow' cosmological evolution and oscillating variations of the fundamental constants including the fine structure constant alpha and particle masses. Recent atomic dysprosium spectroscopy measurements and the primordial helium abundance data allowed us to improve on existing constraints on the quadratic interactions of the scalar dark matter with the photon, electron and light quarks by up to 15 orders of magnitude. Limits on the linear and quadratic interactions of the dark matter with W and Z bosons have been obtained for the first time. In addition to traditional methods to search for the variation of the fundamental constants (atomic clocks, quasar spectra, Big Bang Nucleosynthesis, etc) we discuss variations in phase shifts produced in laser/maser interferometers (such as giant LIGO, Virgo, GEO600 and TAMA300, and the table-top silicon cavity and sapphire interferometers), changes in pulsar rotational frequencies (which may have been observed already in pulsar glitches), non-gravitational lensing of cosmic radiation and the time-delay of pulsar signals. Other effects of dark matter and dark energy include apparent violation of the fundamental symmetries: oscillating or transient atomic electric dipole moments, precession of electron and nuclear spins about the direction of Earth's motion through an axion condensate, and axion-mediated spin-gravity couplings, violation of Lorentz symmetry and Einstein equivalence principle. Finally, we explore a possibility to explain the DAMA collaboration claim of dark matter detection by the dark matter scattering on electrons. We have shown that the electron relativistic effects increase the ionization differential cross section up to 3 orders of magnitude [9].

Direct detection constraints on dark photon dark matter

NASA Astrophysics Data System (ADS)

An, Haipeng; Pospelov, Maxim; Pradler, Josef; Ritz, Adam

2015-07-01

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01- 100 keV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to O (10-15), assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity to dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. We also revisit indirect constraints from V → 3 γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ-ray flux.

Direct detection constraints on dark photon dark matter

DOE PAGES

An, Haipeng; Pospelov, Maxim; Pradler, Josef; ...

2015-06-11

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01–100KeV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to Ο(10 –15), assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity tomore » dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. As a result, we also revisit indirect constraints from V → 3γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ-ray flux.« less

Prospects for Dark Matter Measurements with the Advanced Gamma Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Buckley, James

2009-05-01

AGIS, a concept for a future gamma-ray observatory consisting of an array of 50 atmospheric Cherenkov telescopes, would provide a powerful new tool for determining the nature of dark matter and its role in structure formation in the universe. The advent of more sensitive direct detection experiments, the launch of Fermi and the startup of the LHC make the near future an exciting time for dark matter searches. Indirect measurements of cosmic-ray electrons may already provide a hint of dark matter in our local halo. However, gamma-ray measurements will provide the only means for mapping the dark matter in the halo of our galaxy and other galaxies. In addition, the spectrum of gamma-rays (either direct annihilation to lines or continuum emission from other annihilation channels) will be imprinted with the mass of the dark matter particle, and the particular annihilation channels providing key measurements needed to identify the dark matter particle. While current gamma-ray instruments fall short of the generic sensitivity required to measure the dark matter signal from any sources other than the (confused) region around the Galactic center, we show that the planned AGIS array will have the angular resolution, energy resolution, low threshold energy and large effective area required to detect emission from dark matter annihilation in Galactic substructure or nearby Dwarf spheroidal galaxies.

Fundamental Particle Structure in the Cosmological Dark Matter

NASA Astrophysics Data System (ADS)

Khlopov, Maxim

2013-11-01

The nonbaryonic dark matter of the universe is assumed to consist of new stable forms of matter. Their stability reflects symmetry of micro-world and mechanisms of its symmetry breaking. Particle candidates for cosmological dark matter are lightest particles that bear new conserved quantum numbers. Dark matter particles may represent ideal gas of noninteracting particles. Self-interacting dark matter weakly or superweakly coupled to ordinary matter is also possible, reflecting nontrivial pattern of particle symmetry in the hidden sector of particle theory. In the early universe the structure of particle symmetry breaking gives rise to cosmological phase transitions, from which macroscopic cosmological defects or primordial nonlinear structures can be originated. Primordial black holes (PBHs) can be not only a candidate for dark matter, but also represent a universal probe for superhigh energy physics in the early universe. Evaporating PBHs turn to be a source of even superweakly interacting particles, while clouds of massive PBHs can serve as nonlinear seeds for galaxy formation. The observed broken symmetry of the three known families may provide a simultaneous solution for the problems of the mass of neutrino and strong CP-violation in the unique framework of models of horizontal unification. Dark matter candidates can also appear in the new families of quarks and leptons and the existence of new stable charged leptons and quarks is possible, hidden in elusive "dark atoms." Such possibility, strongly restricted by the constraints on anomalous isotopes of light elements, is not excluded in scenarios that predict stable double charged particles. The excessive -2 charged particles are bound in these scenarios with primordial helium in O-helium "atoms," maintaining specific nuclear-interacting form of the dark matter, which may provide an interesting solution for the puzzles of the direct dark matter searches. In the context of cosmoparticle physics, studying fundamental relationship of micro- and macro-worlds, the problem of cosmological dark matter implies cross disciplinary theoretical, experimental and observational studies for its solution.

An Experiment to Search for Systematic Effects in Long-Lived Radioactive Decays

NASA Astrophysics Data System (ADS)

Reuter, Cassie A.

Franz Zwicky first discovered "Dunkle Materie," or "Dark Matter" over 100 years ago, when he realized galaxy clusters must consist predominately of non-luminous matter. Since then, mounting evidence, has shown that a paltry 4% of the energy density of the universe is baryonic matter. We realize that the energy density of the universe is, in fact, dominated by dark matter and dark energy. Despite the evidence for dark matter, there is a long-standing discrepancy in the interpretation of results from direct dark matter experiments. The Italian DArk MAtter project (DAMA) claims to have discovered WIMPs, a particular variety of dark matter, since 1999. However, other direct detection experiments, provide results that directly contradict DAMA's claims. For years, the dark matter community has worked to reconcile the two opposing sets of results through improved experiments in direct detection and alternative Dark Matter models. This thesis outlines the Modulation Experiment, which is designed to identify and determine possible systematic sources of error that could explain the annually modulating signal attributed to Dark Matter by DAMA. We present a dedicated experiment for the long-term measurement of gamma emissions resulting from beta decays that provides high-quality data and allows for the identification of systematic influences. Up to 16 sources are monitored redundantly by 32 3x3" NaI(Tl) detectors in four separate setups across three continents. In each setup, monitoring of environmental and operational conditions facilitates correlation studies. The deadtime-free performance of the data acquisition system is confirmed and monitored by LED pulsers. Waveforms of all events are recorded individually, enabling a study of time-dependent effects spanning microseconds to years, using both time-binned and unbinned analyses. In this thesis, we show that the experiment is successfully acquiring data, and environmental effects are well-understood. Because of the experimental design, the Modulation Experiment is particularly well-suited to monitor decay rates of various isotopes. Though decay rates are generally considered to be Poisson processes, standards offices such as the National Institute of Standards (NIST) and Physikalisch-Technische Bundesanstalt (PTB) have reported annually modulating rates due to an unknown influence. Some scientists hypothesize that these effects may be due to a solar neutrino influence. Furthermore, some scientists have also examined a potential link from solar effects (e.g. flares and storms) to discrepancies in decay rate. However, these effects may simply be the by-products of some seasonal effects. This thesis explores the reported claims of decay rate modulation, and limits annual modulation amplitudes to < 5.95x10-5 for Ti-44, 1.46x10-4 for Co-60, and 1.8x10-4 Cs-137 at a 3sigma confidence level. No additional periodicities were found to be statistically significant. The Modulation experiment is beginning to explore the true nature of the impact of systematic effects on the measured decay rate. As data continues to be collected and more setups come online, we will be able to lower statistical uncertainties on measurements the half life, measure or set further limits on time-dependent modulations and search for correlations between locations.

Thermal dark matter from a highly decoupled sector

DOE PAGES

Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

2016-11-17

It has recently been shown that if the dark matter is in thermal equilibrium with a sector that is highly decoupled from the Standard Model, it can freeze out with an acceptable relic abundance, even if the dark matter is as heavy as ~1–100 PeV. In such scenarios, both the dark and visible sectors are populated after inflation, but with independent temperatures. The lightest particle in the dark sector will be generically long-lived and can come to dominate the energy density of the Universe. Upon decaying, these particles can significantly reheat the visible sector, diluting the abundance of dark mattermore » and thus allowing for dark matter particles that are much heavier than conventional WIMPs. In this study, we present a systematic and pedagogical treatment of the cosmological history in this class of models, emphasizing the simplest scenarios in which a dark matter candidate annihilates into hidden sector particles which then decay into visible matter through the vector, Higgs, or lepton portals. In each case, we find ample parameter space in which very heavy dark matter particles can provide an acceptable thermal relic abundance. We also discuss possible extensions of models featuring these dynamics.« less

Thermal dark matter from a highly decoupled sector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

It has recently been shown that if the dark matter is in thermal equilibrium with a sector that is highly decoupled from the Standard Model, it can freeze out with an acceptable relic abundance, even if the dark matter is as heavy as ~1–100 PeV. In such scenarios, both the dark and visible sectors are populated after inflation, but with independent temperatures. The lightest particle in the dark sector will be generically long-lived and can come to dominate the energy density of the Universe. Upon decaying, these particles can significantly reheat the visible sector, diluting the abundance of dark mattermore » and thus allowing for dark matter particles that are much heavier than conventional WIMPs. In this study, we present a systematic and pedagogical treatment of the cosmological history in this class of models, emphasizing the simplest scenarios in which a dark matter candidate annihilates into hidden sector particles which then decay into visible matter through the vector, Higgs, or lepton portals. In each case, we find ample parameter space in which very heavy dark matter particles can provide an acceptable thermal relic abundance. We also discuss possible extensions of models featuring these dynamics.« less

Black hole formation due to collapsing dark matter in a presence of dark energy in the brane-world scenario

NASA Astrophysics Data System (ADS)

Shah, Hasrat Hussain

In the last three to four decades, various programs have been studied in order to investigate the final fate of gravitational collapse of massive astronomical objects. In the theoretical context, Black Holes (BHs) are the consequence of final stage of the gravitational collapse. In this work, we investigated the gravitational collapse process of a spherically symmetric star constituted of dark matter (DM), ρM, and Dark Energy (DE), ρ in the context of the brane-world scenario. In our model, we discussed the anisotropy of the pressure in a fluid with Equation of State (EoS) pt = kρ and pr = lρ, (l + 2k < ‑1). We briefly discussed various cases of gravitational collapse and it is found that BH can be formed by the gravitational collapse in brane-world regime while in some cases there is only a naked singularity at their end state.

Dark Matter Search in a Proton Beam Dump with MiniBooNE

NASA Astrophysics Data System (ADS)

Aguilar-Arevalo, A. A.; Backfish, M.; Bashyal, A.; Batell, B.; Brown, B. C.; Carr, R.; Chatterjee, A.; Cooper, R. L.; deNiverville, P.; Dharmapalan, R.; Djurcic, Z.; Ford, R.; Garcia, F. G.; Garvey, G. T.; Grange, J.; Green, J. A.; Huelsnitz, W.; de Icaza Astiz, I. L.; Karagiorgi, G.; Katori, T.; Ketchum, W.; Kobilarcik, T.; Liu, Q.; Louis, W. C.; Marsh, W.; Moore, C. D.; Mills, G. B.; Mirabal, J.; Nienaber, P.; Pavlovic, Z.; Perevalov, D.; Ray, H.; Roe, B. P.; Shaevitz, M. H.; Shahsavarani, S.; Stancu, I.; Tayloe, R.; Taylor, C.; Thornton, R. T.; Van de Water, R.; Wester, W.; White, D. H.; Yu, J.; MiniBooNE-DM Collaboration

2017-06-01

The MiniBooNE-DM Collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8-GeV Booster proton beam in a dedicated run with 1.86 ×1 020 protons delivered to a steel beam dump. The MiniBooNE detector, 490 m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Analysis methods developed for previous MiniBooNE scattering results were employed, and several constraining data sets were simultaneously analyzed to minimize systematic errors from neutrino flux and interaction rates. No excess of events over background was observed, leading to a 90% confidence limit on the dark matter cross section parameter, Y =ɛ2αD(mχ/mV)4≲10-8 , for αD=0.5 and for dark matter masses of 0.01

Dragging force on galaxies due to streaming dark matter

NASA Technical Reports Server (NTRS)

Hara, Tetsuya; Miyoshi, Shigeru

1990-01-01

It has been reported that galaxies in large regions (approx. 10(exp 2) Mpc), including some clusters of galaxies, may be streaming coherently with velocities up to 600 km/sec or more with respect to the rest frame determined by the microwave background radiation. On the other hand, it is suggested that the dominant mass component of the universe is dark matter. Because we can only speculate the motion of dark matter from the galaxy motions, much attention should be paid to the correlation of velocities between the observed galaxies and cold dark matter. So the authors investigated whether such coherent large-scale streaming velocities are due to dark matter or only to baryonic objects which may be formed by piling up of gases due to some explosive events. It seems that, although each galaxy will not follow the motion of dark matter, clusters of galaxies may represent the velocity field of dark matter. The origin of the velocity field of dark matter would be due to the initial adiabatic perturbations and, in fact, the observed peculiar velocities of clusters are within the allowed region constrained from the isotropy of the microwave background radiation.

Single top quarks and dark matter

NASA Astrophysics Data System (ADS)

Pinna, Deborah; Zucchetta, Alberto; Buckley, Matthew R.; Canelli, Florencia

2017-08-01

Processes with dark matter interacting with the standard model fermions through new scalars or pseudoscalars with flavor-diagonal couplings proportional to fermion mass are well motivated theoretically, and provide a useful phenomenological model with which to interpret experimental results. Two modes of dark matter production from these models have been considered in the existing literature: pairs of dark matter produced through top quark loops with an associated monojet in the event, and pair production of dark matter with pairs of heavy flavored quarks (tops or bottoms). In this paper, we demonstrate that a third, previously overlooked channel yields a non-negligible contribution to LHC dark matter searches in these models. In spite of a generally lower production cross section at LHC when compared to the associated top-pair channel, non-flavor violating single top quark processes are kinematically favored and can significantly increase the sensitivity to these models. Including dark matter production in association with a single top quark through scalar or pseudoscalar mediators, the exclusion limit set by the LHC searches for dark matter can be improved by 30% up to a factor of two, depending on the mass assumed for the mediator particle.

Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Albert, A.; Anderson, B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.;

Empirical Determination of Dark Matter Velocities Using Metal-Poor Stars.

PubMed

Herzog-Arbeitman, Jonah; Lisanti, Mariangela; Madau, Piero; Necib, Lina

2018-01-26

The Milky Way dark matter halo is formed from the accretion of smaller subhalos. These sub-units also harbor stars-typically old and metal-poor-that are deposited in the Galactic inner regions by disruption events. In this Letter, we show that the dark matter and metal-poor stars in the Solar neighborhood share similar kinematics due to their common origin. Using the high-resolution eris simulation, which traces the evolution of both the dark matter and baryons in a realistic Milky Way analog galaxy, we demonstrate that metal-poor stars are indeed effective tracers for the local, virialized dark matter velocity distribution. The local dark matter velocities can therefore be inferred from observations of the stellar halo made by the Sloan Digital Sky Survey within 4 kpc of the Sun. This empirical distribution differs from the standard halo model in important ways and suggests that the bounds on the spin-independent scattering cross section may be weakened for dark matter masses below ∼10  GeV. Data from Gaia will allow us to further refine the expected distribution for the smooth dark matter component, and to test for the presence of local substructure.

Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows.

PubMed

Governato, F; Brook, C; Mayer, L; Brooks, A; Rhee, G; Wadsley, J; Jonsson, P; Willman, B; Stinson, G; Quinn, T; Madau, P

2010-01-14

For almost two decades the properties of 'dwarf' galaxies have challenged the cold dark matter (CDM) model of galaxy formation. Most observed dwarf galaxies consist of a rotating stellar disk embedded in a massive dark-matter halo with a near-constant-density core. Models based on the dominance of CDM, however, invariably form galaxies with dense spheroidal stellar bulges and steep central dark-matter profiles, because low-angular-momentum baryons and dark matter sink to the centres of galaxies through accretion and repeated mergers. Processes that decrease the central density of CDM halos have been identified, but have not yet reconciled theory with observations of present-day dwarfs. This failure is potentially catastrophic for the CDM model, possibly requiring a different dark-matter particle candidate. Here we report hydrodynamical simulations (in a framework assuming the presence of CDM and a cosmological constant) in which the inhomogeneous interstellar medium is resolved. Strong outflows from supernovae remove low-angular-momentum gas, which inhibits the formation of bulges and decreases the dark-matter density to less than half of what it would otherwise be within the central kiloparsec. The analogues of dwarf galaxies-bulgeless and with shallow central dark-matter profiles-arise naturally in these simulations.

Dark Matter Search in a Proton Beam Dump with MiniBooNE.

PubMed

Aguilar-Arevalo, A A; Backfish, M; Bashyal, A; Batell, B; Brown, B C; Carr, R; Chatterjee, A; Cooper, R L; deNiverville, P; Dharmapalan, R; Djurcic, Z; Ford, R; Garcia, F G; Garvey, G T; Grange, J; Green, J A; Huelsnitz, W; de Icaza Astiz, I L; Karagiorgi, G; Katori, T; Ketchum, W; Kobilarcik, T; Liu, Q; Louis, W C; Marsh, W; Moore, C D; Mills, G B; Mirabal, J; Nienaber, P; Pavlovic, Z; Perevalov, D; Ray, H; Roe, B P; Shaevitz, M H; Shahsavarani, S; Stancu, I; Tayloe, R; Taylor, C; Thornton, R T; Van de Water, R; Wester, W; White, D H; Yu, J

2017-06-02

The MiniBooNE-DM Collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8-GeV Booster proton beam in a dedicated run with 1.86×10^{20} protons delivered to a steel beam dump. The MiniBooNE detector, 490 m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Analysis methods developed for previous MiniBooNE scattering results were employed, and several constraining data sets were simultaneously analyzed to minimize systematic errors from neutrino flux and interaction rates. No excess of events over background was observed, leading to a 90% confidence limit on the dark matter cross section parameter, Y=ε^{2}α_{D}(m_{χ}/m_{V})^{4}≲10^{-8}, for α_{D}=0.5 and for dark matter masses of 0.01

Search for right-handed neutrinos from dark matter annihilation with gamma-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos, Miguel D.; Queiroz, Farinaldo S.; Yaguna, Carlos E.

Several extensions of the Standard Model contain right-handed (sterile) neutrinos in the GeV-TeV mass range. Due to their mixing with the active neutrinos, they may give rise to novel effects in cosmology, neutrino physics, and collider searches. In addition, right-handed neutrinos can also appear as final states from dark matter annihilations, with important implications for dark matter indirect detection searches. In this paper, we use current data from the Fermi Large Area Telescope (6-year observation of dwarf spheroidal galaxies) and H.E.S.S. (10-year observation of the Galactic center) to constrain the annihilation of dark matter into right-handed neutrinos. We consider right-handedmore » neutrino with masses between 10 GeV and 1 TeV, including both two-body and three-body decays, to derive bounds on the dark matter annihilation rate, ( σ v ), as a function of the dark matter mass. Our results show, in particular, that the thermal dark matter annihilation cross section, 3× 10{sup −26} cm{sup 3} s {sup −1} , into right-handed neutrinos is excluded for dark matter masses smaller than 200 GeV.« less

Empirical Determination of Dark Matter Velocities Using Metal-Poor Stars

NASA Astrophysics Data System (ADS)

Herzog-Arbeitman, Jonah; Lisanti, Mariangela; Madau, Piero; Necib, Lina

2018-01-01

The Milky Way dark matter halo is formed from the accretion of smaller subhalos. These sub-units also harbor stars—typically old and metal-poor—that are deposited in the Galactic inner regions by disruption events. In this Letter, we show that the dark matter and metal-poor stars in the Solar neighborhood share similar kinematics due to their common origin. Using the high-resolution eris simulation, which traces the evolution of both the dark matter and baryons in a realistic Milky Way analog galaxy, we demonstrate that metal-poor stars are indeed effective tracers for the local, virialized dark matter velocity distribution. The local dark matter velocities can therefore be inferred from observations of the stellar halo made by the Sloan Digital Sky Survey within 4 kpc of the Sun. This empirical distribution differs from the standard halo model in important ways and suggests that the bounds on the spin-independent scattering cross section may be weakened for dark matter masses below ˜10 GeV . Data from Gaia will allow us to further refine the expected distribution for the smooth dark matter component, and to test for the presence of local substructure.

Adding Spice to Vanilla LCDM simulations: Alternative Cosmologies & Lighting up Simulations

NASA Astrophysics Data System (ADS)

Jahan Elahi, Pascal

2015-08-01

Cold Dark Matter simulations have formed the backbone of our theoretical understanding of cosmological structure formation. Predictions from the Lambda Cold Dark Matter (LCDM) cosmology, where the Universe contains two dark components, namely Dark Matter & Dark Energy, are in excellent agreement with the Large-Scale Structures observed, i.e., the distribution of galaxies across cosmic time. However, this paradigm is in tension with observations at small-scales, from the number and properties of satellite galaxies around galaxies such as the Milky Way and Andromeda, to the lensing statistics of massive galaxy clusters. I will present several alternative models of cosmology (from Warm Dark Matter to coupled Dark Matter-Dark Energy models) and how they compare to vanilla LCDM by studying formation of groups and clusters dark matter only and adiabatic hydrodynamical zoom simulations. I will show how modifications to the dark sector can lead to some surprising results. For example, Warm Dark Matter, so often examined on small satellite galaxies scales, can be probed observationally using weak lensing at cluster scales. Coupled dark sectors, where dark matter decays into dark energy and experiences an effective gravitational potential that differs from that experienced by normal matter, is effectively hidden away from direct observations of galaxies. Studies like these are vital if we are to pinpoint observations which can look for unique signatures of the physics that governs the hidden Universe. Finally, I will discuss how all of these predictions are affected by uncertain galaxy formation physics. I will present results from a major comparison study of numerous hydrodynamical codes, the nIFTY cluster comparison project. This comparison aims to understand the code-to-code scatter in the properties of dark matter haloes and the galaxies that reside in them. We find that even in purely adiabatic simulations, different codes form clusters with very different X-ray profiles. The galaxies that form in these simulations, which all use codes that attempt to reproduce the observed galaxy population via not unreasonable subgrid physics, vary in stellar mass, morphology and gas fraction, sometimes by an order of magnitude. I will end with a discussion of precision cosmology in light of these results.

Fitting the Fermi-LAT GeV excess: On the importance of including the propagation of electrons from dark matter

NASA Astrophysics Data System (ADS)

Lacroix, Thomas; BÅ`hm, Céline; Silk, Joseph

2014-08-01

An excess of gamma rays at GeV energies has been pointed out in the Fermi-LAT data. This signal comes from a narrow region centred around the Galactic center and has been interpreted as possible evidence for light dark matter particles annihilating either into a mixture of leptons-antileptons and bb ¯ or into bb ¯ only. Focusing on the prompt gamma-ray emission, previous works found that the best fit to the data corresponds to annihilations proceeding predominantly into bb ¯. However, here we show that omitting the photon emission originating from primary and secondary electrons produced in dark matter annihilations, and undergoing diffusion through the Galactic magnetic field, can actually lead to the wrong conclusion. Accounting for this emission, we find that not only are annihilations of ˜10 GeV particles into a purely leptonic final state allowed, but the democratic scenario actually provides a better fit to the spectrum of the excess than the pure bb ¯ channel. We conclude our work with a discussion on constraints on these leptophilic scenarios based on the AMS data and the morphology of the excess.

Signatures of dark radiation in neutrino and dark matter detectors

NASA Astrophysics Data System (ADS)

Cui, Yanou; Pospelov, Maxim; Pradler, Josef

2018-05-01

We consider the generic possibility that the Universe's energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with nongravitational interactions with standard model (SM) particles. Such dark radiation may consist of SM singlets or a nonthermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In particular, for interacting dark radiation carrying a typical momentum of ˜30 MeV /c , both types of experiments provide competitive constraints. This study also demonstrates that non-standard sources of neutrino emission (e.g., via dark matter decay) are capable of creating a "neutrino floor" for dark matter direct detection that is closer to current bounds than is expected from standard neutrino sources.

Partially acoustic dark matter, interacting dark radiation, and large scale structure

NASA Astrophysics Data System (ADS)

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; Okui, Takemichi; Tsai, Yuhsinz

2016-12-01

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

Partially acoustic dark matter, interacting dark radiation, and large scale structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightlymore » coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.« less

Partially acoustic dark matter, interacting dark radiation, and large scale structure

DOE PAGES

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; ...

2016-12-21

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightlymore » coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.« less

Dark Energy and Dark Matter Hidden in the Geometry of Space?

NASA Astrophysics Data System (ADS)

Buchert, Thomas

A spatially flat and infinite Universe in the form of a "concordant" standard model of cosmology rules present-day thinking of cosmologists. The price to pay is an unknown physical origin of Dark Energy and Dark Matter that are supposed to exist and even appear to rule the dynamics of our Universe. A growing number of cosmologists question the existence of dark constituents: the standard model of cosmology may be just too simple, since it neglects the influence of structure in the Universe on its global expansion history. The key-issue appears to be the curvature of space: the formation of structure interacts with the geometry of space, changing our global picture of the Universe. This chapter explains the underlying mechanism that works in the right direction to uncover the dark faces of the standard model of cosmology. If successful, this novel approach furnishes a new paradigm of modern cosmology. Hundreds of researchers have recently embarked into studies of this new subject. We understand much at present, but there are many open questions.

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.;

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

NASA Astrophysics Data System (ADS)

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

2011-12-01

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. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10-26cm3s-1 at 5 GeV to about 5×10-23cm3s-1 at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (˜3×10-26cm3s-1 for a purely s-wave cross section), without assuming additional boost factors.

Dirac dark matter and b →s ℓ+ℓ- with U(1) gauge symmetry

NASA Astrophysics Data System (ADS)

Celis, Alejandro; Feng, Wan-Zhe; Vollmann, Martin

2017-02-01

We revisit the possibility of a Dirac fermion dark matter candidate in the light of current b →s ℓ+ℓ- anomalies by investigating a minimal extension of the Standard Model with a horizontal U(1 ) ' local symmetry. Dark matter stability is protected by a remnant Z2 symmetry arising after spontaneous symmetry breaking of U(1 ) '. The associated Z' gauge boson can accommodate current hints of new physics in b →s ℓ+ℓ- decays, and acts as a vector portal between dark matter and the visible sector. We find that the model is severely constrained by a combination of precision measurements at flavor factories, LHC searches for dilepton resonances, as well as direct and indirect dark matter searches. Despite this, viable regions of the parameter space accommodating the observed dark matter relic abundance and the b →s ℓ+ℓ-anomalies still persist for dark matter and Z ' masses in the TeV range.

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.

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. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% con dence level upper limits range from about 10 -26 cm3s -1 at 5 GeV to about 5 X10 -23 cm3smore » -1 at 1 TeV, depending on the dark matter annihilation nal state. For the rst time, using gamma rays, we are able to rule out models with the most generic cross section (~ 3 X 10 -26 cm 3s -1 for a purely s-wave cross section), without assuming additional boost factors.« less

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

DOE PAGES

Ackermann, M.

2011-12-01

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. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% con dence level upper limits range from about 10 -26 cm3s -1 at 5 GeV to about 5 X10 -23 cm3smore » -1 at 1 TeV, depending on the dark matter annihilation nal state. For the rst time, using gamma rays, we are able to rule out models with the most generic cross section (~ 3 X 10 -26 cm 3s -1 for a purely s-wave cross section), without assuming additional boost factors.« less

Self-Destructing Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grossman, Yuval; Harnik, Roni; Telem, Ofri

We present Self-Destructing Dark Matter (SDDM), a new class of dark matter models which are detectable in large neutrino detectors. In this class of models, a component of dark matter can transition from a long-lived state to a short-lived one by scattering off of a nucleus or an electron in the Earth. The short-lived state then decays to Standard Model particles, generating a dark matter signal with a visible energy of order the dark matter mass rather than just its recoil. This leads to striking signals in large detectors with high energy thresholds. We present a few examples of modelsmore » which exhibit self destruction, all inspired by bound state dynamics in the Standard Model. The models under consideration exhibit a rich phenomenology, possibly featuring events with one, two, or even three lepton pairs, each with a fixed invariant mass and a fixed energy, as well as non-trivial directional distributions. This motivates dedicated searches for dark matter in large underground detectors such as Super-K, Borexino, SNO+, and DUNE.« less

Freeze-in production of sterile neutrino dark matter in U(1){sub B−L} model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, Anirban; Gupta, Aritra

2016-09-27

With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1){sub B−L} model. The U(1){sub B−L} model on the other handmore » is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W{sup ±} decay can also be a dominant production mode of the sterile neutrino DM. To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1){sub B−L} model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.« less

Atomic dark matter with hyperfine interactions

NASA Astrophysics Data System (ADS)

Boddy, Kimberly K.; Kaplinghat, Manoj; Kwa, Anna; Peter, Annika H. G.

2017-11-01

We consider dark matter as an analog of hydrogen in a secluded sector and study its astrophysical implications. The self interactions between dark matter particles include elastic scatterings as well as inelastic processes from hyperfine transitions. We show that for a dark hydrogen mass in the 10-100 GeV range and a dark fine-structure constant larger than 0.01, the self-interaction cross section has the right magnitude and velocity dependence to explain the low dark matter density cores seen in small galaxies while being consistent with all constraints from observations of galaxy clusters. Excitations to the hyperfine state and subsequent decays, however, may cause significant cooling losses and affect the evolution of low-mass halos. We also find minimum halo masses in the range of 103.5-107 M⊙, which are significantly larger than the typical predictions for weakly interacting dark matter models. This pattern of observables in structure formation is unique to this model, making it possible to determine the viability of hidden-sector hydrogen as a dark matter candidate.

Adding Spice to Vanilla LCDM simulations: From Alternative Cosmologies to Lighting up Galaxies

NASA Astrophysics Data System (ADS)

Jahan Elahi, Pascal

2015-08-01

Cold Dark Matter simulations have formed the backbone of our theoretical understanding of cosmological structure formation. Predictions from the Lambda Cold Dark Matter (LCDM) cosmology, in which the Universe contains two major dark components, namely Dark Matter and Dark Energy, are in excellent agreement with the Large-Scale Structures observed, i.e., the distribution of galaxies across cosmic time. However, this paradigm is in tension with observations at small-scales, from the number and properties of satellite galaxies around galaxies such as the Milky Way and Andromeda, to the lensing statistics of massive galaxy clusters. I will present several alternative models of cosmology (from Warm Dark Matter to coupled Dark Matter-Dark Energy models) and how they compare to vanilla LCDM by studying formation of groups and clusters dark matter only and adiabatic hydrodynamical zoom simulations. I will show how modifications to the dark sector can lead to some surprising results. For example, Warm Dark Matter, so often examined on small satellite galaxies scales, can be probed observationally using weak lensing at cluster scales. Coupled dark sectors, where dark matter decays into dark energy and experiences an effective gravitational potential that differs from that experienced by normal matter, is effectively hidden away from direct observations of galaxies. Studies like these are vital if we are to pinpoint observations which can look for unique signatures of the physics that governs the hidden Universe. Of course, all of these predictions are unfortunately affected by uncertain galaxy formation physics. I will end by presenting results from a comparison study of numerous hydrodynamical codes, the nIFTY cluster comparison project, and how even how purely adiabatic simulations run with different codes give in quite different galaxy populations. The galaxies that form in these simulations, which all attempt to reproduce the observed galaxy population via not unreasonable subgrid physics, can and do vary in stellar mass, morphology and gas fraction.

GeV-scale dark matter: Production at the main injector

DOE PAGES

Dobrescu, Bogdan A.; Frugiuele, Claudia

2015-02-03

In this study, assuming that dark matter particles interact with quarks via a GeV-scale mediator, we study dark matter production in fixed target collisions. The ensuing signal in a neutrino near detector consists of neutral-current events with an energy distribution peaked at higher values than the neutrino background. We find that for a Z' boson of mass around a few GeV that decays to dark matter particles, the dark matter beam produced by the Main Injector at Fermilab allows the exploration of a range of values for the gauge coupling that currently satisfy all experimental constraints. The NOνA near detectormore » is well positioned for probing the presence of a dark matter beam, and future LBNF near detectors would provide more sensitive probes.« less

Directional detection of dark matter with two-dimensional targets

DOE PAGES

Hochberg, Yonit; Kahn, Yonatan; Lisanti, Mariangela; ...

2017-09-01

We propose two-dimensional materials as targets for direct detection of dark matter. Using graphene as an example, we focus on the case where dark matter scattering deposits sufficient energy on a valence-band electron to eject it from the target. Here, we show that the sensitivity of graphene to dark matter of MeV to GeV mass can be comparable, for similar exposure and background levels, to that of semiconductor targets such as silicon and germanium. Moreover, a two-dimensional target is an excellent directional detector, as the ejected electron retains information about the angular dependence of the incident dark matter particle. Ourmore » proposal can be implemented by the PTOLEMY experiment, presenting for the first time an opportunity for directional detection of sub-GeV dark matter.« less

Directional detection of dark matter with two-dimensional targets

NASA Astrophysics Data System (ADS)

Hochberg, Yonit; Kahn, Yonatan; Lisanti, Mariangela; Tully, Christopher G.; Zurek, Kathryn M.

2017-09-01

We propose two-dimensional materials as targets for direct detection of dark matter. Using graphene as an example, we focus on the case where dark matter scattering deposits sufficient energy on a valence-band electron to eject it from the target. We show that the sensitivity of graphene to dark matter of MeV to GeV mass can be comparable, for similar exposure and background levels, to that of semiconductor targets such as silicon and germanium. Moreover, a two-dimensional target is an excellent directional detector, as the ejected electron retains information about the angular dependence of the incident dark matter particle. This proposal can be implemented by the PTOLEMY experiment, presenting for the first time an opportunity for directional detection of sub-GeV dark matter.

Asymmetric dark matter and baryogenesis from pseudoscalar inflation

NASA Astrophysics Data System (ADS)

Cado, Yann; Sabancilar, Eray

2017-04-01

We show that both the baryon asymmetry of the Universe and the dark matter abundance can be explained within a single framework that makes use of maximally helical hypermagnetic fields produced during pseudoscalar inflation and the chiral anomaly in the Standard Model. We consider a minimal asymmetric dark matter model free from anomalies and constraints. We find that the observed baryon and the dark matter abundances are achieved for a wide range of inflationary parameters, and the dark matter mass ranges between 7-15 GeV . The novelty of our mechanism stems from the fact that the same source of CP violation occurring during inflation explains both baryonic and dark matter in the Universe with two inflationary parameters, hence addressing all the initial condition problems in an economical way.

Origins and challenges of viral dark matter.

PubMed

Krishnamurthy, Siddharth R; Wang, David

2017-07-15

The accurate classification of viral dark matter - metagenomic sequences that originate from viruses but do not align to any reference virus sequences - is one of the major obstacles in comprehensively defining the virome. Depending on the sample, viral dark matter can make up from anywhere between 40 and 90% of sequences. This review focuses on the specific nature of dark matter as it relates to viral sequences. We identify three factors that contribute to the existence of viral dark matter: the divergence and length of virus sequences, the limitations of alignment based classification, and limited representation of viruses in reference sequence databases. We then discuss current methods that have been developed to at least partially circumvent these limitations and thereby reduce the extent of viral dark matter. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of gravitational focusing on annual modulation in dark-matter direct-detection experiments.

PubMed

Lee, Samuel K; Lisanti, Mariangela; Peter, Annika H G; Safdi, Benjamin R

2014-01-10

The scattering rate in dark-matter direct-detection experiments should modulate annually due to Earth's orbit around the Sun. The rate is typically thought to be extremized around June 1, when the relative velocity of 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.

Asymmetric dark matter and baryogenesis from pseudoscalar inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cado, Yann; Sabancilar, Eray, E-mail: yann.cado@epfl.ch, E-mail: eray.sabancilar@epfl.ch

2017-04-01

We show that both the baryon asymmetry of the Universe and the dark matter abundance can be explained within a single framework that makes use of maximally helical hypermagnetic fields produced during pseudoscalar inflation and the chiral anomaly in the Standard Model. We consider a minimal asymmetric dark matter model free from anomalies and constraints. We find that the observed baryon and the dark matter abundances are achieved for a wide range of inflationary parameters, and the dark matter mass ranges between 7–15 GeV . The novelty of our mechanism stems from the fact that the same source of CPmore » violation occurring during inflation explains both baryonic and dark matter in the Universe with two inflationary parameters, hence addressing all the initial condition problems in an economical way.« less

Vector dark matter annihilation with internal bremsstrahlung

DOE PAGES

Bambhaniya, Gulab; Kumar, Jason; Marfatia, Danny; ...

2017-01-10

We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound state that decays to its ground state before the constituents annihilate. We show that the shape of the resulting photon spectrum ismore » the same as for self-conjugate spin-0 and spin-1/2 dark matter, but the normalization is less heavily suppressed in the limit of heavy mediators.« less

Directional detection of dark matter with two-dimensional targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hochberg, Yonit; Kahn, Yonatan; Lisanti, Mariangela

We propose two-dimensional materials as targets for direct detection of dark matter. Using graphene as an example, we focus on the case where dark matter scattering deposits sufficient energy on a valence-band electron to eject it from the target. Here, we show that the sensitivity of graphene to dark matter of MeV to GeV mass can be comparable, for similar exposure and background levels, to that of semiconductor targets such as silicon and germanium. Moreover, a two-dimensional target is an excellent directional detector, as the ejected electron retains information about the angular dependence of the incident dark matter particle. Ourmore » proposal can be implemented by the PTOLEMY experiment, presenting for the first time an opportunity for directional detection of sub-GeV dark matter.« less

Detailed Characterization of Nuclear Recoil Pulse Shape Discrimination in the DarkSide-50 Direct Dark Matter Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edkins, Erin Elisabeth

While evidence of non-baryonic dark matter has been accumulating for decades, its exact nature continues to remain a mystery. Weakly Interacting Massive Particles (WIMPs) are a well motivated candidate which appear in certain extensions of the Standard Model, independently of dark matter theory. If such particles exist, they should occasionally interact with particles of normal matter, producing a signal which may be detected. The DarkSide-50 direct dark matter experiment aims to detect the energy of recoiling argon atoms due to the elastic scattering of postulated WIMPs. In order to make such a discovery, a clear understanding of both the background and signal region is essential. This understanding requires a careful study of the detector's response to radioactive sources, which in turn requires such sources may be safely introduced into or near the detector volume and reliably removed. The CALibration Insertaion System (CALIS) was designed and built for this purpose in a j oint effort between Fermi National Laboratory and the University of Hawaii. This work describes the design and testing of CALIS, its installation and commissioning at the Laboratori Nazionali del Gran Sasso (LNGS) and the multiple calibration campaigns which have successfully employed it. As nuclear recoils produced by WIMPs are indistinguishable from those produced by neutrons, radiogenic neutrons are both the most dangerous class of background and a vital calibration source for the study of the potential WIMP signal. Prior to the calibration of DarkSide-50 with radioactive neutron sources, the acceptance region was determined by the extrapolation of nuclear recoil data from a separate, dedicated experiment, ScENE, which measured the distribution of the pulse shape discrimination parameter,more » $$f_{90}$$, for nuclear recoils of known energies. This work demonstrates the validity of the extrapolation of ScENE values to DarkSide-50, by direct comparison of the $$f_{90}$$ distributio n of nuclear recoils from ScENE and an AmBe calibration sour! ce. The combined acceptance as defined by ScENE and the \\textit{in-situ} AmBe calibration were used to establish the best WIMP exclusion limit on an argon target. Unfortunately, radioactive sources used for the calibration of DarkSide-50 are universally accompanied by gamma decays, which obscure the low energy region where most WIMP interactions are expected to occur and seem to make continuing dependence on an external measurement such as ScENE inevitable. However, this work presents a novel method of nuclear recoil calibration employing event selection, unique to the design of DarkSide-50, which produces a nearly pure sample of nuclear recoils. Further, it describes the execution of a neutron calibration campaign, from planning to analysis, which yielded a valuable data set for defining the acceptance region. Together with the event selection techniques, this allows for the definition of the acceptance region independent of ScENE values. Two analytical models of the $$f_{90 }$$ distribution are described and their results for nuclear recoils are compared. Finally, a detailed study of integrated noise in nuclear and electron recoil« less

Prospects for detection of target-dependent annual modulation in direct dark matter searches

DOE PAGES

Nobile, Eugenio Del; Gelmini, Graciela B.; Witte, Samuel J.

2016-02-03

Earth's rotation about the Sun produces an annual modulation in the expected scattering rate at direct dark matter detection experiments. The annual modulation as a function of the recoil energy E R imparted by the dark matter particle to a target nucleus is expected to vary depending on the detector material. However, for most interactions a change of variables from E R to v min, the minimum speed a dark matter particle must have to impart a fixed E R to a target nucleus, produces an annual modulation independent of the target element. We recently showed that if the darkmore » matter-nucleus cross section contains a non-factorizable target and dark matter velocity dependence, the annual modulation as a function of v min can be target dependent. Here we examine more extensively the necessary conditions for target-dependent modulation, its observability in present-day experiments, and the extent to which putative signals could identify a dark matter-nucleus differential cross section with a non-factorizable dependence on the dark matter velocity.« less

Hunting for dark matter with ultra-stable fibre as frequency delay system.

PubMed

Yang, Wanpeng; Li, Dawei; Zhang, Shuangyou; Zhao, Jianye

2015-07-10

Many cosmological observations point towards the existence of dark-matter(DM) particles and consider them as the main component of the matter content of the universe. The goal of revealing the nature of dark-matter has triggered the development of new, extremely sensitive detectors. It has been demonstrated that the frequencies and phases of optical clock have a transient shift during the DMs' arrival due to the DM-SM(Standard Model) coupling. A simple, reliable and feasible experimental scheme is firstly proposed in this paper, based on "frequency-delay system" to search dark-matter by "self-frequency comparison" of an optical clock. During the arrival of a dark-matter, frequency discrepancy is expected between two signals with a short time difference(~ms) of the same optical clock to exhibit the interaction between atoms and dark-matter. Furthermore, this process can determine the exact position of dark-matter when it is crossing the optical clocks, therefore a network of detecting stations located in different places is recommended to reduce the misjudgment risk to an acceptable level.

Hunting for dark matter with ultra-stable fibre as frequency delay system

PubMed Central

Yang, Wanpeng; Li, Dawei; Zhang, Shuangyou; Zhao, Jianye

2015-01-01

Many cosmological observations point towards the existence of dark-matter(DM) particles and consider them as the main component of the matter content of the universe. The goal of revealing the nature of dark-matter has triggered the development of new, extremely sensitive detectors. It has been demonstrated that the frequencies and phases of optical clock have a transient shift during the DMs’ arrival due to the DM-SM(Standard Model) coupling. A simple, reliable and feasible experimental scheme is firstly proposed in this paper, based on “frequency-delay system” to search dark-matter by “self-frequency comparison” of an optical clock. During the arrival of a dark-matter, frequency discrepancy is expected between two signals with a short time difference(~ms) of the same optical clock to exhibit the interaction between atoms and dark-matter. Furthermore, this process can determine the exact position of dark-matter when it is crossing the optical clocks, therefore a network of detecting stations located in different places is recommended to reduce the misjudgment risk to an acceptable level. PMID:26159113

Dark matter universe.

PubMed

Bahcall, Neta A

2015-10-06

Most of the mass in the universe is in the form of dark matter--a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations--from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology--a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)--fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

Dark-matter QCD-axion searches.

PubMed

Rosenberg, Leslie J

2015-10-06

In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There's no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10(-(6-3)) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments are discussed, but I hope to give a sense of the current experimental landscape of the search for dark-matter axions.

Dark-matter QCD-axion searches

PubMed Central

Rosenberg, Leslie J

2015-01-01

In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There’s no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10−(6–3) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments are discussed, but I hope to give a sense of the current experimental landscape of the search for dark-matter axions. PMID:25583487

The diverse density profiles of galaxy clusters with self-interacting dark matter plus baryons

NASA Astrophysics Data System (ADS)

Robertson, Andrew; Massey, Richard; Eke, Vincent; Tulin, Sean; Yu, Hai-Bo; Bahé, Yannick; Barnes, David J.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Kay, Scott T.; Schaller, Matthieu; Schaye, Joop

2018-05-01

We present the first simulated galaxy clusters (M200 > 1014 M⊙) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between dark matter self-interactions and baryonic physics. Despite variations in formation history, we demonstrate that analytical Jeans modelling predicts the SIDM density profiles remarkably well, and the diverse properties of the haloes can be understood in terms of their different final baryon distributions.

Sterile neutrino dark matter with supersymmetry

NASA Astrophysics Data System (ADS)

Shakya, Bibhushan; Wells, James D.

2017-08-01

Sterile neutrino dark matter, a popular alternative to the WIMP paradigm, has generally been studied in non-supersymmetric setups. If the underlying theory is supersymmetric, we find that several interesting and novel dark matter features can arise. In particular, in scenarios of freeze-in production of sterile neutrino dark matter, its superpartner, the sterile sneutrino, can play a crucial role in early Universe cosmology as the dominant source of cold, warm, or hot dark matter, or of a subdominant relativistic population of sterile neutrinos that can contribute to the effective number of relativistic degrees of freedom Neff during big bang nucleosynthesis.

Singlet particles as cold dark matter in a noncommutative space-time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ettefaghi, M. M.

2009-03-15

We extend the noncommutative (NC) standard model to incorporate singlet particles as cold dark matter. In the NC space-time, the singlet particles can be coupled to the U(1) gauge field in the adjoint representation. We study the relic density of the singlet particles due to the NC induced interaction. Demanding either the singlet fermion or the singlet scalar to serve as cold dark matter and the NC induced interactions to be relevant to the dark matter production, we obtain the corresponding relations between the NC scale and the dark matter masses, which are consistent with some existing bounds.

Detecting the Disruption of Dark-Matter Halos with Stellar Streams.

PubMed

Bovy, Jo

2016-03-25

Narrow stellar streams in the Milky Way halo are uniquely sensitive to dark-matter subhalos, but many of these subhalos may be tidally disrupted. I calculate the interaction between stellar and dark-matter streams using analytical and N-body calculations, showing that disrupting objects can be detected as low-concentration subhalos. Through this effect, we can constrain the lumpiness of the halo as well as the orbit and present position of individual dark-matter streams. This will have profound implications for the formation of halos and for direct- and indirect-detection dark-matter searches.

Probing dark matter at the LHC using vector boson fusion processes.

PubMed

Delannoy, Andres G; Dutta, Bhaskar; Gurrola, Alfredo; Johns, Will; Kamon, Teruki; Luiggi, Eduardo; Melo, Andrew; Sheldon, Paul; Sinha, Kuver; Wang, Kechen; Wu, Sean

2013-08-09

Vector boson fusion processes at the Large Hadron Collider (LHC) provide a unique opportunity to search for new physics with electroweak couplings. A feasibility study for the search of supersymmetric dark matter in the final state of two vector boson fusion jets and large missing transverse energy is presented at 14 TeV. Prospects for determining the dark matter relic density are studied for the cases of wino and bino-Higgsino dark matter. The LHC could probe wino dark matter with mass up to approximately 600 GeV with a luminosity of 1000  fb(-1).

Upper bounds on asymmetric dark matter self annihilation cross sections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellwanger, Ulrich; Mitropoulos, Pantelis, E-mail: ulrich.ellwanger@th.u-psud.fr, E-mail: pantelis.mitropoulos@th.u-psud.fr

2012-07-01

Most models for asymmetric dark matter allow for dark matter self annihilation processes, which can wash out the asymmetry at temperatures near and below the dark matter mass. We study the coupled set of Boltzmann equations for the symmetric and antisymmetric dark matter number densities, and derive conditions applicable to a large class of models for the absence of a significant wash-out of an asymmetry. These constraints are applied to various existing scenarios. In the case of left- or right-handed sneutrinos, very large electroweak gaugino masses, or very small mixing angles are required.

Visible and dark matter from a first-order phase transition in a baryon-symmetric universe

DOE PAGES

Petraki, Kalliopi; Trodden, Mark; Volkas, Raymond R.

2012-02-28

The similar cosmological abundances observed for visible and dark matter suggest a common origin for both. By viewing the dark matter density as a dark-sector asymmetry, mirroring the situation in the visible sector, we show that the visible and dark matter asymmetries may have arisen simultaneously through a first-order phase transition in the early universe. The additional scalar particles in the theory can mix with the standard Higgs boson and provide other striking signatures.

Search for Low-Mass Dark Matter wtih SuperCDMS Soudan and Study of Shorted Electric Field Configurations in CDMS Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneck, Kristiana

The area of dark matter is one of the most interesting and exciting topics in physics today. Existing at the intersection of particle physics and astrophysics, the existence of a new dark matter particle can be used to explain many astrophysical and cosmological observations, as well as to reconcile outstanding issues in the standard model of particle physics. Experiments such as SuperCDMS are built to detect dark matter in the lab by looking for low-energy nuclear recoils produced by collisions between dark matter particles and atoms in terrestrial detectors. SuperCDMS Soudan is particularly well-suited to follow up on possible hintsmore » of low-mass dark matter seen by other recent experiments because of its low thresholds and excellent background discrimination. Analyzing SuperCDMS Soudan data to look for low-mass dark matter comes with particular challenges because of the low signal-to-noise very near threshold. However, with a detailed background model developed by scaling high-energy events down into the low-energy signal region, SuperCDMS Soudan produced worldleading limits on the existence of low-mass dark matter. In addition, a few SuperCDMS Soudan detectors experienced cold hardware problems that can affect the data collected. Of particular interest is one detector considered for the low-mass WIMP search that has one of its charge electrodes shorted to chassis ground. Three events were observed in this detector upon unblinding the SuperCDMS Soudan low-energy data, even though <1 event was expected based on pre-unblinding calulations. However, the data collected by the shorted detector may have been compromised since an electrode shorted to ground will modify the electric field in the detector. The SuperCDMS Detector Monte Carlo (DMC) provides an excellent way to model the effects of the modified electric field, so a new model of the expected backgrounds in the low-mass WIMP search is developed using the DMC to try to explain how the short may have affected the data collected. This thesis is organized as follows: Chapter 1 gives a broad introduction to dark matter, discussing the astrophysical and cosmological evidence for its existence, listing several possible particle physics candidates, and outlining several experimental strategies to look for dark matter. Chapter 2 is an overview of CDMS detector technology and the experimental setup at the Soudan Underground Laboratory, with a focus on how data coming out of Soudan is analyzed. Chapter 3 presents results from a search for low-mass dark matter at SuperCDMS Soudan and discusses the interpretation of the results. Chapter 4 contains follow-up work that uses the CDMS Detector Monte Carlo (DMC) to understand the possible systematics associated with a detector that had one of its charge electrodes shorted to ground. This chapter represents the first time the DMC has been used to inform ongoing CDMS analysis. Chapter 5 takes a brief detour into the world of effective field theory (EFT), examining the consequences of an expanded set of possible WIMP-nucleon interactions in the EFT framework. Finally, Chapter 6 wraps up the material of the previous chapters and discusses how the research presented in this thesis can be applied as CDMS moves toward SuperCDMS SNOLAB.« less

Stealth Dark Matter: Dark scalar baryons through the Higgs portal

DOE PAGES

Appelquist, T.; Brower, R. C.; Buchoff, M. I.; ...

2015-10-23

We present a new model of "Stealth Dark Matter": a composite baryonic scalar of an SU(N D) strongly coupled theory with even N D ≥ 4. All mass scales are technically natural, and dark matter stability is automatic without imposing an additional discrete or global symmetry. Constituent fermions transform in vectorlike representations of the electroweak group that permit both electroweak-breaking and electroweak-preserving mass terms. This gives a tunable coupling of stealth dark matter to the Higgs boson independent of the dark matter mass itself. We specialize to SU(4), and investigate the constraints on the model from dark meson decay, electroweakmore » precision measurements, basic collider limits, and spin-independent direct detection scattering through Higgs exchange. We exploit our earlier lattice simulations that determined the composite spectrum as well as the effective Higgs coupling of stealth dark matter in order to place bounds from direct detection, excluding constituent fermions with dominantly electroweak-breaking masses. A lower bound on the dark baryon mass m B ≳ 300 GeV is obtained from the indirect requirement that the lightest dark meson not be observable at LEP II. Furthermore, we briefly survey some intriguing properties of stealth dark matter that are worthy of future study, including collider studies of dark meson production and decay; indirect detection signals from annihilation; relic abundance estimates for both symmetric and asymmetric mechanisms; and direct detection through electromagnetic polarizability, a detailed study of which will appear in a companion paper.« less

Remapping dark matter halo catalogues between cosmological simulations

NASA Astrophysics Data System (ADS)

Mead, A. J.; Peacock, J. A.

2014-05-01

We present and test a method for modifying the catalogue of dark matter haloes produced from a given cosmological simulation, so that it resembles the result of a simulation with an entirely different set of parameters. This extends the method of Angulo & White, which rescales the full particle distribution from a simulation. Working directly with the halo catalogue offers an advantage in speed, and also allows modifications of the internal structure of the haloes to account for non-linear differences between cosmologies. Our method can be used directly on a halo catalogue in a self-contained manner without any additional information about the overall density field; although the large-scale displacement field is required by the method, this can be inferred from the halo catalogue alone. We show proof of concept of our method by rescaling a matter-only simulation with no baryon acoustic oscillation (BAO) features to a more standard Λ cold dark matter model containing a cosmological constant and a BAO signal. In conjunction with the halo occupation approach, this method provides a basis for the rapid generation of mock galaxy samples spanning a wide range of cosmological parameters.

New Views on Dark Matter from Emergent Gravity

NASA Astrophysics Data System (ADS)

Sun, Sichun; Zhang, Yun-Long

2018-01-01

We discuss a scenario that apparent dark matter comes from the induced gravity in the (3+1)- dimensional spacetime, which can be embedded into one higher dimensional flat spacetime. The stress tensor of dark energy and dark matter is identified with the Brown-York stress tensor on the hypersurface, and we find an interesting constraint relation between the dark matter and dark energy density parameter and baryonic density parameter. Our approach may show a new understanding for Verlinde's emergent gravity from higher dimensions. We also comment on some phenomenological implications, including gravitational wave solutions and MOND limit.

The Search for Dark Matter

ScienceCinema

Orrell, John

2018-05-01

More than 25 years ago, PNNL scientists began the first underground measurements searching for dark matter using specialized radiation detector technology. Dark matter is yet to be discovered says Physicist John L. Orrell.

The Search for Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orrell, John

More than 25 years ago, PNNL scientists began the first underground measurements searching for dark matter using specialized radiation detector technology. Dark matter is yet to be discovered says Physicist John L. Orrell.

Is Dark Matter Similar to the Force?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, Adam; Vranas, Pavlos

When Obi Wan Kenobi explained the Force to Luke Skywalker, he said, "It's an energy field created by all living things. It surrounds us and penetrates us; it binds the galaxy together." The same thing could be said of the invisible, elusive, yet ubiquitous dark matter. Explore the similarities and differences between dark matter and the Force and find out why LLNL studies dark matter.

Dark matter as a cancer hazard

NASA Astrophysics Data System (ADS)

Chashchina, Olga; Silagadze, Zurab

2016-07-01

We comment on the paper ;Dark matter collisions with the human body; by K. Freese and C. Savage (2012) [1] and describe a dark matter model for which the results of the previous paper do not quite apply. Within this mirror dark matter model, potentially hazardous objects, mirror micrometeorites, can exist and may lead to diseases triggered by multiple mutations, such as cancer, though with very low probability.

SuperCDMS - Home

Science.gov Websites

radiation and therefore it cannot be seen, which has earned it the title Dark Matter. Dark matter rest (approximately three quarters) of all the matter and energy in the universe is referred to as dark energy. Dark matter is most commonly hypothesized to be made up of exotic particles such as WIMPS (Weakly

Press Release | News | Page 2

Science.gov Websites

: Attend a Dark Matter Day event October 23, 2017 The world will soon be celebrating the hunt for the universe's most elusive matter in a series of Dark Matter Day events planned in over a dozen countries reveals most accurate measurement of dark matter structure in the universe August 3, 2017 Dark Energy

Press Release | News | Page 3

Science.gov Websites

, technology, engineering and math fields. New world-leading limit on dark matter search from PICO experiment February 27, 2017 The PICO-60 dark matter bubble chamber experiment has produced a new dark matter limit . Construction of world's most sensitive dark matter detector moves forward September 26, 2016 LUX-ZEPLIN (LZ), a

Review of indirect detection of dark matter with neutrinos

NASA Astrophysics Data System (ADS)

Danninger, Matthias

2017-09-01

Dark Matter could be detected indirectly through the observation of neutrinos produced in dark matter self-annihilations or decays. Searches for such neutrino signals have resulted in stringent constraints on the dark matter self-annihilation cross section and the scattering cross section with matter. In recent years these searches have made significant progress in sensitivity through new search methodologies, new detection channels, and through the availability of rich datasets from neutrino telescopes and detectors, like IceCube, ANTARES, Super-Kamiokande, etc. We review recent experimental results and put them in context with respect to other direct and indirect dark matter searches. We also discuss prospects for discoveries at current and next generation neutrino detectors.

Dark photons from the center of the Earth: Smoking-gun signals of dark matter

NASA Astrophysics Data System (ADS)

Feng, Jonathan L.; Smolinsky, Jordan; Tanedo, Philip

2016-01-01

Dark matter may be charged under dark electromagnetism with a dark photon that kinetically mixes with the Standard Model photon. In this framework, dark matter will collect at the center of the Earth and annihilate into dark photons, which may reach the surface of the Earth and decay into observable particles. We determine the resulting signal rates, including Sommerfeld enhancements, which play an important role in bringing the Earth's dark matter population to their maximal, equilibrium value. For dark matter masses mX˜100 GeV - 10 TeV , dark photon masses mA'˜MeV -GeV , and kinetic mixing parameters ɛ ˜1 0-9- 1 0-7 , the resulting electrons, muons, photons, and hadrons that point back to the center of the Earth are a smoking-gun signal of dark matter that may be detected by a variety of experiments, including neutrino telescopes, such as IceCube, and space-based cosmic ray detectors, such as Fermi-LAT and AMS. We determine the signal rates and characteristics and show that large and striking signals—such as parallel muon tracks—are possible in regions of the (mA',ɛ ) plane that are not probed by direct detection, accelerator experiments, or astrophysical observations.

Form factors for dark matter capture by the Sun in effective theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Catena, Riccardo; Schwabe, Bodo

2015-04-24

In the effective theory of isoscalar and isovector dark matter-nucleon interactions mediated by a heavy spin-1 or spin-0 particle, 8 isotope-dependent nuclear response functions can be generated in the dark matter scattering by nuclei. We compute the 8 nuclear response functions for the 16 most abundant elements in the Sun, i.e. H, {sup 3}He, {sup 4}He, {sup 12}C, {sup 14}N, {sup 16}O, {sup 20}Ne, {sup 23}Na, {sup 24}Mg, {sup 27}Al, {sup 28}Si, {sup 32}S, {sup 40}Ar, {sup 40}Ca, {sup 56}Fe, and {sup 59}Ni, through numerical shell model calculations. We use our response functions to compute the rate of dark mattermore » capture by the Sun for all isoscalar and isovector dark matter-nucleon effective interactions, including several operators previously considered for dark matter direct detection only. We study in detail the dependence of the capture rate on specific dark matter-nucleon interaction operators, and on the different elements in the Sun. We find that a so far neglected momentum dependent dark matter coupling to the nuclear vector charge gives a larger contribution to the capture rate than the constant spin-dependent interaction commonly included in dark matter searches at neutrino telescopes. Our investigation lays the foundations for model independent analyses of dark matter induced neutrino signals from the Sun. The nuclear response functions obtained in this study are listed in analytic form in an appendix, ready to be used in other projects.« less

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

PubMed

Appelquist, T; Berkowitz, E; Brower, R C; Buchoff, M I; Fleming, G T; Jin, X-Y; Kiskis, J; Kribs, G D; Neil, E T; Osborn, J C; Rebbi, C; Rinaldi, E; Schaich, D; Schroeder, C; Syritsyn, S; Vranas, P; Weinberg, E; Witzel, O

2015-10-23

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m(B)(6), suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

A small amount of mini-charged dark matter could cool the baryons in the early Universe.

PubMed

Muñoz, Julian B; Loeb, Abraham

2018-05-01

The dynamics of our Universe is strongly influenced by pervasive-albeit elusive-dark matter, with a total mass about five times the mass of all the baryons 1,2 . Despite this, its origin and composition remain a mystery. All evidence for dark matter relies on its gravitational pull on baryons, and thus such evidence does not require any non-gravitational coupling between baryons and dark matter. Nonetheless, some small coupling would explain the comparable cosmic abundances of dark matter and baryons 3 , as well as solving structure-formation puzzles in the pure cold-dark-matter models 4 . A vast array of observations has been unable to find conclusive evidence for any non-gravitational interactions of baryons with dark matter 5-9 . Recent observations by the EDGES collaboration, however, suggest that during the cosmic dawn, roughly 200 million years after the Big Bang, the baryonic temperature was half of its expected value 10 . This observation is difficult to reconcile with the standard cosmological model but could be explained if baryons are cooled down by interactions with dark matter, as expected if their interaction rate grows steeply at low velocities 11 . Here we report that if a small fraction-less than one per cent-of the dark matter has a mini-charge, a million times smaller than the charge on the electron, and a mass in the range of 1-100 times the electron mass, then the data 10 from the EDGES experiment can be explained while remaining consistent with all other observations. We also show that the entirety of the dark matter cannot have a mini-charge.

Direct detection of sub-GeV dark matter with semiconductor targets

DOE PAGES

Essig, Rouven; Fernández-Serra, Marivi; Mardon, Jeremy; ...

2016-05-09

Dark matter in the sub-GeV mass range is a theoretically motivated but largely unexplored paradigm. Such light masses are out of reach for conventional nuclear recoil direct detection experiments, but may be detected through the small ionization signals caused by dark matter-electron scattering. Semiconductors are well-studied and are particularly promising target materials because their O(1 eV) band gaps allow for ionization signals from dark matter particles as light as a few hundred keV. Current direct detection technologies are being adapted for dark matter-electron scattering. In this paper, we provide the theoretical calculations for dark matter-electron scattering rate in semiconductors, overcomingmore » several complications that stem from the many-body nature of the problem. We use density functional theory to numerically calculate the rates for dark matter-electron scattering in silicon and germanium, and estimate the sensitivity for upcoming experiments such as DAMIC and SuperCDMS. We find that the reach for these upcoming experiments has the potential to be orders of magnitude beyond current direct detection constraints and that sub-GeV dark matter has a sizable modulation signal. We also give the first direct detection limits on sub-GeV dark matter from its scattering off electrons in a semiconductor target (silicon) based on published results from DAMIC. We make available publicly our code, QEdark, with which we calculate our results. Our results can be used by experimental collaborations to calculate their own sensitivities based on their specific setup. In conclusion, the searches we propose will probe vast new regions of unexplored dark matter model and parameter space.« less

Toward (finally!) ruling out Z and Higgs mediated dark matter models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escudero, Miguel; Berlin, Asher; Hooper, Dan

2016-12-01

In recent years, direct detection, indirect detection, and collider experiments have placed increasingly stringent constraints on particle dark matter, exploring much of the parameter space associated with the WIMP paradigm. In this paper, we focus on the subset of WIMP models in which the dark matter annihilates in the early universe through couplings to either the Standard Model Z or the Standard Model Higgs boson. Considering fermionic, scalar, and vector dark matter candidates within a model-independent context, we find that the overwhelming majority of these dark matter candidates are already ruled out by existing experiments. In the case of Zmore » mediated dark matter, the only scenarios that are not currently excluded are those in which the dark matter is a fermion with an axial coupling and with a mass either within a few GeV of the Z resonance ( m {sub DM} ≅ m {sub Z} /2) or greater than 200 GeV, or with a vector coupling and with m {sub DM} > 6 TeV . Several Higgs mediated scenarios are currently viable if the mass of the dark matter is near the Higgs pole ( m {sub DM} ≅ m {sub H} /2). Otherwise, the only scenarios that are not excluded are those in which the dark matter is a scalar (vector) heavier than 400 GeV (1160 GeV) with a Higgs portal coupling, or a fermion with a pseudoscalar (CP violating) coupling to the Standard Model Higgs boson. With the exception of dark matter with a purely pseudoscalar coupling to the Higgs, it is anticipated that planned direct detection experiments will probe nearly the entire range of models considered in this study.« less

Toward (finally!) ruling out Z and Higgs mediated dark matter models

DOE PAGES

Escudero, Miguel; Fermi National Accelerator Lab.; Berlin, Asher; ...

2016-12-15

In recent years, direct detection, indirect detection, and collider experiments have placed increasingly stringent constraints on particle dark matter, exploring much of the parameter space associated with the WIMP paradigm. In this paper, we focus on the subset of WIMP models in which the dark matter annihilates in the early universe through couplings to either the Standard Model Z or the Standard Model Higgs boson. Considering fermionic, scalar, and vector dark matter candidates within a model-independent context, we find that the overwhelming majority of these dark matter candidates are already ruled out by existing experiments. In the case of Zmore » mediated dark matter, the only scenarios that are not currently excluded are those in which the dark matter is a fermion with an axial coupling and with a mass either within a few GeV of the Z resonance (m DM ≃ m Z/2) or greater than 200 GeV, or with a vector coupling and with m DM > 6 TeV . Several Higgs mediated scenarios are currently viable if the mass of the dark matter is near the Higgs pole (m DM ≃ m H/2). Otherwise, the only scenarios that are not excluded are those in which the dark matter is a scalar (vector) heavier than 400 GeV (1160 GeV) with a Higgs portal coupling, or a fermion with a pseudoscalar (CP violating) coupling to the Standard Model Higgs boson. Furthermore, with the exception of dark matter with a purely pseudoscalar coupling to the Higgs, it is anticipated that planned direct detection experiments will probe nearly the entire range of models considered in this study.« less

Searching for dark matter with neutron star mergers and quiet kilonovae

NASA Astrophysics Data System (ADS)

Bramante, Joseph; Linden, Tim; Tsai, Yu-Dai

2018-03-01

We identify new astrophysical signatures of dark matter that implodes neutron stars (NSs), which could decisively test whether NS-imploding dark matter is responsible for missing pulsars in the Milky Way galactic center, the source of some r -process elements, and the origin of fast-radio bursts. First, NS-imploding dark matter forms ˜10-10 solar mass or smaller black holes inside neutron stars, which proceed to convert neutron stars into ˜1.5 solar mass black holes (BHs). This decreases the number of neutron star mergers seen by LIGO/Virgo (LV) and associated merger kilonovae seen by telescopes like DES, BlackGEM, and ZTF, instead producing a population of "black mergers" containing ˜1.5 solar mass black holes. Second, dark matter-induced neutron star implosions may create a new kind of kilonovae that lacks a detectable, accompanying gravitational signal, which we call "quiet kilonovae." Using DES data and the Milky Way's r-process abundance, we constrain quiet kilonovae. Third, the spatial distribution of neutron star merger kilonovae and quiet kilonovae in galaxies can be used to detect dark matter. NS-imploding dark matter destroys most neutron stars at the centers of disc galaxies, so that neutron star merger kilonovae would appear mostly in a donut at large radii. We find that as few as ten neutron star merger kilonova events, located to ˜1 kpc precision could validate or exclude dark matter-induced neutron star implosions at 2 σ confidence, exploring dark matter-nucleon cross-sections 4-10 orders of magnitude below current direct detection experimental limits. Similarly, NS-imploding dark matter as the source of fast radio bursts can be tested at 2 σ confidence once 20 bursts are located in host galaxies by radio arrays like CHIME and HIRAX.

Toward (finally!) ruling out Z and Higgs mediated dark matter models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escudero, Miguel; Fermi National Accelerator Lab.; Berlin, Asher

In recent years, direct detection, indirect detection, and collider experiments have placed increasingly stringent constraints on particle dark matter, exploring much of the parameter space associated with the WIMP paradigm. In this paper, we focus on the subset of WIMP models in which the dark matter annihilates in the early universe through couplings to either the Standard Model Z or the Standard Model Higgs boson. Considering fermionic, scalar, and vector dark matter candidates within a model-independent context, we find that the overwhelming majority of these dark matter candidates are already ruled out by existing experiments. In the case of Zmore » mediated dark matter, the only scenarios that are not currently excluded are those in which the dark matter is a fermion with an axial coupling and with a mass either within a few GeV of the Z resonance (m DM ≃ m Z/2) or greater than 200 GeV, or with a vector coupling and with m DM > 6 TeV . Several Higgs mediated scenarios are currently viable if the mass of the dark matter is near the Higgs pole (m DM ≃ m H/2). Otherwise, the only scenarios that are not excluded are those in which the dark matter is a scalar (vector) heavier than 400 GeV (1160 GeV) with a Higgs portal coupling, or a fermion with a pseudoscalar (CP violating) coupling to the Standard Model Higgs boson. Furthermore, with the exception of dark matter with a purely pseudoscalar coupling to the Higgs, it is anticipated that planned direct detection experiments will probe nearly the entire range of models considered in this study.« less

Dark matter directionality revisited with a high pressure xenon gas detector

DOE PAGES

Mohlabeng, Gopolang; Kong, Kyoungchul; Li, Jin; ...

2015-07-20

An observation of the anisotropy of dark matter interactions in a direction-sensitive detector would provide decisive evidence for the discovery of galactic dark matter. Directional information would also provide a crucial input to understanding its distribution in the local Universe. Most of the existing directional dark matter detectors utilize particle tracking methods in a low-pressure gas time projection chamber. These low pressure detectors require excessively large volumes in order to be competitive in the search for physics beyond the current limit. In order to avoid these volume limitations, we consider a novel proposal, which exploits a columnar recombination effect inmore » a high-pressure gas time projection chamber. The ratio of scintillation to ionization signals observed in the detector carries the angular information of the particle interactions. In this paper, we investigate the sensitivity of a future directional detector focused on the proposed high-pressure Xenon gas time projection chamber. We study the prospect of detecting an anisotropy in the dark matter velocity distribution. We find that tens of events are needed to exclude an isotropic distribution of dark matter interactions at 95% confidence level in the most optimistic case with head-to-tail information. However, one needs at least 10-20 times more events without head-to-tail information for light dark matter below ~50 GeV. For an intermediate mass range, we find it challenging to observe an anisotropy of the dark matter distribution. Our results also show that the directional information significantly improves precision measurements of dark matter mass and the elastic scattering cross section for a heavy dark matter.« less

On the effective operators for Dark Matter annihilations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simone, Andrea De; Thamm, Andrea; Monin, Alexander

2013-02-01

We consider effective operators describing Dark Matter (DM) interactions with Standard Model fermions. In the non-relativistic limit of the DM field, the operators can be organized according to their mass dimension and their velocity behaviour, i.e. whether they describe s- or p-wave annihilations. The analysis is carried out for self-conjugate DM (real scalar or Majorana fermion). In this case, the helicity suppression at work in the annihilation into fermions is lifted by electroweak bremsstrahlung. We construct and study all dimension-8 operators encoding such an effect. These results are of interest in indirect DM searches.

Supersymmetric resonant dark matter: A thermal model for the AMS-02 positron excess

NASA Astrophysics Data System (ADS)

Bai, Yang; Berger, Joshua; Lu, Sida

2018-06-01

We construct a thermal dark matter model with annihilation mediated by a resonance to explain the positron excess observed by PAMELA, Fermi-LAT and AMS-02, while satisfying constraints from cosmic microwave background (CMB) measurements. The challenging requirement is that the resonance has twice the dark matter mass to one part in a million. We achieve this by introducing an S U (3 )f dark flavor symmetry that is spontaneously broken to S U (2 )f×U (1 )f . The resonance is the heaviest state in the dark matter flavor multiplet, and the required mass relation is protected by the vacuum structure and supersymmetry from radiative corrections. The pseudo-Nambu-Goldstone bosons (PNGBs) from the dark flavor symmetry breaking can be slightly lighter than one GeV and dominantly decay into two muons just from kinematics, with subsequent decay into positrons. The PNGBs are produced in resonant dark matter semiannihilation, where two dark matter particles annihilate into an anti-dark matter particle and a PNGB. The dark matter mass in our model is constrained to be below around 1.9 TeV from fitting thermal relic abundance, AMS-02 data and CMB constraints. The superpartners of Standard Model (SM) particles can cascade decay into a light PNGB along with SM particles, yielding a correlated signal of this model at colliders. One of the interesting signatures is a resonance of a SM Higgs boson plus two collimated muons, which has superb discovery potential at LHC Run 2.

On the Matter of Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orrell, John L.

The mission of the USS Enterprise was to “boldly go where no one has gone before.” And so it is with Particle Physicist John Orrell as he seeks to solve the conundrum of elusive dark matter. It’s a mystery that PNNL scientists have chased for more than 25 years. And, if dark matter is discovered, it will change our entire understanding of how the universe was formed. The first experiments to locate dark matter were conducted underground using specialized, radiation detector technology developed at PNNL.

Dark matter and electroweak phase transition in the mixed scalar dark matter model

NASA Astrophysics Data System (ADS)

Liu, Xuewen; Bian, Ligong

2018-03-01

We study the electroweak phase transition in the framework of the scalar singlet-doublet mixed dark matter model, in which the particle dark matter candidate is the lightest neutral Higgs that comprises the C P -even component of the inert doublet and a singlet scalar. The dark matter can be dominated by the inert doublet or singlet scalar depending on the mixing. We present several benchmark models to investigate the two situations after imposing several theoretical and experimental constraints. An additional singlet scalar and the inert doublet drive the electroweak phase transition to be strongly first order. A strong first-order electroweak phase transition and a viable dark matter candidate can be accomplished in two benchmark models simultaneously, for which a proper mass splitting among the neutral and charged Higgs masses is needed.

Multiplicative-Generated Dark Matter Accelerated Cosmic Expansion

NASA Astrophysics Data System (ADS)

Zhang, Weijia; Kelly, Neil

2011-02-01

In order to make the increase of Astronomical Unit consistent with observations of the Earth's orbital period variation, an increase of the Solar dark matter as 10-12/yr is needed. This implies that dark matter has an increase ratio, and therefore supports Dirac's multiplicative matter creation, and provides another explanation to the accelerating expansion of the universe. This is in accordance with the analysis on orbital dynamics around a mass varying central body to the phenomenon of accretion of dark matter assumed not self-annihilating-on the Sun and the major bodies of the solar system due to its motion throughout the Milky Way halo. Dark matter and dark energy, two of the most vexing problems in science today which dominate the universe, comprising some 96 percent of all mass and energy, seem to be two sides of the same coin.

A New Target Object for Constraining Annihilating Dark Matter

NASA Astrophysics Data System (ADS)

Chan, Man Ho

2017-07-01

In the past decade, gamma-ray observations and radio observations of our Milky Way and the Milky Way dwarf spheroidal satellite galaxies put very strong constraints on annihilation cross sections of dark matter. In this paper, we suggest a new target object (NGC 2976) that can be used for constraining annihilating dark matter. The radio and X-ray data of NGC 2976 can put very tight constraints on the leptophilic channels of dark matter annihilation. The lower limits of dark matter mass annihilating via {e}+{e}-, {μ }+{μ }-, and {τ }+{τ }- channels are 200 GeV, 130 GeV, and 110 GeV, respectively, with the canonical thermal relic cross section. We suggest that this kind of large nearby dwarf galaxy with a relatively high magnetic field can be a good candidate for constraining annihilating dark matter in future analyses.

Gravitational waves in cold dark matter

NASA Astrophysics Data System (ADS)

Flauger, Raphael; Weinberg, Steven

2018-06-01

We study the effects of cold dark matter on the propagation of gravitational waves of astrophysical and primordial origin. We show that the dominant effect of cold dark matter on gravitational waves from astrophysical sources is a small frequency dependent modification of the propagation speed of gravitational waves. However, the magnitude of the effect is too small to be detected in the near future. We furthermore show that the spectrum of primordial gravitational waves in principle contains detailed information about the properties of dark matter. However, depending on the wavelength, the effects are either suppressed because the dark matter is highly nonrelativistic or because it contributes a small fraction of the energy density of the universe. As a consequence, the effects of cold dark matter on primordial gravitational waves in practice also appear too small to be detectable.

Beyond the bump-hunt: A game plan for discovering dynamical dark matter at the LHC

NASA Astrophysics Data System (ADS)

Dienes, Keith R.; Su, Shufang; Thomas, Brooks

2016-06-01

Dynamical Dark Matter (DDM) is an alternative framework for dark-matter physics in which an ensemble of individual constituent fields with a spectrum of masses, lifetimes, and cosmological abundances collectively constitute the dark-matter candidate, and in which the traditional notion of dark-matter stability is replaced by a balancing between lifetimes and abundances across the ensemble. In this talk, we discuss the prospects for distinguishing between DDM ensembles and traditional dark-matter candidates at hadron colliders - and in particular, at the upgraded LHC - via the analysis of event-shape distributions of kine-matic variables. We also examine the correlations between these kinematic variables and other relevant collider variables in order to assess how imposing cuts on these additional variables may distort - for better or worse - their event-shape distributions.

Simplified phenomenology for colored dark sectors

NASA Astrophysics Data System (ADS)

El Hedri, Sonia; Kaminska, Anna; de Vries, Maikel; Zurita, Jose

2017-04-01

We perform a general study of the relic density and LHC constraints on simplified models where the dark matter coannihilates with a strongly interacting particle X. In these models, the dark matter depletion is driven by the self-annihilation of X to pairs of quarks and gluons through the strong interaction. The phenomenology of these scenarios therefore only depends on the dark matter mass and the mass splitting between dark matter and X as well as the quantum numbers of X. In this paper, we consider simplified models where X can be either a scalar, a fermion or a vector, as well as a color triplet, sextet or octet. We compute the dark matter relic density constraints taking into account Sommerfeld corrections and bound state formation. Furthermore, we examine the restrictions from thermal equilibrium, the lifetime of X and the current and future LHC bounds on X pair production. All constraints are comprehensively presented in the mass splitting versus dark matter mass plane. While the relic density constraints can lead to upper bounds on the dark matter mass ranging from 2 TeV to more than 10 TeV across our models, the prospective LHC bounds range from 800 to 1500 GeV. A full coverage of the strongly coannihilating dark matter parameter space would therefore require hadron colliders with significantly higher center-of-mass energies.

Multi-component dark matter through a radiative Higgs portal

DOE PAGES

DiFranzo, Anthony; Univ. of California, Irvine, CA; Rutgers Univ., Piscataway, NJ; ...

2017-01-18

Here, we study a multi-component dark matter model where interactions with the Standard Model are primarily via the Higgs boson. The model contains vector-like fermions charged undermore » $$SU(2)_W \\times U(1)_Y$$ and under the dark gauge group, $$U(1)^\\prime$$. This results in two dark matter candidates. A spin-1 and a spin-1/2 candidate, which have loop and tree-level couplings to the Higgs, respectively. We explore the resulting effect on the dark matter relic abundance, while also evaluating constraints on the Higgs invisible width and from direct detection experiments. Generally, we find that this model is highly constrained when the fermionic candidate is the predominant fraction of the dark matter relic abundance.« less

The dark side of cosmology: dark matter and dark energy.

PubMed

Spergel, David N

2015-03-06

A simple model with only six parameters (the age of the universe, the density of atoms, the density of matter, the amplitude of the initial fluctuations, the scale dependence of this amplitude, and the epoch of first star formation) fits all of our cosmological data . Although simple, this standard model is strange. The model implies that most of the matter in our Galaxy is in the form of "dark matter," a new type of particle not yet detected in the laboratory, and most of the energy in the universe is in the form of "dark energy," energy associated with empty space. Both dark matter and dark energy require extensions to our current understanding of particle physics or point toward a breakdown of general relativity on cosmological scales. Copyright © 2015, American Association for the Advancement of Science.

Radial dependence of the dark matter distribution in M33

NASA Astrophysics Data System (ADS)

López Fune, E.; Salucci, P.; Corbelli, E.

2017-06-01

The stellar and gaseous mass distributions, as well as the extended rotation curve, in the nearby galaxy M33 are used to derive the radial distribution of dark matter density in the halo and to test cosmological models of galaxy formation and evolution. Two methods are examined to constrain the dark mass density profiles. The first method deals directly with fitting the rotation curve data in the range of galactocentric distances 0.24 ≤ r ≤ 22.72 kpc. Using the results of collisionless Λ cold dark matter numerical simulations, we confirm that the Navarro-Frenkel-White (NFW) dark matter profile provides a better fit to the rotation curve data than the cored Burkert profile (BRK) profile. The second method relies on the local equation of centrifugal equilibrium and on the rotation curve slope. In the aforementioned range of distances, we fit the observed velocity profile, using a function that has a rational dependence on the radius, and we derive the slope of the rotation curve. Then, we infer the effective matter densities. In the radial range 9.53 ≤ r ≤ 22.72 kpc, the uncertainties induced by the luminous matter (stars and gas) become negligible, because the dark matter density dominates, and we can determine locally the radial distribution of dark matter. With this second method, we tested the NFW and BRK dark matter profiles and we can confirm that both profiles are compatible with the data, even though in this case the cored BRK density profile provides a more reasonable value for the baryonic-to-dark matter ratio.

Dark matter universe

PubMed Central

Bahcall, Neta A.

2015-01-01

Most of the mass in the universe is in the form of dark matter—a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations—from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is “cold” (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology—a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)—fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle. PMID:26417091

Healthy imperfect dark matter from effective theory of mimetic cosmological perturbations

NASA Astrophysics Data System (ADS)

Hirano, Shin'ichi; Nishi, Sakine; Kobayashi, Tsutomu

2017-07-01

We study the stability of a recently proposed model of scalar-field matter called mimetic dark matter or imperfect dark matter. It has been known that mimetic matter with higher derivative terms suffers from gradient instabilities in scalar perturbations. To seek for an instability-free extension of imperfect dark matter, we develop an effective theory of cosmological perturbations subject to the constraint on the scalar field's kinetic term. This is done by using the unifying framework of general scalar-tensor theories based on the ADM formalism. We demonstrate that it is indeed possible to construct a model of imperfect dark matter which is free from ghost and gradient instabilities. As a side remark, we also show that mimetic F(Script R) theory is plagued with the Ostrogradsky instability.

Indirect dark matter signatures in the cosmic dark ages. I. Generalizing the bound on s -wave dark matter annihilation from Planck results

NASA Astrophysics Data System (ADS)

Slatyer, Tracy R.

2016-01-01

Recent measurements of the cosmic microwave background (CMB) anisotropies by Planck provide a sensitive probe of dark matter annihilation during the cosmic dark ages, and specifically constrain the annihilation parameter feff⟨σ v ⟩/mχ. Using new results (paper II) for the ionization produced by particles injected at arbitrary energies, we calculate and provide feff values for photons and e+e- pairs injected at keV-TeV energies; the feff value for any dark matter model can be obtained straightforwardly by weighting these results by the spectrum of annihilation products. This result allows the sensitive and robust constraints on dark matter annihilation presented by the Planck collaboration to be applied to arbitrary dark matter models with s -wave annihilation. We demonstrate the validity of this approach using principal component analysis. As an example, we integrate over the spectrum of annihilation products for a range of Standard Model final states to determine the CMB bounds on these models as a function of dark matter mass, and demonstrate that the new limits generically exclude models proposed to explain the observed high-energy rise in the cosmic ray positron fraction. We make our results publicly available at http://nebel.rc.fas.harvard.edu/epsilon.

Dark matter reflection of particle symmetry

NASA Astrophysics Data System (ADS)

Khlopov, Maxim Yu.

2017-05-01

In the context of the relationship between physics of cosmological dark matter and symmetry of elementary particles, a wide list of dark matter candidates is possible. New symmetries provide stability of different new particles and their combination can lead to a multicomponent dark matter. The pattern of symmetry breaking involves phase transitions in the very early Universe, extending the list of candidates by topological defects and even primordial nonlinear structures.

Clumpy cold dark matter

NASA Technical Reports Server (NTRS)

Silk, Joseph; Stebbins, Albert

1993-01-01

A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

Simulated Milky Way analogues: implications for dark matter direct searches

NASA Astrophysics Data System (ADS)

Bozorgnia, Nassim; Calore, Francesca; Schaller, Matthieu; Lovell, Mark; Bertone, Gianfranco; Frenk, Carlos S.; Crain, Robert A.; Navarro, Julio F.; Schaye, Joop; Theuns, Tom

2016-05-01

We study the implications of galaxy formation on dark matter direct detection using high resolution hydrodynamic simulations of Milky Way-like galaxies simulated within the EAGLE and APOSTLE projects. We identify Milky Way analogues that satisfy observational constraints on the Milky Way rotation curve and total stellar mass. We then extract the dark matter density and velocity distribution in the Solar neighbourhood for this set of Milky Way analogues, and use them to analyse the results of current direct detection experiments. For most Milky Way analogues, the event rates in direct detection experiments obtained from the best fit Maxwellian distribution (with peak speed of 223-289 km/s) are similar to those obtained directly from the simulations. As a consequence, the allowed regions and exclusion limits set by direct detection experiments in the dark matter mass and spin-independent cross section plane shift by a few GeV compared to the Standard Halo Model, at low dark matter masses. For each dark matter mass, the halo-to-halo variation of the local dark matter density results in an overall shift of the allowed regions and exclusion limits for the cross section. However, the compatibility of the possible hints for a dark matter signal from DAMA and CDMS-Si and null results from LUX and SuperCDMS is not improved.

A fresh look into the interacting dark matter scenario

NASA Astrophysics Data System (ADS)

Escudero, Miguel; Lopez-Honorez, Laura; Mena, Olga; Palomares-Ruiz, Sergio; Villanueva-Domingo, Pablo

2018-06-01

The elastic scattering between dark matter particles and radiation represents an attractive possibility to solve a number of discrepancies between observations and standard cold dark matter predictions, as the induced collisional damping would imply a suppression of small-scale structures. We consider this scenario and confront it with measurements of the ionization history of the Universe at several redshifts and with recent estimates of the counts of Milky Way satellite galaxies. We derive a conservative upper bound on the dark matter-photon elastic scattering cross section of σγ DM < 8 × 10‑10 σT (mDM/GeV) at 95% CL, about one order of magnitude tighter than previous constraints from satellite number counts. Due to the strong degeneracies with astrophysical parameters, the bound on the dark matter-photon scattering cross section derived here is driven by the estimate of the number of Milky Way satellite galaxies. Finally, we also argue that future 21 cm probes could help in disentangling among possible non-cold dark matter candidates, such as interacting and warm dark matter scenarios. Let us emphasize that bounds of similar magnitude to the ones obtained here could be also derived for models with dark matter-neutrino interactions and would be as constraining as the tightest limits on such scenarios.

Hidden Sector Dark Matter Models for the Galactic Center Gamma-Ray Excess

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berlin, Asher; Gratia, Pierre; Hooper, Dan

2014-07-24

The gamma-ray excess observed from the Galactic Center can be interpreted as dark matter particles annihilating into Standard Model fermions with a cross section near that expected for a thermal relic. Although many particle physics models have been shown to be able to account for this signal, the fact that this particle has not yet been observed in direct detection experiments somewhat restricts the nature of its interactions. One way to suppress the dark matter's elastic scattering cross section with nuclei is to consider models in which the dark matter is part of a hidden sector. In such models, themore » dark matter can annihilate into other hidden sector particles, which then decay into Standard Model fermions through a small degree of mixing with the photon, Z, or Higgs bosons. After discussing the gamma-ray signal from hidden sector dark matter in general terms, we consider two concrete realizations: a hidden photon model in which the dark matter annihilates into a pair of vector gauge bosons that decay through kinetic mixing with the photon, and a scenario within the generalized NMSSM in which the dark matter is a singlino-like neutralino that annihilates into a pair of singlet Higgs bosons, which decay through their mixing with the Higgs bosons of the MSSM.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, K.; Itow, Y.; Rott, C., E-mail: koun@stelab.nagoya-u.ac.jp, E-mail: rott@skku.edu, E-mail: itow@stelab.nagoya-u.ac.jp

Dark matter could be captured in the Sun and self-annihilate, giving rise to an observable neutrino flux. Indirect searches for dark matter looking for this signal with neutrino telescopes have resulted in tight constraints on the interaction cross-section of dark matter with ordinary matter. We investigate how robust limits are against astro-physical uncertainties. We study the effect of the velocity distribution of dark matter in our Galaxy on capture rates in the Sun. We investigate four sources of uncertainties: orbital speed of the Sun, escape velocity of dark matter from the halo, dark matter velocity distribution functions and existence ofmore » a dark disc. We find that even extreme cases currently discussed do not decrease the sensitivity of indirect detection significantly because the capture is achieved over a broad range of the velocity distribution by integration over the velocity distribution. The effect of the uncertainty in the high-velocity tail of dark matter halo is very marginal as the capture process is rather inefficient at this region. The difference in capture rate in the Sun for various scenarios is compared to the expected change in event rates for direct detection. The possibility of co-rotating structure with the Sun can largely boost the signal and hence makes the interpretation of indirect detection conservative compared to direct detection.« less

Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope

DOE PAGES

Ackermann, M.; Albert, A.; Anderson, B.; ...

2014-02-11

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 γ rays. We report on γ -ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in γ rays, and we present γ -ray flux upper limits between 500 MeVmore » and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. Furthermore, we set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We also find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse γ -ray background modeling, and assumed dark matter density profile.« less

Indirect detection of neutrino portal dark matter

NASA Astrophysics Data System (ADS)

Batell, Brian; Han, Tao; Shams Es Haghi, Barmak

2018-05-01

We investigate the feasibility of the indirect detection of dark matter in a simple model using the neutrino portal. The model is very economical, with right-handed neutrinos generating neutrino masses through the type-I seesaw mechanism and simultaneously mediating interactions with dark matter. Given the small neutrino Yukawa couplings expected in a type-I seesaw, direct detection and accelerator probes of dark matter in this scenario are challenging. However, dark matter can efficiently annihilate to right-handed neutrinos, which then decay via active-sterile mixing through the weak interactions, leading to a variety of indirect astronomical signatures. We derive the existing constraints on this scenario from Planck cosmic microwave background measurements, Fermi dwarf spheroidal galaxy and Galactic center gamma-ray observations, and AMS-02 antiproton observations, and we also discuss the future prospects of Fermi and the Cherenkov Telescope Array. Thermal annihilation rates are already being probed for dark matter lighter than about 50 GeV, and this can be extended to dark matter masses of 100 GeV and beyond in the future. This scenario can also provide a dark matter interpretation of the Fermi Galactic center gamma-ray excess, and we confront this interpretation with other indirect constraints. Finally we discuss some of the exciting implications of extensions of the minimal model with large neutrino Yukawa couplings and Higgs portal couplings.

Dark matter and alternative recipes for the missing mass

NASA Astrophysics Data System (ADS)

Tortora, Crescenzo; Jetzer, Philippe; Napolitano, Nicola R.

2012-03-01

Within the standard cosmological scenario the Universe is found to be filled by obscure components (dark matter and dark energy) for ~ 95% of its energy budget. In particular, almost all the matter content in the Universe is given by dark matter, which dominates the mass budget and drives the dynamics of galaxies and clusters of galaxies. Unfortunately, dark matter and dark energy have not been detected and no direct or indirected observations have allowed to prove their existence and amount. For this reason, some authors have suggested that a modification of Einstein Relativity or the change of the Newton's dynamics law (within a relativistic and classical framework, respectively) could allow to replace these unobserved components. We will start discussing the role of dark matter in the early-type galaxies, mainly in their central regions, investigating how its content changes as a function of the mass and the size of each galaxy and few considerations about the stellar Initial mass function have been made. In the second part of the paper we have described, as examples, some ways to overcome the dark matter hypothesis, by fitting to the observations the modified dynamics coming out from general relativistic extended theories and the MOdyfled Newtonian dynamics (MOND).

Constraints on cosmological dark matter annihilation from the Fermi-LAT isotropic diffuse gamma-ray measurement

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-04-01

The first published Fermi large area telescope (Fermi-LAT) measurement of the isotropic diffuse gamma-ray emission is in good agreement with a single power law, and is not showing any signature of a dominant contribution from dark matter sources in the energy range from 20 to 100 GeV. Here, we use the absolute size and spectral shape of this measured flux to derive cross section limits on three types of generic dark matter candidates: annihilating into quarks, charged leptons and monochromatic photons. Predicted gamma-ray fluxes from annihilating dark matter are strongly affected by the underlying distribution of dark matter, and bymore » using different available results of matter structure formation we assess these uncertainties. We also quantify how the dark matter constraints depend on the assumed conventional backgrounds and on the Universe's transparency to high-energy gamma-rays. In reasonable background and dark matter structure scenarios (but not in all scenarios we consider) it is possible to exclude models proposed to explain the excess of electrons and positrons measured by the Fermi-LAT and PAMELA experiments. Derived limits also start to probe cross sections expected from thermally produced relics (e.g. in minimal supersymmetry models) annihilating predominantly into quarks. Finally, for the monochromatic gamma-ray signature, the current measurement constrains only dark matter scenarios with very strong signals.« less

The Mysterious Universe - Exploring Our World with Particle Accelerators

ScienceCinema

Brau, James E [University of Oregon

2018-04-24

The universe is dark and mysterious, more so than even Einstein imagined. While modern science has established deep understanding of ordinary matter, unidentified elements ("Dark Matter" and "Dark Energy") dominate the structure of the universe, its behavior and its destiny. What are these curious elements? We are now working on answers to these and other challenging questions posed by the universe with experiments at particle accelerators on Earth. Results of this research may revolutionize our view of nature as dramatically as the advances of Einstein and other quantum pioneers one hundred years ago. Professor Brau will explain for the general audience the mysteries, introduce facilities which explore them experimentally and discuss our current understanding of the underlying science. The presentation is at an introductory level, appropriate for anyone interested in physics and astronomy.

Dark Matter Reality Check: Chandra Casts Cloud On Alternative Theory

NASA Astrophysics Data System (ADS)

2002-10-01

New evidence from NASA's Chandra X-ray Observatory challenges an alternative theory of gravity that eliminates the need for dark matter. The observation also narrows the field for competing forms of dark matter, the elusive material thought to be the dominant form of matter in the universe. An observation of the galaxy NGC 720 shows it is enveloped in a slightly flattened, or ellipsoidal cloud of hot gas that has an orientation different from that of the optical image of the galaxy. The flattening is too large to be explained by theories in which stars and gas are assumed to contain most of the mass in the galaxy. "The shape and orientation of the hot gas cloud require it to be confined by an egg-shaped dark matter halo," said David Buote of the University of California, Irvine, and lead author of a report on this research in the 2002 September 20 issue of The Astrophysical Journal. "This means that dark matter is not just an illusion due to a shortcoming of the standard theory of gravity - it is real." According to the generally accepted standard theory of gravity, the hot X-ray cloud would need an additional source of gravity - a halo of dark matter - to keep the hot gas from expanding away. The mass of dark matter required would be about five to ten times the mass of the stars in the galaxy. If the dark matter tracked the optical light from the stars in the galaxy, the hot X-ray cloud would be more round than it is. The flattened shape of the hot gas cloud requires a flattened dark matter halo. An alternative theory of gravity called MOND, for Modified Newtonian Dynamics, was proposed in 1983 by Mordecai Milgrom of the Weizmann Institute in Israel, and has remained viable over the years. MOND does away with the need for dark matter by modifying the theory where the acceleration produced by gravity is very small, such as the outskirts of galaxies. However, MOND cannot explain the Chandra observation of NGC 720. This is apparently the first dynamical evidence that has successfully distinguished dark matter from MOND. The researchers also found that the Chandra data fit predictions of the cold dark matter theories, according to which dark matter consists of slowly moving particles, which interact with each other and "normal" matter only through gravity. Other forms of dark matter, such as self-interacting dark matter, and cold molecular dark matter, are not consistent with the observation in that they require a dark matter halo that is too round or too flat, respectively. "Chandra's ability to precisely identify and locate the point-like sources contaminating the diffuse emission in the X-ray image was absolutely essential," said Buote. "Only then could we make accurate measurements of the shape and orientation of the X-ray image contours." The conclusion from the Chandra data that NGC 720 possesses a dark matter halo assumes that the hot gas cloud has not been unduly disturbed by collisions or mergers with other galaxies in the last 100 million years. The lack of evidence of such activity indicates that this assumption is valid. Chandra observed NGC 720, which is about 80 million light years from Earth, for 11 hours with the Advanced CCD Imaging Spectrometer (ACIS). Other members of the team include Tesla Jeltema and Claude Canizares of Massachusetts Institute of Technology (MIT) in Cambridge, and Gordon Garmire of Pennsylvania State University in University Park. Penn State and MIT developed the instrument for NASA. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program, and TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass.

Big Questions: Dark Matter

ScienceCinema

Lincoln, Don

2018-01-16

Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.

The Preferential Tidal Stripping of Dark Matter versus Stars in Galaxies

NASA Astrophysics Data System (ADS)

Smith, Rory; Choi, Hoseung; Lee, Jaehyun; Rhee, Jinsu; Sanchez-Janssen, Ruben; Yi, Sukyoung K.

2016-12-01

Using high-resolution hydrodynamical cosmological simulations, we conduct a comprehensive study of how tidal stripping removes dark matter and stars from galaxies. We find that dark matter is always stripped far more significantly than the stars—galaxies that lose ˜80% of their dark matter, typically lose only 10% of their stars. This is because the dark matter halo is initially much more extended than the stars. As such, we find that the stellar-to-halo size-ratio (measured using r eff/r vir) is a key parameter controlling the relative amounts of dark matter and stellar stripping. We use simple fitting formulae to measure the relation between the fraction of bound dark matter and the fraction of bound stars. We measure a negligible dependence on cluster mass or galaxy mass. Therefore, these formulae have general applicability in cosmological simulations, and are ideal to improve stellar stripping recipes in semi-analytical models, and/or to estimate the impact that tidal stripping would have on galaxies when only their halo mass evolution is known.

Cogenerating and pre-annihilating dark matter by a new gauge interaction in a unified model

DOE PAGES

Barr, S. M.; Scherrer, Robert J.

2016-05-31

Here, grand unified theories based on large groups (with rank ≥ 6) are a natural context for dark matter models. They contain Standard-Model-singlet fermions that could be dark matter candidates, and can contain new non-abelian interactions whose sphalerons convert baryons, leptons, and dark matter into each other, ''cogenerating" a dark matter asymmetry comparable to the baryon asymmetry. In this paper it is shown that the same non-abelian interactions can ''pre-annihilate" the symmetric component of heavy dark matter particles χ, which then decay late into light stable dark matter particles ζ that inherit their asymmetry. We derive cosmological constraints on themore » parameters of such models. The mass of χ must be < 3000 TeV and their decays must happen when 2 × 10 –7 < T dec/mχ < 10 –4. It is shown that such decays can come from d=5 operators with coefficients of order 1/MGUT or 1/M Pℓ. We present a simple realization of our model based on the group SU(7).« less

Dark matter dynamics in Abell 3827: new data consistent with standard cold dark matter

NASA Astrophysics Data System (ADS)

Massey, Richard; Harvey, David; Liesenborgs, Jori; Richard, Johan; Stach, Stuart; Swinbank, Mark; Taylor, Peter; Williams, Liliya; Clowe, Douglas; Courbin, Frédéric; Edge, Alastair; Israel, Holger; Jauzac, Mathilde; Joseph, Rémy; Jullo, Eric; Kitching, Thomas D.; Leonard, Adrienne; Merten, Julian; Nagai, Daisuke; Nightingale, James; Robertson, Andrew; Romualdez, Luis Javier; Saha, Prasenjit; Smit, Renske; Tam, Sut-Ieng; Tittley, Eric

2018-06-01

We present integral field spectroscopy of galaxy cluster Abell 3827, using Atacama Large Millimetre Array (ALMA) and Very Large Telescope/Multi-Unit Spectroscopic Explorer. It reveals an unusual configuration of strong gravitational lensing in the cluster core, with at least seven lensed images of a single background spiral galaxy. Lens modelling based on Hubble Space Telescope imaging had suggested that the dark matter associated with one of the cluster's central galaxies may be offset. The new spectroscopic data enable better subtraction of foreground light, and better identification of multiple background images. The inferred distribution of dark matter is consistent with being centred on the galaxies, as expected by Λ cold dark matter. Each galaxy's dark matter also appears to be symmetric. Whilst, we do not find an offset between mass and light (suggestive of self-interacting dark matter) as previously reported, the numerical simulations that have been performed to calibrate Abell 3827 indicate that offsets and asymmetry are still worth looking for in collisions with particular geometries. Meanwhile, ALMA proves exceptionally useful for strong lens image identifications.

Nonstandard Yukawa couplings and Higgs portal dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishara, Fady; Brod, Joachim; Uttayarat, Patipan

We study the implications of non-standard Higgs Yukawa couplings to light quarks on Higgs-portal dark matter phenomenology. Saturating the present experimental bounds on up-quark, down-quark, or strange-quark Yukawa couplings, the predicted direct dark matter detection scattering rate can increase by up to four orders of magnitude. The effect on the dark matter annihilation cross-section, on the other hand, is subleading unless the dark matter is very light — a scenario that is already excluded by measurements of the Higgs invisible decay width. We investigate the expected size of corrections in multi-Higgs-doublet models with natural flavor conservation, the type-II two-Higgs-doublet model,more » the Giudice-Lebedev model of light quark masses, minimal flavor violation new physics models, Randall-Sundrum, and composite Higgs models. We find that an enhancement in the dark matter scattering rate of an order of magnitude is possible. In conclusion, we point out that a discovery of Higgs-portal dark matter could lead to interesting bounds on the light-quark Yukawa couplings.« less

Fermion dark matter in gauge-Higgs unification

DOE PAGES

Maru, Nobuhito; Miyaji, Takashi; Okada, Nobuchika; ...

2017-07-11

Here, we propose a Majorana fermion dark matter in the context of a s imple gauge-Higgs Unification (GHU) scenario based on the gauge group SU(3)×U(1)' in 5-dimensional Minkowski space with a compactification of the 5th dimension on S 1/Z 2 orbifold. The dark matter particle is identified with the lightest mode in SU(3) triplet fermions additionally introduced in the 5-dimensional bulk. We find an allowed parameter region for the dark matter mass around a half of the Standard Model Higgs boson mass, which is consistent with the observed dark matter density and the constraint from the LUX 2016 result formore » the direct dark matter search. The entire allowed region will be covered by, for example, the LUX-ZEPLIN dark matter experiment in the near future. We also show that in the presence of the bulk SU(3) triplet fermions the 125 GeV Higgs boson mas s is reproduced through the renormalization group evolution of Higgs quartic coupling with the compactification scale of around 10 8 GeV.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.

A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector ismore » cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.« less

Enlightening Students about Dark Matter

NASA Astrophysics Data System (ADS)

Hamilton, Kathleen; Barr, Alex; Eidelman, Dave

2018-01-01

Dark matter pervades the universe. While it is invisible to us, we can detect its influence on matter we can see. To illuminate this concept, we have created an interactive javascript program illustrating predictions made by six different models for dark matter distributions in galaxies. Students are able to match the predicted data with actual experimental results, drawn from several astronomy papers discussing dark matter’s impact on galactic rotation curves. Programming each new model requires integration of density equations with parameters determined by nonlinear curve-fitting using MATLAB scripts we developed. Using our javascript simulation, students can determine the most plausible dark matter models as well as the average percentage of dark matter lurking in galaxies, areas where the scientific community is still continuing to research. In that light, we strive to use the most up-to-date and accepted concepts: two of our dark matter models are the pseudo-isothermal halo and Navarro-Frenk-White, and we integrate out to each galaxy’s virial radius. Currently, our simulation includes NGC3198, NGC2403, and our own Milky Way.

Constraining particle dark matter using local galaxy distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ando, Shin’ichiro; Ishiwata, Koji

It has been long discussed that cosmic rays may contain signals of dark matter. In the last couple of years an anomaly of cosmic-ray positrons has drawn a lot of attentions, and recently an excess in cosmic-ray anti-proton has been reported by AMS-02 collaboration. Both excesses may indicate towards decaying or annihilating dark matter with a mass of around 1–10 TeV. In this article we study the gamma rays from dark matter and constraints from cross correlations with distribution of galaxies, particularly in a local volume. We find that gamma rays due to inverse-Compton process have large intensity, and hencemore » they give stringent constraints on dark matter scenarios in the TeV scale mass regime. Taking the recent developments in modeling astrophysical gamma-ray sources as well as comprehensive possibilities of the final state products of dark matter decay or annihilation into account, we show that the parameter regions of decaying dark matter that are suggested to explain the excesses are excluded. We also discuss the constrains on annihilating scenarios.« less

Nonstandard Yukawa couplings and Higgs portal dark matter

DOE PAGES

Bishara, Fady; Brod, Joachim; Uttayarat, Patipan; ...

2016-01-04

We study the implications of non-standard Higgs Yukawa couplings to light quarks on Higgs-portal dark matter phenomenology. Saturating the present experimental bounds on up-quark, down-quark, or strange-quark Yukawa couplings, the predicted direct dark matter detection scattering rate can increase by up to four orders of magnitude. The effect on the dark matter annihilation cross-section, on the other hand, is subleading unless the dark matter is very light — a scenario that is already excluded by measurements of the Higgs invisible decay width. We investigate the expected size of corrections in multi-Higgs-doublet models with natural flavor conservation, the type-II two-Higgs-doublet model,more » the Giudice-Lebedev model of light quark masses, minimal flavor violation new physics models, Randall-Sundrum, and composite Higgs models. We find that an enhancement in the dark matter scattering rate of an order of magnitude is possible. In conclusion, we point out that a discovery of Higgs-portal dark matter could lead to interesting bounds on the light-quark Yukawa couplings.« less

SENSEI: First Direct-Detection Constraints on sub-GeV Dark Matter from a Surface Run

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crisler, Michael; Essig, Rouven; Estrada, Juan

The Sub-Electron-Noise Skipper CCD Experimental Instrument (SENSEI) uses the recently developed Skipper-CCD technology to search for electron recoils from the interaction of sub-GeV dark matter particles with electrons in silicon. We report first results from a prototype SENSEI detector, which collected 0.019 gram-days of commissioning data above ground at Fermi National Accelerator Laboratory. These commissioning data are sufficient to set new direct-detection constraints for dark matter particles with masses between ~500 keV and 4 MeV. Moreover, since these data were taken on the surface, they disfavor previously allowed strongly interacting dark matter particles with masses between ~500 keV and amore » few hundred MeV. We discuss the implications of these data for several dark matter candidates, including one model proposed to explain the anomalously large 21-cm signal observed by the EDGES Collaboration. SENSEI is the first experiment dedicated to the search for electron recoils from dark matter, and these results demonstrate the power of the Skipper-CCD technology for dark matter searches.« less

Indirect detection constraints on s- and t-channel simplified models of dark matter

NASA Astrophysics Data System (ADS)

Carpenter, Linda M.; Colburn, Russell; Goodman, Jessica; Linden, Tim

2016-09-01

Recent Fermi-LAT observations of dwarf spheroidal galaxies in the Milky Way have placed strong limits on the gamma-ray flux from dark matter annihilation. In order to produce the strongest limit on the dark matter annihilation cross section, the observations of each dwarf galaxy have typically been "stacked" in a joint-likelihood analysis, utilizing optical observations to constrain the dark matter density profile in each dwarf. These limits have typically been computed only for singular annihilation final states, such as b b ¯ or τ+τ- . In this paper, we generalize this approach by producing an independent joint-likelihood analysis to set constraints on models where the dark matter particle annihilates to multiple final-state fermions. We interpret these results in the context of the most popular simplified models, including those with s- and t-channel dark matter annihilation through scalar and vector mediators. We present our results as constraints on the minimum dark matter mass and the mediator sector parameters. Additionally, we compare our simplified model results to those of effective field theory contact interactions in the high-mass limit.

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.; Ajello, M.; /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC

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. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10{sup -26} cm{sup 3} s{sup -1} at 5 GeV to about 5 x 10{supmore » -23} cm{sup 3} s{sup -1} at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section ({approx}3 x 10{sup -26} cm{sup 3} s{sup -1} for a purely s-wave cross section), without assuming additional boost factors.« less

Constraining dark matter models from a combined analysis of Milky Way satellites with the Fermi Large Area Telescope.

PubMed

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

2011-12-09

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. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10(-26)  cm3  s(-1) at 5 GeV to about 5×10(-23)   cm3  s(-1) at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (∼3×10(-26)  cm3  s(-1) for a purely s-wave cross section), without assuming additional boost factors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aurich, R.; Lustig, S., E-mail: ralf.aurich@uni-ulm.de, E-mail: sven.lustig@uni-ulm.de

Early-matter-like dark energy is defined as a dark energy component whose equation of state approaches that of cold dark matter (CDM) at early times. Such a component is an ingredient of unified dark matter (UDM) models, which unify the cold dark matter and the cosmological constant of the ΛCDM concordance model into a single dark fluid. Power series expansions in conformal time of the perturbations of the various components for a model with early-matter-like dark energy are provided. They allow the calculation of the cosmic microwave background (CMB) anisotropy from the primordial initial values of the perturbations. For a phenomenologicalmore » UDM model, which agrees with the observations of the local Universe, the CMB anisotropy is computed and compared with the CMB data. It is found that a match to the CMB observations is possible if the so-called effective velocity of sound c{sub eff} of the early-matter-like dark energy component is very close to zero. The modifications on the CMB temperature and polarization power spectra caused by varying the effective velocity of sound are studied.« less

Dark matter admixed strange quark stars in the Starobinsky model

NASA Astrophysics Data System (ADS)

Lopes, Ilídio; Panotopoulos, Grigoris

2018-01-01

We compute the mass-to-radius profiles for dark matter admixed strange quark stars in the Starobinsky model of modified gravity. For quark matter, we assume the MIT bag model, while self-interacting dark matter inside the star is modeled as a Bose-Einstein condensate with a polytropic equation of state. We numerically integrate the structure equations in the Einstein frame, adopting the two-fluid formalism, and we treat the curvature correction term nonperturbatively. The effects on the properties of the stars of the amount of dark matter as well as the higher curvature term are investigated. We find that strange quark stars (in agreement with current observational constraints) with the highest masses are equally affected by dark matter and modified gravity.

Dark-matter QCD-axion searches

DOE PAGES

Rosenberg, Leslie J.

2015-01-12

In the late 20th century, cosmology became a precision science. At the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There’s no known such elementary particle, so the strong presumption is the darkmore » matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10 -(6–3) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. But, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. Our paper is a selective overview of the current generation of sensitive axion searches. Finally, not all techniques and experiments are discussed, but I hope to give a sense of the current experimental landscape of the search for dark-matter axions.« less

Dark matter and baryogenesis in the Fermi-bounce curvaton mechanism

NASA Astrophysics Data System (ADS)

Addazi, Andrea; Alexander, Stephon; Cai, Yi-Fu; Marcianò, Antonino

2018-05-01

We elaborate on a toy model of matter bounce, in which the matter content is constituted by two fermion species endowed with four fermion interaction terms. We describe the curvaton mechanism that is thus generated, and then argue that one of the two fermionic species may realize baryogenesis, while the other (lighter) one is compatible with constraints on extra hot dark matter particles. The work of AA was partially supported during this collaboration by the MIUR research grant Theoretical Astroparticle Physics PRIN 2012CPPYP7 and by SdC Progetto speciale Multiasse La Società della Conoscenza in Abruzzo PO FSE Abruzzo 2007-2013. The work of YFC is supported in part by the Chinese National Youth Thousand Talents Program (KJ2030220006), by the USTC start-up funding (KY2030000049), by the NSFC (11421303, 11653002), and by the Fund for Fostering Talents in Basic Science of the NSFC (J1310021). AM wishes to acknowledge support by the Shanghai Municipality, through the grant No. KBH1512299, and by Fudan University, through the grant No. JJH1512105

The Universe Adventure - What is Dark Matter?

Science.gov Websites

scientists today believe to be Dark Matter (DM). In fact, DM is most probably non-baryonic, meaning it does , scientists are convinced that 70-90% of matter in The Universe is non-baryonic DM and that ordinary luminous the Universe's matter must be non-baryonic dark matter. The degree to which light is bent by galaxies

Dark matter influence on black objects thermodynamics

NASA Astrophysics Data System (ADS)

Rogatko, Marek; Wojnar, Aneta

2018-05-01

Physical process version of the first law of black hole thermodynamics in Einstein-Maxwell dark matter gravity was derived. The dark matter sector is mimicked by the additional U(1)-gauge field coupled to the ordinary Maxwell one. By considering any cross section of the black hole event horizon to the future of the bifurcation surface, the equilibrium state version of the first law of black hole mechanics was achieved. The considerations were generalized to the case of Einstein-Yang-Mills dark matter gravity theory. The main conclusion is that the influence of dark matter is crucial in the formation process of black objects. This fact may constitute the explanation of the recent observations of the enormous mass of the super luminous quasars formed in a relatively short time after Big Bang. We also pay attention to the compact binaries thermodynamics, when dark matter sector enters the game.

First direct detection limits on sub-GeV dark matter from XENON10.

PubMed

Essig, Rouven; Manalaysay, Aaron; Mardon, Jeremy; Sorensen, Peter; Volansky, Tomer

2012-07-13

The first direct detection limits on dark matter in the MeV to GeV mass range are presented, using XENON10 data. Such light dark matter can scatter with electrons, causing ionization of atoms in a detector target material and leading to single- or few-electron events. We use 15  kg day of data acquired in 2006 to set limits on the dark-matter-electron scattering cross section. The strongest bound is obtained at 100 MeV where σ(e)<3×10(-38)  cm2 at 90% C.L., while dark-matter masses between 20 MeV and 1 GeV are bounded by σ(e)<10(-37)  cm2 at 90% C.L. This analysis provides a first proof of principle that direct detection experiments can be sensitive to dark-matter candidates with masses well below the GeV scale.

Dark Matter or Modified Dynamics? Hints from Galaxy Kinematics

NASA Astrophysics Data System (ADS)

Gentile, G.

2010-12-01

I show two observational projects I am involved in, which are aimed at understanding better the existence and nature of dark matter, and also aimed at testing alternatives to galactic dark matter such as MOND (Modified Newtonian Dynamics). I present new HI observations of the nearby dwarf galaxy NGC 3741. This galaxy has an extremely extended HI disc (42 B-band exponential scalelengths). The distribution and kinematics are accurately derived by building model data cubes, which closely reproduce the observations. Mass modelling of the rotation curve shows that a cored dark matter halo or MOND provide very good fits, whereas Cold Dark Matter density profiles fail to fit the data. I also show new results about tidal dwarf galaxies, which within the CDM framework are expected to be dark matter-free but whose kinematics instead show a mass discrepancy, exactly of the magnitude that is expected in MOND (Modified Newtonian Dynamics).

Gravity-mediated dark matter annihilation in the Randall-Sundrum model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rueter, T. D.; Rizzo, T. G.; Hewett, J. L.

Observational evidence for dark matter stems from its gravitational interactions, and as of yet there has been no evidence for dark matter interacting via other means. We examine models where dark matter interactions are purely gravitational in a Randall-Sundrum background. In particular, the Kaluza-Klein tower of gravitons which result from the warped fifth dimension can provide viable annihilation channels into Standard Model final states, and we find that we can achieve values of the annihilation cross section, < σv >, which are consistent with the observed relic abundance in the case of spin-1 dark matter. As a result, we examinemore » constraints on these models employing both the current photon line and continuum indirect dark matter searches, and assess the prospects of hunting for the signals of such models in future direct and indirect detection experiments.« less

PeV-scale dark matter as a thermal relic of a decoupled sector

DOE PAGES

Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

2016-06-21

We consider a class of scenarios in which the dark matter is part of a heavy hidden sector that is thermally decoupled from the Standard Model in the early universe. The dark matter freezes-out by annihilating to a lighter, metastable state, whose subsequent abundance can naturally come to dominate the energy density of the universe. Moreover, when this state decays, it reheats the visible sector and dilutes all relic abundances, thereby allowing the dark matter to be orders of magnitude heavier than the weak scale. For concreteness, we consider a simple realization with a Dirac fermion dark matter candidate coupledmore » to a massive gauge boson that decays to the Standard Model through its kinetic mixing with hypercharge. Finally, we identify viable parameter space in which the dark matter can be as heavy as ~1-100 PeV without being overproduced in the early universe.« less

Gravity-mediated dark matter annihilation in the Randall-Sundrum model

DOE PAGES

Rueter, T. D.; Rizzo, T. G.; Hewett, J. L.

2017-10-13

Observational evidence for dark matter stems from its gravitational interactions, and as of yet there has been no evidence for dark matter interacting via other means. We examine models where dark matter interactions are purely gravitational in a Randall-Sundrum background. In particular, the Kaluza-Klein tower of gravitons which result from the warped fifth dimension can provide viable annihilation channels into Standard Model final states, and we find that we can achieve values of the annihilation cross section, < σv >, which are consistent with the observed relic abundance in the case of spin-1 dark matter. As a result, we examinemore » constraints on these models employing both the current photon line and continuum indirect dark matter searches, and assess the prospects of hunting for the signals of such models in future direct and indirect detection experiments.« less

Theoretical Astrophysics at Fermilab

NASA Technical Reports Server (NTRS)

2004-01-01

The Theoretical Astrophysics Group works on a broad range of topics ranging from string theory to data analysis in the Sloan Digital Sky Survey. The group is motivated by the belief that a deep understanding of fundamental physics is necessary to explain a wide variety of phenomena in the universe. During the three years 2001-2003 of our previous NASA grant, over 120 papers were written; ten of our postdocs went on to faculty positions; and we hosted or organized many workshops and conferences. Kolb and collaborators focused on the early universe, in particular and models and ramifications of the theory of inflation. They also studied models with extra dimensions, new types of dark matter, and the second order effects of super-horizon perturbations. S tebbins, Frieman, Hui, and Dodelson worked on phenomenological cosmology, extracting cosmological constraints from surveys such as the Sloan Digital Sky Survey. They also worked on theoretical topics such as weak lensing, reionization, and dark energy. This work has proved important to a number of experimental groups [including those at Fermilab] planning future observations. In general, the work of the Theoretical Astrophysics Group has served as a catalyst for experimental projects at Fennilab. An example of this is the Joint Dark Energy Mission. Fennilab is now a member of SNAP, and much of the work done here is by people formerly working on the accelerator. We have created an environment where many of these people made transition from physics to astronomy. We also worked on many other topics related to NASA s focus: cosmic rays, dark matter, the Sunyaev-Zel dovich effect, the galaxy distribution in the universe, and the Lyman alpha forest. The group organized and hosted a number of conferences and workshop over the years covered by the grant. Among them were:

Dark Matter Mystery Deepens in Cosmic "Train Wreck"

NASA Astrophysics Data System (ADS)

2007-08-01

Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior. "These results challenge our understanding of the way clusters merge," said Dr. Andisheh Mahdavi of the University of Victoria, British Columbia. "Or, they possibly make us even reexamine the nature of dark matter itself." There are three main components to galaxy clusters: individual galaxies composed of billions of stars, hot gas in between the galaxies, and dark matter, a mysterious substance that dominates the cluster mass and can be detected only through its gravitational effects. Illustration of Abell 520 System Illustration of Abell 520 System Optical telescopes can observe the starlight from the individual galaxies, and can infer the location of dark matter by its subtle light-bending effects on distant galaxies. X-ray telescopes like Chandra detect the multimillion-degree gas. A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies. "It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves." Animation of Galaxy Cluster Animation of Galaxy Cluster In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies. "The observation of this group of galaxies that is almost devoid of dark matter flies in the face of our current understanding of the cosmos," said Dr. Arif Babul, University of Victoria. "Our standard model is that a bound group of galaxies like this should have a lot of dark matter. What does it mean that this one doesn't?" In the Bullet Cluster, known as 1E 0657-56, the hot gas is slowed down during the collision but the galaxies and dark matter appear to continue on unimpeded. In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas. Mahdavi and his colleagues have two possible explanations for their findings, both of which are uncomfortable for prevailing theories. The first option is that the galaxies were separated from the dark matter through a complex set of gravitational "slingshots." This explanation is problematic because computer simulations have not been able to produce slingshots that are nearly powerful enough to cause such a separation. The second option is that dark matter is affected not only by gravity, but also by an as-yet-unknown interaction between dark matter particles. This exciting alternative would require new physics and could be difficult to reconcile with observations of other galaxies and galaxy clusters, such as the aforementioned Bullet Cluster. In order to confirm and fully untangle the evidence for the Abell 520 dark matter core, the researchers have secured time for new data from Chandra plus the Hubble Space Telescope. With the additional observations, the team hopes to resolve the mystery surrounding this system. These results are scheduled to appear in the October 20th issue of The Astrophysical Journal. Other members of the research team included David Balam (University of Victoria) and Peter Capak (California Institute of Technology). NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. CFHT is a joint facility of National Research Council of Canada, Centre National de la Recherche Scientifique of France, and University of Hawaii.

The distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter dominated universe

NASA Technical Reports Server (NTRS)

Ryu, Dongsu; Vishniac, Ethan T.; Chiang, Wei-Hwan

1988-01-01

The evolution and distribution of galaxies and the intergalactic medium (IGM) have been studied, along with collisionless dark matter in a Universe dominated by cold dark matter. The Einstein-deSitter universe with omega sub 0 = 1 and h = 0.5 was considered (here h = H sub 0 bar 100/kms/Mpc and H sub 0 is the present value of the Hubble constant). It is assumed that initially dark matter composes 90 pct and baryonic matter composes 10 pct of total mass, and that the primordial baryonic matter is comprised of H and He, with the abundance of He equal to 10 pct of H by number. Galaxies are allowed to form out of the IGM, if the total density and baryonic density satisfy an overdensity criterion. Subsequently, the newly formed galaxies release 10 to the 60th ergs of energy into the IGM over a period of 10 to the 8th years. Calculations have been performed with 32 to the 3rd dark matter particles and 32 to the 3rd cells in a cube with comoving side length L = 9.6/h Mpc. Dark matter particles and galaxies have been followed with an N-body code, while the IGM has been followed with a fluid code.

The distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter dominated universe

NASA Astrophysics Data System (ADS)

Ryu, Dongsu; Vishniac, Ethan T.; Chiang, Wei-Hwan

1988-11-01

The evolution and distribution of galaxies and the intergalactic medium (IGM) have been studied, along with collisionless dark matter in a Universe dominated by cold dark matter. The Einstein-deSitter universe with omega0 = 1 and h = 0.5 was considered (here h = H0 bar 100/kms/Mpc and H0 is the present value of the Hubble constant). It is assumed that initially dark matter composes 90 pct and baryonic matter composes 10 pct of total mass, and that the primordial baryonic matter is comprised of H and He, with the abundance of He equal to 10 pct of H by number. Galaxies are allowed to form out of the IGM, if the total density and baryonic density satisfy an overdensity criterion. Subsequently, the newly formed galaxies release 10 to the 60th ergs of energy into the IGM over a period of 10 to the 8th years. Calculations have been performed with 32 to the 3rd dark matter particles and 32 to the 3rd cells in a cube with comoving side length L = 9.6/h Mpc. Dark matter particles and galaxies have been followed with an N-body code, while the IGM has been followed with a fluid code.

Dark matter and dark energy from the solution of the strong CP problem.

PubMed

Mainini, Roberto; Bonometto, Silvio A

2004-09-17

The Peccei-Quinn (PQ) solution of the strong CP problem requires the existence of axions, which are viable candidates for dark matter. If the Nambu-Goldstone potential of the PQ model is replaced by a potential V(|Phi|) admitting a tracker solution, the scalar field |Phi| can account for dark energy, while the phase of Phi yields axion dark matter. If V is a supergravity (SUGRA) potential, the model essentially depends on a single parameter, the energy scale Lambda. Once we set Lambda approximately equal to 10(10) GeV at the quark-hadron transition, |Phi| naturally passes through values suitable to solve the strong CP problem, later growing to values providing fair amounts of dark matter and dark energy.

The impact of baryons on the direct detection of dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelso, Chris; Savage, Christopher; Freese, Katherine

2016-08-01

The spatial and velocity distributions of dark matter particles in the Milky Way Halo affect the signals expected to be observed in searches for dark matter. Results from direct detection experiments are often analyzed assuming a simple isothermal distribution of dark matter, the Standard Halo Model (SHM). Yet there has been skepticism regarding the validity of this simple model due to the complicated gravitational collapse and merger history of actual galaxies. In this paper we compare the SHM to the results of cosmological hydrodynamical simulations of galaxy formation to investigate whether or not the SHM is a good representation ofmore » the true WIMP distribution in the analysis of direct detection data. We examine two Milky Way-like galaxies from the MaGICC cosmological simulations (a) with dark matter only and (b) with baryonic physics included. The inclusion of baryons drives the shape of the DM halo to become more spherical and makes the velocity distribution of dark matter particles less anisotropic especially at large heliocentric velocities, thereby making the SHM a better fit. We also note that we do not find a significant disk-like rotating dark matter component in either of the two galaxy halos with baryons that we examine, suggesting that dark disks are not a generic prediction of cosmological hydrodynamical simulations. We conclude that in the Solar neighborhood, the SHM is in fact a good approximation to the true dark matter distribution in these cosmological simulations (with baryons) which are reasonable representations of the Milky Way, and hence can also be used for the purpose of dark matter direct detection calculations.« less

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability

DOE PAGES

Appelquist, T.; Berkowitz, E.; Brower, R. C.; ...

2015-10-23

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar “stealth baryon” dark matter candidate, arising from a dark SU(4) confining gauge theory—“stealth dark matter.” In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest “baryon” states in SU(3) and SU(4) gauge theories using themore » background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be possibly detectable in the dark matter mass range of about 200–700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m 6 B, suggests the observable dark matter mass range is not appreciably modified. We highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.« less

Identifying Anomalies in Gravitational Lens Time Delays

NASA Astrophysics Data System (ADS)

Congdon, Arthur B.; Keeton, C. R.; Nordgren, C. E.

2009-05-01

Gravitational lensing has become a powerful probe of cold dark matter substructure. Earlier work using anomalous flux ratios in four-image quasar lenses has shown that lensing is sensitive to substructure which raises the exciting prospect of constraining the mass function and spatial distribution of dark matter satellites in galaxies. We examine the ability of gravitational lens time delays to reveal complex structure in lens potentials. We use Monte Carlo simulations to determine the range of time delays that can be produced by realistic smooth lens models consisting of isothermal ellipsoid galaxies with tidal shear. We can then identify outliers as "time-delay anomalies." We find evidence for anomalies in close image pairs in the cusp lenses RX J1131-1231 and B1422+231. The anomalies in RX J1131-1231 provide strong evidence for substructure in the lens potential, while at this point the apparent anomalies in B1422+231 mainly indicate that the time delay measurements need to be improved. We also find evidence for time-delay anomalies in larger-separation image pairs in four additional lenses. We suggest that these anomalies are caused by some combination of substructure and a complex lens environment. Our work argues for a large sample of strong lenses with precisely-measured time delays. The first of these objectives will be readily achievable as the next generation of optical and radio telescopes come online, while the second will require a dedicated one-meter class space-based observatory. Meeting these goals will make it possible to examine the properties of dark matter on sub-galactic scales, which is essential for distinguishing among the various dark matter candidates from particle physics. Part of this work was funded by NSF grant AST-0747311. ABC is currently supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Oak Ridge Associated Universities through a contract with NASA.

Ordinary Dark Matter versus Mysterious Dark Matter in Galactic Rotation

NASA Astrophysics Data System (ADS)

Gallo, C. F.; Feng, James

2008-04-01

To theoretically describe the measured rotational velocity curves of spiral galaxies, there are two different approaches and conclusions. (1) ORDINARY DARK MATTER. We assume Newtonian gravity/dynamics and successfully find (via computer) mass distributions in bulge/disk configurations that duplicate the measured rotational velocities. There is ordinary dark matter within the galactic disk towards the cooler periphery which has lower emissivity/opacity. There are no mysteries in this scenario based on verified physics. (2) MYSTERIOUS DARK MATTER. Others INaccurately assume the galactic mass distributions follow the measured light distributions, and then the measured rotational velocity curves are NOT duplicated. To alleviate this discrepancy, speculations are invoked re ``Massive Peripheral Spherical Halos of Mysterious Dark Matter.'' But NO matter has been detected in this UNtenable Halo configuration. Many UNverified ``Mysteries'' are invoked as necessary and convenient. CONCLUSION. The first approach utilizing Newtonian gravity/dynamics and searching for the ordinary mass distributions within the galactic disk simulates reality and agrees with data.

Search for domain wall dark matter with atomic clocks on board global positioning system satellites.

PubMed

Roberts, Benjamin M; Blewitt, Geoffrey; Dailey, Conner; Murphy, Mac; Pospelov, Maxim; Rollings, Alex; Sherman, Jeff; Williams, Wyatt; Derevianko, Andrei

2017-10-30

Cosmological observations indicate that dark matter makes up 85% of all matter in the universe yet its microscopic composition remains a mystery. Dark matter could arise from ultralight quantum fields that form macroscopic objects. Here we use the global positioning system as a ~ 50,000 km aperture dark matter detector to search for such objects in the form of domain walls. Global positioning system navigation relies on precision timing signals furnished by atomic clocks. As the Earth moves through the galactic dark matter halo, interactions with domain walls could cause a sequence of atomic clock perturbations that propagate through the satellite constellation at galactic velocities ~ 300 km s -1 . Mining 16 years of archival data, we find no evidence for domain walls at our current sensitivity level. This improves the limits on certain quadratic scalar couplings of domain wall dark matter to standard model particles by several orders of magnitude.

MadDM: Computation of dark matter relic abundance

NASA Astrophysics Data System (ADS)

Backović, Mihailo; Kong, Kyoungchul; McCaskey, Mathew

2017-12-01

MadDM computes dark matter relic abundance and dark matter nucleus scattering rates in a generic model. The code is based on the existing MadGraph 5 architecture and as such is easily integrable into any MadGraph collider study. A simple Python interface offers a level of user-friendliness characteristic of MadGraph 5 without sacrificing functionality. MadDM is able to calculate the dark matter relic abundance in models which include a multi-component dark sector, resonance annihilation channels and co-annihilations. The direct detection module of MadDM calculates spin independent / spin dependent dark matter-nucleon cross sections and differential recoil rates as a function of recoil energy, angle and time. The code provides a simplified simulation of detector effects for a wide range of target materials and volumes.

Annihilation of singlet fermionic dark matter into two photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ettefaghi, M.M.; Moazzemi, R., E-mail: mettefaghi@qom.ac.ir, E-mail: r.moazzemi@qom.ac.ir

2013-02-01

We consider an extension of the standard model in which a singlet fermionic particle, to serve as cold dark matter, and a singlet Higgs are added. We perform a reanalysis on the free parameters. In particular, demanding a correct relic abundance of dark matter, we derive and plot the coupling of the singlet fermion with the singlet Higgs, g{sub s}, versus the dark matter mass. We analytically compute the pair annihilation cross section of singlet fermionic dark matter into two photons. The thermally averaged of this cross section is calculated for wide range of energies and plotted versus dark mattermore » mass using g{sub s} consistent with the relic abundance condition. We also compare our results with the Fermi-Lat observations.« less

Non-standard interactions and neutrinos from dark matter annihilation in the Sun

NASA Astrophysics Data System (ADS)

Demidov, S. V.

2018-02-01

We perform an analysis of the influence of non-standard neutrino interactions (NSI) on neutrino signal from dark matter annihilations in the Sun. Taking experimentally allowed benchmark values for the matter NSI parameters we show that the evolution of such neutrinos with energies at GeV scale can be considerably modified. We simulate propagation of neutrinos from the Sun to the Earth for realistic dark matter annihilation channels and find that the matter NSI can result in at most 30% correction to the signal rate of muon track events at neutrino telescopes. Still present experimental bounds on dark matter from these searches are robust in the presence of NSI within considerable part of their allowed parameter space. At the same time electron neutrino flux from dark matter annihilation in the Sun can be changed by a factor of few.

Detailed Characterization of Nuclear Recoil Pulse Shape Discrimination in the Darkside-50 Direct Dark Matter Experiment

NASA Astrophysics Data System (ADS)

Ludert, Erin Edkins

While evidence of non-baryonic dark matter has been accumulating for decades, its exact nature continues to remain a mystery. Weakly Interacting Massive Particles (WIMPs) are a well motivated candidate which appear in certain extensions of the Standard Model, independently of dark matter theory. If such particles exist, they should occasionally interact with particles of normal matter, producing a signal which may be detected. The DarkSide-50 direct dark matter experiment aims to detect the energy of recoiling argon atoms due to the elastic scattering of postulated WIMPs. In order to make such a discovery, a clear understanding of both the background and signal region is essential. This understanding requires a careful study of the detector's response to radioactive sources, which in turn requires such sources may be safely introduced into or near the detector volume and reliably removed. The CALibration Insertaion System (CALIS) was designed and built for this purpose in a joint effort between Fermi National Laboratory and the University of Hawaii. This work describes the design and testing of CALIS, its installation and commissioning at the Laboratori Nazionali del Gran Sasso (LNGS) and the multiple calibration campaigns which have successfully employed it. As nuclear recoils produced by WIMPs are indistinguishable from those produced by neutrons, radiogenic neutrons are both the most dangerous class of background and a vital calibration source for the study of the potential WIMP signal. Prior to the calibration of DarkSide-50 with radioactive neutron sources, the acceptance region was determined by the extrapolation of nuclear recoil data from a separate, dedicated experiment, ScENE, which measured the distribution of the pulse shape discrimination parameter, f 90, for nuclear recoils of known energies. This work demonstrates the validity of the extrapolation of ScENE values to DarkSide-50, by direct comparison of the f90 distribution of nuclear recoils from ScENE and an AmBe calibration source. The combined acceptance as defined by ScENE and the in-situ AmBe calibration were used to establish the best WIMP exclusion limit on an argon target. Unfortunately, radioactive sources used for the calibration of DarkSide-50 are universally accompanied by gamma decays, which obscure the low energy region where most WIMP interactions are expected to occur and seem to make continuing dependence on an external measurement such as ScENE inevitable. However, this work presents a novel method of nuclear recoil calibration employing event selection, unique to the design of DarkSide-50, which produces a nearly pure sample of nuclear recoils. Further, it describes the execution of a neutron calibration campaign, from planning to analysis, which yielded a valuable data set for defining the acceptance region. Together with the event selection techniques, this allows for the definition of the acceptance region independent of ScENE values. Two analytical models of the f90 distribution are described and their results for nuclear recoils are compared. Finally, a detailed study of integrated noise in nuclear and electron recoil events is presented, which demonstrates a difference between these classes of events for the first time.

On the Matter of Dark Matter

ScienceCinema

Orrell, John L.

2018-05-31

The mission of the USS Enterprise was to “boldly go where no one has gone before.” And so it is with Particle Physicist John Orrell as he seeks to solve the conundrum of elusive dark matter. It’s a mystery that PNNL scientists have chased for more than 25 years. And, if dark matter is discovered, it will change our entire understanding of how the universe was formed. The first experiments to locate dark matter were conducted underground using specialized, radiation detector technology developed at PNNL.

General circular velocity relation of a test particle in a 3D gravitational potential: application to the rotation curves analysis and total mass determination of UGC 8490 and UGC 9753

NASA Astrophysics Data System (ADS)

Repetto, P.; Martínez-García, E. E.; Rosado, M.; Gabbasov, R.

2018-06-01

In this paper, we derive a novel circular velocity relation for a test particle in a 3D gravitational potential applicable to every system of curvilinear coordinates, suitable to be reduced to orthogonal form. As an illustration of the potentiality of the determined circular velocity expression, we perform the rotation curves analysis of UGC 8490 and UGC 9753 and we estimate the total and dark matter mass of these two galaxies under the assumption that their respective dark matter haloes have spherical, prolate, and oblate spheroidal mass distributions. We employ stellar population synthesis models and the total H I density map to obtain the stellar and H I+He+metals rotation curves of both galaxies. The subtraction of the stellar plus gas rotation curves from the observed rotation curves of UGC 8490 and UGC 9753 generates the dark matter circular velocity curves of both galaxies. We fit the dark matter rotation curves of UGC 8490 and UGC 9753 through the newly established circular velocity formula specialized to the spherical, prolate, and oblate spheroidal mass distributions, considering the Navarro, Frenk, and White, Burkert, Di Cintio, Einasto, and Stadel dark matter haloes. Our principal findings are the following: globally, cored dark matter profiles Burkert and Einasto prevail over cuspy Navarro, Frenk, and White, and Di Cintio. Also, spherical/oblate dark matter models fit better the dark matter rotation curves of both galaxies than prolate dark matter haloes.

Realistic estimation for the detectability of dark matter subhalos using Fermi-LAT catalogs

NASA Astrophysics Data System (ADS)

Calore, Francesca; De Romeri, Valentina; Di Mauro, Mattia; Donato, Fiorenza; Marinacci, Federico

2017-09-01

Numerical simulations of structure formation have made remarkable progress in recent years, in particular due to the inclusion of baryonic physics evolving with the dark matter component. We generate Monte Carlo realizations of the dark matter subhalo population based on the results of the recent hydrodynamical simulation suite of Milky Way-sized galaxies [F. Marinacci, R. Pakmor, and V. Springel, Mon. Not. R. Astron. Soc. 437, 1750 (2014)., 10.1093/mnras/stt2003]. We then simulate the gamma-ray sky for both the setup of the 3FGL and 2FHL Fermi Large Area Telescope (LAT) catalogs, including the contribution from the annihilation of dark matter in the subhalos. We find that the flux sensitivity threshold strongly depends on the particle dark matter mass and, more mildly, also on its annihilation channel and the observation latitude. The results differ for the 3FGL and 2FHL catalogs, given their different energy thresholds. We also predict that the number of dark matter subhalos among the unassociated sources is very small. A null number of detectable subhalos in the Fermi-LAT 3FGL catalog would imply upper limits on the dark matter annihilation cross section into b b ¯ of 2 ×10-26(5 ×10-25) cm3 /s with MDM=50 (1000 ) GeV . We find less than one extended subhalo in the Fermi-LAT 3FGL catalog. As a matter of fact, the differences in the spatial and mass distribution of subhalos between hydrodynamic and dark matter-only runs do not have significant impact on the detectability of dark subhalos in gamma rays.

Effect of black holes in local dwarf spheroidal galaxies on gamma-ray constraints on dark matter annihilation

NASA Astrophysics Data System (ADS)

Gonzalez-Morales, Alma X.; Profumo, Stefano; Queiroz, Farinaldo S.

2014-11-01

Recent discoveries of optical signatures of black holes in dwarf galaxies indicates that low-mass galaxies can indeed host intermediate massive black holes. This motivates the assessment of the resulting effect on the host dark matter density profile, and the consequences for the constraints on the plane of the dark matter annihilation cross section versus mass, stemming from the nonobservation of gamma rays from local dwarf spheroidals with the Fermi Large Area Telescope. We compute the density profile using three different prescriptions for the black hole mass associated with a given spheroidal galaxy, and taking into account the cutoff to the density from dark matter pair-annihilation. We find that the limits on the dark matter annihilation rate from observations of individual dwarfs are enhanced by factors of a few up to 1 06 , depending on the specific galaxy, on the black hole mass prescription, and on the dark matter particle mass. We estimate limits from combined observations of a sample of 15 dwarfs, for a variety of assumptions on the dwarf black hole mass and on the dark matter density profile prior to adiabatic contraction. We find that if black holes are indeed present in local dwarf spheroidals, then, independent of assumptions, (i) the dark matter interpretation of the Galactic center gamma-ray excess would be conclusively ruled out, (ii) wino dark matter would be excluded up to masses of about 3 TeV, and (iii) vanilla thermal relic weakly interacting massive particles must be heavier than 100 GeV.

Kerr–anti-de Sitter/de Sitter black hole in perfect fluid dark matter background

NASA Astrophysics Data System (ADS)

Xu, Zhaoyi; Hou, Xian; Wang, Jiancheng

2018-06-01

We obtain the Kerr–anti-de-sitter (Kerr–AdS) and Kerr–de-sitter (Kerr–dS) black hole (BH) solutions to the Einstein field equation in the perfect fluid dark matter background using the Newman–Janis method and Mathematica package. We discuss in detail the black hole properties and obtain the following main results: (i) From the horizon equation g rr   =  0, we derive the relation between the perfect fluid dark matter parameter α and the cosmological constant Λ when the cosmological horizon exists. For , we find that α is in the range for and for . For positive cosmological constant Λ (Kerr–AdS BH), decreases if , and increases if . For negative cosmological constant (Kerr–dS BH), increases if and decreases if ; (ii) An ergosphere exists between the event horizon and the outer static limit surface. The size of the ergosphere evolves oppositely for and , while decreasing with the increasing . When there is sufficient dark matter around the black hole, the black hole spacetime changes remarkably; (iii) The singularity of these black holes is the same as that of rotational black holes. In addition, we study the geodesic motion using the Hamilton–Jacobi formalism and find that when α is in the above ranges for , stable orbits exist. Furthermore, the rotational velocity of the black hole in the equatorial plane has different behaviour for different α and the black hole spin a. It is asymptotically flat and independent of α if while is asymptotically flat only when α is close to zero if . We anticipate that Kerr–Ads/dS black holes could exist in the universe and our future work will focus on the observational effects of the perfect fluid dark matter on these black holes.

Constraints on dark matter annihilations from diffuse gamma-ray emission in the Galaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavakoli, Maryam; Evoli, Carmelo; Cholis, Ilias

2014-01-01

Recent advances in γ-ray cosmic ray, infrared and radio astronomy have allowed us to develop a significantly better understanding of the galactic medium properties in the last few years. In this work using the DRAGON code, that numerically solves the CR propagation equation and calculating γ-ray emissivities in a 2-dimensional grid enclosing the Galaxy, we study in a self consistent manner models for the galactic diffuse γ-ray emission. Our models are cross-checked to both the available CR and γ-ray data. We address the extend to which dark matter annihilations in the Galaxy can contribute to the diffuse γ-ray flux towardsmore » different directions on the sky. Moreover we discuss the impact that astrophysical uncertainties of non DM nature, have on the derived γ-ray limits. Such uncertainties are related to the diffusion properties on the Galaxy, the interstellar gas and the interstellar radiation field energy densities. Light ∼ 10 GeV dark matter annihilating dominantly to hadrons is more strongly constrained by γ-ray observations towards the inner parts of the Galaxy and influenced the most by assumptions of the gas distribution; while TeV scale DM annihilating dominantly to leptons has its tightest constraints from observations towards the galactic center avoiding the galactic disk plane, with the main astrophysical uncertainty being the radiation field energy density. In addition, we present a method of deriving constraints on the dark matter distribution profile from the diffuse γ-ray spectra. These results critically depend on the assumed mass of the dark matter particles and the type of its end annihilation products.« less

A balance for dark matter bound states

NASA Astrophysics Data System (ADS)

Nozzoli, F.

2017-05-01

Massive particles with self interactions of the order of 0.2 barn/GeV are intriguing Dark Matter candidates from an astrophysical point of view. Current and past experiments for direct detection of massive Dark Matter particles are focusing to relatively low cross sections with ordinary matter, however they cannot rule out very large cross sections, σ/M > 0.01 barn/GeV, due to atmosphere and material shielding. Cosmology places a strong indirect limit for the presence of large interactions among Dark Matter and baryons in the Universe, however such a limit cannot rule out the existence of a small sub-dominant component of Dark Matter with non negligible interactions with ordinary matter in our galactic halo. Here, the possibility of the existence of bound states with ordinary matter, for a similar Dark Matter candidate with not negligible interactions, is considered. The existence of bound states, with binding energy larger than ∼ 1 meV, would offer the possibility to test in laboratory capture cross sections of the order of a barn (or larger). The signature of the detection for a mass increasing of cryogenic samples, due to the possible particle accumulation, would allow the investigation of these Dark Matter candidates with mass up to the GUT scale. A proof of concept for a possible detection set-up and the evaluation of some noise sources are described.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Catena, Riccardo; Schwabe, Bodo, E-mail: riccardo.catena@theorie.physik.uni-goettingen.de, E-mail: bodo.schwabe@theorie.physik.uni-goettingen.de

In the effective theory of isoscalar and isovector dark matter-nucleon interactions mediated by a heavy spin-1 or spin-0 particle, 8 isotope-dependent nuclear response functions can be generated in the dark matter scattering by nuclei. We compute the 8 nuclear response functions for the 16 most abundant elements in the Sun, i.e. H, {sup 3}He, {sup 4}He, {sup 12}C, {sup 14}N, {sup 16}O, {sup 20}Ne, {sup 23}Na, {sup 24}Mg, {sup 27}Al, {sup 28}Si, {sup 32}S, {sup 40}Ar, {sup 40}Ca, {sup 56}Fe, and {sup 59}Ni, through numerical shell model calculations. We use our response functions to compute the rate of dark mattermore » capture by the Sun for all isoscalar and isovector dark matter-nucleon effective interactions, including several operators previously considered for dark matter direct detection only. We study in detail the dependence of the capture rate on specific dark matter-nucleon interaction operators, and on the different elements in the Sun. We find that a so far neglected momentum dependent dark matter coupling to the nuclear vector charge gives a larger contribution to the capture rate than the constant spin-dependent interaction commonly included in dark matter searches at neutrino telescopes. Our investigation lays the foundations for model independent analyses of dark matter induced neutrino signals from the Sun. The nuclear response functions obtained in this study are listed in analytic form in an appendix, ready to be used in other projects.« less

Fermilab Center for Particle Astrophysics | FCPA

Science.gov Websites

Us About Us Contact Science Dark Matter Dark Energy Cosmic Microwave Background Radiation (CMBR) New detection and detailed study of the properties of cosmic dark matter particles in the laboratory » Hunting for Light Dark Matter in a Bubble Chamber September 18, 2013 | Hugh Lippincott The

FNAL Student Resources

Science.gov Websites

understandings lead to new fundamental questions and a new world of discovery. What is dark matter? What happened NOvA Detector Dark Energy Camera Whispers of Dark Matter Elusive Neutrino Particle physics research World Particle Diversity Dark Matter Neutrino Secrets The Birth of the Universe The Universe's History

Planetarium Show on Dark Matter

DOE PAGES

Barnett, R. Michael

2016-05-31

We describe a new planetarium show about Dark Matter entitled “Phantom of the Universe”. When completed in late 2014, it will feature the exciting story of dark matter, from the Big Bang to its anticipated discovery at the Large Hadron Collider.

Astronomical Constraints on Quantum Cold Dark Matter

NASA Astrophysics Data System (ADS)

Spivey, Shane; Musielak, Z.; Fry, J.

2012-01-01

A model of quantum (`fuzzy') cold dark matter that accounts for both the halo core problem and the missing dwarf galaxies problem, which plague the usual cold dark matter paradigm, is developed. The model requires that a cold dark matter particle has a mass so small that its only allowed physical description is a quantum wave function. Each such particle in a galactic halo is bound to a gravitational potential that is created by luminous matter and by the halo itself, and the resulting wave function is described by a Schrödinger equation. To solve this equation on a galactic scale, we impose astronomical constraints that involve several density profiles used to fit data from simulations of dark matter galactic halos. The solutions to the Schrödinger equation are quantum waves which resemble the density profiles acquired from simulations, and they are used to determine the mass of the cold dark matter particle. The effects of adding certain types of baryonic matter to the halo, such as a dwarf elliptical galaxy or a supermassive black hole, are also discussed.

Will there be again a transition from acceleration to deceleration in course of the dark energy evolution of the universe?

NASA Astrophysics Data System (ADS)

Pan, Supriya; Chakraborty, Subenoy

2013-09-01

In this work we consider the evolution of the interactive dark fluids in the background of homogeneous and isotropic FRW model of the universe. The dark fluids consist of a warm dark matter and a dark energy and both are described as perfect fluid with barotropic equation of state. The dark species interact non-gravitationally through an additional term in the energy conservation equations. An autonomous system is formed in the energy density spaces and fixed points are analyzed. A general expression for the deceleration parameter has been obtained and it is possible to have more than one zero of the deceleration parameter. Finally, vanishing of the deceleration parameter has been examined with some examples.

Dark matter in dwarf spheroidal galaxies and indirect detection: a review

NASA Astrophysics Data System (ADS)

Strigari, Louis E.

2018-05-01

Indirect dark matter searches targeting dwarf spheroidal galaxies (dSphs) have matured rapidly during the past decade. This has been because of the substantial increase in kinematic data sets from the dSphs, the new dSphs that have been discovered, and the operation of the Fermi-LAT and many ground-based gamma-ray experiments. Here we review the analysis methods that have been used to determine the dSph dark matter distributions, in particular the ‘J-factors’, comparing and contrasting them, and detailing the underlying systematics that still affect the analysis. We discuss prospects for improving measurements of dark matter distributions, and how these interplay with future indirect dark matter searches.

Search for light dark matter in XENON10 data.

PubMed

Angle, J; Aprile, E; Arneodo, F; Baudis, L; Bernstein, A; Bolozdynya, A I; Coelho, L C C; Dahl, C E; DeViveiros, L; Ferella, A D; Fernandes, L M P; Fiorucci, S; Gaitskell, R J; Giboni, K L; Gomez, R; Hasty, R; Kastens, L; Kwong, J; Lopes, J A M; Madden, N; Manalaysay, A; Manzur, A; McKinsey, D N; Monzani, M E; Ni, K; Oberlack, U; Orboeck, J; Plante, G; Santorelli, R; dos Santos, J M F; Schulte, S; Shagin, P; Shutt, T; Sorensen, P; Winant, C; Yamashita, M

2011-07-29

We report results of a search for light (≲10  GeV) particle dark matter with the XENON10 detector. The event trigger was sensitive to a single electron, with the analysis threshold of 5 electrons corresponding to 1.4 keV nuclear recoil energy. Considering spin-independent dark matter-nucleon scattering, we exclude cross sections σ(n)>7×10(-42)  cm(2), for a dark matter particle mass m(χ)=7  GeV. We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II, as well as the DAMA annual modulation signal.

Dark matter in dwarf spheroidal galaxies and indirect detection: a review.

PubMed

Strigari, Louis E

2018-05-01

Indirect dark matter searches targeting dwarf spheroidal galaxies (dSphs) have matured rapidly during the past decade. This has been because of the substantial increase in kinematic data sets from the dSphs, the new dSphs that have been discovered, and the operation of the Fermi-LAT and many ground-based gamma-ray experiments. Here we review the analysis methods that have been used to determine the dSph dark matter distributions, in particular the 'J-factors', comparing and contrasting them, and detailing the underlying systematics that still affect the analysis. We discuss prospects for improving measurements of dark matter distributions, and how these interplay with future indirect dark matter searches.

Chance Discovery with Data Crystallization: A Basic Research for Discovering Unobservable Events

DTIC Science & Technology

2006-05-10

matter in cosmology. The dark matter refers to hypothetical particles which do not emit or reflect radiation to be detected directly. But its presence...can be inferred from gravitational effects on visible matter such as stars and galaxies. The dark matter hypothesis aims to explain several anomalous...astronomical observations in the stellar dynamics. Estimates of the amount of the dark matter suggest that there is far more matter than is directly

Big Questions: Dark Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lincoln, Don

Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter ideamore » is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.« less

Constraints on interacting dark energy models from Planck 2015 and redshift-space distortion data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Costa, André A.; Abdalla, E.; Xu, Xiao-Dong

2017-01-01

We investigate phenomenological interactions between dark matter and dark energy and constrain these models by employing the most recent cosmological data including the cosmic microwave background radiation anisotropies from Planck 2015, Type Ia supernovae, baryon acoustic oscillations, the Hubble constant and redshift-space distortions. We find that the interaction in the dark sector parameterized as an energy transfer from dark matter to dark energy is strongly suppressed by the whole updated cosmological data. On the other hand, an interaction between dark sectors with the energy flow from dark energy to dark matter is proved in better agreement with the available cosmologicalmore » observations. This coupling between dark sectors is needed to alleviate the coincidence problem.« less

Dark Matter Indirect Detection with Gamma Rays

DOE PAGES

Patrick Harding, J.

2017-07-27

Searches for weakly interacting massive particle (WIMP) dark matter with gamma-ray instruments are a way to get a unique observational handle on the particle nature of dark matter. I will discuss the details of how to perform these searches, both for annihilating and decaying WIMPs. I will discuss the calculation of the gamma-ray flux from possible sources of dark matter annihilation or decay and show examples of limits which have been calculated using these techniques.

Model-independent constraints on dark matter annihilation in dwarf spheroidal galaxies

NASA Astrophysics Data System (ADS)

Boddy, Kimberly K.; Kumar, Jason; Marfatia, Danny; Sandick, Pearl

2018-05-01

We present a general, model-independent formalism for determining bounds on the production of photons in dwarf spheroidal galaxies via dark matter annihilation, applicable to any set of assumptions about dark matter particle physics or astrophysics. As an illustration, we analyze gamma-ray data from the Fermi Large Area Telescope to constrain a variety of nonstandard dark matter models, several of which have not previously been studied in the context of dwarf galaxy searches.

Axions and dark matter

NASA Astrophysics Data System (ADS)

Yang, Qiaoli

2017-05-01

Dark matter constitutes about 23% of the total energy density of the universe, but its properties are still little known besides that it should be composed by cold and weakly interacting particles. Many beyond Standard Model theories can provide proper candidates to serve as dark matter and the axion introduced to solve the strong CP problem turns out to be an attractive one. In this paper, we briefly review several important features of the axion and the axion dark matter.

Constraints on the Dark Matter Particle Mass from the Number of Milky Way Satellites

DTIC Science & Technology

2010-04-12

but our lower mass limits do not necessarily apply to mixed dark matter cosmologies . Higgs decay produced sterile neutrinos can, however, constitute...simulations of the growth of Milky Way-sized halos in cold and warm dark matter cosmologies . The number of dark matter satellites in our simulated Milky...tions of WDM cosmologies due to numerical artifacts produced by discrete sampling of the gravitational poten- tial with a finite number of particles

Point sources from dissipative dark matter

NASA Astrophysics Data System (ADS)

Agrawal, Prateek; Randall, Lisa

2017-12-01

If a component of dark matter has dissipative interactions, it can cool to form compact astrophysical objects with higher density than that of conventional cold dark matter (sub)haloes. Dark matter annihilations might then appear as point sources, leading to novel morphology for indirect detection. We explore dissipative models where interaction with the Standard Model might provide visible signals, and show how such objects might give rise to the observed excess in gamma rays arising from the galactic center.

Indirect search for dark matter in the Sun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rott, Carsten, E-mail: rott@skku.edu

If dark matter is be captured in the Sun and self-annihilate, evidence of this process might be observable on the Earth in form of a neutrinos, which are copiously produced in the annihilation process. We discuss a novel signature of dark matter annihilations in the Sun that originates from monoenergetic neutrinos produced in pion and kaon decays. Based on this signature we find competitive sensitivities for the detection of dark matter at present and next-generation neutrino detectors.

Search for dark matter produced in association with bottom or top quarks in √{s}=13 TeV pp collisions with the ATLAS detector

NASA Astrophysics Data System (ADS)

Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adelman, J.; Adersberger, M.; Adye, T.; Affolder, A. A.; Afik, Y.; Agatonovic-Jovin, T.; Agheorghiesei, C.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akatsuka, S.; Akerstedt, H.; Åkesson, T. P. A.; Akilli, E.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albicocco, P.; Alconada Verzini, M. J.; Alderweireldt, S. C.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M. I.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amoroso, S.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Antrim, D. J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Araujo Ferraz, V.; Arce, A. T. H.; Ardell, R. E.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Bagnaia, P.; Bahmani, M.; Bahrasemani, H.; Baines, J. T.; Bajic, M.; Baker, O. K.; Bakker, P. J.; Baldin, E. M.; Balek, P.; Balli, F.; Balunas, W. K.; Banas, E.; Bandyopadhyay, A.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barkeloo, J. T.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Beck, H. C.; Becker, K.; Becker, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beermann, T. A.; Begalli, M.; Begel, M.; Behr, J. K.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Bergsten, L. J.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernardi, G.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertram, I. A.; Bertsche, C.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Bethani, A.; Bethke, S.; Betti, A.; Bevan, A. J.; Beyer, J.; Bianchi, R. M.; Biebel, O.; Biedermann, D.; Bielski, R.; Bierwagen, K.; Biesuz, N. V.; Biglietti, M.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bittrich, C.; Bjergaard, D. M.; Black, J. E.; Black, K. M.; Blair, R. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bolz, A. E.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozson, A. J.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Braren, F.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Briglin, D. L.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruni, A.; Bruni, G.; Bruni, L. S.; Bruno, S.; Brunt, B. H.; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burch, T. J.; Burdin, S.; Burgard, C. D.; Burger, A. M.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Changqiao, C.-Q.; Cabrera Urbán, S.; Caforio, D.; Cai, H.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carlson, B. T.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrá, S.; Carrillo-Montoya, G. D.; Casadei, D.; Casado, M. P.; Casha, A. F.; Casolino, M.; Casper, D. W.; Castelijn, R.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Celebi, E.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, W. S.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, C.; Chen, H.; Chen, J.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Cheu, E.; Cheung, K.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chiu, Y. H.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Chow, Y. S.; Christodoulou, V.; Chu, M. C.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Citterio, M.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, M. R.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Colasurdo, L.; Cole, B.; Colijn, A. P.; Collot, J.; Colombo, T.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Constantinescu, S.; Conti, G.; Conventi, F.; Cooke, M.; Cooper-Sarkar, A. M.; Cormier, F.; Cormier, K. J. R.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Costa, G.; Costa, M. J.; Costanzo, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Crawley, S. J.; Creager, R. A.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cueto, A.; Cuhadar Donszelmann, T.; Cukierman, A. R.; Cummings, J.; Curatolo, M.; Cúth, J.; Czekierda, S.; Czodrowski, P.; D'amen, G.; D'Auria, S.; D'eramo, L.; D'Onofrio, M.; Da Cunha Sargedas De Sousa, M. J.; Da Via, C.; Dabrowski, W.; Dado, T.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Daneri, M. F.; Dang, N. P.; Daniells, A. C.; Dann, N. S.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Daubney, T.; Davey, W.; David, C.; Davidek, T.; Davis, D. R.; Davison, P.; Dawe, E.; Dawson, I.; De, K.; de Asmundis, R.; De Benedetti, A.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Maria, A.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vasconcelos Corga, K.; De Vivie De Regie, J. B.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Dehghanian, N.; Deigaard, I.; Del Gaudio, M.; Del Peso, J.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Dell'Acqua, A.; Dell'Asta, L.; Dell'Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delporte, C.; Delsart, P. A.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Denysiuk, D.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Devesa, M. R.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Bello, F. A.; Di Ciaccio, A.; Di Ciaccio, L.; Di Clemente, W. K.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Micco, B.; Di Nardo, R.; Di Petrillo, K. F.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Dickinson, J.; Diehl, E. B.; Dietrich, J.; Díez Cornell, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Dodsworth, D.; Doglioni, C.; Dolejsi, J.; Dolezal, Z.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Du, Y.; Duarte-Campderros, J.; Dubinin, F.; Dubreuil, A.; Duchovni, E.; Duckeck, G.; Ducourthial, A.; Ducu, O. A.; Duda, D.; Dudarev, A.; Dudder, A. Chr.; Duffield, E. M.; Duflot, L.; Dührssen, M.; Dulsen, C.; Dumancic, M.; Dumitriu, A. E.; Duncan, A. K.; Dunford, M.; Duperrin, A.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Duvnjak, D.; Dyndal, M.; Dziedzic, B. S.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; El Kosseifi, R.; Ellajosyula, V.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Ennis, J. S.; Epland, M. B.; Erdmann, J.; Ereditato, A.; Ernst, M.; Errede, S.; Escalier, M.; Escobar, C.; Esposito, B.; Estrada Pastor, O.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Ezzi, M.; Fabbri, F.; Fabbri, L.; Fabiani, V.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farina, C.; Farina, E. M.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Faucci Giannelli, M.; Favareto, A.; Fawcett, W. J.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Fenton, M. J.; Fenyuk, A. B.; Feremenga, L.; Fernandez Martinez, P.; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferreira de Lima, D. E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fletcher, R. R. M.; Flick, T.; Flierl, B. M.; Flores Castillo, L. R.; Flowerdew, M. J.; Forcolin, G. T.; Formica, A.; Förster, F. A.; Forti, A.; Foster, A. G.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Franchino, S.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; Fressard-Batraneanu, S. M.; Freund, B.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Fusayasu, T.; Fuster, J.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gach, G. P.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, L. G.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Ganguly, S.; Gao, Y.; Gao, Y. S.; Garay Walls, F. M.; García, C.; García Navarro, J. E.; García Pascual, J. A.; Garcia-Sciveres, M.; Gardner, R. W.; Garelli, N.; Garonne, V.; Gascon Bravo, A.; Gasnikova, K.; Gatti, C.; Gaudiello, A.; Gaudio, G.; Gavrilenko, I. L.; Gay, C.; Gaycken, G.; Gazis, E. N.; Gee, C. N. P.; Geisen, J.; Geisen, M.; Geisler, M. P.; Gellerstedt, K.; Gemme, C.; Genest, M. H.; Geng, C.; Gentile, S.; Gentsos, C.; George, S.; Gerbaudo, D.; Geßner, G.; Ghasemi, S.; Ghneimat, M.; Giacobbe, B.; Giagu, S.; Giangiacomi, N.; Giannetti, P.; Gibson, S. M.; Gignac, M.; Gilchriese, M.; Gillberg, D.; Gilles, G.; Gingrich, D. M.; Giordani, M. P.; Giorgi, F. M.; Giraud, P. F.; Giromini, P.; Giugliarelli, G.; Giugni, D.; Giuli, F.; Giuliani, C.; Giulini, M.; Gjelsten, B. K.; Gkaitatzis, S.; Gkialas, I.; Gkougkousis, E. L.; Gkountoumis, P.; Gladilin, L. K.; Glasman, C.; Glatzer, J.; Glaysher, P. C. F.; Glazov, A.; Goblirsch-Kolb, M.; Godlewski, J.; Goldfarb, S.; Golling, T.; Golubkov, D.; Gomes, A.; Gonçalo, R.; Goncalves Gama, R.; Goncalves Pinto Firmino Da Costa, J.; Gonella, G.; Gonella, L.; Gongadze, A.; Gonnella, F.; Gonski, J. L.; González de la Hoz, S.; Gonzalez-Sevilla, S.; Goossens, L.; Gorbounov, P. A.; Gordon, H. A.; Gorini, B.; Gorini, E.; Gorišek, A.; Goshaw, A. T.; Gössling, C.; Gostkin, M. I.; Gottardo, C. A.; Goudet, C. R.; Goujdami, D.; Goussiou, A. G.; Govender, N.; Gozani, E.; Grabowska-Bold, I.; Gradin, P. O. J.; Gramling, J.; Gramstad, E.; Grancagnolo, S.; Gratchev, V.; Gravila, P. M.; Gray, C.; Gray, H. M.; Greenwood, Z. D.; Grefe, C.; Gregersen, K.; Gregor, I. M.; Grenier, P.; Grevtsov, K.; Griffiths, J.; Grillo, A. A.; Grimm, K.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Groh, S.; Gross, E.; Grosse-Knetter, J.; Grossi, G. C.; Grout, Z. J.; Grummer, A.; Guan, L.; Guan, W.; Guenther, J.; Guescini, F.; Guest, D.; Gueta, O.; Gui, B.; Guido, E.; Guillemin, T.; Guindon, S.; Gul, U.; Gumpert, C.; Guo, J.; Guo, W.; Guo, Y.; Gupta, R.; Gurbuz, S.; Gustavino, G.; Gutelman, B. J.; Gutierrez, P.; Gutierrez Ortiz, N. G.; Gutschow, C.; Guyot, C.; Guzik, M. P.; Gwenlan, C.; Gwilliam, C. B.; Haas, A.; Haber, C.; Hadavand, H. K.; Haddad, N.; Hadef, A.; Hageböck, S.; Hagihara, M.; Hakobyan, H.; Haleem, M.; Haley, J.; Halladjian, G.; Hallewell, G. D.; Hamacher, K.; Hamal, P.; Hamano, K.; Hamilton, A.; Hamity, G. N.; Hamnett, P. G.; Han, L.; Han, S.; Hanagaki, K.; Hanawa, K.; Hance, M.; Handl, D. M.; Haney, B.; Hanke, P.; Hansen, J. B.; Hansen, J. D.; Hansen, M. C.; Hansen, P. H.; Hara, K.; Hard, A. S.; Harenberg, T.; Hariri, F.; Harkusha, S.; Harrison, P. F.; Hartmann, N. M.; Hasegawa, Y.; Hasib, A.; Hassani, S.; Haug, S.; Hauser, R.; Hauswald, L.; Havener, L. B.; Havranek, M.; Hawkes, C. M.; Hawkings, R. J.; Hayakawa, D.; Hayden, D.; Hays, C. P.; Hays, J. M.; Hayward, H. S.; Haywood, S. J.; Head, S. J.; Heck, T.; Hedberg, V.; Heelan, L.; Heer, S.; Heidegger, K. K.; Heim, S.; Heim, T.; Heinemann, B.; Heinrich, J. J.; Heinrich, L.; Heinz, C.; Hejbal, J.; Helary, L.; Held, A.; Hellman, S.; Helsens, C.; Henderson, R. C. W.; Heng, Y.; Henkelmann, S.; Henriques Correia, A. M.; Henrot-Versille, S.; Herbert, G. H.; Herde, H.; Herget, V.; Hernández Jiménez, Y.; Herr, H.; Herten, G.; Hertenberger, R.; Hervas, L.; Herwig, T. C.; Hesketh, G. G.; Hessey, N. P.; Hetherly, J. W.; Higashino, S.; Higón-Rodriguez, E.; Hildebrand, K.; Hill, E.; Hill, J. C.; Hiller, K. H.; Hillier, S. J.; Hils, M.; Hinchliffe, I.; Hirose, M.; Hirschbuehl, D.; Hiti, B.; Hladik, O.; Hlaluku, D. R.; Hoad, X.; Hobbs, J.; Hod, N.; Hodgkinson, M. C.; Hodgson, P.; Hoecker, A.; Hoeferkamp, M. R.; Hoenig, F.; Hohn, D.; Holmes, T. R.; Holzbock, M.; Homann, M.; Honda, S.; Honda, T.; Hong, T. M.; Hooberman, B. H.; Hopkins, W. H.; Horii, Y.; Horton, A. J.; Hostachy, J.-Y.; Hostiuc, A.; Hou, S.; Hoummada, A.; Howarth, J.; Hoya, J.; Hrabovsky, M.; Hrdinka, J.; Hristova, I.; Hrivnac, J.; Hryn'ova, T.; Hrynevich, A.; Hsu, P. J.; Hsu, S.-C.; Hu, Q.; Hu, S.; Huang, Y.; Hubacek, Z.; Hubaut, F.; Huegging, F.; Huffman, T. B.; Hughes, E. W.; Huhtinen, M.; Hunter, R. F. 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B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Shen, Y.; Sherafati, N.; Sherman, A. D.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shipsey, I. P. J.; Shirabe, S.; Shiyakova, M.; Shlomi, J.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shope, D. R.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sickles, A. M.; Sidebo, P. E.; Sideras Haddad, E.; Sidiropoulou, O.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silverstein, S. B.; Simak, V.; Simic, L.; Simion, S.; Simioni, E.; Simmons, B.; Simon, M.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Siral, I.; Sivoklokov, S. Yu.; Sjölin, J.; Skinner, M. B.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Slovak, R.; Smakhtin, V.; Smart, B. H.; Smiesko, J.; Smirnov, N.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, J. W.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, I. M.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Søgaard, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Sopczak, A.; Sosa, D.; Sotiropoulou, C. L.; Sottocornola, S.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spieker, T. M.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanitzki, M. M.; Stapf, B. S.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Stark, S. H.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Stegler, M.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stevenson, T. J.; Stewart, G. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultan, D. M. S.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Suruliz, K.; Suster, C. J. E.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Swift, S. P.; Sykora, I.; Sykora, T.; Ta, D.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Tahirovic, E.; Taiblum, N.; Takai, H.; Takashima, R.; Takasugi, E. H.; Takeda, K.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, A. J.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teixeira-Dias, P.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Thais, S. J.; Theveneaux-Pelzer, T.; Thiele, F.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tian, Y.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorova-Nova, S.; Todt, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Treado, C. J.; Trefzger, T.; Tresoldi, F.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tsang, K. W.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tulbure, T. T.; Tuna, A. N.; Turchikhin, S.; Turgeman, D.; Turk Cakir, I.; Turra, R.; Tuts, P. M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Uno, K.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Vadla, K. O. H.; Vaidya, A.; Valderanis, C.; Valdes Santurio, E.; Valente, M.; Valentinetti, S.; Valero, A.; Valéry, L.; Valkar, S.; Vallier, A.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; van der Graaf, H.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varni, C.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Furelos, D.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, A. T.; Vermeulen, J. C.; Vetterli, M. C.; Viaux Maira, N.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vishwakarma, A.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vogel, M.; Vokac, P.; Volpi, G.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Wagner, P.; Wagner, W.; Wagner-Kuhr, J.; Wahlberg, H.; Wahrmund, S.; Wakamiya, K.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, Q.; Wang, R.-J.; Wang, R.; Wang, S. M.; Wang, T.; Wang, W.; Wang, W.; Wang, Z.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, A. F.; Webb, S.; Weber, M. S.; Weber, S. M.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weirich, M.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M. D.; Werner, P.; Wessels, M.; Weston, T. D.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A. S.; White, A.; White, M. J.; White, R.; Whiteson, D.; Whitmore, B. W.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winkels, E.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wobisch, M.; Wolf, A.; Wolf, T. M. H.; Wolff, R.; Wolter, M. W.; Wolters, H.; Wong, V. W. S.; Woods, N. L.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Wozniak, K. W.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xi, Z.; Xia, L.; Xu, D.; Xu, L.; Xu, T.; Xu, W.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamane, F.; Yamatani, M.; Yamazaki, T.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yigitbasi, E.; Yildirim, E.; Yorita, K.; Yoshihara, K.; Young, C.; Young, C. J. S.; Yu, J.; Yu, J.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zacharis, G.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanzi, D.; Zeitnitz, C.; Zemaityte, G.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, L.; Zhang, M.; Zhang, P.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Y.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, M.; Zhou, M.; Zhou, N.; Zhou, Y.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zou, R.; zur Nedden, M.; Zwalinski, L.

2018-01-01

A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses 36.1 fb^{-1} of proton-proton collision data recorded by the ATLAS experiment at √{s}=13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are interpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour-neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross-section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour-charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements.

A strong test of the dark matter origin of a TeV electron excess using icecube neutrinos

NASA Astrophysics Data System (ADS)

Zhao, Yue; Fang, Ke; Su, Meng; Miller, M. Coleman

2018-06-01

Due to the electroweak symmetry, high energy neutrinos and charged leptons are generically produced simultaneously in heavy dark matter decay or annihilation process. Correlating these two channels in dark matter indirect detections may provide important information on the intrinsic production mechanism. In this paper, we demonstrate this point by studying the tentative excess in the electron spectrum at 1.4 TeV reported by the DArk Matter Particle Explorer (DAMPE). A non-astrophysical scenario in which dark matter particles annihilate or decay in a local clump has been invoked to explain the excess. If e± annihilation channels in the final states are mediated by left-handed leptons as a component in the SU(2)L doublet, neutrinos with similar energies should have been simultaneously produced. We demonstrate that generic dark matter models can be decisively tested by the existing IceCube data. In case of a non-detection, such models would be excluded at the 5σ level by the five-year data for a point-like source and by the ten-year data for an extended source of dark matter particles with left-handed leptons. This serves as an example of the importance of correlating charged lepton and neutrino channels. It would be fruitful to conduct similar studies related to other approaches to the indirect detection of dark matter.

Simulated Milky Way analogues: implications for dark matter direct searches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozorgnia, Nassim; Calore, Francesca; Lovell, Mark

2016-05-01

We study the implications of galaxy formation on dark matter direct detection using high resolution hydrodynamic simulations of Milky Way-like galaxies simulated within the EAGLE and APOSTLE projects. We identify Milky Way analogues that satisfy observational constraints on the Milky Way rotation curve and total stellar mass. We then extract the dark matter density and velocity distribution in the Solar neighbourhood for this set of Milky Way analogues, and use them to analyse the results of current direct detection experiments. For most Milky Way analogues, the event rates in direct detection experiments obtained from the best fit Maxwellian distribution (withmore » peak speed of 223–289 km/s) are similar to those obtained directly from the simulations. As a consequence, the allowed regions and exclusion limits set by direct detection experiments in the dark matter mass and spin-independent cross section plane shift by a few GeV compared to the Standard Halo Model, at low dark matter masses. For each dark matter mass, the halo-to-halo variation of the local dark matter density results in an overall shift of the allowed regions and exclusion limits for the cross section. However, the compatibility of the possible hints for a dark matter signal from DAMA and CDMS-Si and null results from LUX and SuperCDMS is not improved.« less

Constraints on the interaction between dark matter and Baryons from cooling flow clusters.

PubMed

Qin, B; Wu, X P

2001-08-06

Other nongravitational heating processes are needed to resolve the disagreement between the absence of cool gas components in the centers of galaxy clusters revealed recently by Chandra and XMM observations and the expectations of conventional radiative cooling models. We propose that the interaction between dark matter and baryonic matter may act as an alternative for the reheating of intracluster medium (ICM) in the inner regions of clusters, in which kinetic energy of dark matter is transported to ICM to balance radiative cooling. Using the Chandra and XMM data, we set a useful constraint on the dark-matter-baryon cross section: sigma(xp)/m(x) approximately 1x10(-25) cm(2) GeV-1, where m(x) is the mass of dark matter particles.

Chiral gravitational waves and baryon superfluid dark matter

NASA Astrophysics Data System (ADS)

Alexander, Stephon; McDonough, Evan; Spergel, David N.

2018-05-01

We develop a unified model of darkgenesis and baryogenesis involving strongly interacting dark quarks, utilizing the gravitational anomaly of chiral gauge theories. In these models, both the visible and dark baryon asymmetries are generated by the gravitational anomaly induced by the presence of chiral primordial gravitational waves. We provide a concrete model of an SU(2) gauge theory with two massless quarks. In this model, the dark quarks condense and form a dark baryon charge superfluid (DBS), in which the Higgs-mode acts as cold dark matter. We elucidate the essential features of this dark matter scenario and discuss its phenomenological prospects.

Hints on the nature of dark matter from the properties of Milky Way satellites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderhalden, Donnino; Diemand, Juerg; Schneider, Aurel

2013-03-01

The nature of dark matter is still unknown and one of the most fundamental scientific mysteries. Although successfully describing large scales, the standard cold dark matter model (CDM) exhibits possible shortcomings on galactic and sub-galactic scales. It is exactly at these highly non-linear scales where strong astrophysical constraints can be set on the nature of the dark matter particle. While observations of the Lyman-α forest probe the matter power spectrum in the mildly non-linear regime, satellite galaxies of the Milky Way provide an excellent laboratory as a test of the underlying cosmology on much smaller scales. Here we present resultsmore » from a set of high resolution simulations of a Milky Way sized dark matter halo in eight distinct cosmologies: CDM, warm dark matter (WDM) with a particle mass of 2 keV and six different cold plus warm dark matter (C+WDM) models, varying the fraction, f{sub wdm}, and the mass, m{sub wdm}, of the warm component. We used three different observational tests based on Milky Way satellite observations: the total satellite abundance, their radial distribution and their mass profile. We show that the requirement of simultaneously satisfying all three constraints sets very strong limits on the nature of dark matter. This shows the power of a multi-dimensional small scale approach in ruling out models which would be still allowed by large scale observations.« less

Prospecting for new physics in the Higgs and flavor sectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishara, Fady

We explore two directions in beyond the standard model physics: dark matter model building and probing new sources of CP violation. In dark matter model building, we consider two scenarios where the stability of dark matter derives from the flavor symmetries of the standard model. The first model contains a flavor singlet dark matter candidate whose couplings to the visible sector are proportional to the flavor breaking parameters. This leads to a metastable dark matter with TeV scale mediators. In the second model, we consider a fully gauged SU(3) 3 flavor model with a flavor triplet dark matter. Consequently, the dark matter multiplet is charged while the standard model fields are neutral under a remnant Z 3 which ensures dark matter stability. We show that a Dirac fermion dark matter with radiative splitting in the multiplet must have a mass in the range [0:5; 5] TeV in order to satisfy all experimental constraints. We then turn our attention to Higgs portal dark matter and investigate the possibility of obtaining bounds on the up, down, and strange quark Yukawa couplings. If Higgs portal dark matter is discovered, we find that direct detection rates are insensitive to vanishing light quark Yukawa couplings. We then review flavor models and give the expected enhancement or suppression of the Yukawa couplings in those models. Finally, in the last two chapters, we develop techniques for probing CP violation in the Higgs coupling to photons and in rare radiative decays of B mesons. While theoretically clean, we find that these methods are not practical with current and planned detectors. However, these techniques can be useful with a dedicated detector (e.g., a gaseous TPC). In the case of radiative B meson decay B 0 → (K* → Kππ) γ, the techniques we develop also allow the extraction of the photon polarization fraction which is sensitive to new physics contributions since, in the standard model, the right(left) handed polarization fraction is of O( Λ QCD=m b) formore » $$\\bar{B}^{0}$$(B 0) meson decays.« less