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Sample records for peculiar dark matter

  1. The peculiar velocities of rich clusters in the hot and cold dark matter scenarios

    NASA Technical Reports Server (NTRS)

    Rhee, George F.; West, Michael J.; Villumsen, Jens V.

    1993-01-01

    We present the results of a study of the peculiar velocities of rich clusters of galaxies. The peculiar motion of rich clusters in various cosmological scenarios is of interest for a number of reasons. Observationally, one can measure the peculiar motion of clusters to greater distances than galaxies because cluster peculiar motions can be determined to greater accuracy. One can also test the slope of distance indicator relations using clusters to see if galaxy properties vary with environment. We have used N-body simulations to measure the amplitude and rms cluster peculiar velocity as a function of bias parameter in the hot and cold dark matter scenarios. In addition to measuring the mean and rms peculiar velocity of clusters in the two models, we determined whether the peculiar velocity vector of a given cluster is well aligned with the gravity vector due to all the particles in the simulation and the gravity vector due to the particles present only in the clusters. We have investigated the peculiar velocities of rich clusters of galaxies in the cold dark matter and hot dark matter galaxy formation scenarios. We have derived peculiar velocities and associated errors for the scenarios using four values of the bias parameter ranging from b = 1 to b = 2.5. The growth of the mean peculiar velocity with scale factor has been determined and compared to that predicted by linear theory. In addition, we have compared the orientation of force and velocity in these simulations to see if a program such as that proposed by Bertschinger and Dekel (1989) for elliptical galaxy peculiar motions can be applied to clusters. The method they describe enables one to recover the density field from large scale redshift distance samples. The method makes it possible to do this when only radial velocities are known by assuming that the velocity field is curl free. Our analysis suggests that this program if applied to clusters is only realizable for models with a low value of the bias

  2. Cosmic web alignments with the shape, angular momentum and peculiar velocities of dark matter haloes

    NASA Astrophysics Data System (ADS)

    Forero-Romero, Jaime E.; Contreras, Sergio; Padilla, Nelson

    2014-09-01

    We study the alignment of dark matter haloes with the cosmic web characterized by the tidal and velocity shear fields. We focus on the alignment of their shape, angular momentum and peculiar velocities. We use a cosmological N-body simulation that allows us to study dark matter haloes spanning almost five orders of magnitude in mass (109-1014) h-1 M⊙ and spatial scales of (0.5-1.0) h-1 Mpc to define the cosmic web. The strongest alignment is measured for halo shape along the smallest tidal eigenvector, e.g. along filaments and walls, with a signal that gets stronger as the halo mass increases. In the case of the velocity shear field only massive haloes >1012 h-1 M⊙ tend to have their shapes aligned along the largest tidal eigenvector, i.e. perpendicular to filaments and walls. For the angular momentum we find alignment signals only for haloes more massive than 1012 h-1 M⊙ both in the tidal and velocity shear fields where the preferences is to be parallel to the middle eigenvector; perpendicular to filaments and parallel to walls. Finally, the peculiar velocities show a strong alignment along the smallest tidal eigenvector for all halo masses; haloes move along filaments and walls. The same alignment is present with the velocity shear, albeit weaker and only for haloes less massive than 1012 h-1 M⊙. Our results show that the two different algorithms used to define the cosmic web describe different physical aspects of non-linear collapse and should be used in a complementary way to understand the cosmic web influence on galaxy evolution.

  3. The effect of dark matter and dark energy interactions on the peculiar velocity field and the kinetic Sunyaev-Zel'dovich effect

    SciTech Connect

    Xu, Xiao-Dong; Wang, Bin; Zhang, Pengjie; Atrio-Barandela, Fernando E-mail: wang_b@sjtu.edu.cn E-mail: atrio@usal.es

    2013-12-01

    The interaction between Dark Matter and Dark Energy has been proposed as a mechanism to alleviate the coincidence problem. We analyze its effects on the evolution of the gravitational and the peculiar velocity fields. We find that for different model parameters peculiar velocities vary from a factor five times smaller to two times larger than in the ΛCDM cosmological model at the same scales. We propose two new observables sensitive to such interactions based on their effect on the velocity field. We compare the effects on peculiar velocities with those on the Integrated Sachs-Wolfe effect demonstrating that velocities are more sensitive to the interaction. We show that the current upper limits on the amplitude of the kinetic Sunyaev-Zel'dovich power spectrum of temperature anisotropies provide constraints on the coupling within the dark sectors that are consistent with those obtained previously from the Cosmic Microwave Background and galaxy clusters. In particular, we show that Atacama Cosmology Telescope and South Pole Telescope data favor the decay of Dark Energy into Dark Matter, as required to solve the coincidence problem.

  4. Large-scale structure after COBE: Peculiar velocities and correlations of cold dark matter halos

    NASA Technical Reports Server (NTRS)

    Zurek, Wojciech H.; Quinn, Peter J.; Salmon, John K.; Warren, Michael S.

    1994-01-01

    Large N-body simulations on parallel supercomputers allow one to simultaneously investigate large-scale structure and the formation of galactic halos with unprecedented resolution. Our study shows that the masses as well as the spatial distribution of halos on scales of tens of megaparsecs in a cold dark matter (CDM) universe with the spectrum normalized to the anisotropies detected by Cosmic Background Explorer (COBE) is compatible with the observations. We also show that the average value of the relative pairwise velocity dispersion sigma(sub v) - used as a principal argument against COBE-normalized CDM models-is significantly lower for halos than for individual particles. When the observational methods of extracting sigma(sub v) are applied to the redshift catalogs obtained from the numerical experiments, estimates differ significantly between different observation-sized samples and overlap observational estimates obtained following the same procedure.

  5. Dark Matters

    ScienceCinema

    Joseph Silk

    2010-01-08

    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.

  6. Dark Matters

    SciTech Connect

    Joseph Silk

    2009-09-23

    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.

  7. Dark matters

    NASA Astrophysics Data System (ADS)

    Steigman, Gary

    The observational evidence for dark matter in the universe is reviewed. Constraints on the baryon density from primordial nucleosynthesis are presented and compared to the dynamical estimates of the mass on various scales. Baryons can account for the observed luminous mass as well as some, perhaps most, of the 'observed' dark mass. However if, as inflation/naturalness suggest, the total density of the universe is equal to the critical density, then nonbaryonic dark matter is required. The assets and liabilities of, as well as the candidates for, hot and cold dark matter are outlined. At present, there is no completely satisfactory candidate for nonbaryonic dark matter.

  8. Dark Matter

    SciTech Connect

    Bashir, A.; Cotti, U.; De Leon, C. L.; Raya, A; Villasenor, L.

    2008-07-02

    One of the biggest scientific mysteries of our time resides in the identification of the particles that constitute a large fraction of the mass of our Universe, generically known as dark matter. We review the observations and the experimental data that imply the existence of dark matter. We briefly discuss the properties of the two best dark-matter candidate particles and the experimental techniques presently used to try to discover them. Finally, we mention a proposed project that has recently emerged within the Mexican community to look for dark matter.

  9. Dark matter.

    PubMed

    Peebles, P James E

    2015-10-01

    The evidence for the dark matter (DM) of the hot big bang cosmology is about as good as it gets in natural science. The exploration of its nature is now led by direct and indirect detection experiments, to be complemented by advances in the full range of cosmological tests, including judicious consideration of the rich phenomenology of galaxies. The results may confirm ideas about DM already under discussion. If we are lucky, we also will be surprised once again. PMID:24794526

  10. Dark matter

    PubMed Central

    Peebles, P. James E.

    2015-01-01

    The evidence for the dark matter (DM) of the hot big bang cosmology is about as good as it gets in natural science. The exploration of its nature is now led by direct and indirect detection experiments, to be complemented by advances in the full range of cosmological tests, including judicious consideration of the rich phenomenology of galaxies. The results may confirm ideas about DM already under discussion. If we are lucky, we also will be surprised once again. PMID:24794526

  11. Dark Matter

    ERIC Educational Resources Information Center

    Lincoln, Don

    2013-01-01

    It's a dark, dark universe out there, and I don't mean because the night sky is black. After all, once you leave the shadow of the Earth and get out into space, you're surrounded by countless lights glittering everywhere you look. But for all of Sagan's billions and billions of stars and galaxies, it's a jaw-dropping fact that the ordinary kind of…

  12. Dark matter and dark radiation

    SciTech Connect

    Ackerman, Lotty; Buckley, Matthew R.; Carroll, Sean M.; Kamionkowski, Marc

    2009-01-15

    We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ('dark electromagnetism') that couples only to dark matter, not to the standard model. The dark matter consists of an equal number of positive and negative charges under the new force, but annihilations are suppressed if the dark-matter mass is sufficiently high and the dark fine-structure constant {alpha}-circumflex is sufficiently small. The correct relic abundance can be obtained if the dark matter also couples to the conventional weak interactions, and we verify that this is consistent with particle-physics constraints. The primary limit on {alpha}-circumflex comes from the demand that the dark matter be effectively collisionless in galactic dynamics, which implies {alpha}-circumflex < or approx. 10{sup -3} for TeV-scale dark matter. These values are easily compatible with constraints from structure formation and primordial nucleosynthesis. We raise the prospect of interesting new plasma effects in dark-matter dynamics, which remain to be explored.

  13. Asymmetric dark matter

    SciTech Connect

    Kumar, Jason

    2014-06-24

    We review the theoretical framework underlying models of asymmetric dark matter, describe astrophysical constraints which arise from observations of neutron stars, and discuss the prospects for detecting asymmetric dark matter.

  14. 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.

  15. The Dark Matter Problem

    NASA Astrophysics Data System (ADS)

    Sanders, Robert H.

    2014-02-01

    1. Introduction; 2. Early history of the dark matter hypothesis; 3. The stability of disk galaxies: the dark halo solutions; 4. Direct evidence: extended rotation curves of spiral galaxies; 5. The maximum disk: light traces mass; 6. Cosmology and the birth of astroparticle physics; 7. Clusters revisited: missing mass found; 8. CDM confronts galaxy rotation curves; 9. The new cosmology: dark matter is not enough; 10. An alternative to dark matter: Modified Newtonian Dynamics; 11. Seeing dark matter: the theory and practice of detection; 12. Reflections: a personal point of view; Appendix; References; Index.

  16. Dark matter and sterility

    NASA Astrophysics Data System (ADS)

    Smith, Peter F.

    2014-10-01

    In reply to Louise Mayor's dark-matter flow-chart "What's the matter?" (July pp30-31), which summarized the most likely candidates for galactic dark matter, and to Jon Cartwright's feature "A fourth type of neutrino" on the possibility of "sterile" neutrinos (August pp24-28).

  17. Neutrinos and dark matter

    SciTech Connect

    Ibarra, Alejandro

    2015-07-15

    Neutrinos could be key particles to unravel the nature of the dark matter of the Universe. On the one hand, sterile neutrinos in minimal extensions of the Standard Model are excellent dark matter candidates, producing potentially observable signals in the form of a line in the X-ray sky. On the other hand, the annihilation or the decay of dark matter particles produces, in many plausible dark matter scenarios, a neutrino flux that could be detected at neutrino telescopes, thus providing non-gravitational evidence for dark matter. More conservatively, the non-observation of a significant excess in the neutrino fluxes with respect to the expected astrophysical backgrounds can be used to constrain dark matter properties, such as the self-annihilation cross section, the scattering cross section with nucleons and the lifetime.

  18. 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.

  19. Dark Matter 2013

    NASA Astrophysics Data System (ADS)

    Schumann, Marc

    2014-10-01

    This article reviews the status of the exciting and fastly evolving field of dark matter research as of summer 2013, when it was discussed at the International Cosmic Ray Conference (ICRC) 2013 in Rio de Janeiro. It focuses on the three main avenues to detect weakly interacting massive particle (WIMP) dark matter: direct detection, indirect detection, and collider searches. The article is based on the dark matter rapporteur talk summarizing the presentations given at the conference, filling some gaps for completeness.

  20. Dark matter and cosmology

    SciTech Connect

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  1. Dark matter and cosmology

    SciTech Connect

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  2. Analysis of dark matter and dark energy

    NASA Astrophysics Data System (ADS)

    Yongquan, Han

    2016-05-01

    As the law of unity of opposites of the Philosophy tells us, the bright material exists, the dark matter also exists. Dark matter and dark energy should allow the law of unity of opposites. The Common attributes of the matter is radiation, then common attributes of dark matter must be absorb radiation. Only the rotation speed is lower than the speed of light radiation, can the matter radiate, since the speed of the matter is lower than the speed of light, so the matter is radiate; The rotate speed of the dark matter is faster than the light , so the dark matter doesn't radiate, it absorbs radiation. The energy that the dark matter absorb radiation produced (affect the measurement of time and space distribution of variations) is dark energy, so the dark matter produce dark energy only when it absorbs radiation. Dark matter does not radiate, two dark matters does not exist inevitably forces, and also no dark energy. Called the space-time ripples, the gravitational wave is bent radiation, radiation particles should be graviton, graviton is mainly refers to the radiation particles whose wavelength is small. Dark matter, dark energy also confirms the existence of the law of symmetry.

  3. Condensate dark matter stars

    SciTech Connect

    Li, X.Y.; Harko, T.; Cheng, K.S. E-mail: harko@hkucc.hku.hk

    2012-06-01

    We investigate the structure and stability properties of compact astrophysical objects that may be formed from the Bose-Einstein condensation of dark matter. Once the critical temperature of a boson gas is less than the critical temperature, a Bose-Einstein Condensation process can always take place during the cosmic history of the universe. Therefore we model the dark matter inside the star as a Bose-Einstein condensate. In the condensate dark matter star model, the dark matter equation of state can be described by a polytropic equation of state, with polytropic index equal to one. We derive the basic general relativistic equations describing the equilibrium structure of the condensate dark matter star with spherically symmetric static geometry. The structure equations of the condensate dark matter stars are studied numerically. The critical mass and radius of the dark matter star are given by M{sub crit} ≈ 2(l{sub a}/1fm){sup 1/2}(m{sub χ}/1 GeV){sup −3/2}M{sub s}un and R{sub crit} ≈ 1.1 × 10{sup 6}(l{sub a}/1 fm){sup 1/2}(m{sub χ}/1 GeV){sup −3/2} cm respectively, where l{sub a} and m{sub χ} are the scattering length and the mass of dark matter particle, respectively.

  4. Composite millicharged dark matter

    NASA Astrophysics Data System (ADS)

    Kouvaris, Chris

    2013-07-01

    We study a composite millicharged dark matter model. The dark matter is in the form of pionlike objects emerging from a higher scale QCD-like theory. We present two distinct possibilities with interesting phenomenological consequences based on the choice of the parameters. In the first one, the dark matter is produced nonthermally, and it could potentially account for the 130 GeV Fermi photon line via decays of the “dark pions.” We estimate the self-interaction cross section, which might play an important role both in changing the dark matter halo profile at the center of the galaxy and in making the dark matter warmer. In the second version the dark matter is produced via the freeze-in mechanism. Finally we impose all possible astrophysical, cosmological and experimental constraints. We study in detail generic constraints on millicharged dark matter that can arise from anomalous isotope searches of different elements and we show why constraints based on direct searches from underground detectors are not generally valid.

  5. Ghost dark matter

    SciTech Connect

    Furukawa, Tomonori; Yokoyama, Shuichiro; Ichiki, Kiyotomo; Sugiyama, Naoshi; Mukohyama, Shinji E-mail: shu@a.phys.nagoya-u.ac.jp E-mail: naoshi@a.phys.nagoya-u.ac.jp

    2010-05-01

    We revisit ghost dark matter, the possibility that ghost condensation may serve as an alternative to dark matter. In particular, we investigate the Friedmann-Robertson-Walker (FRW) background evolution and the large-scale structure (LSS) in the ΛGDM universe, i.e. a late-time universe dominated by a cosmological constant and ghost dark matter. The FRW background of the ΛGDM universe is indistinguishable from that of the standard ΛCDM universe if M∼>1eV, where M is the scale of spontaneous Lorentz breaking. From the LSS we find a stronger bound: M∼>10eV. For smaller M, ghost dark matter would have non-negligible sound speed after the matter-radiation equality, and thus the matter power spectrum would significantly differ from observation. These bounds are compatible with the phenomenological upper bound M∼<100GeV known in the literature.

  6. Interacting warm dark matter

    SciTech Connect

    Cruz, Norman; Palma, Guillermo; Zambrano, David; Avelino, Arturo E-mail: guillermo.palma@usach.cl E-mail: avelino@fisica.ugto.mx

    2013-05-01

    We explore a cosmological model composed by a dark matter fluid interacting with a dark energy fluid. The interaction term has the non-linear λρ{sub m}{sup α}ρ{sub e}{sup β} form, where ρ{sub m} and ρ{sub e} are the energy densities of the dark matter and dark energy, respectively. The parameters α and β are in principle not constrained to take any particular values, and were estimated from observations. We perform an analytical study of the evolution equations, finding the fixed points and their stability properties in order to characterize suitable physical regions in the phase space of the dark matter and dark energy densities. The constants (λ,α,β) as well as w{sub m} and w{sub e} of the EoS of dark matter and dark energy respectively, were estimated using the cosmological observations of the type Ia supernovae and the Hubble expansion rate H(z) data sets. We find that the best estimated values for the free parameters of the model correspond to a warm dark matter interacting with a phantom dark energy component, with a well goodness-of-fit to data. However, using the Bayesian Information Criterion (BIC) we find that this model is overcame by a warm dark matter – phantom dark energy model without interaction, as well as by the ΛCDM model. We find also a large dispersion on the best estimated values of the (λ,α,β) parameters, so even if we are not able to set strong constraints on their values, given the goodness-of-fit to data of the model, we find that a large variety of theirs values are well compatible with the observational data used.

  7. Exothermic dark matter

    SciTech Connect

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

    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. 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.

  8. Big Questions: Dark Matter

    ScienceCinema

    Lincoln, Don

    2014-08-07

    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.

  9. Big Questions: Dark Matter

    SciTech Connect

    Lincoln, Don

    2013-12-05

    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.

  10. Dark matter universe.

    PubMed

    Bahcall, Neta A

    2015-10-01

    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

  11. Dark matter universe

    NASA Astrophysics Data System (ADS)

    Bahcall, Neta A.

    2015-10-01

    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.

  12. 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

  13. Resonant SIMP dark matter

    NASA Astrophysics Data System (ADS)

    Choi, Soo-Min; Lee, Hyun Min

    2016-07-01

    We consider a resonant SIMP dark matter in models with two singlet complex scalar fields charged under a local dark U(1)D. After the U(1)D is broken down to a Z5 discrete subgroup, the lighter scalar field becomes a SIMP dark matter which has the enhanced 3 → 2 annihilation cross section near the resonance of the heavier scalar field. Bounds on the SIMP self-scattering cross section and the relic density can be fulfilled at the same time for perturbative couplings of SIMP. A small gauge kinetic mixing between the SM hypercharge and dark gauge bosons can be used to make SIMP dark matter in kinetic equilibrium with the SM during freeze-out.

  14. Inflatable Dark Matter.

    PubMed

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D

    2016-01-22

    We describe a general scenario, dubbed "inflatable dark matter," in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levels without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ∼MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model. PMID:26849584

  15. Xenophobic dark matter

    NASA Astrophysics Data System (ADS)

    Feng, Jonathan L.; Kumar, Jason; Sanford, David

    2013-07-01

    We consider models of xenophobic dark matter, in which isospin-violating dark matter-nucleon interactions significantly degrade the response of xenon direct detection experiments. For models of near-maximal xenophobia, with neutron-to-proton coupling ratio fn/fp≈-0.64, and dark matter mass near 8 GeV, the regions of interest for CoGeNT and CDMS-Si and the region of interest identified by Collar and Fields in CDMS-Ge data can be brought into agreement. This model may be tested in future direct, indirect, and collider searches. Interestingly, because the natural isotope abundance of xenon implies that xenophobia has its limits, we find that this xenophobic model may be probed in the near future by xenon experiments. Near-future data from the LHC and Fermi-LAT may also provide interesting alternative probes of xenophobic dark matter.

  16. The Local Dark Matter

    SciTech Connect

    Helfer, H.L.

    2005-10-21

    The observations of the extended rotation curves of some galaxies provide important constraints upon the nature of the local dark matter present in the halos of these galaxies. Using these constraints, one can show that the halo dark matter cannot be some population of conventional astronomical objects and (most probably) cannot be a population of exotic non-interacting particles. We suggest that the halos can be regarded as large spatial fluctuations in a classic scalar field.

  17. Elastically Decoupling Dark Matter

    NASA Astrophysics Data System (ADS)

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2016-06-01

    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10-3- 1 fb range.

  18. Elastically Decoupling Dark Matter.

    PubMed

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2016-06-01

    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10^{-3}-1  fb range. PMID:27314712

  19. Dark matter: theoretical perspectives.

    PubMed Central

    Turner, M S

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that (i) there are no dark-matter candidates within the "standard model" of particle physics, (ii) there are several compelling candidates within attractive extensions of the standard model of particle physics, and (iii) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for "new physics." The compelling candidates are a very light axion (10(-6)-10(-4) eV), a light neutrino (20-90 eV), and a heavy neutralino (10 GeV-2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos. PMID:11607395

  20. Dark matter: Theoretical perspectives

    SciTech Connect

    Turner, M.S. . Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL )

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for new physics.'' The compelling candidates are: a very light axion ( 10[sup [minus]6] eV--10[sup [minus]4] eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  1. Dark matter: Theoretical perspectives

    SciTech Connect

    Turner, M.S. |

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ``new physics.`` The compelling candidates are: a very light axion ( 10{sup {minus}6} eV--10{sup {minus}4} eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  2. Dark matter possibilities

    NASA Astrophysics Data System (ADS)

    Wagner, Orvin

    2015-04-01

    In my research I observe signals that penetrate dense matter and I hypothesize that they are due to waves in dark matter. Since they readily penetrate thick matter I hypothesize that they are due to small dark matter particles instead of the usual hypothesized Wimps. For example I observed signals that penetrate my local hill at near 77 m/s. In addition the solar cycle appears to be due to to dark matter oscillating in the sun producing standing waves that have to due with planet placement and stability of the solar system. Dozens of experiments, over the past 20 years, confirm the penetrating waves. Examples of the experiments are presented on my website darkmatterwaves.com and US patent number 8,669,917 B1.

  3. Quirky composite dark matter

    NASA Astrophysics Data System (ADS)

    Kribs, Graham D.; Roy, Tuhin S.; Terning, John; Zurek, Kathryn M.

    2010-05-01

    We propose a new dark matter candidate, “quirky dark matter,” that is a scalar baryonic bound state of a new non-Abelian force that becomes strong below the electroweak scale. The bound state is made of chiral quirks: new fermions that transform under both the new strong force as well as in a chiral representation of the electroweak group, acquiring mass from the Higgs mechanism. Electric charge neutrality of the lightest baryon requires approximately degenerate quirk masses which also causes the charge radius of the bound state to be negligible. The abundance is determined by an asymmetry that is linked to the baryon and lepton numbers of the universe through electroweak sphalerons. Dark matter elastic scattering with nuclei proceeds through Higgs exchange as well as an electromagnetic polarizability operator which is just now being tested in direct detection experiments. A novel method to search for quirky dark matter is to look for a gamma-ray “dark line” spectroscopic feature in galaxy clusters that result from the quirky Lyman-alpha or quirky hyperfine transitions. Colliders are expected to dominantly produce quirky mesons, not quirky baryons, consequently large missing energy is not the primary collider signal of the physics associated with quirky dark matter.

  4. Tunguska dark matter ball

    NASA Astrophysics Data System (ADS)

    Froggatt, C. D.; Nielsen, H. B.

    2015-04-01

    It is suggested that the Tunguska event in June 1908 was due to a cm-large ball of a condensate of bound states of 6 top and 6 antitop quarks containing highly compressed ordinary matter. Such balls are supposed to make up the dark matter as we earlier proposed. The expected rate of impact of this kind of dark matter ball with the earth seems to crudely match a time scale of 200 years between the impacts. The main explosion of the Tunguska event is explained in our picture as material coming out from deep within the earth, where it has been heated and compressed by the ball penetrating to a depth of several thousand km. Thus the effect has some similarity with volcanic activity as suggested by Kundt. We discuss the possible identification of kimberlite pipes with earlier Tunguska-like events. A discussion of how the dark matter balls may have formed in the early universe is also given.

  5. Vectorlike sneutrino dark matter

    NASA Astrophysics Data System (ADS)

    Tang, Yi-Lei; Zhu, Shou-hua

    2016-05-01

    In this paper, we discuss the minimal supersymmetric standard model (MSSM) extended with one vectorlike lepton doublet L -L ¯ and one right-handed neutrino N . The neutral vecotorlike sneutrino can be a candidate of dark matter. To avoid the interaction with the nucleons by exchanging a Z boson, the mass splitting between the real part and the imaginary part of the sneutrino field is needed. Compared with the MSSM sneutrino dark matter, the mass splitting between the vectorlike sneutrino field can be more naturally acquired without large A terms and constraints on the neutralino masses. We have also calculated the relic density and the elastic scattering cross sections with the nucleons in the cases that the dark matter particles coannihilate with or without the MSSM slepton doublets. The elastic scattering cross sections with the nucleons are well below the LUX bounds. In the case that the dark matter coannihilates with all the MSSM slepton doublets, the mass of the dark matter can be as light as 370 GeV.

  6. Complex Dark Matter

    SciTech Connect

    Lincoln, Don

    2015-04-16

    After a century of study, scientists have come to the realization that the ordinary matter made of atoms is a minority in the universe. In order to explain observations, it appears that there exists a new and undiscovered kind of matter, called dark matter, that is five times more prevalent than ordinary matter. The evidence for this new matter’s existence is very strong, but scientists know only a little about its nature. In today’s video, Fermilab’s Dr. Don Lincoln talks about an exciting and unconventional idea, specifically that dark matter might have a very complex set of structures and interactions. While this idea is entirely speculative, it is an interesting hypothesis and one that scientists are investigating.

  7. Axion dark matter searches

    SciTech Connect

    Stern, Ian P.; Collaboration: ADMX Collaboration; ADMX-HF Collaboration

    2014-06-24

    Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.

  8. Axion dark matter searches

    DOE PAGESBeta

    Stern, Ian P.

    2014-01-01

    We report nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axionsmore » at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.« less

  9. Dark matter candidates

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1989-01-01

    The types of particles which may provide the nonluminous mass required by big-bang cosmological models are listed and briefly characterized. The observational evidence for the existence of dark matter (outweighing the luminous component by at least a factor of 10) is reviewed; the theoretical arguments favoring mainly nonbaryonic dark matter are summarized; and particular attention is given to weakly interacting massive particles (WIMPs) remaining as relics from the early universe. The WIMPs are classified as thermal relics (heavy stable neutrinos and lighter neutralinos), asymmetric relics (including baryons), nonthermal relics (superheavy magnetic monopoles, axions, and soliton stars), and truly exotic relics (relativistic debris or vacuum energy). Explanations for the current apparent baryon/exotica ratio of about 0.1 in different theoretical scenarios are considered, and the problems of experimental and/or observational dark-matter detection are examined.

  10. Asymmetric twin Dark Matter

    SciTech Connect

    Farina, Marco

    2015-11-09

    We study a natural implementation of Asymmetric Dark Matter in Twin Higgs models. The mirroring of the Standard Model strong sector suggests that a twin baryon with mass around 5 GeV is a natural Dark Matter candidate once a twin baryon number asymmetry comparable to the SM asymmetry is generated. We explore twin baryon Dark Matter in two different scenarios, one with minimal content in the twin sector and one with a complete copy of the SM, including a light twin photon. The essential requirements for successful thermal history are presented, and in doing so we address some of the cosmological issues common to many Twin Higgs models. The required interactions we introduce predict signatures at direct detection experiments and at the LHC.

  11. Axion dark matter searches

    SciTech Connect

    Stern, Ian P.

    2014-01-01

    We report nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.

  12. Signatures of dark matter

    NASA Astrophysics Data System (ADS)

    Baltz, Edward Anthony

    It is well known that most of the mass in the universe remains unobserved save for its gravitational effect on luminous matter. The nature of this ``dark matter'' remains a mystery. From measurements of the primordial deuterium abundance, the theory of big bang nucleosynthesis predicts that there are not enough baryons to account for the amount of dark matter observed, thus the missing mass must take an exotic form. Several promising candidates have been proposed. In this work I will describe my research along two main lines of inquiry into the dark matter puzzle. The first possibility is that the dark matter is exotic massive particles, such as those predicted by supersymmetric extensions to the standard model of particle physics. Such particles are generically called WIMPs, for weakly interacting massive particles. Focusing on the so-called neutralino in supersymmetric models, I discuss the possible signatures of such particles, including their direct detection via nuclear recoil experiments and their indirect detection via annihilations in the halos of galaxies, producing high energy antiprotons, positrons and gamma rays. I also discuss signatures of the possible slow decays of such particles. The second possibility is that there is a population of black holes formed in the early universe. Any dark objects in galactic halos, black holes included, are called MACHOs, for massive compact halo objects. Such objects can be detected by their gravitational microlensing effects. Several possibilities for sources of baryonic dark matter are also interesting for gravitational microlensing. These include brown dwarf stars and old, cool white dwarf stars. I discuss the theory of gravitational microlensing, focusing on the technique of pixel microlensing. I make predictions for several planned microlensing experiments with ground based and space based telescopes. Furthermore, I discuss binary lenses in the context of pixel microlensing. Finally, I develop a new technique for

  13. Light dark matter and dark radiation

    NASA Astrophysics Data System (ADS)

    Heo, Jae Ho; Kim, C. S.

    2016-03-01

    Light ( M ≤ 20 MeV) dark-matter particles freeze out after neutrino decoupling. If the dark-matter particle couples to a neutrino or an electromagnetic plasma, the late time entropy production from dark-matter annihilation can change the neutrino-to-photon temperature ratio, and equally the effective number of neutrinos N eff. We study the non-equilibrium effects of dark-matter annihilation on the N eff and the effects by using a thermal equilibrium approximation. Both results are constrained with Planck observations. We demonstrate that the lower bounds of the dark-matter mass and the possibilities of the existence of additional radiation particles are more strongly constrained for dark-matter annihilation process in non-equilibrium.

  14. Asymmetric condensed dark matter

    NASA Astrophysics Data System (ADS)

    Aguirre, Anthony; Diez-Tejedor, Alberto

    2016-04-01

    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate must be lighter than a few tens of eV so that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of decoupling to the scale of the QCD phase transition or above. This requires large dark matter-to-photon ratios and very weak interactions with standard model particles.

  15. Dark matter detection

    NASA Astrophysics Data System (ADS)

    Baudis, Laura

    2016-08-01

    More than 80 years after its first postulation in modern form, the existence and distribution of dark matter in our Universe is well established. Dark matter is the gravitational glue that holds together galaxies, galaxy clusters and structures on the largest cosmological scales, and an essential component to explain the observed fluctuations in the cosmic microwave background. Yet its existence is inferred indirectly, through its gravitational influence on luminous matter, and its nature is not known. A viable hypothesis is that dark matter is made of new, elementary particles, with allowed masses and interaction strengths spanning a wide range. Two well-motivated classes of candidates are axions and weakly interacting massive particles (WIMPs), and experimental efforts have now reached sensitivities that allow them to test this hypothesis. Axions, produced non-thermally in the early Universe, can be detected by exploiting their predicted couplings to photons and electrons. WIMPs can be detected directly by looking for their collisions with atomic nuclei ultra-low background detectors, or indirectly, through the observation of their annihilation products such as neutrinos, gamma rays, positrons and antiprotons over the astrophysical background. A complementary method is the production of dark matter particles at colliders such as the Large Hadron Collider, where they could be observed indirectly via missing transverse energy, or via associated particle production. I will review the main experimental efforts to search for dark matter particles, and the existing constraints on the interaction cross sections. I will also discuss future experiments, their complementarity and their ability to measure the properties of these particles.

  16. Inflatable dark matter

    DOE PAGESBeta

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel

    2016-01-22

    Here, we describe a general scenario, dubbed “inflatable dark matter,” in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levelsmore » without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ~MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model.« less

  17. Little Higgs dark matter

    SciTech Connect

    Birkedal, Andreas; Noble, Andrew; Perelstein, Maxim; Spray, Andrew

    2006-08-01

    The introduction of T parity dramatically improves the consistency of little Higgs models with precision electroweak data, and renders the lightest T-odd particle (LTP) stable. In the littlest Higgs model with T parity, the LTP is typically the T-odd heavy photon, which is weakly interacting and can play the role of dark matter. We analyze the relic abundance of the heavy photon, including its coannihilations with other T-odd particles, and map out the regions of the parameter space where it can account for the observed dark matter. We evaluate the prospects for direct and indirect discovery of the heavy photon dark matter. The direct detection rates are quite low and a substantial improvement in experimental sensitivity would be required for observation. A substantial flux of energetic gamma rays is produced in the annihilation of the heavy photons in the galactic halo. This flux can be observed by the GLAST telescope, and, if the distribution of dark matter in the halo is favorable, by ground-based telescope arrays such as VERITAS and HESS.

  18. Dark matter on top

    SciTech Connect

    Gómez, M.A.; Jackson, C.B.; Shaughnessy, G. E-mail: chris@uta.edu

    2014-12-01

    We consider a simplified model of fermionic dark matter which couples exclusively to the right-handed top quark via a renormalizable interaction with a color-charged scalar. We first compute the relic abundance of this type of dark matter and investigate constraints placed on the model parameter space by the latest direct detection data. We also perform a detailed analysis for the production of dark matter at the LHC for this model. We find several kinematic variables that allow for a clean signal extraction and we show that the parameter space of this model will be well probed during LHC Run-II. Finally, we investigate the possibility of detecting this type of dark matter via its annihilations into gamma rays. We compute the continuum and the line emission (which includes a possible ''Higgs in Space!'' line) and its possible discovery by future gamma-ray telescopes. We find that the annihilation spectrum has distinctive features which may distinguish it from other models.

  19. Cold dark matter halos

    NASA Astrophysics Data System (ADS)

    Dubinski, John Joseph

    The dark halos arising in the Cold Dark Matter (CDM) cosmology are simulated to investigate the relationship between the structure and kinematics of dark halos and galaxies. Realistic cosmological initial conditions and tidal field boundary conditions are used in N-body simulations of the collapse of density peaks to form dark halos. The core radii of dark halos are no greater than the softening radius, rs = 1.4 kpc. The density profiles can be fit with an analytical Hernquist (1990) profile with an effective power law which varies between -1 in the center to -4 at large radii. The rotation curves of dark halos resemble the flat rotation curves of spiral galaxies in the observed range, 1.5 approximately less than r approximately less than 30 kpc. The halos are strongly triaxial and very flat with (c/a) = 0.50 and (b/a) = 0.71. The distribution of ellipticities for dark halos reaches a maximum at epsilon = 0.5 in contrast to the distribution for elliptical galaxies which peaks at epsilon = 0.2 suggesting that ellipticals are much rounder than dark halos. Dark halos are generally flatter than their progenitor density peaks. The final shape and orientation of a dark halo are largely determined by tidal torquing and are sensitive to changes in the strength and orientation of a tidal field. Dark halos are pressure supported objects with negligible rotational support as indicated by the mean dimensionless spin, lamda = 0.042 +/- 0.024. The angular momentum vector tends to align with the true minor axis of dark halos. Elliptical galaxies have a similar behavior implied by the observation of the tendency for alignment of the rotation vector and the apparent minor axis. The origin of this behavior may be traced to the tendency for tidal torques to misalign with the major axis of a density peak. Tidal torques are found to isotropize the velocity ellipsoids of dark halos at large radii, contrary to the expectation of radially anisotropic velocity ellipsoids in cold collapse

  20. The Search for Dark Matter

    SciTech Connect

    Orrell, John

    2013-11-20

    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.

  1. The Search for Dark Matter

    ScienceCinema

    Orrell, John

    2014-07-24

    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.

  2. Particle Dark Matter and DAMA/LIBRA

    SciTech Connect

    Bernabei, R.; Nozzoli, F.; Belli, P.; Cappella, F.; D'Angelo, A.; Prosperi, D.; Cerulli, R.; Dai, C. J.; He, H. L.; Ma, X. H.; Sheng, X. D.; Wang, R. G.; Montecchia, F.; Ye, Z. P.

    2010-03-26

    The DAMA/LIBRA set-up (about 250 kg highly radiopure NaI(Tl) sensitive mass) is running at the Gran Sasso National Laboratory of the I.N.F.N.. The first DAMA/LIBRA results confirm the evidence for the presence of a Dark Matter particle component in the galactic halo, as pointed out by the former DAMA/NaI set-up; cumulatively the data support such evidence at 8.2 sigma C.L. and satisfy all the many peculiarities of the Dark Matter annual modulation signature. The main aspects and prospects of this model independent experimental approach will be outlined.

  3. Levitating dark matter

    NASA Astrophysics Data System (ADS)

    Kaloper, Nemanja; Padilla, Antonio

    2009-10-01

    A sizable fraction of the total energy density of the universe may be in heavy particles with a net dark U(1)' charge comparable to its mass. When the charges have the same sign the cancellation between their gravitational and gauge forces may lead to a mismatch between different measures of masses in the universe. Measuring galactic masses by orbits of normal matter, such as galaxy rotation curves or lensing, will give the total mass, while the flows of dark matter agglomerates may yield smaller values if the gauge repulsion is not accounted for. If distant galaxies which house light beacons like SNe Ia contain such dark particles, the observations of their cosmic recession may mistake the weaker forces for an extra `antigravity', and infer an effective dark energy equation of state smaller than the real one. In some cases, including that of a cosmological constant, these effects can mimic w < -1. They can also lead to a local variation of galaxy-galaxy forces, yielding a larger `Hubble Flow' in those regions of space that could be taken for a dynamical dark energy, or superhorizon effects.

  4. Levitating dark matter

    SciTech Connect

    Kaloper, Nemanja; Padilla, Antonio E-mail: antonio.padilla@nottingham.ac.uk

    2009-10-01

    A sizable fraction of the total energy density of the universe may be in heavy particles with a net dark U(1)' charge comparable to its mass. When the charges have the same sign the cancellation between their gravitational and gauge forces may lead to a mismatch between different measures of masses in the universe. Measuring galactic masses by orbits of normal matter, such as galaxy rotation curves or lensing, will give the total mass, while the flows of dark matter agglomerates may yield smaller values if the gauge repulsion is not accounted for. If distant galaxies which house light beacons like SNe Ia contain such dark particles, the observations of their cosmic recession may mistake the weaker forces for an extra 'antigravity', and infer an effective dark energy equation of state smaller than the real one. In some cases, including that of a cosmological constant, these effects can mimic w < −1. They can also lead to a local variation of galaxy-galaxy forces, yielding a larger 'Hubble Flow' in those regions of space that could be taken for a dynamical dark energy, or superhorizon effects.

  5. Inflatable Dark Matter

    SciTech Connect

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D.

    2015-07-30

    We describe a general scenario, dubbed “Inflatable Dark Matter”, in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early universe. The overproduction of dark matter that is predicted within many otherwise well-motivated models of new physics can be elegantly remedied within this context, without the need to tune underlying parameters or to appeal to anthropic considerations. Thermal relics that would otherwise be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the non-thermal abundance of GUT or Planck scale axions can be brought to acceptable levels, without invoking anthropic tuning of initial conditions. Additionally, a period of late-time inflation could have occurred over a wide range of scales from ~ MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the Standard Model.

  6. Inflatable Dark Matter

    DOE PAGESBeta

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D.

    2016-01-22

    We describe a general scenario, dubbed “Inflatable Dark Matter”, in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early universe. The overproduction of dark matter that is predicted within many otherwise well-motivated models of new physics can be elegantly remedied within this context, without the need to tune underlying parameters or to appeal to anthropic considerations. Thermal relics that would otherwise be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the non-thermal abundance of GUTmore » or Planck scale axions can be brought to acceptable levels, without invoking anthropic tuning of initial conditions. Additionally, a period of late-time inflation could have occurred over a wide range of scales from ~ MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the Standard Model.« less

  7. Dark matter candidates

    SciTech Connect

    Turner, M.S.

    1989-01-01

    One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of. Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs.

  8. Dark matter axions revisited

    NASA Astrophysics Data System (ADS)

    Visinelli, Luca; Gondolo, Paolo

    2009-08-01

    We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae, and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma=(85±3)μeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma<15meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.

  9. Direct search for dark matter

    SciTech Connect

    Yoo, Jonghee; /Fermilab

    2009-12-01

    Dark matter is hypothetical matter which does not interact with electromagnetic radiation. The existence of dark matter is only inferred from gravitational effects of astrophysical observations to explain the missing mass component of the Universe. Weakly Interacting Massive Particles are currently the most popular candidate to explain the missing mass component. I review the current status of experimental searches of dark matter through direct detection using terrestrial detectors.

  10. Coupling dark energy to dark matter inhomogeneities

    NASA Astrophysics Data System (ADS)

    Marra, Valerio

    2016-09-01

    We propose that dark energy in the form of a scalar field could effectively couple to dark matter inhomogeneities. Through this coupling energy could be transferred to/from the scalar field, which could possibly enter an accelerated regime. Though phenomenological, this scenario is interesting as it provides a natural trigger for the onset of the acceleration of the universe, since dark energy starts driving the expansion of the universe when matter inhomogeneities become sufficiently strong. Here we study a possible realization of this idea by coupling dark energy to dark matter via the linear growth function of matter perturbations. The numerical results show that it is indeed possible to obtain a viable cosmology with the expected series of radiation, matter and dark-energy dominated eras. In particular, the current density of dark energy is given by the value of the coupling parameters rather than by very special initial conditions for the scalar field. In other words, this model-unlike standard models of cosmic late acceleration-does not suffer from the so-called "coincidence problem" and its related fine tuning of initial conditions.

  11. Multi-Component Dark Matter

    SciTech Connect

    Zurek, Kathryn M.

    2008-11-01

    We explore multi-component dark matter models where the dark sector consists of multiple stable states with different mass scales, and dark forces coupling these states further enrich the dynamics. The multi-component nature of the dark matter naturally arises in supersymmetric models, where both R parity and an additional symmetry, such as a Z{sub 2}, is preserved. We focus on a particular model where the heavier component of dark matter carries lepton number and annihilates mostly to leptons. The heavier component, which is essentially a sterile neutrino, naturally explains the PAMELA, ATIC and synchrotron signals, without an excess in antiprotons which typically mars other models of weak scale dark matter. The lighter component, which may have a mass from a GeV to a TeV, may explain the DAMA signal, and may be visible in low threshold runs of CDMS and XENON, which search for light dark matter.

  12. Imperfect Dark Matter

    NASA Astrophysics Data System (ADS)

    Mirzagholi, Leila; Vikman, Alexander

    2015-06-01

    We consider cosmology of the recently introduced mimetic matter with higher derivatives (HD). Without HD this system describes irrotational dust—Dark Matter (DM) as we see it on cosmologically large scales. DM particles correspond to the shift-charges—Noether charges of the shifts in the field space. Higher derivative corrections usually describe a deviation from the thermodynamical equilibrium in the relativistic hydrodynamics. Thus we show that mimetic matter with HD corresponds to an imperfect DM which: i) renormalises the Newton's constant in the Friedmann equations, ii) has zero pressure when there is no extra matter in the universe, iii) survives the inflationary expansion which puts the system on a dynamical attractor with a vanishing shift-charge, iv) perfectly tracks any external matter on this attractor, v) can become the main (and possibly the only) source of DM, provided the shift-symmetry in the HD terms is broken during some small time interval in the radiation domination époque. In the second part of the paper we present a hydrodynamical description of general anisotropic and inhomogeneous configurations of the system. This imperfect mimetic fluid has an energy flow in the field's rest frame. We find that in the Eckart and in the Landau-Lifshitz frames the mimetic fluid possesses nonvanishing vorticity appearing already at the first order in the HD. Thus, the structure formation and gravitational collapse should proceed in a rather different fashion from the simple irrotational DM models.

  13. Dark Forces and Light Dark Matter

    SciTech Connect

    Hooper, Dan; Weiner, Neal; Xue, Wei

    2012-09-01

    We consider a simple class of models in which the dark matter, X, is coupled to a new gauge boson, phi, with a relatively low mass (m_phi \\sim 100 MeV-3 GeV). Neither the dark matter nor the new gauge boson have tree-level couplings to the Standard Model. The dark matter in this model annihilates to phi pairs, and for a coupling of g_X \\sim 0.06 (m_X/10 GeV)^1/2 yields a thermal relic abundance consistent with the cosmological density of dark matter. The phi's produced in such annihilations decay through a small degree of kinetic mixing with the photon to combinations of Standard Model leptons and mesons. For dark matter with a mass of \\sim10 GeV, the shape of the resulting gamma-ray spectrum provides a good fit to that observed from the Galactic Center, and can also provide the very hard electron spectrum required to account for the observed synchrotron emission from the Milky Way's radio filaments. For kinetic mixing near the level naively expected from loop-suppressed operators (epsilon \\sim 10^{-4}), the dark matter is predicted to scatter elastically with protons with a cross section consistent with that required to accommodate the signals reported by DAMA/LIBRA, CoGeNT and CRESST-II.

  14. Dark matter axions

    SciTech Connect

    Sikivie, P. |

    1992-09-01

    The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)

  15. Dark matter axions

    SciTech Connect

    Sikivie, P. . Inst. for Theoretical Physics Florida Univ., Gainesville, FL . Dept. of Physics)

    1992-01-01

    The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)

  16. Dark Matter Velocity Spectroscopy.

    PubMed

    Speckhard, Eric G; Ng, Kenny C Y; Beacom, John F; Laha, Ranjan

    2016-01-22

    Dark matter decays or annihilations that produce linelike spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will have the precision needed. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications. PMID:26849582

  17. Gravitino Dark Matter

    SciTech Connect

    Buchmueller, Wilfried

    2010-02-10

    Gravitino dark matter, together with thermal leptogenesis, implies an upper bound on the masses of superparticles. In the case of broken R-parity the constraints from primordial nucleosynthesis are naturally satisfied and decaying gravitinos lead to characteristic signatures in high energy cosmic rays. Electron and positron fluxes from gravitino decays cannot explain both, the PAMELA positron fraction and the electron+positron flux recently measured by Fermi LAT. The observed fluxes require astrophysical sources. The measured antiproton flux allows for a sizable contribution of decaying gravitinos to the gamma-ray spectrum, in particular a line at an energy below 300 GeV.

  18. Dark Matter Velocity Spectroscopy

    NASA Astrophysics Data System (ADS)

    Speckhard, Eric G.; Ng, Kenny C. Y.; Beacom, John F.; Laha, Ranjan

    2016-01-01

    Dark matter decays or annihilations that produce linelike spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy—the measurement of energy shifts induced by relative motion of source and observer—can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will have the precision needed. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.

  19. Planckian Interacting Massive Particles as Dark Matter

    NASA Astrophysics Data System (ADS)

    Garny, Mathias; Sandora, McCullen; Sloth, Martin S.

    2016-03-01

    The standard model could be self-consistent up to the Planck scale according to the present measurements of the Higgs boson mass and top quark Yukawa coupling. It is therefore possible that new physics is only coupled to the standard model through Planck suppressed higher dimensional operators. In this case the weakly interacting massive particle miracle is a mirage, and instead minimality as dictated by Occam's razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian interacting massive particle, we show that the most natural mass larger than 0.01 Mp is already ruled out by the absence of tensor modes in the cosmic microwave background (CMB). This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the Kaluza-Klein graviton mode as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. This paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark matter.

  20. Planckian Interacting Massive Particles as Dark Matter.

    PubMed

    Garny, Mathias; Sandora, McCullen; Sloth, Martin S

    2016-03-11

    The standard model could be self-consistent up to the Planck scale according to the present measurements of the Higgs boson mass and top quark Yukawa coupling. It is therefore possible that new physics is only coupled to the standard model through Planck suppressed higher dimensional operators. In this case the weakly interacting massive particle miracle is a mirage, and instead minimality as dictated by Occam's razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian interacting massive particle, we show that the most natural mass larger than 0.01M_{p} is already ruled out by the absence of tensor modes in the cosmic microwave background (CMB). This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the Kaluza-Klein graviton mode as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. This paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark matter. PMID:27015472

  1. Direct detection of Dark Matter

    NASA Astrophysics Data System (ADS)

    Belli, P.

    2016-07-01

    An overview of the latest results of Dark Matter direct detection will be summarized, with particular care to the DAMA/LIBRA-phase1 results and the evidence with high confidence level obtained by exploiting the model independent Dark Matter annual modulation signature for the presence of Dark Matter particles in the galactic halo. Results from other experiments using different procedures, different techniques and different target-materials will be shortly discussed. Results, implications and experimental perspectives will be addressed.

  2. DarkSide search for dark matter

    NASA Astrophysics Data System (ADS)

    Alexander, T.; Alton, D.; Arisaka, K.; Back, H. O.; Beltrame, P.; Benziger, J.; Bonfini, G.; Brigatti, A.; Brodsky, J.; Bussino, S.; Cadonati, L.; Calaprice, F.; Candela, A.; Cao, H.; Cavalcante, P.; Chepurnov, A.; Chidzik, S.; Cocco, A. G.; Condon, C.; D'Angelo, D.; Davini, S.; De Vincenzi, M.; De Haas, E.; Derbin, A.; Di Pietro, G.; Dratchnev, I.; Durben, D.; Empl, A.; Etenko, A.; Fan, A.; Fiorillo, G.; Franco, D.; Fomenko, K.; Forster, G.; Gabriele, F.; Galbiati, C.; Gazzana, S.; Ghiano, C.; Goretti, A.; Grandi, L.; Gromov, M.; Guan, M.; Guo, C.; Guray, G.; Hungerford, E. V.; Ianni, Al; Ianni, An; Joliet, C.; Kayunov, A.; Keeter, K.; Kendziora, C.; Kidner, S.; Klemmer, R.; Kobychev, V.; Koh, G.; Komor, M.; Korablev, D.; Korga, G.; Li, P.; Loer, B.; Lombardi, P.; Love, C.; Ludhova, L.; Luitz, S.; Lukyanchenko, L.; Lund, A.; Lung, K.; Ma, Y.; Machulin, I.; Mari, S.; Maricic, J.; Martoff, C. J.; Meregaglia, A.; Meroni, E.; Meyers, P.; Mohayai, T.; Montanari, D.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B.; Muratova, V.; Nelson, A.; Nemtzow, A.; Nurakhov, N.; Orsini, M.; Ortica, F.; Pallavicini, M.; Pantic, E.; Parmeggiano, S.; Parsells, R.; Pelliccia, N.; Perasso, L.; Perasso, S.; Perfetto, F.; Pinsky, L.; Pocar, A.; Pordes, S.; Randle, K.; Ranucci, G.; Razeto, A.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Saggese, P.; Saldanha, R.; Salvo, C.; Sands, W.; Seigar, M.; Semenov, D.; Shields, E.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvarov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Thompson, J.; Tonazzo, A.; Unzhakov, E.; Vogelaar, R. B.; Wang, H.; Westerdale, S.; Wojcik, M.; Wright, A.; Xu, J.; Yang, C.; Zavatarelli, S.; Zehfus, M.; Zhong, W.; Zuzel, G.

    2013-11-01

    The DarkSide staged program utilizes a two-phase time projection chamber (TPC) with liquid argon as the target material for the scattering of dark matter particles. Efficient background reduction is achieved using low radioactivity underground argon as well as several experimental handles such as pulse shape, ratio of ionization over scintillation signal, 3D event reconstruction, and active neutron and muon vetos. The DarkSide-10 prototype detector has proven high scintillation light yield, which is a particularly important parameter as it sets the energy threshold for the pulse shape discrimination technique. The DarkSide-50 detector system, currently in commissioning phase at the Gran Sasso Underground Laboratory, will reach a sensitivity to dark matter spin-independent scattering cross section of 10-45 cm2 within 3 years of operation.

  3. 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.

  4. Dark Matter, Waves, and Identification

    NASA Astrophysics Data System (ADS)

    Wagner, Orvin

    2011-10-01

    In 1994 I wrote article for Physics Essays (Waves in Dark Matter) showing how the solar system is organized and stabilized by dark matter standing waves from the dark matter oscillating sun. Wave velocity is apparently inversely proportional to the square root of the dark matter density. At the sun's surface the wave velocity is near 1.25 m/s. More recently I have found local dark matter waves that appear to travel near 25 m/s near April 1 and appear to organize plants. They travel between plants and artificial transmitters and receivers, and penetrate my local hill. From my measurements the local dark matter density is a function of the time of year. The data indicate that dark matter interacts much more than just with gravity as others have surmised. I present experimental proofs and a local dark matter density equation in terms of the measured velocity. The waves and the earth's location may be very important for nature's organization. The observed behavior appears to go a long way towards dark matter identification. These waves also may explain the rings of the gaseous planets in terms of oscillating layers. See the ring article on the web site Darkmatterwaves.com.

  5. Dark Matter and Dark Energy Explained

    NASA Astrophysics Data System (ADS)

    Aisenberg, Sol

    2006-03-01

    The standard model of the universe has many mysteries and defects requiring the use of large fudge factors such as Dark Matter and Dark Energy. We will show that Dark Matter is needed when we try to extend Newton's law of gravity (based upon observations in our solar system) to galactic distances. Dark Matter was introduced to explain the observed flat velocity rotation curves of the outer parts of spiral galaxies, as observed by Vera. Rubin. Much earlier, the (under appreciated) Fritz Zwicky introduced the need for large amounts of missing invisible matter to explain the surprising observed motion of groups of remote galaxies. In our hypothesis, the modification of Newton's laws by the addition of a linear term to the gravitational constant that increases with distance will eliminate the need for dark matter. Our hypothesis is different from the MOND theory of Milgrom, which depends upon acceleration. The Red shift observations by Hubble as a function of distance, and interpreted as ``apparent Doppler effect'' led to the unproven belief that the universe is expanding, and thus to the Big Bang. In turn the apparent acceleration of the expansion required the introduction of Dark Energy. Actually there are three additional components of the red shift that are solely due to gravity and distance and can be larger than the Doppler contribution.

  6. Baryonic dark matter

    SciTech Connect

    Lynden-Bell, D. ); Gilmore, G. )

    1990-01-01

    Dark matter, first definitely found in the large clusters of galaxies, is now known to be dominant mass in the outer parts of galaxies. All the mass definitely deduced could be made up of baryons, and this would fit well with the requirements of nucleosynthesis in a big bang of small {Omega}{sub B}. However, if inflation is the explanation of the expansion and large scale homogeneity of the universe and of baryon synthesis, and if the universe did not have an infinite extent at the big bang, then {Omega} should be minutely greater than unity. It is commonly hypothesized that most mass is composed of some unknown, non-baryonic form. This book first discusses the known forms, comets, planets, brown dwarfs, stars, gas, galaxies and Lyman {alpha} clouds in which baryons are known to exist. Limits on the amount of dark matter in baryonic form are discussed in the context of the big bang. Inhomogeneities of the right type alleviate the difficulties associated with {Omega}{sub B} = 1 cosmological nucleosynthesis.

  7. (Mainly) axion dark matter

    NASA Astrophysics Data System (ADS)

    Baer, Howard

    2016-06-01

    The strong CP problem of QCD is at heart a problem of naturalness: why is the FF ˜ term highly suppressed in the QCD Lagrangian when it seems necessary to explain why there are three and not four light pions? The most elegant solution posits a spontaneously broken Peccei-Quinn (PQ) symmetry which requires the existence of the axion field a. The axion field settles to the minimum of its potential thus removing the offensive term but giving rise to the physical axion whose coherent oscillations can make up the cold dark matter. Only now are experiments such as ADMX beginning to explore QCD axion parameter space. Since a bonafide scalar particle- the Higgs boson- has been discovered, one might expect its mass to reside at the axion scale fa ˜ 1011 GeV. The Higgs mass is elegantly stabilized by supersymmetry: in this case the axion is accompanied by its axino and saxion superpartners. Requiring naturalness also in the electroweak sector implies higgsino-like WIMPs so then we expect mixed axion-WIMP dark matter. Ultimately we would expect detection of both an axion and a WIMP while signals for light higgsinos may show up at LHC and must show up at ILC.

  8. Quantum vacuum and dark matter

    NASA Astrophysics Data System (ADS)

    Hajdukovic, Dragan Slavkov

    2012-01-01

    Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.

  9. Gamma-ray anisotropies from decaying dark matter

    NASA Astrophysics Data System (ADS)

    Weniger, C.

    2011-06-01

    Many theoretically well-motivated models predict the decay of dark matter with lifetimes much longer than the age of the universe. This can potentially lead to peculiar features in the observed cosmic-ray fluxes. In particular the gamma-ray channel, which carries directional information, is promising for dark matter searches, since it is sensitive to the underlying source distribution. We will discuss the peculiar dipole-like anisotropy of prompt gamma-ray radiation from dark matter decay inside our galaxy, as well as the angular power-spectrum of gamma-rays from dark matter decay outside of our galaxy. We will comment on the experimental detectability of such anisotropies.

  10. The Hunt for Dark Matter

    NASA Astrophysics Data System (ADS)

    Gelmini, Graciela B.

    These lectures, given at the 2014 Theoretical Advanced Study Institute (TASI), are an introduction to what we know at present about dark matter and the major current experimental and observational efforts to identify what it consists of. They attempt to present the complexities of the subject, making clear common simplifying assumptions, to better understand the reach of dark matter searches.

  11. Indirect Dark Matter Signals

    SciTech Connect

    Boer, Wim de

    2008-11-23

    Dark Matter annihilation (DMA) may yield an excess of gamma rays and antimatter particles, like antiprotons and positrons, above the background from cosmic ray interactions. Several signatures, ranging from the positron excess, as observed by HEAT, AMS-01 and PAMELA, the gamma ray excess, as observed by the EGRET spectrometer, the WMAP-haze, and constraints from antiprotons, as observed by CAPRICE, BESS and PAMELA, have been discussed in the literature. Unfortunately, the different signatures all lead to different WIMP masses, indicating that at least some of these interpretations are likely to be incorrect. Here we review them and discuss their relative merits and uncertainties. New x-ray data from ROSAT suggests non-negligible convection in our Galaxy, which leads to an order of magnitude uncertainty in the yield of charged particles from DMA, since even a rather small convection will let drift the charged particles in the halo to outer space.

  12. Bright galaxies, dark matters.

    NASA Astrophysics Data System (ADS)

    Rubin, V.

    This book charts two extraordinary journeys: the road to a better understanding of the structure and composition of the universe, and V. Rubin's own pathbreaking career. The scientific papers included here offer an overview of the topic that has been the major focus of her career: the motions of stars within galaxies and the evidence from these motions that most of the matter in the universe is dark. Elsewhere the author examines some of the tools of her trade - from star charts to the Hubble Telescope to some of the observatories where she has worked. The concluding section, "The astronomical life", finds V. Rubin writing candidly about the demands and rewards of her career, offering insightful portraits of colleagues, friends, and other notable women in science.

  13. Estimating Dark Matter Distributions

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Woodroofe, Michael; Walker, Matthew G.; Mateo, Mario; Olszewski, Edward

    2005-06-01

    Thanks to instrumental advances, new, very large kinematic data sets for nearby dwarf spheroidal (dSph) galaxies are on the horizon. A key aim of these data sets is to help determine the distribution of dark matter in these galaxies. Past analyses have generally relied on specific dynamical models or highly restrictive dynamical assumptions. We describe a new, nonparametric analysis of the kinematics of nearby dSph galaxies designed to take full advantage of the future large data sets. The method takes as input the projected positions and radial velocities of stars known to be members of the galaxies but does not use any parametric dynamical model or the assumption that the mass distribution follows that of the visible matter. The problem of estimating the radial mass distribution M(r) (the mass within the true radius r) is converted into a problem of estimating a regression function nonparametrically. From the Jeans equation we show that the unknown regression function is subject to fundamental shape restrictions, which we exploit in our analysis using statistical techniques borrowed from isotonic estimation and spline smoothing. Simulations indicate that M(r) can be estimated to within a factor of 2 or better with samples as small as 1000 stars over almost the entire radial range sampled by the kinematic data. The technique is applied to a sample of 181 stars in the Fornax dSph galaxy. We show that the galaxy contains a significant, extended dark halo some 10 times more massive than its baryonic component. Although applied here to dSph kinematics, this approach can be used in the analysis of any kinematically hot stellar system in which the radial velocity field is discretely sampled.

  14. The search for dark matter

    NASA Astrophysics Data System (ADS)

    Cline, David B.

    2016-03-01

    We discuss the search for dark matter. We first review the data from LUX that excludes the low-mass WIMP region and slightly lowers the XENON100 limits. We provide a brief review of the problems with the claimed low-mass signals. We discuss the current expectations for SUSY-WIMP dark matter and show why very massive detectors like Darwin may be required. We discuss some theoretical predictions from the meeting. There was compelling evidence from events observed in the Galactic Center by Fermi-LAT of WIMP dark matter at the UCLA meeting. We recount the Richard Arnowitt Lectures at UCLA dark matter symposiums and his role in the development of the strategy to detect SUGRA dark matter. In Honor of Richard Arnowitt.

  15. Alternatives to dark matter and dark energy

    NASA Astrophysics Data System (ADS)

    Mannheim, Philip D.

    2006-04-01

    We review the underpinnings of the standard Newton Einstein theory of gravity, and identify where it could possibly go wrong. In particular, we discuss the logical independence from each other of the general covariance principle, the equivalence principle and the Einstein equations, and discuss how to constrain the matter energy momentum tensor which serves as the source of gravity. We identify the a priori assumption of the validity of standard gravity on all distance scales as the root cause of the dark matter and dark energy problems, and discuss how the freedom currently present in gravitational theory can enable us to construct candidate alternatives to the standard theory in which the dark matter and dark energy problems could then be resolved. We identify three generic aspects of these alternate approaches: that it is a universal acceleration scale which determines when a luminous Newtonian expectation is to fail to fit data, that there is a global cosmological effect on local galactic motions which can replace galactic dark matter, and that to solve the cosmological constant problem it is not necessary to quench the cosmological constant itself, but only the amount by which it gravitates.

  16. Solving the Dark Matter Problem

    ScienceCinema

    Baltz, Ted

    2009-09-01

    Cosmological observations have firmly established that the majority of matter in the universe is of an unknown type, called 'dark matter'. A compelling hypothesis is that the dark matter consists of weakly interacting massive particles (WIMPs) in the mass range around 100 GeV. If the WIMP hypothesis is correct, such particles could be created and studied at accelerators. Furthermore they could be directly detected as the primary component of our galaxy. Solving the dark matter problem requires that the connection be made between the two. We describe some theoretical and experimental avenues that might lead to this connection.

  17. Dark matter, dark energy and gravity

    NASA Astrophysics Data System (ADS)

    Robson, B. A.

    2015-02-01

    Within the framework of the Generation Model (GM) of particle physics, gravity is identified with the very weak, universal and attractive residual color interactions acting between the colorless particles of ordinary matter (electrons, neutrons and protons), which are composite structures. This gravitational interaction is mediated by massless vector bosons (hypergluons), which self-interact so that the interaction has two additional features not present in Newtonian gravitation: (i) asymptotic freedom and (ii) color confinement. These two additional properties of the gravitational interaction negate the need for the notions of both dark matter and dark energy.

  18. Dark Matter Searches With GLAST

    SciTech Connect

    Wai, Lawrence; Nuss, E.

    2007-02-05

    Indirect detection of particle dark matter relies upon pair annihilation of Weakly Interaction Massive Particles (WIMPs), which is complementary to the well known techniques of direct detection (WIMP-nucleus scattering) and collider production (WIMP pair production). Pair annihilation of WIMPs results in the production of gamma-rays, neutrinos, and anti-matter. Of the various experiments sensitive to indirect detection of dark matter, the Gamma-ray Large Area Space Telescope (GLAST) may play the most crucial role in the next few years. After launch in late 2007, The GLAST Large Area Telescope (LAT) will survey the gamma-ray sky in the energy range of 20MeV-300GeV. By eliminating charged particle background above 100 MeV, GLAST may be sensitive to as yet to be observed Milky Way dark matter subhalos, as well as WIMP pair annihilation spectral lines from the Milky Way halo. Discovery of gamma-ray signals from dark matter in the Milky Way would not only demonstrate the particle nature of dark matter; it would also open a new observational window on galactic dark matter substructure. Location of new dark matter sources by GLAST would dramatically alter the experimental landscape; ground based gamma ray telescopes could follow up on the new GLAST sources with precision measurements of the WIMP pair annihilation spectrum.

  19. Dark energy and extended dark matter halos

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2012-03-01

    The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ωm = 0.27. Independently, the local mean density is estimated to be Ωloc = 0.08-0.23 from recent data on galaxy groups at redshifts up to z = 0.01-0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498). If the lower values of Ωloc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even

  20. Plasma dark matter direct detection

    NASA Astrophysics Data System (ADS)

    Clarke, J. D.; Foot, R.

    2016-01-01

    Dark matter in spiral galaxies like the Milky Way may take the form of a dark plasma. Hidden sector dark matter charged under an unbroken U(1)' gauge interaction provides a simple and well defined particle physics model realising this possibility. The assumed U(1)' neutrality of the Universe then implies (at least) two oppositely charged dark matter components with self-interactions mediated via a massless "dark photon" (the U(1)' gauge boson). In addition to nuclear recoils such dark matter can give rise to keV electron recoils in direct detection experiments. In this context, the detailed physical properties of the dark matter plasma interacting with the Earth is required. This is a complex system, which is here modelled as a fluid governed by the magnetohydrodynamic equations. These equations are numerically solved for some illustrative examples, and implications for direct detection experiments discussed. In particular, the analysis presented here leaves open the intriguing possibility that the DAMA annual modulation signal is due primarily to electron recoils (or even a combination of electron recoils and nuclear recoils). The importance of diurnal modulation (in addition to annual modulation) as a means of probing this kind of dark matter is also emphasised.

  1. Asymmetric Dark Matter and Dark Radiation

    SciTech Connect

    Blennow, Mattias; Martinez, Enrique Fernandez; Mena, Olga; Redondo, Javier; Serra, Paolo E-mail: enfmarti@cern.ch E-mail: redondo@mppmu.mpg.de

    2012-07-01

    Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, precise measurements of the number of relativistic species, such as those expected from the Planck satellite, can provide information on the structure of the dark sector. We also discuss the constraints of the interactions between DM and Dark Radiation from their imprint in the matter power spectrum.

  2. 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.

  3. Astrophysical Probes of Dark Matter

    NASA Astrophysics Data System (ADS)

    Profumo, S.

    2013-08-01

    What is the connection between how the dark matter was produced in the early universe and how we can detect it today? Where does the WIMP miracle come from, and is it really a "WIMP" miracle? What brackets the mass range for thermal relics? Where does <συ> come from, and what does it mean? What is the difference between chemical and kinetic decoupling? Why do some people think that dark matter cannot be lighter than 40 GeV? Why is bbar b such a popular annihilation final state? Why is antimatter a good way to look for dark matter? Why should the cosmic-ray positron fraction decline with energy? How do you calculate the flux of neutrinos from dark matter annihilation in a celestial body, and when is it independent of the dark matter pair-annihilation rate? How does dark matter produce photons? -- Read these lecture notes, do the suggested 10 exercises, and you will find answers to all of these questions (and to many more on what You Always Wanted to Know About Dark Matter But Were Afraid to Ask).

  4. Reionization and dark matter decay

    NASA Astrophysics Data System (ADS)

    Oldengott, Isabel M.; Boriero, Daniel; Schwarz, Dominik J.

    2016-08-01

    Cosmic reionization and dark matter decay can impact observations of the cosmic microwave sky in a similar way. A simultaneous study of both effects is required to constrain unstable dark matter from cosmic microwave background observations. We compare two reionization models with and without dark matter decay. We find that a reionization model that fits also data from quasars and star forming galaxies results in tighter constraints on the reionization optical depth τreio, but weaker constraints on the spectral index ns than the conventional parametrization. We use the Planck 2015 data to constrain the effective decay rate of dark matter to Γeff < 2.9 × 10‑25/s at 95% C.L. This limit is robust and model independent. It holds for any type of decaying dark matter and it depends only weakly on the chosen parametrization of astrophysical reionization. For light dark matter particles that decay exclusively into electromagnetic components this implies a limit of Γ < 5.3 × 10‑26/s at 95% C.L. Specifying the decay channels, we apply our result to the case of keV-mass sterile neutrinos as dark matter candidates and obtain constraints on their mixing angle and mass, which are comparable to the ones from the diffuse X-ray background.

  5. Direct Dark Matter Detection Phenomenology

    NASA Astrophysics Data System (ADS)

    Newstead, Jayden L.

    The identity and origin of dark matter is one of the more elusive mysteries in the fields of particle physics and cosmology. In the near future, direct dark matter detectors will offer a chance at observing dark matter non-gravitationally for the first time. In this thesis, formalisms are developed to analyze direct detection experiments and to quantify the extent to which properties of the dark matter can be determined. A range of non-standard assumptions about the dark matter are considered, including inelastic scattering, isospin violation and momentum dependent scattering. Bayesian inference is applied to realistic detector configurations to evaluate parameter estimation and model selection ability. A complete set of simplified models for spin-0, spin-1/2 and spin-1 dark matter candidates are formulated. The corresponding non-relativistic operators are found, and are used to derive observational signals for the simplified models. The ability to discern these simplified models with direct detection experiments is demonstrated. In the near future direct dark matter detectors will be sensitive to coherent neutrino scattering, which will limit the discovery potential of these experiments. It was found that eleven of the fourteen non-relativistic operators considered produce signals distinct from coherent scattering, and thus the neutrino background does not greatly affect the discovery potential in these cases.

  6. The dark side of cosmology: dark matter and dark energy.

    PubMed

    Spergel, David N

    2015-03-01

    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. PMID:25745164

  7. Oscillating asymmetric dark matter

    SciTech Connect

    Tulin, Sean; Yu, Hai-Bo; Zurek, Kathryn M. E-mail: haiboyu@umich.edu

    2012-05-01

    We study the dynamics of dark matter (DM) particle-antiparticle oscillations within the context of asymmetric DM. Oscillations arise due to small DM number-violating Majorana-type mass terms, and can lead to recoupling of annihilation after freeze-out and washout of the DM density. Asymmetric DM oscillations 'interpolate' between symmetric and asymmetric DM freeze-out scenarios, and allow for a larger DM model-building parameter space. We derive the density matrix equations for DM oscillations and freeze-out from first principles using nonequilibrium field theory, and our results are qualitatively different than in previous studies. DM dynamics exhibits particle-vs-antiparticle 'flavor' effects, depending on the interaction type, analogous to neutrino oscillations in a medium. 'Flavor-sensitive' DM interactions include scattering or annihilation through a new vector boson, while 'flavor-blind' interactions include scattering or s-channel annihilation through a new scalar boson. In particular, we find that flavor-sensitive annihilation does not recouple when coherent oscillations begin, and that flavor-blind scattering does not lead to decoherence.

  8. Probing gravitational dark matter

    NASA Astrophysics Data System (ADS)

    Ren, Jing; He, Hong-Jian

    2015-03-01

    So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to the gravitational interactions of DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle χs. It is a Bbb Z2 odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, ξsχs2Script R, where ξs is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction ξsχs2Script R, together with Higgs-curvature nonminimal coupling term ξhH†HScript R, induces effective couplings between χs2 and SM fields, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.

  9. Probing gravitational dark matter

    SciTech Connect

    Ren, Jing; He, Hong-Jian

    2015-03-27

    So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to the gravitational interactions of DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle χ{sub s}. It is a ℤ{sub 2} odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, ξ{sub s}χ{sub s}{sup 2}R, where ξ{sub s} is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction ξ{sub s}χ{sub s}{sup 2}R, together with Higgs-curvature nonminimal coupling term ξ{sub h}H{sup †}HR, induces effective couplings between χ{sub s}{sup 2} and SM fields, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.

  10. Bright Galaxies, Dark Matters

    NASA Astrophysics Data System (ADS)

    Rubin, Vera

    In 1965, Vera Rubin was the first woman permitted to observe at Palomar Observatory. In the intervening years, she has become one of the world's finest and most respected astronomers. This particular collection of essays is compiled from work written over the past 15 years and deals with a variety of subjects in astronomy and astrophysics, specifically galaxies and dark matter. The book also contains biographical sketches of astronomers who have been colleagues and friends, providing a stimulating view of a woman in science. About the Author Since 1965 Vera Rubin has been a staff member at the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. Dr. Rubin has authored nearly 200 papers on the structure of our galaxy, motions within other galaxies, and large scale motions in the universe. She has been a distinguished visiting astronomer at the Cerro Tololo Inter American Observatory in Chile; a Chancellor's Distinguished Professor at the University of California, Berkeley; a President's Distinguished Visitor at Vassar College; and a Beatrice Tinsley visiting professor at the University of Texas, Austin.

  11. Triplet-quadruplet dark matter

    NASA Astrophysics Data System (ADS)

    Tait, Tim M. P.; Yu, Zhao-Huan

    2016-03-01

    We explore a dark matter model extending the standard model particle content by one fermionic SU(2) L triplet and two fermionic SU(2) L quadruplets, leading to a minimal realistic UV-complete model of electroweakly interacting dark matter which interacts with the Higgs doublet at tree level via two kinds of Yukawa couplings. After electroweak symmetry-breaking, the physical spectrum of the dark sector consists of three Majorana fermions, three singly charged fermions, and one doubly charged fermion, with the lightest neutral fermion χ 1 0 serving as a dark matter candidate. A typical spectrum exhibits a large degree of degeneracy in mass between the neutral and charged fermions, and we examine the one-loop corrections to the mass differences to ensure that the lightest particle is neutral. We identify regions of parameter space for which the dark matter abundance is saturated for a standard cosmology, including coannihilation channels, and find that this is typically achieved for {m}_{χ_1^0}˜ 2.4 TeV. Constraints from precision electroweak measurements, searches for dark matter scattering with nuclei, and dark matter annihilation are important, but leave open a viable range for a thermal relic.

  12. Skew-flavored dark matter

    DOE PAGESBeta

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

    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

  13. Skew-flavored dark matter

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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 which 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. These events exhibit a characteristic flavor pattern that may allow this class of models to be distinguished from other theories of dark matter.

  14. Cosmology of atomic dark matter

    NASA Astrophysics Data System (ADS)

    Cyr-Racine, Francis-Yan; Sigurdson, Kris

    2013-05-01

    While, to ensure successful cosmology, dark matter (DM) must kinematically decouple from the standard model plasma very early in the history of the Universe, it can remain coupled to a bath of “dark radiation” until a relatively late epoch. One minimal theory that realizes such a scenario is the atomic dark matter model, in which two fermions oppositely charged under a new U(1) dark force are initially coupled to a thermal bath of “dark photons” but eventually recombine into neutral atomlike bound states and begin forming gravitationally bound structures. As dark atoms have (dark) atom-sized geometric cross sections, this model also provides an example of self-interacting DM with a velocity-dependent cross section. Delayed kinetic decoupling in this scenario predicts novel DM properties on small scales but retains the success of cold DM on larger scales. We calculate the atomic physics necessary to capture the thermal history of this dark sector and show significant improvements over the standard atomic hydrogen calculation are needed. We solve the Boltzmann equations that govern the evolution of cosmological fluctuations in this model and find in detail the impact of the atomic DM scenario on the matter power spectrum and the cosmic microwave background (CMB). This scenario imprints a new length scale, the dark-acoustic-oscillation scale, on the matter density field. This dark-acoustic-oscillation scale shapes the small-scale matter power spectrum and determines the minimal DM halo mass at late times, which may be many orders of magnitude larger than in a typical weakly interacting-massive-particle scenario. This model necessarily includes an extra dark radiation component, which may be favored by current CMB experiments, and we quantify CMB signatures that distinguish an atomic DM scenario from a standard ΛCDM model containing extra free-streaming particles. We finally discuss the impacts of atomic DM on galactic dynamics and show that these provide the

  15. Galactic Interactions and Dark Matter

    NASA Astrophysics Data System (ADS)

    Willig, T.; Storrs, A.

    2005-12-01

    In studying galactic interactions is it possible with present instrumentation to find evidence of dark matter within these interactions? The present theory is that dark matter and its gravitational force is what accounts for much of spiral galaxy rotation curves. If this is true, we should be able to find evidence of dark matter when two galaxies (one being a spiral galaxy) interact. Several pairs of interacting galaxies in various stages of interaction will be studied. In addition, several non interacting spiral galaxies will be studied for comparisons. We present analysis of a variety of archival imaging data from radio maps through x-ray images in an attempt to observe the effects of dark matter in galaxy interactions.

  16. The Dark Matter of Biology.

    PubMed

    Ross, Jennifer L

    2016-09-01

    The inside of the cell is full of important, yet invisible species of molecules and proteins that interact weakly but couple together to have huge and important effects in many biological processes. Such "dark matter" inside cells remains mostly hidden, because our tools were developed to investigate strongly interacting species and folded proteins. Example dark-matter species include intrinsically disordered proteins, posttranslational states, ion species, and rare, transient, and weak interactions undetectable by biochemical assays. The dark matter of biology is likely to have multiple, vital roles to regulate signaling, rates of reactions, water structure and viscosity, crowding, and other cellular activities. We need to create new tools to image, detect, and understand these dark-matter species if we are to truly understand fundamental physical principles of biology. PMID:27602719

  17. The LZ dark matter experiment

    NASA Astrophysics Data System (ADS)

    McKinsey, D. N.; LZ Collaboration

    2016-05-01

    The LUX and ZEPLIN collaborations have merged to construct a 7 tonne two-phase Xe dark matter detector, known as LUX-ZEPLIN or LZ. Chosen as one of the Generation 2 suite of dark matter direct detection experiments, LZ will probe spin-independent WIMP-nucleon cross sections down to 2 × 10-48 cm2 at 50 GeV/c2 within 3 years of operation, covering a substantial range of theoretically-motivated dark matter candidates. Along with dark matter interactions with Xe nuclei, LZ will also be sensitive to solar neutrinos emitted by the pp fusion process in the sun, neutrinos emitted by a nearby supernova and detected by coherent neutrino-nucleus scattering, certain classes of axions and axion-like particles, and neutrinoless double-beta decay of 136Xe. The design of LZ is presented, along with its expected backgrounds and projected sensitivity.

  18. Double-Disk Dark Matter

    NASA Astrophysics Data System (ADS)

    Fan, JiJi; Katz, Andrey; Randall, Lisa; Reece, Matthew

    2013-09-01

    Based on observational tests of large scale structure and constraints on halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant component’s interactions can lead to interesting and potentially observable consequences. Our primary focus will be the special case of Double-Disk Dark Matter (DDDM), in which self-interactions allow the dark matter to lose enough energy to lead to dynamics similar to those in the baryonic sector. We explore a simple model in which DDDM can cool efficiently and form a disk within galaxies, and we evaluate some of the possible observational signatures. The most prominent signal of such a scenario could be an enhanced indirect detection signature with a distinctive spatial distribution. Even though subdominant, the enhanced density at the center of the galaxy and possibly throughout the plane of the galaxy (depending on precise alignment) can lead to large boost factors, and could even explain a signature as large as the 130 GeV Fermi line. Such scenarios also predict additional dark radiation degrees of freedom that could soon be detectable and would influence the interpretation of future data, such as that from Planck and from the Gaia satellite. We consider this to be the first step toward exploring a rich array of new possibilities for dark matter dynamics.

  19. Dark matter in massive galaxies

    NASA Astrophysics Data System (ADS)

    Gerhard, Ortwin

    2013-07-01

    The spatial distributions of luminous and dark matter in massive early-type galaxies (ETGs) reflect the formation processes which shaped these systems. This article reviews the predictions of cosmological simulations for the dark and baryonic components of ETGs, and the observational constraints from lensing, hydrostatic X-ray gas atmospheres, and outer halo stellar dynamics.

  20. Dark matter triggers of supernovae

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Rajendran, Surjeet; Varela, Jaime

    2015-09-01

    The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to 1.25 M⊙ rules out primordial black holes with masses ˜1019- 1020 gm as a dominant constituent of the local dark matter density. Black holes with masses as large as 1024 gm will be excluded if recent observations by the NuStar Collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range 1020- 1022 gm are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large spacetime volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass.

  1. Light Dark Matter

    NASA Astrophysics Data System (ADS)

    Cassé, M.; Fayet, P.

    The SPI spectrometer aboard of the INTEGRAL satellite has released a map of the e^+e- annihilation emission line of unprecedented quality, showing that most of the photons arise from a region coinciding with the stellar bulge of the Milky Way. The impressive intensity (≃ 10-3 photon cm-2 s-1) and morphology (round and wide) of the emission is begging an explanation. Different classes of astrophysical objects could inject positrons in the interstellar medium of the bulge, but the only acceptable ones should inject them at energies low enough to avoid excessive bremsstrahlung emission in the soft gamma ray regime. Among the ~ MeV injectors, none seems generous enough to sustain the high level of annihilation observed. Even the most profuse candidate, namely the β+ radioactivity of 56Co nuclei created and expelled in the interstellar medium by explosive nucleosynthesis of type Ia supernovae, falls short explaining the phenomenon due to the small fraction of positrons leaking out from the ejecta (≈ 3%), together with the low SNIa rate in the bulge (≈ 0.03 per century). It is therefore worth exploring alternative solutions, as for instance, the idea that the source of the positrons is the annihilation of light dark matter (LDM) particles of the kind recently proposed, totally independently, by Bœhm and Fayet. Assuming that LDM is the culprit, crucial constraints on the characteristics (mass and annihilation cross-section) of the associated particle may be discussed, combining direct gamma ray observations and models of the early Universe. In particular, the mass of the LDM particles should be significantly less than 100 MeV, so that the e+ and e- resulting from their annihilations do not radiate exceedingly through bremsstrahlung in the interstellar gas of the galactic bulge.

  2. Sterile neutrinos as dark matter

    SciTech Connect

    Dodelson, S.; Widrow, L.M. |

    1993-03-01

    The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed or sterile neutrinos. This model has been studied extensively in the context of the hot dark matter scenario. We reexamine this model and find that hot, warm, and cold dark matter are all possibilities. We focus on the case where sterile neutrinos are the dark matter. Since their only direct coupling is to left-handed or active neutrinos, the most efficient production mechanism is via neutrino oscillations. If the production rate is always less than the expansion rate, then these neutrinos will never be in thermal equilibrium. However, they may still play a significant role in the dynamics of the Universe and possibly provide the missing mass necessary for closure. We consider a single generation of neutrino fields ({nu}{sub L}, {nu}{sub R}) with a Dirac mass, {mu}, and a Majorana mass for the right-handed components only, M. For M {much_gt} {mu} we show that the number density of sterile neutrinos is proportional to {mu}{sup 2}/M so that the energy density today is independent of M. However M is crucial in determining the large scale structure of the Universe. In particular, M {approx_equal} 0.1--1.0 key leads to warm dark matter and a structure formation scenario that may have some advantages over both the standard hot and cold dark matter scenarios.

  3. Sterile neutrinos as dark matter

    SciTech Connect

    Dodelson, S. ); Widrow, L.M. . Dept. of Physics Toronto Univ., ON . Canadian Inst. for Theoretical Astrophysics)

    1993-03-01

    The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed or sterile neutrinos. This model has been studied extensively in the context of the hot dark matter scenario. We reexamine this model and find that hot, warm, and cold dark matter are all possibilities. We focus on the case where sterile neutrinos are the dark matter. Since their only direct coupling is to left-handed or active neutrinos, the most efficient production mechanism is via neutrino oscillations. If the production rate is always less than the expansion rate, then these neutrinos will never be in thermal equilibrium. However, they may still play a significant role in the dynamics of the Universe and possibly provide the missing mass necessary for closure. We consider a single generation of neutrino fields ([nu][sub L], [nu][sub R]) with a Dirac mass, [mu], and a Majorana mass for the right-handed components only, M. For M [much gt] [mu] we show that the number density of sterile neutrinos is proportional to [mu][sup 2]/M so that the energy density today is independent of M. However M is crucial in determining the large scale structure of the Universe. In particular, M [approx equal] 0.1--1.0 key leads to warm dark matter and a structure formation scenario that may have some advantages over both the standard hot and cold dark matter scenarios.

  4. Dark matter and global symmetries

    NASA Astrophysics Data System (ADS)

    Mambrini, Yann; Profumo, Stefano; Queiroz, Farinaldo S.

    2016-09-01

    General considerations in general relativity and quantum mechanics are known to potentially rule out continuous global symmetries in the context of any consistent theory of quantum gravity. Assuming the validity of such considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray, neutrino, and CMB data on models that invoke global symmetries to stabilize the dark matter particle. We compute up-to-date, robust model-independent limits on the dark matter lifetime for a variety of Planck-scale suppressed dimension-five effective operators. We then specialize our analysis and apply our bounds to specific models including the Two-Higgs-Doublet, Left-Right, Singlet Fermionic, Zee-Babu, 3-3-1 and Radiative See-Saw models. Assuming that (i) global symmetries are broken at the Planck scale, that (ii) the non-renormalizable operators mediating dark matter decay have O (1) couplings, that (iii) the dark matter is a singlet field, and that (iv) the dark matter density distribution is well described by a NFW profile, we are able to rule out fermionic, vector, and scalar dark matter candidates across a broad mass range (keV-TeV), including the WIMP regime.

  5. Dark matter beams at LBNF

    NASA Astrophysics Data System (ADS)

    Coloma, Pilar; Dobrescu, Bogdan A.; Frugiuele, Claudia; Harnik, Roni

    2016-04-01

    High-intensity neutrino beam facilities may produce a beam of light dark matter when protons strike the target. Searches for such a dark matter beam using its scattering in a nearby detector must overcome the large neutrino background. We characterize the spatial and energy distributions of the dark matter and neutrino beams, focusing on their differences to enhance the sensitivity to dark matter. We find that a dark matter beam produced by a Z ' boson in the GeV mass range is both broader and more energetic than the neutrino beam. The reach for dark matter is maximized for a detector sensitive to hard neutral-current scatterings, placed at a sizable angle off the neutrino beam axis. In the case of the Long-Baseline Neutrino Facility (LBNF), a detector placed at roughly 6 degrees off axis and at a distance of about 200 m from the target would be sensitive to Z ' couplings as low as 0.05. This search can proceed symbiotically with neutrino measurements. We also show that the MiniBooNE and MicroBooNE detectors, which are on Fermilab's Booster beamline, happen to be at an optimal angle from the NuMI beam and could perform searches with existing data. This illustrates potential synergies between LBNF and the short-baseline neutrino program if the detectors are positioned appropriately.

  6. Dark matter beams at LBNF

    DOE PAGESBeta

    Coloma, Pilar; Dobrescu, Bogdan A.; Frugiuele, Claudia; Harnik, Roni

    2016-04-08

    High-intensity neutrino beam facilities may produce a beam of light dark matter when protons strike the target. Searches for such a dark matter beam using its scattering in a nearby detector must overcome the large neutrino background. We characterize the spatial and energy distributions of the dark matter and neutrino beams, focusing on their differences to enhance the sensitivity to dark matter. We find that a dark matter beam produced by a Zmore » $$^{'}$$ boson in the GeV mass range is both broader and more energetic than the neutrino beam. The reach for dark matter is maximized for a detector sensitive to hard neutral-current scatterings, placed at a sizable angle off the neutrino beam axis. In the case of the Long-Baseline Neutrino Facility (LBNF), a detector placed at roughly 6 degrees off axis and at a distance of about 200 m from the target would be sensitive to Z$$^{'}$$ couplings as low as 0.05. This search can proceed symbiotically with neutrino measurements. We also show that the MiniBooNE and MicroBooNE detectors, which are on Fermilab’s Booster beamline, happen to be at an optimal angle from the NuMI beam and could perform searches with existing data. As a result, this illustrates potential synergies between LBNF and the short-baseline neutrino program if the detectors are positioned appropriately.« less

  7. Composite strongly interacting dark matter

    NASA Astrophysics Data System (ADS)

    Cline, James M.; Liu, Zuowei; Moore, Guy D.; Xue, Wei

    2014-07-01

    It has been suggested that cold dark matter (CDM) has difficulties in explaining tentative evidence for noncuspy halo profiles in small galaxies, and the low velocity dispersions observed in the largest Milky Way satellites ("too-big-to-fail" problem). Strongly self-interacting dark matter has been noted as a robust solution to these problems. The elastic cross sections required are much larger than predicted by generic CDM models, but could naturally be of the right size if dark matter is composite. We explore in a general way the constraints on models where strongly interacting CDM is in the form of dark "atoms" or "molecules," or bound states of a confining gauge interaction ("hadrons"). These constraints include considerations of relic density, direct detection, big bang nucleosynthesis, the cosmic microwave background, and LHC data.

  8. Cold dark matter heats up.

    PubMed

    Pontzen, Andrew; Governato, Fabio

    2014-02-13

    A principal discovery in modern cosmology is that standard model particles comprise only 5 per cent of the mass-energy budget of the Universe. In the ΛCDM paradigm, the remaining 95 per cent consists of dark energy (Λ) and cold dark matter. ΛCDM is being challenged by its apparent inability to explain the low-density 'cores' of dark matter measured at the centre of galaxies, where centrally concentrated high-density 'cusps' were predicted. But before drawing conclusions, it is necessary to include the effect of gas and stars, historically seen as passive components of galaxies. We now understand that these can inject heat energy into the cold dark matter through a coupling based on rapid gravitational potential fluctuations, explaining the observed low central densities. PMID:24522596

  9. Cosmological Simulations of Dark Matter

    NASA Astrophysics Data System (ADS)

    Vogelsberger, Mark

    2015-04-01

    Dark matter is supposed to be the backbone of structure formation in the universe. It dominates the energy content of the universe together with dark energy. Modern computer simulation allow the detailed prediction of the distribution of dark matter on very large and small scales. The main inputs for these simulations are the initial conditions observed through the cosmic microwave background and gravity as the main force behind structure formation. I will present in my talk recent advances in cosmological simulations and how state-of-the-art simulations lead to virtual universes which agree remarkably well with observations of the real universe. Despite this success the small-scale structure predicted by these simulations does not agree perfectly with observations. I will discuss possible solutions to these problems that might also point to new theories of dark matter.

  10. Dark-matter 'paparazzi' exposed

    NASA Astrophysics Data System (ADS)

    Harris, Margaret

    2008-10-01

    After waiting almost two years for data that may shed light on the mysterious substance that makes up almost a quarter of the universe, some physicists thought a new result on dark matter was just too exciting to keep quiet. So when a member of the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) team recently gave a conference talk, a few audience members could not resist taking photos of the slides. By incorporating their snapshots into papers posted on the arXiv preprint server, these "paparazzi" physicists sparked a debate on both dark matter and datasharing etiquette in a digital world.

  11. Cryogenic Dark Matter Search (CDMS): The Hunt for Dark Matter

    SciTech Connect

    Sadoulet, Bernard

    2006-03-06

    Deciphering the nature of dark matter has great scientific importance. A leading hypothesis is that dark matter is made of Weakly Interactive Massive Particles (WIMPs), which may result from supersymmetry or additional spatial dimensions. The underground search for elastic scattering of WIMPs on suitable targets (the so-called 'direct detection') is currently led by the Cryogenic Dark Matter Search II (CDMS II) experiment. Its sensitivity is ten times better than any other experiment and we hope to obtain another factor ten in the coming two years. After a brief recall of our recent results, I will describe the complementarity between direct detection experiments, the LHC and the ILC and I will outline the role that SLAC could play in this SuperCDMS program.

  12. Dark Energy and The Dark Matter Relic Abundance

    SciTech Connect

    Rosati, Francesca

    2004-11-17

    Two mechanisms by which the quintessence scalar could enhance the relic abundance of dark matter particles are discussed. These effects can have an impact on supersymmetric candidates for dark matter.

  13. Dark matter versus Mach's principle.

    NASA Astrophysics Data System (ADS)

    von Borzeszkowski, H.-H.; Treder, H.-J.

    1998-02-01

    Empirical and theoretical evidence show that the astrophysical problem of dark matter might be solved by a theory of Einstein-Mayer type. In this theory up to global Lorentz rotations the reference system is determined by the motion of cosmic matter. Thus one is led to a "Riemannian space with teleparallelism" realizing a geometric version of the Mach-Einstein doctrine. The field equations of this gravitational theory contain hidden matter terms where the existence of hidden matter is inferred safely from its gravitational effects. It is argued that in the nonrelativistic mechanical approximation they provide an inertia-free mechanics where the inertial mass of a body is induced by the gravitational action of the comic masses. Interpreted form the Newtonian point of view this mechanics shows that the effective gravitational mass of astrophysical objects depends on r such that one expects the existence of dark matter.

  14. Scalar graviton as dark matter

    SciTech Connect

    Pirogov, Yu. F.

    2015-06-15

    The basics of the theory of unimodular bimode gravity built on the principles of unimodular gauge invariance/relativity and general covariance are exposed. Besides the massless tensor graviton of General Relativity, the theory includes an (almost) massless scalar graviton treated as the gravitational dark matter. A spherically symmetric vacuum solution describing the coherent scalar-graviton field for the soft-core dark halos, with the asymptotically flat rotation curves, is demonstrated as an example.

  15. Dark matter in 3D

    NASA Astrophysics Data System (ADS)

    Alves, Daniele S. M.; El Hedri, Sonia; Wacker, Jay G.

    2016-03-01

    We discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. The first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. The second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. We illustrate our method using the Via Lactea II N-body simulation as well as an analytical model for the dark matter halo. We conclude that {O}(1000) events are necessary to measure deviations from the Standard Halo Model and constrain or measure the presence of anisotropies.

  16. The DAMIC Dark Matter Experiment

    SciTech Connect

    de Mello Neto, J. R.T.

    2015-10-07

    The DAMIC (DArk Matter In CCDs) experiment uses high-resistivity, scientific-grade CCDs to search for dark matter. The CCD’s low electronic noise allows an unprecedently low energy threshold of a few tens of eV; this characteristic makes it possible to detect silicon recoils resulting from interactions of low-mass WIMPs. In addition, the CCD’s high spatial resolution and the excellent energy response results in very effective background identification techniques. The experiment has a unique sensitivity to dark matter particles with masses below 10 GeV/c2. Previous results have motivated the construction of DAMIC100, a 100 grams silicon target detector currently being installed at SNOLAB. The mode of operation and unique imaging capabilities of the CCDs, and how they may be exploited to characterize and suppress backgrounds are discussed, as well as physics results after one year of data taking.

  17. Dark Matter in 3D

    SciTech Connect

    Alves, Daniele S.M.; Hedri, Sonia El; Wacker, Jay G.

    2012-04-01

    We discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. The first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. The second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. We illustrate our method using the Via Lactea II N-body simulation as well as an analytical model for the dark matter halo. We conclude that O(1000) events are necessary to measure deviations from the Standard Halo Model and constrain or measure the presence of anisotropies.

  18. Dark matter in 3D

    DOE PAGESBeta

    Alves, Daniele S. M.; El Hedri, Sonia; Wacker, Jay G.

    2016-03-21

    We discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. The first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. The second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. We illustrate our methodmore » using the Via Lactea II N-body simulation as well as an analytical model for the dark matter halo. Furthermore, we conclude that O(1000) events are necessary to measure deviations from the Standard Halo Model and constrain or measure the presence of anisotropies.« less

  19. Natural supersymmetric minimal dark matter

    NASA Astrophysics Data System (ADS)

    Fabbrichesi, Marco; Urbano, Alfredo

    2016-03-01

    We show how the Higgs boson mass is protected from the potentially large corrections due to the introduction of minimal dark matter if the new physics sector is made supersymmetric. The fermionic dark matter candidate (a 5-plet of S U (2 )L) is accompanied by a scalar state. The weak gauge sector is made supersymmetric, and the Higgs boson is embedded in a supersymmetric multiplet. The remaining standard model states are nonsupersymmetric. Nonvanishing corrections to the Higgs boson mass only appear at three-loop level, and the model is natural for dark matter masses up to 15 TeV—a value larger than the one required by the cosmological relic density. The construction presented stands as an example of a general approach to naturalness that solves the little hierarchy problem which arises when new physics is added beyond the standard model at an energy scale around 10 TeV.

  20. Dark matter via massive bigravity

    NASA Astrophysics Data System (ADS)

    Blanchet, Luc; Heisenberg, Lavinia

    2015-05-01

    In this work we investigate the existence of relativistic models for dark matter in the context of bimetric gravity, used here to reproduce the modified Newtonian dynamics (MOND) at galactic scales. For this purpose we consider two different species of dark matter particles that separately couple to the two metrics of bigravity. These two sectors are linked together via an internal U (1 ) vector field, and some effective composite metric built out of the two metrics. Among possible models only certain classes of kinetic and interaction terms are allowed without invoking ghost degrees of freedom. Along these lines we explore the number of allowed kinetic terms in the theory and point out the presence of ghosts in a previous model. Finally, we propose a promising class of ghost-free candidate theories that could provide the MOND phenomenology at galactic scales while reproducing the standard cold dark matter model at cosmological scales.

  1. Decoupling dark energy from matter

    SciTech Connect

    Brax, Philippe; Davis, Anne-Christine; Martin, Jérôme E-mail: c.vandebruck@sheffield.ac.uk E-mail: jmartin@iap.fr

    2009-09-01

    We examine the embedding of dark energy in high energy models based upon supergravity and extend the usual phenomenological setting comprising an observable sector and a hidden supersymmetry breaking sector by including a third sector leading to the acceleration of the expansion of the universe. We find that gravitational constraints on the non-existence of a fifth force naturally imply that the dark energy sector must possess an approximate shift symmetry. When exact, the shift symmetry provides an example of a dark energy sector with a runaway potential and a nearly massless dark energy field whose coupling to matter is very weak, contrary to the usual lore that dark energy fields must couple strongly to matter and lead to gravitational inconsistencies. Moreover, the shape of the potential is stable under one-loop radiative corrections. When the shift symmetry is slightly broken by higher order terms in the Kähler potential, the coupling to matter remains small. However, the cosmological dynamics are largely affected by the shift symmetry breaking operators leading to the appearance of a minimum of the scalar potential such that dark energy behaves like an effective cosmological constant from very early on in the history of the universe.

  2. Z-portal dark matter

    SciTech Connect

    Arcadi, Giorgio; Mambrini, Yann; Richard, Francois

    2015-03-11

    We propose to generalize the extensions of the Standard Model where the Z boson serves as a mediator between the Standard Model sector and the dark sector χ. We show that, like in the Higgs portal case, the combined constraints from the recent direct searches restrict severely the nature of the coupling of the dark matter to the Z boson and set a limit m{sub χ}≳200 GeV (except in a very narrow region around the Z-pole region). Using complementarity between spin dependent, spin independent and FERMI limits, we predict the nature of this coupling, more specifically the axial/vectorial ratio that respects a thermal dark matter coupled through a Z-portal while not being excluded by the current observations. We also show that the next generation of experiments of the type LZ or XENON1T will test Z-portal scenario for dark matter mass up to 2 TeV. The condition of a thermal dark matter naturally predicts the spin-dependent scattering cross section on the neutron to be σ{sub χn}{sup SD}≃10{sup −40} cm{sup 2}, which then becomes a clear prediction of the model and a signature testable in the near future experiments.

  3. Dark matter searches at ATLAS

    NASA Astrophysics Data System (ADS)

    Mehlhase, Sascha

    2016-06-01

    The large excess of Dark Matter observed in the Universe and its particle nature is one of the key problems yet to be solved in particle physics. Despite the extensive success of the Standard Model, it is not able to explain this excess, which instead might be due to yet unknown particles, such as Weakly Interacting Massive Particles, that could be produced at the Large Hadron Collider. This contribution will give an overview of different approaches to finding evidence for Dark Matter with the ATLAS experiment in √{s }=8 TeV Run-1 data.

  4. Exploring Baryons for Dark Matter

    NASA Astrophysics Data System (ADS)

    Goradia, Shantilal

    There is on-going research for the detection of WIMP's based on a speculative idea of supersymmetry, which attempts to unify the fundamental forces of nature, including gravity. The detection of WIMP's is expected to find a solution to the issue of dark matter. We continue to hold and support our view of the millennium that gravity is not a fundamental force of Nature. We are therefore exploring baryons as the particles to address the issue of dark matter. We poster present our analyses to support our proposal.

  5. Did LIGO Detect Dark Matter?

    NASA Astrophysics Data System (ADS)

    Bird, Simeon; Cholis, Ilias; Muñoz, Julian B.; Ali-Haïmoud, Yacine; Kamionkowski, Marc; Kovetz, Ely D.; Raccanelli, Alvise; Riess, Adam G.

    2016-05-01

    We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses 20 M⊙≲Mbh≲100 M⊙ where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to the emission of gravitational radiation and ultimately will merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the 2 - 53 Gpc-3 yr-1 rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have neither optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next-generation experiments will be invaluable in performing these tests.

  6. Did LIGO Detect Dark Matter?

    PubMed

    Bird, Simeon; Cholis, Ilias; Muñoz, Julian B; Ali-Haïmoud, Yacine; Kamionkowski, Marc; Kovetz, Ely D; Raccanelli, Alvise; Riess, Adam G

    2016-05-20

    We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses 20M_{⊙}≲M_{bh}≲100M_{⊙} where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to the emission of gravitational radiation and ultimately will merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the 2-53  Gpc^{-3} yr^{-1} rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have neither optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next-generation experiments will be invaluable in performing these tests. PMID:27258861

  7. 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.

  8. Dark matter and dark energy: The critical questions

    SciTech Connect

    Michael S. Turner

    2002-11-19

    Stars account for only about 0.5% of the content of the Universe; the bulk of the Universe is optically dark. The dark side of the Universe is comprised of: at least 0.1% light neutrinos; 3.5% {+-} 1% baryons; 29% {+-} 4% cold dark matter; and 66% {+-} 6% dark energy. Now that we have characterized the dark side of the Universe, the challenge is to understand it. The critical questions are: (1) What form do the dark baryons take? (2) What is (are) the constituent(s) of the cold dark matter? (3) What is the nature of the mysterious dark energy that is causing the Universe to speed up.

  9. Dark matter from dark energy-baryonic matter couplings

    NASA Astrophysics Data System (ADS)

    Avilés, Alejandro; Cervantes-Cota, Jorge L.

    2011-01-01

    We present a scenario in which a scalar field dark energy is coupled to the trace of the energy momentum tensor of the baryonic matter fields. In the slow-roll regime, this interaction could give rise to the cosmological features of dark matter. We work out the cosmological background solutions and fit the parameters of the model using the Union 2 supernovae data set. Then, we develop cosmological perturbations up to linear order, and we find that the perturbed variables have an acceptable behavior, in particular, the density contrast of baryonic matter grows similar to that in the ΛCDM model for a suitable choice of the strength parameter of the coupling.

  10. Two-portal dark matter

    NASA Astrophysics Data System (ADS)

    Ghorbani, Karim; Ghorbani, Hossein

    2015-06-01

    We propose a renormalizable dark matter model in which a fermionic dark matter (DM) candidate communicates with the standard model particles through two distinct portals: Higgs and vector portals. The dark sector is charged under a U (1 )' gauge symmetry while the standard model has a leptophobic interaction with the dark vector boson. The leading contribution of the DM-nucleon elastic scattering cross section begins at one-loop level. The model meets all the constraints imposed by direct detection experiments provided by LUX and XENON100, observed relic abundance according to WMAP and Planck, and the invisible Higgs decay width measured at the LHC. It turns out that the dark matter mass in the viable parameter space can take values from a few GeV up to 1 TeV. This is a new feature which is absent in the models with only one portal. In addition, we can find in the constrained regions of the parameter space a DM mass of ˜34 GeV annihilating into b quark pair, which explains the Fermi-LAT gamma-ray excess.

  11. Wino dark matter under siege

    SciTech Connect

    Cohen, Timothy; Lisanti, Mariangela; Pierce, Aaron; Slatyer, Tracy R. E-mail: mlisanti@princeton.edu E-mail: tslatyer@mit.edu

    2013-10-01

    A fermion triplet of SU(2){sub L} — a wino — is a well-motivated dark matter candidate. This work shows that present-day wino annihilations are constrained by indirect detection experiments, with the strongest limits coming from H.E.S.S. and Fermi. The bounds on wino dark matter are presented as a function of mass for two scenarios: thermal (winos constitute a subdominant component of the dark matter for masses less than 3.1 TeV) and non-thermal (winos comprise all the dark matter). Assuming the NFW halo model, the H.E.S.S. search for gamma-ray lines excludes the 3.1 TeV thermal wino; the combined H.E.S.S. and Fermi results completely exclude the non-thermal scenario. Uncertainties in the exclusions are explored. Indirect detection may provide the only probe for models of anomaly plus gravity mediation where the wino is the lightest superpartner and scalars reside at the 100 TeV scale.

  12. Diphoton resonance confronts dark matter

    NASA Astrophysics Data System (ADS)

    Choi, Soo-Min; Kang, Yoo-Jin; Lee, Hyun Min

    2016-07-01

    As an interpretation of the 750 GeV diphoton excesses recently reported by both ATLAS and CMS collaborations, we consider a simple extension of the Standard Model with a Dirac fermion dark matter where a singlet complex scalar field mediates between dark matter and SM particles via effective couplings to SM gauge bosons and/or Higgs-portal. In this model, we can accommodate the diphoton events through the direct and/or cascade decays of pseudo-scalar and real scalar partners of the complex scalar field. We show that mono-jet searches and gamma-ray observations are complementary in constraining the region where the width of the diphoton resonance can be enhanced due to the couplings of the resonance to dark matter and the correct relic density is obtained. In the case of cascade decay of the resonance, the effective couplings of singlet scalars can be smaller, but the model is still testable by the future discrimination between single photon and photon-jet at the LHC as well as the gamma-ray searches for the cascade annihilation of dark matter.

  13. Dark matter in NGC 4472

    NASA Technical Reports Server (NTRS)

    Loewenstein, Michael

    1992-01-01

    An attempt is made to constrain the total mass distribution of the giant elliptical galaxy NGC 4472 by constructing simultaneous equilibrium models for the gas and stars. Emphasis is given to reconciling the value of the emission-weighted average value of kT derived from the Ginga spectrum with the amount of dark matter needed to account for velocity dispersion observations.

  14. Dissipative hidden sector dark matter

    NASA Astrophysics Data System (ADS)

    Foot, R.; Vagnozzi, S.

    2015-01-01

    A simple way of explaining dark matter without modifying known Standard Model physics is to require the existence of a hidden (dark) sector, which interacts with the visible one predominantly via gravity. We consider a hidden sector containing two stable particles charged under an unbroken U (1 )' gauge symmetry, hence featuring dissipative interactions. The massless gauge field associated with this symmetry, the dark photon, can interact via kinetic mixing with the ordinary photon. In fact, such an interaction of strength ε ˜10-9 appears to be necessary in order to explain galactic structure. We calculate the effect of this new physics on big bang nucleosynthesis and its contribution to the relativistic energy density at hydrogen recombination. We then examine the process of dark recombination, during which neutral dark states are formed, which is important for large-scale structure formation. Galactic structure is considered next, focusing on spiral and irregular galaxies. For these galaxies we modeled the dark matter halo (at the current epoch) as a dissipative plasma of dark matter particles, where the energy lost due to dissipation is compensated by the energy produced from ordinary supernovae (the core-collapse energy is transferred to the hidden sector via kinetic mixing induced processes in the supernova core). We find that such a dynamical halo model can reproduce several observed features of disk galaxies, including the cored density profile and the Tully-Fisher relation. We also discuss how elliptical and dwarf spheroidal galaxies could fit into this picture. Finally, these analyses are combined to set bounds on the parameter space of our model, which can serve as a guideline for future experimental searches.

  15. Dark matter axions and caustic rings

    SciTech Connect

    Sikivie, P.

    1997-11-01

    This report contains discussions on the following topics: the strong CP problem; dark matter axions; the cavity detector of galactic halo axions; and caustic rings in the density distribution of cold dark matter halos.

  16. Dark matter from split seesaw

    NASA Astrophysics Data System (ADS)

    Kusenko, Alexander; Takahashi, Fuminobu; Yanagida, Tsutomu T.

    2010-09-01

    The seesaw mechanism in models with extra dimensions is shown to be generically consistent with a broad range of Majorana masses. The resulting democracy of scales implies that the seesaw mechanism can naturally explain the smallness of neutrino masses for an arbitrarily small right-handed neutrino mass. If the scales of the seesaw parameters are split, with two right-handed neutrinos at a high scale and one at a keV scale, one can explain the matter-antimatter asymmetry of the universe, as well as dark matter. The dark matter candidate, a sterile right-handed neutrino with mass of several keV, can account for the observed pulsar velocities and for the recent data from Chandra X-ray Observatory, which suggest the existence of a 5 keV sterile right-handed neutrino.

  17. New spectral features from bound dark matter

    NASA Astrophysics Data System (ADS)

    Catena, Riccardo; Kouvaris, Chris

    2016-07-01

    We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature that we predict can provide a complementary verification of dark matter discovery at experiments with positive signal but unclear background. The effect is generically expected, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section.

  18. Dark matter in a bouncing universe

    SciTech Connect

    Cheung, Yeuk-Kwan E.; Kang, Jin U; Li, Changhong E-mail: jin.u.kang2@gmail.com

    2014-11-01

    We investigate a new scenario of dark matter production in a bouncing universe, in which dark matter was produced completely out of equilibrium in the contracting as well as expanding phase. We explore possibilities of using dark matter as a probe of the bouncing universe, focusing on the relationship between a critical temperature of the bouncing universe and the present relic abundance of dark matter.

  19. Nonthermal dark matter in mirage mediation

    SciTech Connect

    Nagai, Minoru; Nakayama, Kazunori

    2007-12-15

    In mirage-mediation models there exists a modulus field whose mass is O(1000) TeV and its late decay may significantly change the standard thermal relic scenario of the dark matter. We study nonthermal production of the dark matter directly from the modulus decay, and find that for some parameter regions nonthermally produced neutralinos can become the dark matter.

  20. Dark matter in elliptical galaxies

    NASA Technical Reports Server (NTRS)

    Carollo, C. M.; Zeeuw, P. T. DE; Marel, R. P. Van Der; Danziger, I. J.; Qian, E. E.

    1995-01-01

    We present measurements of the shape of the stellar line-of-sight velocity distribution out to two effective radii along the major axes of the four elliptical galaxies NGC 2434, 2663, 3706, and 5018. The velocity dispersion profiles are flat or decline gently with radius. We compare the data to the predictions of f = f(E, L(sub z)) axisymmetric models with and without dark matter. Strong tangential anisotropy is ruled out at large radii. We conclude from our measurements that massive dark halos must be present in three of the four galaxies, while for the fourth galaxy (NGC 2663) the case is inconclusive.

  1. 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

  2. Dark Matter Annihilation at the Galactic Center

    SciTech Connect

    Linden, Timothy Ryan

    2013-06-01

    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 ve times as much dark matter as baryonic matter. However, e orts 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 rst multiwavelength analysis of the GC, with suitable e ective 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 e orts which have successfully detected an excess in -ray emission from the region immediately surrounding the GC, which is di cult to describe in terms of standard di use 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

  3. Propagation of Light through Composite Dark Matter

    NASA Astrophysics Data System (ADS)

    Kvam, Audrey; Latimer, David

    2013-10-01

    A concordance of observations indicates that around 80% of the matter in the universe is some unknown dark matter. This dark matter could be comprised of a single structureless particle, but much richer theories exist. Signals from the DAMA, CoGeNT, and CDMS-II dark matter detectors along with the non-observation of dark matter by other detectors motivate theories of composite dark matter along with a ``dark'' electromagnetic sector. The composite models propose baryon-like or atom-like dark matter. If photons kinetically mix with the ``dark'' photons, then light traveling through dark matter will experience dispersion. We expect the dispersion to be approximated by the Drude-Lorentz model where the model parameters are particular to a given dark matter candidate. As light travels through the dispersive medium, it can accrue to a frequency-dependent time lag. Measurement of such a time lag can yield clues as to the nature of the dark matter. As a first application, we model hydrogenic dark atoms and use astrophysical data to constrain the mass, binding energy, and the fractional electric charge of the dark atoms.

  4. 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.

  5. Non-baryonic dark matter in cosmology

    NASA Astrophysics Data System (ADS)

    Del Popolo, A.

    2013-07-01

    This paper is based on lectures given at the IX Mexican School on Gravitation and Mathematical Physics. The lectures (as the paper) were a broad-band review of the current status of non-baryonic dark matter research. I start with a historical overview of the evidences of dark matter existence, then I discuss how dark matter is distributed from small scale to large scale, and I then verge the attention to dark matter nature: dark matter candidates and their detection. I finally discuss some of the limits of the ΛCDM model, with particular emphasis on the small scale problems of the paradigm.

  6. Superconducting Detectors for Superlight Dark Matter.

    PubMed

    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, 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. PMID:26799009

  7. Large Extra Dimension and Dark Matter Detection

    SciTech Connect

    Qin Bo; Starkman, Glenn D.; Silk, Joseph

    2008-01-03

    If our space has the large extra dimensions as proposed by Arkani-Hamed, Dimopoulos and Dvali (ADD), then gravity would start to deviate from Newtonian gravity and be greatly enhanced in sub-millimeter scales. Here we show that in the ADD scenario, gravity could play an important role (compared to the weak interaction) in the interactions between dark matter particles and the electron. We find that for typical WIMP dark matter, such dark matter-electron 'gravitational' scattering cross section may be much larger than the dark matter-nucleon cross section constrained by current dark matter experiments.

  8. Large Extra Dimension and Dark Matter Detection

    NASA Astrophysics Data System (ADS)

    Qin, Bo; Starkman, Glenn D.; Silk, Joseph

    2008-01-01

    If our space has the large extra dimensions as proposed by Arkani-Hamed, Dimopoulos and Dvali (ADD), then gravity would start to deviate from Newtonian gravity and be greatly enhanced in sub-millimeter scales. Here we show that in the ADD scenario, gravity could play an important role (compared to the weak interaction) in the interactions between dark matter particles and the electron. We find that for typical WIMP dark matter, such dark matter-electron ``gravitational'' scattering cross section may be much larger than the dark matter-nucleon cross section constrained by current dark matter experiments.

  9. 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.

  10. The local dark matter density

    NASA Astrophysics Data System (ADS)

    Read, J. I.

    2014-06-01

    I review current efforts to measure the mean density of dark matter near the Sun. This encodes valuable dynamical information about our Galaxy and is also of great importance for ‘direct detection’ dark matter experiments. I discuss theoretical expectations in our current cosmology; the theory behind mass modelling of the Galaxy; and I show how combining local and global measures probes the shape of the Milky Way dark matter halo and the possible presence of a ‘dark disc’. I stress the strengths and weaknesses of different methodologies and highlight the continuing need for detailed tests on mock data—particularly in the light of recently discovered evidence for disequilibria in the Milky Way disc. I collate the latest measurements of ρdm and show that, once the baryonic surface density contribution Σb is normalized across different groups, there is remarkably good agreement. Compiling data from the literature, I estimate Σb = 54.2 ± 4.9 M⊙pc-2, where the dominant source of uncertainty is in the H i gas contribution. Assuming this contribution from the baryons, I highlight several recent measurements of ρdm in order of increasing data complexity and prior, and, correspondingly, decreasing formal error bars. Comparing these measurements with spherical extrapolations from the Milky Way’s rotation curve, I show that the Milky Way is consistent with having a spherical dark matter halo at R0 ˜ 8 kpc. The very latest measures of ρdm based on ˜10 000 stars from the Sloan Digital Sky Survey appear to favour little halo flattening at R0, suggesting that the Galaxy has a rather weak dark matter disc, with a correspondingly quiescent merger history. I caution, however, that this result hinges on there being no large systematics that remain to be uncovered in the SDSS data, and on the local baryonic surface density being Σb ˜ 55 M⊙pc-2. I conclude by discussing how the new Gaia satellite will be transformative. We will obtain much tighter

  11. Number-theory dark matter

    NASA Astrophysics Data System (ADS)

    Nakayama, Kazunori; Takahashi, Fuminobu; Yanagida, Tsutomu T.

    2011-05-01

    We propose that the stability of dark matter is ensured by a discrete subgroup of the U(1)B-L gauge symmetry, Z(B-L). We introduce a set of chiral fermions charged under the U(1)B-L in addition to the right-handed neutrinos, and require the anomaly-cancellation conditions associated with the U(1)B-L gauge symmetry. We find that the possible number of fermions and their charges are tightly constrained, and that non-trivial solutions appear when at least five additional chiral fermions are introduced. The Fermat theorem in the number theory plays an important role in this argument. Focusing on one of the solutions, we show that there is indeed a good candidate for dark matter, whose stability is guaranteed by Z(B-L).

  12. Dark energy and dark matter from primordial QGP

    NASA Astrophysics Data System (ADS)

    Vaidya, Vaishali; Upadhyaya, G. K.

    2015-07-01

    Coloured relics servived after hadronization might have given birth to dark matter and dark energy. Theoretical ideas to solve mystery of cosmic acceleration, its origin and its status with reference to recent past are of much interest and are being proposed by many workers. In the present paper, we present a critical review of work done to understand the earliest appearance of dark matter and dark energy in the scenario of primordial quark gluon plasma (QGP) phase after Big Bang.

  13. Dark energy and dark matter from primordial QGP

    SciTech Connect

    Vaidya, Vaishali Upadhyaya, G. K.

    2015-07-31

    Coloured relics servived after hadronization might have given birth to dark matter and dark energy. Theoretical ideas to solve mystery of cosmic acceleration, its origin and its status with reference to recent past are of much interest and are being proposed by many workers. In the present paper, we present a critical review of work done to understand the earliest appearance of dark matter and dark energy in the scenario of primordial quark gluon plasma (QGP) phase after Big Bang.

  14. Baryon asymmetry and dark matter

    NASA Astrophysics Data System (ADS)

    Bolz, M.; Buchmüller, W.; Plümacher, M.

    1998-12-01

    We study the implications of a large baryogenesis temperature, TB=≀(1010 GeV), on the mass spectrum of superparticles in supersymmetric extensions of the standard model. Models with a neutralino as lightest superparticle (LSP) are excluded. A consistent picture is obtained with the gravitino as LSP, followed by a higgsino-like neutralino (NSP). Gravitinos with masses from 10 to 100 GeV may be the dominant component of dark matter.

  15. Implications of quaternionic dark matter

    NASA Astrophysics Data System (ADS)

    Brumby, S. P.; Hanlon, B. E.; Joshi, G. C.

    1997-02-01

    Taking the complex nature of quantum mechanics which we observe today as a low energy effect of a broken quaternionic theory we explore the possibility that dark matter arises as a consequence of this underlying quaternionic structure to our universe. We introduce a low energy, effective, Lagrangian which incorporates the remnants of a local quaternionic algebra, investigate the stellar production of the resultant exotic bosons and explore the possible low energy consequences of our remnant extended Hilbert space.

  16. Isocurvature cold dark matter fluctuations

    NASA Technical Reports Server (NTRS)

    Efstathiou, G.; Bond, J. R.

    1986-01-01

    According to Preskill et al. (1983), the axion field represents a particularly attractive candidate for the dark matter in the universe. In many respects it behaves like other forms of cold dark matter, such as massive gravitinos, photinos, and monopoles. It is, however, a pseudo-Goldstone boson of very low mass, and it is only because of rapid coherent oscillations of the field that it can dominate the mass density of the universe. In the present paper it is assumed that the isocurvature mode is dominant. The linear evolution calculations conducted do not depend upon specific details of particle physics. For this reason, the conducted discussion is applicable to any cold dark matter model with isocurvature perturbations. The results of the study lead to the conclusion that scale-invariant isocurvature perturbations do not seem an attractive possibility for the origin of large-scale structure. The findings strengthen the review that primordial adiabatic perturbations were the dominant fluctuations in the early stages of the Big Bang.

  17. Axion cold dark matter revisited

    NASA Astrophysics Data System (ADS)

    Visinelli, L.; Gondolo, P.

    2010-01-01

    We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae [1], and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass ma = (85 ± 3) μeV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for ma < 15 meV provided a specific value of the initial misalignment angle θi is chosen in correspondence to a given value of its mass ma. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle θi.

  18. Collisional versus Collisionless Dark Matter.

    PubMed

    Moore; Gelato; Jenkins; Pearce; Quilis

    2000-05-20

    We compare the structure and substructure of dark matter halos in model universes dominated by collisional, strongly self-interacting dark matter (SIDM) and collisionless, weakly interacting dark matter (CDM). While SIDM virialized halos are more nearly spherical than CDM halos, they can be rotationally flattened by as much as 20% in their inner regions. Substructure halos suffer ram-pressure truncation and drag, which are more rapid and severe than their gravitational counterparts tidal stripping and dynamical friction. Lensing constraints on the size of galactic halos in clusters are a factor of 2 smaller than predicted by gravitational stripping, and the recent detection of tidal streams of stars escaping from the satellite galaxy Carina suggests that its tidal radius is close to its optical radius of a few hundred parsecs-an order of magnitude smaller than predicted by CDM models but consistent with SIDM models. The orbits of SIDM satellites suffer significant velocity bias, sigmaSIDM&solm0;sigmaCDM=0.85, and are more circular than CDM satellites, betaSIDM approximately 0.5, in agreement with the inferred orbits of the Galaxy's satellites. In the limit of a short mean free path, SIDM halos have singular isothermal density profiles; thus, in its simplest incarnation SIDM, is inconsistent with galactic rotation curves. PMID:10828999

  19. Dark matter in the Universe

    SciTech Connect

    Turner, M.S. Chicago Univ., IL . Enrico Fermi Inst.)

    1991-03-01

    What is the quantity and composition of material in the universe This is one of the most fundamental questions we can ask about the universe, and its answer bears on a number of important issues including the formation of structure in the universe, and the ultimate fate and the earliest history of the universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: most of the material in the universe does not give off detectable radiation, i.e., is dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments -- structure formation, the temporal Copernican principle, and inflation -- and by some observational data. If {Omega} is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10{sup {minus}6} eV to 10{sup {minus}4} eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 71 refs., 6 figs.

  20. Dark matter in the universe

    SciTech Connect

    Turner, M.S. Chicago Univ., IL . Enrico Fermi Inst.)

    1990-11-01

    What is the quantity and composition of material in the Universe This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: Most of the material in the Universe does not give off detectable radiation, i.e., is dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments--structure formation, the temporal Copernican principle, and inflation--and by some observational data. If {Omega} is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10{sup {minus}6} eV to 10{sup {minus}4} eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 63 refs.

  1. Flavored dark matter beyond Minimal Flavor Violation

    SciTech Connect

    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 as 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.

  2. Flavored dark matter beyond Minimal Flavor Violation

    DOE PAGESBeta

    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

  3. 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.

  4. The Dark Matter Problem: A Historical Perspective

    NASA Astrophysics Data System (ADS)

    Sanders, Robert H.

    2010-04-01

    1. Introduction; 2. Early history of the dark matter hypothesis; 3. The stability of disk galaxies: the dark halo solutions; 4. Direct evidence: extended rotation curves of spiral galaxies; 5. The maximum disk: light traces mass; 6. Cosmology and the birth of astroparticle physics; 7. Clusters revisited: missing mass found; 8. CDM confronts galaxy rotation curves; 9. The new cosmology: dark matter is not enough; 10. An alternative to dark matter: Modified Newtonian Dynamics; 11. Seeing dark matter: the theory and practice of detection; 12. Reflections: a personal point of view; Appendix; References; Index.

  5. Astrophysical Probes of Dark Matter Interactions

    NASA Astrophysics Data System (ADS)

    Reece, Matthew

    The majority of matter in the universe is dark matter, made up of some particle beyond those in the Standard Model of particle physics. So far we have very little information about what dark matter is and how it interacts, except through gravity. Constraints from halo shapes and the Bullet Cluster give upper bounds on the self-interaction strength of dark matter, but these bounds are very weak: roughly the same size as nuclear physics cross sections, which are very large by the standards of particle physics. Given how little we know about dark matter, it is important to search for it in as broad a context as possible. Existing direct and indirect detection analyses are typically motivated by simple particle physics models like WIMP dark matter. This research will aim to widen the scope of searches for dark matter by considering a more complete range of particle physics models, working out their implications for astrophysical data, and interpreting existing data in terms of these new models. New models of dark matter can affect searches in a variety of ways. Signals may show up in conventional indirect detection searches, e.g. in gamma rays detected by Fermi-LAT or in antiprotons detected by AMS-02. The new particle physics content of the models could be reflected in surprising spectral shapes or other features of such signals, or in gamma rays with a different profile on the sky than expected in typical models. The PI has worked, for example, on a model in which signals may arise from a dark disk, which is just one of many possibilities. Signals of new dark matter models might also arise in more subtle ways. Structure in the dark sector could influence the development of structure in the visible sector, indirectly. For instance, a dark matter disk or other dark structures could alter the orbits of stars in the galaxy and may be detectable through detailed studies of the kinematics of stellar populations. Dark accretion disks could exist around astrophysical objects

  6. The Cosmology of Composite Inelastic Dark Matter

    SciTech Connect

    Spier Moreira Alves, Daniele; Behbahani, Siavosh R.; Schuster, Philip; Wacker, Jay G.; /SLAC

    2011-08-19

    Composite dark matter is a natural setting for implementing inelastic dark matter - the O(100 keV) mass splitting arises from spin-spin interactions of constituent fermions. In models where the constituents are charged under an axial U(1) gauge symmetry that also couples to the Standard Model quarks, dark matter scatters inelastically off Standard Model nuclei and can explain the DAMA/LIBRA annual modulation signal. This article describes the early Universe cosmology of a minimal implementation of a composite inelastic dark matter model where the dark matter is a meson composed of a light and a heavy quark. The synthesis of the constituent quarks into dark hadrons results in several qualitatively different configurations of the resulting dark matter composition depending on the relative mass scales in the system.

  7. Baryon destruction by asymmetric dark matter

    SciTech Connect

    Davoudiasl H.; Morrissey, D.; Sigurdson, K.; Tulin, S.

    2011-11-10

    We investigate new and unusual signals that arise in theories where dark matter is asymmetric and carries a net antibaryon number, as may occur when the dark matter abundance is linked to the baryon abundance. Antibaryonic dark matter can cause induced nucleon decay by annihilating visible baryons through inelastic scattering. These processes lead to an effective nucleon lifetime of 10{sup 29}-10{sup 32} yrs in terrestrial nucleon decay experiments, if baryon number transfer between visible and dark sectors arises through new physics at the weak scale. The possibility of induced nucleon decay motivates a novel approach for direct detection of cosmic dark matter in nucleon decay experiments. Monojet searches (and related signatures) at hadron colliders also provide a complementary probe of weak-scale dark-matter-induced baryon number violation. Finally, we discuss the effects of baryon-destroying dark matter on stellar systems and show that it can be consistent with existing observations.

  8. Baryon destruction by asymmetric dark matter

    SciTech Connect

    Davoudiasl, Hooman; Morrissey, David E.; Tulin, Sean; Sigurdson, Kris

    2011-11-01

    We investigate new and unusual signals that arise in theories where dark matter is asymmetric and carries a net antibaryon number, as may occur when the dark matter abundance is linked to the baryon abundance. Antibaryonic dark matter can cause induced nucleon decay by annihilating visible baryons through inelastic scattering. These processes lead to an effective nucleon lifetime of 10{sup 29}-10{sup 32} yrs in terrestrial nucleon decay experiments, if baryon number transfer between visible and dark sectors arises through new physics at the weak scale. The possibility of induced nucleon decay motivates a novel approach for direct detection of cosmic dark matter in nucleon decay experiments. Monojet searches (and related signatures) at hadron colliders also provide a complementary probe of weak-scale dark-matter-induced baryon number violation. Finally, we discuss the effects of baryon-destroying dark matter on stellar systems and show that it can be consistent with existing observations.

  9. Cosmological evolution with interaction between dark energy and dark matter

    NASA Astrophysics Data System (ADS)

    Bolotin, Yuri L.; Kostenko, Alexander; Lemets, Oleg A.; Yerokhin, Danylo A.

    2015-12-01

    In this review we consider in detail different theoretical topics associated with interaction in the dark sector. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities. We consider a number of different models (including the holographic dark energy and dark energy in a fractal universe), with interacting dark energy and dark matter, have done a thorough analysis of these models. The main task of this review was not only to give an idea about the modern set of different models of dark energy, but to show how much can be diverse dynamics of the universe in these models. We find that the dynamics of a universe that contains interaction in the dark sector can differ significantly from the Standard Cosmological Model.

  10. Dark matter in the universe

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1991-01-01

    What is the quantity and composition of material in the Universe? This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand. Most of the radiation in the Universe does not give off detectable radiation; it is dark. The dark matter associated with bright galaxies contributes somewhere between 10 and 30 percent of the critical density; baryonic matter contributes between 1.1 and 12 percent of the critical. The case for the spatially flat, Einstein-de Sitter model is supported by three compelling theoretical arguments - structure formation, the temporal Copernican principle, and inflation - and by some observational data. If Omega is indeed unity, or even just significantly greater than 0.1, then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark matter candidates: an axion of mass 10 (exp -6) eV to 10 (exp -4) eV; a neutrino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either planned or are underway.

  11. Twin Higgs Asymmetric Dark Matter

    NASA Astrophysics Data System (ADS)

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-01

    We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)'×SU(2)', atwin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD' scale ΛQCD'≃0.5 - 20 GeV , and that t' is heavy. We focus on the light b' quark regime, mb'≲ΛQCD', where QCD' is characterized by a single scale ΛQCD' with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3 /2 twin baryon, Δ'˜b'b'b', with a dynamically determined mass (˜5 ΛQCD') in the preferred range for the DM-to-baryon ratio ΩDM/Ωbaryon≃5 . Gauging the U (1 )' group leads to twin atoms (Δ'-τ' ¯ bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.

  12. Twin Higgs Asymmetric Dark Matter.

    PubMed

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-18

    We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^{'}×SU(2)^{'}, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^{'} scale Λ_{QCD}^{'}≃0.5-20  GeV, and that t^{'} is heavy. We focus on the light b^{'} quark regime, m_{b^{'}}≲Λ_{QCD}^{'}, where QCD^{'} is characterized by a single scale Λ_{QCD}^{'} with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3/2 twin baryon, Δ^{'}∼b^{'}b^{'}b^{'}, with a dynamically determined mass (∼5Λ_{QCD}^{'}) in the preferred range for the DM-to-baryon ratio Ω_{DM}/Ω_{baryon}≃5. Gauging the U(1)^{'} group leads to twin atoms (Δ^{'}-τ^{'}[over ¯] bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors. PMID:26430985

  13. Dissipative dark matter explains rotation curves

    NASA Astrophysics Data System (ADS)

    Foot, R.

    2015-06-01

    Dissipative dark matter, where dark matter particles interact with a massless (or very light) boson, is studied. Such dark matter can arise in simple hidden sector gauge models, including those featuring an unbroken U (1 )' gauge symmetry, leading to a dark photon. Previous work has shown that such models can not only explain the large scale structure and cosmic microwave background, but potentially also dark matter phenomena on small scales, such as the inferred cored structure of dark matter halos. In this picture, dark matter halos of disk galaxies not only cool via dissipative interactions but are also heated via ordinary supernovae (facilitated by an assumed photon-dark photon kinetic mixing interaction). This interaction between the dark matter halo and ordinary baryons, a very special feature of these types of models, plays a critical role in governing the physical properties of the dark matter halo. Here, we further study the implications of this type of dissipative dark matter for disk galaxies. Building on earlier work, we develop a simple formalism which aims to describe the effects of dissipative dark matter in a fairly model independent way. This formalism is then applied to generic disk galaxies. We also consider specific examples, including NGC 1560 and a sample of dwarf galaxies from the LITTLE THINGS survey. We find that dissipative dark matter, as developed here, does a fairly good job accounting for the rotation curves of the galaxies considered. Not only does dissipative dark matter explain the linear rise of the rotational velocity of dwarf galaxies at small radii, but it can also explain the observed wiggles in rotation curves which are known to be correlated with corresponding features in the disk gas distribution.

  14. EXTRAGALACTIC DARK MATTER AND DIRECT DETECTION EXPERIMENTS

    SciTech Connect

    Baushev, A. N.

    2013-07-10

    Recent astronomical data strongly suggest that a significant part of the dark matter content of the Local Group and Virgo Supercluster is not incorporated into the galaxy halos and forms diffuse components of these galaxy clusters. A portion of the particles from these components may penetrate the Milky Way and make an extragalactic contribution to the total dark matter containment of our Galaxy. We find that the particles of the diffuse component of the Local Group are apt to contribute {approx}12% to the total dark matter density near Earth. The particles of the extragalactic dark matter stand out because of their high speed ({approx}600 km s{sup -1}), i.e., they are much faster than the galactic dark matter. In addition, their speed distribution is very narrow ({approx}20 km s{sup -1}). The particles have an isotropic velocity distribution (perhaps, in contrast to the galactic dark matter). The extragalactic dark matter should provide a significant contribution to the direct detection signal. If the detector is sensitive only to the fast particles (v > 450 km s{sup -1}), then the signal may even dominate. The density of other possible types of the extragalactic dark matter (for instance, of the diffuse component of the Virgo Supercluster) should be relatively small and comparable with the average dark matter density of the universe. However, these particles can generate anomaly high-energy collisions in direct dark matter detectors.

  15. New astrophysical probes of dark matter

    NASA Astrophysics Data System (ADS)

    Wang, Mei-Yu

    In my thesis, I present four studies to explore astrophysical methods for understanding dark matter properties. To understand the nature of dark matter, I explore a few unstable dark matter models that are invoked as ways to address apparent discrepancies between the predictions of standard cold dark matter and observations of small-scale galactic structure. My studies are aimed at developing independent large-scale constraints on these models. One of the model is a decaying dark matter model such that one dark matter particle decays into two relativistic non-interacting particles. In the second model, a dark matter particle decays into a less massive, stable dark matter particle with a recoil kick velocity Vk and a relativistic non-interacting particle. I consider two types of experiments: one is weak lensing cosmic shear with future or forthcoming surveys like Dark Energy Survey (DES) and Large Synoptic Survey Telescope (LSST); the other one is Lyman-alpha forest spectrum, which has contemporary data from Sloan Digital Sky Survey (SDSS) and other observations. I found that large-scale structure growth is sensitive to the change of dark matter properties due to these decay processes, and they can provide competitive constraints comparing to other existing limits. On small scale, the gravitational interplay of baryon and dark matter can affect the clustering of dark matter. I examine adiabatic contraction (AC) models what are traditionally used to parametrize the dark matter response to the cooling of baryons by investigating a suite of numerical simulations. We found that the errors in AC reconstructions are correlated with baryonic physics and certain halo properties. Our results indicate that existing AC models need significant calibration in order to predicting realistic matter distribution.

  16. Is Cold Dark Matter a Vacuum Effect?

    NASA Astrophysics Data System (ADS)

    Houlden, Michael A.

    Current theories about the Universe based on an FLRW model conclude that it is composed of ~4% normal matter, ~28 % dark matter and ~68% Dark Energy which is responsible for the well-established accelerated expansion: this model works extremely well. As the Universe expands the density of normal and dark matter decreases while the proportion of Dark Energy increases. This model assumes that the amount of dark matter, whose nature at present is totally unknown, has remained constant. This is a natural assumption if dark matter is a particle of some kind - WIMP, sterile neutrino, lightest supersysmmetric particle or axion, etc. - that must have emerged from the early high temperature phase of the Big Bang. This paper proposes that dark matter is not a particle such as these but a vacuum effect, and that the proportion of dark matter in the Universe is actually increasing with time. The idea that led to this suggestion was that a quantum process (possibly the Higgs mechanism) might operate in the nilpotent vacuum that Rowlands postulates is a dual space to the real space where Standard Model fundamental fermions (and we) reside. This could produce a vacuum quantum state that has mass, which interacts gravitationally, and such states would be `dark matter'. It is proposed that the rate of production of dark matter by this process might depend on local circumstances, such as the density of dark matter and/or normal matter. This proposal makes the testable prediction that the ratio of baryonic to dark matter varies with redshift and offers an explanation, within the framework of Rowlands' ideas, of the coincidence problem - why has cosmic acceleration started in the recent epoch at redshift z ~0.55 when the Dark Energy density first became equal to the matter density?. This process also offers a potential solution to the `missing baryon' problem.

  17. Stealth dark matter: Dark scalar baryons through the Higgs portal

    NASA Astrophysics Data System (ADS)

    Appelquist, T.; 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.; Lattice Strong Dynamics LSD Collaboration

    2015-10-01

    We present a new model of stealth dark matter: a composite baryonic scalar of an S U (ND) strongly coupled theory with even ND≥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 S U (4 ), and investigate the constraints on the model from dark meson decay, electroweak 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 mB≳300 GeV is obtained from the indirect requirement that the lightest dark meson not be observable at LEP II. 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.

  18. Dynamics of dark energy with a coupling to dark matter

    SciTech Connect

    Boehmer, Christian G.; Caldera-Cabral, Gabriela; Maartens, Roy; Lazkoz, Ruth

    2008-07-15

    Dark energy and dark matter are the dominant sources in the evolution of the late universe. They are currently only indirectly detected via their gravitational effects, and there could be a coupling between them without violating observational constraints. We investigate the background dynamics when dark energy is modeled as exponential quintessence and is coupled to dark matter via simple models of energy exchange. We introduce a new form of dark sector coupling, which leads to a more complicated dynamical phase space and has a better physical motivation than previous mathematically similar couplings.

  19. Turning off the lights: How dark is dark matter?

    NASA Astrophysics Data System (ADS)

    McDermott, Samuel D.; Yu, Hai-Bo; Zurek, Kathryn M.

    2011-03-01

    We consider current observational constraints on the electromagnetic charge of dark matter. The velocity dependence of the scattering cross section through the photon gives rise to qualitatively different constraints than standard dark matter scattering through massive force carriers. In particular, recombination epoch observations of dark matter density perturbations require that ɛ, the ratio of the dark matter to electronic charge, is less than 10-6 for mX=1GeV, rising to ɛ<10-4 for mX=10TeV. Though naively one would expect that dark matter carrying a charge well below this constraint could still give rise to large scattering in current direct detection experiments, we show that charged dark matter particles that could be detected with upcoming experiments are expected to be evacuated from the Galactic disk by the Galactic magnetic fields and supernova shock waves and hence will not give rise to a signal. Thus dark matter with a small charge is likely not a source of a signal in current or upcoming dark matter direct detection experiments.

  20. Dark matter from Affleck-Dine baryogenesis

    SciTech Connect

    Kusenko, Alexander

    1999-07-15

    Fragmentation of the Affleck-Dine condensate into Q-balls could fill the Universe with dark matter either in the form of stable baryonic balls, or LSP produced from the decay of unstable Q-balls. The dark matter and the ordinary matter in the Universe may share the same origin.

  1. Dark Matter in the MSSM

    SciTech Connect

    Cotta, R.C.; Gainer, J.S.; Hewett, J.L.; Rizzo, T.G.; /SLAC

    2009-04-07

    We have recently examined a large number of points in the parameter space of the phenomenological MSSM, the 19-dimensional parameter space of the CP-conserving MSSM with Minimal Flavor Violation. We determined whether each of these points satisfied existing experimental and theoretical constraints. This analysis provides insight into general features of the MSSM without reference to a particular SUSY breaking scenario or any other assumptions at the GUT scale. This study opens up new possibilities for SUSY phenomenology both in colliders and in astrophysical experiments. Here we shall discuss the implications of this analysis relevant to the study of dark matter.

  2. Introduction to Dark Matter Experiments

    NASA Astrophysics Data System (ADS)

    Schnee, Richard W.

    2011-03-01

    I provide an introduction to experiments designed to detect WIMP dark matter directly, focussing on building intuitive understanding of the characteristics of potential WIMP signals and the experimental techniques. After deriving the characteristics of potential signals in direct-detection experiments for standard WIMP models, I summarize the general experimental methods shared by most direct-detection experiments and review the advantages, challenges, and status of such searches. Experiments are already probing SUSY models, with best limits on the spin-independent coupling below 10-7 pb. Combined information from direct and indirect detection, along with detection at colliders, promises to teach us much about fundamental particle physics, cosmology, and astrophysics.

  3. Self-interacting dark matter

    SciTech Connect

    Tulin, Sean

    2014-06-24

    The particle physics nature of dark matter (DM) can leave an imprint on the structure of Universe. If DM has a sizable cross section for self-interactions (much larger than the typical weak scale cross section), this can affect the density profiles of DM halos. Moreover, there exist long-standing discrepancies on small scales between astrophysical observations and predictions from N-body simulations of collisionless DM, which suggests that DM may be self-interacting. Here, we review these discrepancies, we discuss the particle physics implications of self-interacting DM, and we show that DM self-interactions have interesting implications for direct and indirect detection searches.

  4. How cold is cold dark matter?

    SciTech Connect

    Armendariz-Picon, Cristian; Neelakanta, Jayanth T. E-mail: jtneelak@syr.edu

    2014-03-01

    If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed.

  5. Dark matter dynamics and indirect detection

    SciTech Connect

    Bertone, Gianfranco; Merritt, David; /Rochester Inst. Tech.

    2005-04-01

    Non-baryonic, or ''dark'', matter is believed to be a major component of the total mass budget of the universe. We review the candidates for particle dark matter and discuss the prospects for direct detection (via interaction of dark matter particles with laboratory detectors) and indirect detection (via observations of the products of dark matter self-annihilations), focusing in particular on the Galactic center, which is among the most promising targets for indirect detection studies. The gravitational potential at the Galactic center is dominated by stars and by the supermassive black hole, and the dark matter distribution is expected to evolve on sub-parsec scales due to interaction with these components. We discuss the dominant interaction mechanisms and show how they can be used to rule out certain extreme models for the dark matter distribution, thus increasing the information that can be gleaned from indirect detection searches.

  6. Improved constraints on inelastic dark matter

    SciTech Connect

    Schmidt-Hoberg, Kai; Winkler, Martin Wolfgang E-mail: mwinkler@ph.tum.de

    2009-09-01

    We perform an extensive study of the DAMA annual modulation data in the context of inelastic dark matter. We find that inelastic dark matter with mass m{sub χ}∼>15 GeV is excluded at the 95% confidence level by the combination of DAMA spectral information and results from other direct detection experiments. However, at smaller m{sub χ}, inelastic dark matter constitutes a possible solution to the DAMA puzzle.

  7. 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.

  8. Current and future searches for dark matter

    SciTech Connect

    Bauer, Daniel A.; /Fermilab

    2005-07-01

    Recent experimental data confirms that approximately one quarter of the universe consists of cold dark matter. Particle theories provide natural candidates for this dark matter in the form of either Axions or Weakly Interacting Massive Particles (WIMPs). A growing body of experiments is aimed at direct or indirect detection of particle dark matter. I summarize the current status of these experiments and offer projections of their future sensitivity.

  9. Dark matter more mysterious than expected

    NASA Astrophysics Data System (ADS)

    Jałocha, Joanna

    2015-12-01

    Based on the lecture Dark Matter --- more mysterious than expected}, given by me at the Cosmology School in Kielce on 18 July 2015, I will briefly discuss in this essay the history of dark matter and why this notion is so essential for the contemporary physics. Next, I will present the point of view of the research team I work with, on the presence of nonbaryonic dark matter in the Universe and in spiral galaxies.

  10. Dark Matter Jets at the LHC

    SciTech Connect

    Bai, Yang; Rajaraman, Arvind; /UC, Irvine

    2012-03-28

    We argue that dark matter particles which have strong interactions with the Standard Model particles are not excluded by current astrophysical constraints. These dark matter particles have unique signatures at colliders; instead of missing energy, the dark matter particles produce jets. We propose a new search strategy for such strongly interacting particles by looking for a signal of two trackless jets. We show that suitable cuts can plausibly allow us to find these signals at the LHC even in early data.

  11. Future Observations and Simulations for Dark Matter

    NASA Astrophysics Data System (ADS)

    Tollerud, Erik Jon; Collins, Michelle; Brooks, Alyson; Wechsler, Risa H.; Dawson, William; Keeton, Charles R.; Read, Justin; Bullock, James; Somerville, Rachel S.

    2016-01-01

    We look to the future of astronomical observations that may provide new measurements of dark matter properties, and discuss their relative sensitivity, potential, and relative complexity of pursuing, analyzing, and interpreting these observations. We present the key details of relevant projects and missions in the context of dark matter constraints, including GAIA, LSST, WFIRST, TMT, etc. We also look to the future of numerical work for N-body and hydrodynamic simulations on galaxy or cosmological scales for different dark matter properties.

  12. TASI 2008 Lectures on Dark Matter

    SciTech Connect

    Hooper, Dan; /Fermilab /Chicago U., Astron. Astrophys. Ctr.

    2009-01-01

    Based on lectures given at the 2008 Theoretical Advanced Study Institute (TASI), I review here some aspects of the phenomenology of particle dark matter, including the process of thermal freeze-out in the early universe, and the direct and indirect detection of WIMPs. I also describe some of the most popular particle candidates for dark matter and summarize the current status of the quest to discover dark matter's particle identity.

  13. Regenerating a symmetry in asymmetric dark matter.

    PubMed

    Buckley, Matthew R; Profumo, Stefano

    2012-01-01

    Asymmetric dark matter theories generically allow for mass terms that lead to particle-antiparticle mixing. Over the age of the Universe, dark matter can thus oscillate from a purely asymmetric configuration into a symmetric mix of particles and antiparticles, allowing for pair-annihilation processes. Additionally, requiring efficient depletion of the primordial thermal (symmetric) component generically entails large annihilation rates. We show that unless some symmetry completely forbids dark matter particle-antiparticle mixing, asymmetric dark matter is effectively ruled out for a large range of masses, for almost any oscillation time scale shorter than the age of the Universe. PMID:22304253

  14. The emerging case for axion dark matter

    NASA Astrophysics Data System (ADS)

    Sikivie, P.

    2011-01-01

    Dark matter axions form a rethermalizing Bose-Einstein condensate. This provides an opportunity to distinguish axions from other forms of dark matter on observational grounds. I show that if the dark matter is axions, tidal torque theory predicts a specific structure for the phase space distribution of the halos of isolated disk galaxies, such as the Milky Way. This phase space structure is precisely that of the caustic ring model, for which observational support had been found earlier. The other dark matter candidates predict a different phase space structure for galactic halos.

  15. Neutrino signals from dark matter decay

    SciTech Connect

    Covi, Laura; Grefe, Michael; Ibarra, Alejandro; Tran, David E-mail: michael.grefe@desy.de E-mail: david.tran@ph.tum.de

    2010-04-01

    We investigate different neutrino signals from the decay of dark matter particles to determine the prospects for their detection, and more specifically if any spectral signature can be disentangled from the background in present and future neutrino observatories. If detected, such a signal could bring an independent confirmation of the dark matter interpretation of the dramatic rise in the positron fraction above 10 GeV recently observed by the PAMELA satellite experiment and offer the possibility of distinguishing between astrophysical sources and dark matter decay or annihilation. In combination with other signals, it may also be possible to distinguish among different dark matter decay channels.

  16. Dipolar dark matter with massive bigravity

    SciTech Connect

    Blanchet, Luc; Heisenberg, Lavinia

    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 two 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.

  17. Dipolar dark matter with massive bigravity

    NASA Astrophysics Data System (ADS)

    Blanchet, Luc; Heisenberg, Lavinia

    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 two 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.

  18. Dark matter from decaying topological defects

    SciTech Connect

    Hindmarsh, Mark; Kirk, Russell; West, Stephen M. E-mail: russell.kirk.2008@live.rhul.ac.uk

    2014-03-01

    We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or ''top-down'' (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent p−4. We find a formula in closed form for the yield for all p < 3/2, which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (p = 1, p = 7/6) motivated by cosmic strings which decay into TeV-scale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by s-wave or p-wave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freeze-out calculation under-predicts the relic density and hence can lead to potentially large ''boost factor'' enhancements in the dark matter annihilation rate. We examine dark matter model-independent limits on this scenario arising from unitarity and discuss example model-dependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on Gμ for strings with an appreciable channel into TeV-scale states is significantly more stringent than the current Cosmic Microwave Background limits.

  19. Dark matter: an overview of direct searches.

    NASA Astrophysics Data System (ADS)

    Gerbier, G.

    1991-11-01

    The purpose of this paper is to give a flavour of the experimental challenges raised by the detection of dark matter. It summarizes the detection methods of the MACHO's, celestial bodies candidate for the baryonic dark matter and of the WIMP's, particles candidate for the non-baryonic dark matter. Current status and hopes are given. Two side aspects not directly related to the experimental search will be evoked to illustrate that the dark matter puzzle is indeed at the common frontier of various fields of physics.

  20. Dark matter from spacetime nonlocality

    NASA Astrophysics Data System (ADS)

    Saravani, Mehdi; Aslanbeigi, Siavash

    2015-11-01

    We propose that dark matter is not yet another new particle in nature, but that it is a remnant of quantum gravitational effects on known fields. We arrive at this possibility in an indirect and surprising manner: by considering retarded, nonlocal, and Lorentzian evolution for quantum fields. This is inspired by recent developments in causal set theory, where such an evolution shows up as the continuum limit of scalar field propagation on a background causal set. Concretely, we study the quantum theory of a massless scalar field whose evolution is given not by the the d'Alembertian □, but by an operator □˜ which is Lorentz invariant, reduces to □ at low energies, and defines an explicitly retarded evolution: (□˜ϕ )(x ) only depends on ϕ (y ), where y is in the causal past of x . This modification results in the existence of a continuum of massive particles, in addition to the usual massless ones, in the free theory. When interactions are introduced, these massive or off-shell quanta can be produced by the scattering of massless particles, but once produced, they no longer interact, which makes them a natural candidate for dark matter.

  1. Unified dark energy-dark matter model with inverse quintessence

    SciTech Connect

    Ansoldi, Stefano; Guendelman, Eduardo I. E-mail: guendel@bgu.ac.il

    2013-05-01

    We consider a model where both dark energy and dark matter originate from the coupling of a scalar field with a non-canonical kinetic term to, both, a metric measure and a non-metric measure. An interacting dark energy/dark matter scenario can be obtained by introducing an additional scalar that can produce non constant vacuum energy and associated variations in dark matter. The phenomenology is most interesting when the kinetic term of the additional scalar field is ghost-type, since in this case the dark energy vanishes in the early universe and then grows with time. This constitutes an ''inverse quintessence scenario'', where the universe starts from a zero vacuum energy density state, instead of approaching it in the future.

  2. Chandra Probes Nature of Dark Matter

    NASA Astrophysics Data System (ADS)

    2001-09-01

    Astronomers have shed new light on dark matter, the invisible and unknown material that comprises most of the universe. Using NASA's Chandra X-ray Observatory, scientists have precisely determined the distribution of dark matter in a distant galaxy cluster. These new measurements serve to narrow the field of candidates that explain this puzzling element. John Arabadjis and Mark Bautz of the Massachusetts Institute of Technology (MIT) in Cambridge, Mass., and Gordon Garmire of Pennsylvania State University (Penn State) in University Park, announced their results today at the "Two Years of Science with Chandra" symposium in Washington. Their observations enabled them to trace the distribution of dark matter in the galaxy cluster EMSS 1358+6245. Previous evidence from radio, optical and X-ray observations convinced astronomers that most of the matter in the universe is in some dark, as yet undetected, form that makes its presence felt only through gravity. "The new Chandra observations are providing new clues about the nature of this mysterious stuff," said Bautz. "When combined with data from the Hubble Space Telescope, we are able to place restrictions on the cross section, or size, of the dark matter particles," said Arabadjis. "The larger the particles, the more strongly they interact, and the more they alter the dark matter distribution." In galaxy clusters, the amount of dark matter can be inferred by measuring the pressure in hot gas that emits X-rays. Astronomers can then determine how much dark matter would be required to provide the gravity necessary to keep the gas from escaping the cluster. In the cluster EMSS 1358+6245, the mass of the dark matter is found to be about four times that of the "normal" matter (matter not comprised of exotic particles), typical of large galaxy clusters. The distribution of dark matter holds the key to understanding its composition. The most popular model for dark matter invokes slowly moving particles called cold dark matter

  3. Theory of dark matter superfluidity

    NASA Astrophysics Data System (ADS)

    Berezhiani, Lasha; Khoury, Justin

    2015-11-01

    We propose a novel theory of dark matter (DM) superfluidity that matches the successes of the Λ cold dark matter (Λ CDM ) model on cosmological scales while simultaneously reproducing the modified Newtonian dynamics (MOND) phenomenology on galactic scales. The DM and MOND components have a common origin, representing different phases of a single underlying substance. DM consists of axionlike particles with mass of order eV and strong self-interactions. The condensate has a polytropic equation of state P ˜ρ3 giving rise to a superfluid core within galaxies. Instead of behaving as individual collisionless particles, the DM superfluid is more aptly described as collective excitations. Superfluid phonons, in particular, are assumed to be governed by a MOND-like effective action and mediate a MONDian acceleration between baryonic matter particles. Our framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not); due to the higher velocity dispersion in clusters, and correspondingly higher temperature, the DM in clusters is either in a mixture of superfluid and the normal phase or fully in the normal phase. The rich and well-studied physics of superfluidity leads to a number of observational signatures: an array of low-density vortices in galaxies; merger dynamics that depend on the infall velocity vs phonon sound speed; distinct mass peaks in bulletlike cluster mergers, corresponding to superfluid and normal components; and interference patters in supercritical mergers. Remarkably, the superfluid phonon effective theory is strikingly similar to that of the unitary Fermi gas, which has attracted much excitement in the cold atom community in recent years. The critical temperature for DM superfluidity is of order mK, comparable to known cold atom Bose-Einstein condensates. Identifying a precise cold atom analog would give important insights on the microphysical interactions underlying DM superfluidity

  4. Dark Matter Burners: Preliminary Estimate

    SciTech Connect

    Moskalenko, Igor V.; Wai, L.; /SLAC

    2006-09-11

    We show that a star orbiting close enough to an adiabatically grown supermassive black hole can capture a large number of weakly interacting massive particles (WIMPs) during its lifetime. WIMP annihilation energy release in low- to medium-mass stars is comparable with or even exceeds the luminosity of such stars due to thermonuclear burning. The excessive energy release in the stellar core may result in an evolution scenario different from what is expected for a regular star. The model thus predicts the existence of unusual stars within the central parsec of galactic nuclei. If found, such stars would provide evidence for the existence of particle dark matter. The excess luminosity of such stars attributed to WIMP ''burning'' can be used to infer the local WIMP matter density. A white dwarf with a highly eccentric orbit around the central black hole may exhibit variations in brightness correlated with the orbital phase. On the other hand, white dwarfs shown to lack such orbital brightness variations can be used to provide constraints on WIMP matter density, WIMP-nucleus scattering and pair annihilation cross sections.

  5. Dark matter near the sun

    NASA Technical Reports Server (NTRS)

    Bahcall, J. N.

    1986-01-01

    The amount of dark matter in the disk of the Galaxy at the solar position is determined by comparing the observed distributions of tracer stars with the predictions obtained from different assumptions of how the unseen matter is distributed. The major uncertainties, observational and theoretical, are estimated. For all the observed samples, typical models imply that about half of the mass in the solar vicinity must be in the form of unobserved matter. The volume density of unobserved material near the sun is about 0.1 solar mass/cu pc; the corresponding column density is about 30 solar masses/cu pc. This, so far unseen, material must be in a disk with an exponential scale height of less than 0.7 kpc. All the existing observations are consistent with the unseen disk material being in the form of stars not massive enough to burn hydrogen. It is suggested that the unseen material that is required to hold up the rotation curves of galaxies and to satisfy the virial theorem for clusters of galaxies might also be in the form of low-mass stars.

  6. Correlation between dark matter and dark radiation in string compactifications

    NASA Astrophysics Data System (ADS)

    Allahverdi, Rouzbeh; Cicoli, Michele; Dutta, Bhaskar; Sinha, Kuver

    2014-10-01

    Reheating in string compactifications is generically driven by the decay of the lightest modulus which produces Standard Model particles, dark matter and light hidden sector degrees of freedom that behave as dark radiation. This common origin allows us to find an interesting correlation between dark matter and dark radiation. By combining present upper bounds on the effective number of neutrino species Neff with lower bounds on the reheating temperature as a function of the dark matter mass mDM from Fermi data, we obtain strong constraints on the (Neff, mDM)-plane. Most of the allowed region in this plane corresponds to non-thermal scenarios with Higgsino-like dark matter. Thermal dark matter can be allowed only if Neff tends to its Standard Model value. We show that the above situation is realised in models with perturbative moduli stabilisation where the production of dark radiation is unavoidable since bulk closed string axions remain light and do not get eaten up by anomalous U(1)s.

  7. Correlation between dark matter and dark radiation in string compactifications

    SciTech Connect

    Allahverdi, Rouzbeh; Cicoli, Michele; Dutta, Bhaskar; Sinha, Kuver E-mail: mcicoli@ictp.it E-mail: kusinha@syr.edu

    2014-10-01

    Reheating in string compactifications is generically driven by the decay of the lightest modulus which produces Standard Model particles, dark matter and light hidden sector degrees of freedom that behave as dark radiation. This common origin allows us to find an interesting correlation between dark matter and dark radiation. By combining present upper bounds on the effective number of neutrino species N{sub eff} with lower bounds on the reheating temperature as a function of the dark matter mass m{sub DM} from Fermi data, we obtain strong constraints on the (N{sub eff}, m{sub DM})-plane. Most of the allowed region in this plane corresponds to non-thermal scenarios with Higgsino-like dark matter. Thermal dark matter can be allowed only if N{sub eff} tends to its Standard Model value. We show that the above situation is realised in models with perturbative moduli stabilisation where the production of dark radiation is unavoidable since bulk closed string axions remain light and do not get eaten up by anomalous U(1)s.

  8. Scalar-field theory of dark matter

    NASA Astrophysics Data System (ADS)

    Huang, Kerson; Xiong, Chi; Zhao, Xiaofei

    2014-05-01

    We develop a theory of dark matter based on a previously proposed picture, in which a complex vacuum scalar field makes the universe a superfluid, with the energy density of the superfluid giving rise to dark energy, and variations from vacuum density giving rise to dark matter. We formulate a nonlinear Klein-Gordon equation to describe the superfluid, treating galaxies as external sources. We study the response of the superfluid to the galaxies, in particular, the emergence of the dark-matter galactic halo, contortions during galaxy collisions and the creation of vortices due to galactic rotation.

  9. Dark-matter admixed neutron stars

    NASA Astrophysics Data System (ADS)

    Leung, S.-C.; Chu, M.-C.; Lin, L.-M.

    2011-11-01

    We study the hydrostatic equilibrium configuration of an admixture of degenerate dark matter and normal nuclear matter by using a general relativistic two-fluid formalism. We consider non-self-annihilating dark matter particles of mass ˜1GeV. The mass-radius relations and moments of inertia of these dark-matter admixed neutron stars are investigated and the stability of these stars is demonstrated by performing a radial perturbation analysis. We find a new class of compact stars which consists of a small normal matter core with radius of a few kilometers embedded in a ten-kilometer-sized dark matter halo. These stellar objects may be observed as extraordinarily small neutron stars that are incompatible with realistic nuclear matter models.

  10. Bbb Z2 SIMP dark matter

    NASA Astrophysics Data System (ADS)

    Bernal, Nicolás; Chu, Xiaoyong

    2016-01-01

    Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N' processes, where N dark matter particles annihilate to N' of them. In the most common scenarios, where dark matter stability is guaranteed by a Bbb Z2 symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model.

  11. Marriage between the baryonic and dark matters

    NASA Astrophysics Data System (ADS)

    Berezhiani, Zurab

    2006-11-01

    The baryonic and dark matter fractions in the universe can be both generated simultaneously and with comparable amounts, if dark matter is constituted by the baryons of the mirror world, a parallel hidden sector with the same microphysics as that of the observable world.

  12. Gamma ray lines from dark matter annihilation

    SciTech Connect

    Giudice, G.F.

    1989-08-01

    If direct annihilation of dark matter particles into a pair of photons occurs in the galactic halo, a narrow {gamma}-ray line can be discovered at future {gamma}-ray detectors sensitive to the GeV region. The signals predicted by different dark matter candidates are analyzed. 16 refs., 3 figs.

  13. Collision of Bose Condensate Dark Matter structures

    SciTech Connect

    Guzman, F. S.

    2008-12-04

    The status of the scalar field or Bose condensate dark matter model is presented. Results about the solitonic behavior in collision of structures is presented as a possible explanation to the recent-possibly-solitonic behavior in the bullet cluster merger. Some estimates about the possibility to simulate the bullet cluster under the Bose Condensate dark matter model are indicated.

  14. The status of neutralino dark matter

    SciTech Connect

    Shakya, Bibhushan

    2014-06-24

    The lightest neutralino in supersymmetry is the most studied dark matter candidate. This writeup reviews the status of neutralino dark matter in minimal and nonminimal supersymmetric models in light of recent null results at the XENON100 experiment and the observation of a 130 GeV gamma ray signal from the Galactic Center by the Fermi LAT.

  15. 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.

  16. Singlet-Doublet Dark Matter

    SciTech Connect

    Cohen, Timothy; Kearney, John; Pierce, Aaron; Tucker-Smith, David; /Williams Coll.

    2012-02-15

    In light of recent data from direct detection experiments and the Large Hadron Collider, we explore models of dark matter in which an SU(2){sub L} doublet is mixed with a Standard Model singlet. We impose a thermal history. If the new particles are fermions, this model is already constrained due to null results from XENON100. We comment on remaining regions of parameter space and assess prospects for future discovery. We do the same for the model where the new particles are scalars, which at present is less constrained. Much of the remaining parameter space for both models will be probed by the next generation of direct detection experiments. For the fermion model, DeepCore may also play an important role.

  17. The Cryogenic Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Sander, Joel

    2004-05-01

    The Cryogenic Dark Matter Search (CDMS) is an experiment to search for Weakly Interacting Massive Particles (WIMPs). The experiment initially was deployed at a shallow underground site, and is currently deployed at a deep underground site at the Soudan Mine in Minnesota. The detectors operate at cryogenic temperature, and are capable of distinguishing nuclear recoils from WIMP interactions from various backgrounds. The detectors are shielded from background by both active and passive elements. We will describe the components of the overall experiment, and focus on the novel data acquisition system that has been develop to control and monitor the experiment via the World Wide Web. Preliminary signals from the operation at Soudan will be discussed.

  18. The PICASSO Dark Matter Experiment

    NASA Astrophysics Data System (ADS)

    Wichoski, Ubi

    2011-12-01

    The PICASSO experiment searches for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs) via their spin-dependent interactions with fluorine at SNOLAB, Sudbury—ON, Canada since 2002. The detection principle is based on the superheated droplet technique; the detectors consist of a gel matrix with millions of liquid droplets of superheated fluorocarbon (C4F10) dispersed in it. Recently, a new setup has been built and installed in the Ladder Lab area at SNOLAB. In the present phase of the experiment the Collaboration is running 4.5-litre detector modules with approximately 85 g of active mass per module. Here, we give an overview of the experiment and discuss the progress in background mitigation, in particular background discrimination in the PICASSO detectors.

  19. Modified gravity and dark matter

    NASA Astrophysics Data System (ADS)

    Cembranos, Jose A. R.

    2016-05-01

    The fundamental nature of Dark Matter (DM) has not been established. Indeed, beyond its gravitational effects, DM remains undetected by present experiments. In this situation, it is reasonable to wonder if other alternatives can effectively explain the observations usually associated with the existence of DM. The modification of the gravitational interaction has been studied in this context from many different approaches. However, the large amount of different astrophysical evidences makes difficult to think that modified gravity can account for all these observations. On the other hand, if such a modification introduces new degrees of freedom, they may work as DM candidates. We will summarize the phenomenology of these gravitational DM candidates by analyzing minimal models.

  20. 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

  1. Lifetime constraints for late dark matter decay

    SciTech Connect

    Bell, Nicole F.; Galea, Ahmad J.; Petraki, Kalliopi

    2010-07-15

    We consider a class of late-decaying dark matter models, in which a dark matter particle decays to a heavy stable daughter of approximately the same mass, together with one or more relativistic particles which carry away only a small fraction of the parent rest mass. Such decays can affect galactic halo structure and evolution, and have been invoked as a remedy to some of the small-scale structure formation problems of cold dark matter. There are existing stringent limits on the dark matter lifetime if the decays produce photons. By considering examples in which the relativistic decay products instead consist of neutrinos or electron-position pairs, we derive stringent limits on these scenarios for a wide range of dark matter masses. We thus eliminate a sizable portion of the parameter space for these late-decay models if the dominant decay channel involves standard model final states.

  2. Dark matter direct-detection experiments

    NASA Astrophysics Data System (ADS)

    Marrodán Undagoitia, Teresa; Rauch, Ludwig

    2016-01-01

    In recent decades, several detector technologies have been developed with the quest to directly detect dark matter interactions and to test one of the most important unsolved questions in modern physics. The sensitivity of these experiments has improved with a tremendous speed due to a constant development of the detectors and analysis methods, proving uniquely suited devices to solve the dark matter puzzle, as all other discovery strategies can only indirectly infer its existence. Despite the overwhelming evidence for dark matter from cosmological indications at small and large scales, clear evidence for a particle explaining these observations remains absent. This review summarises the status of direct dark matter searches, focusing on the detector technologies used to directly detect a dark matter particle producing recoil energies in the keV energy scale. The phenomenological signal expectations, main background sources, statistical treatment of data and calibration strategies are discussed.

  3. 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. PMID:25170698

  4. Dark matter and the habitability of planets

    SciTech Connect

    Hooper, Dan; Steffen, Jason H. E-mail: jsteffen@fnal.gov

    2012-07-01

    In many models, dark matter particles can elastically scatter with nuclei in planets, causing those particles to become gravitationally bound. While the energy expected to be released through the subsequent annihilations of dark matter particles in the interior of the Earth is negligibly small (a few megawatts in the most optimistic models), larger planets that reside in regions with higher densities of slow moving dark matter could plausibly capture and annihilate dark matter at a rate high enough to maintain liquid water on their surfaces, even in the absence of additional energy from starlight or other sources. On these rare planets, it may be dark matter rather than light from a host star that makes it possible for life to emerge, evolve, and survive.

  5. Gravity-mediated (or composite) dark matter

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Min; Park, Myeonghun; Sanz, Verónica

    2014-02-01

    Dark matter could have an electroweak origin, yet it could communicate with the visible sector exclusively through gravitational interactions. In a setup addressing the hierarchy problem, we propose a new dark-matter scenario where gravitational mediators, arising from the compactification of extra dimensions, are responsible for dark-matter interactions and its relic abundance in the Universe. We write an explicit example of this mechanism in warped extra dimensions and work out its constraints. We also develop a dual picture of the model, based on a four-dimensional scenario with partial compositeness. We show that gravity-mediated dark matter is equivalent to a mechanism of generating viable dark matter scenarios in a strongly coupled, near-conformal theory, such as in composite Higgs models.

  6. Neutron stars as dark matter probes

    SciTech Connect

    Lavallaz, Arnaud de; Fairbairn, Malcolm

    2010-06-15

    We examine whether the accretion of dark matter onto neutron stars could ever have any visible external effects. Captured dark matter which subsequently annihilates will heat the neutron stars, although it seems the effect will be too small to heat close neutron stars at an observable rate while those at the galactic center are obscured by dust. Nonannihilating dark matter would accumulate at the center of the neutron star. In a very dense region of dark matter such as that which may be found at the center of the galaxy, a neutron star might accrete enough to cause it to collapse within a period of time less than the age of the Universe. We calculate what value of the stable dark matter-nucleon cross section would cause this to occur for a large range of masses.

  7. Stealth Dark Matter: Dark scalar baryons through the Higgs portal

    DOE PAGESBeta

    Appelquist, T.; 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.; et al

    2015-10-23

    We present a new model of "Stealth Dark Matter": a composite baryonic scalar of an SU(ND) strongly coupled theory with even ND ≥ 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, electroweak precision measurements,more » 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 mB ≳ 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

  8. Stealth Dark Matter: Dark scalar baryons through the Higgs portal

    SciTech Connect

    Appelquist, T.; 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 present a new model of "Stealth Dark Matter": a composite baryonic scalar of an SU(ND) strongly coupled theory with even ND ≥ 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, electroweak 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 mB ≳ 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.

  9. Neutrinos from the terrestrial passage of supersymmetric dark-matter Q-balls

    SciTech Connect

    Kusenko, Alexander; Shoemaker, Ian M.

    2009-07-15

    Supersymmetry implies that stable nontopological solitons, Q-balls, could form in the early universe and could make up all or part of dark matter. We show that the relic Q-balls passing through Earth can produce a detectable neutrino flux. The peculiar zenith angle dependence and a small annual modulation of this flux can be used as signatures of dark-matter Q-balls.

  10. The second coming of cold dark matter?

    SciTech Connect

    Zurek, W.H.; Warren, M.S.; Quinn, P.J.; Salmon, J.K.

    1993-12-31

    In recent years standard cold dark matter (CDM) theory, which enjoyed a large following throughout much of the past decade, has been abandoned by virtually all of its early supporters. The most serious argument against CDM was the incompatibility between the relatively high value of the pairwise radial velocity dispersion between galaxies, {sigma}{sub v}, inferred from numerical simulation with the much lower observational estimates. We reexamine this argument in the light of our new, high-resolution, COBE-normalized simulations and conclude that {sigma}{sub v} is significantly overestimated in simulations which do not have sufficient resolution (i.e., which have masses of galaxies comparable to the mass of N-body particles) and that it is also difficult to reliably estimate {sigma}{sub v} from the observational catalogues used for this purpose. We conclude that inflationary cosmology and CDM are not -- contrary to the presently prevailing prejudice -- incompatible with the observations of small scale peculiar velocities, as characterized, for example, by {sigma}{sub v}.

  11. The second coming of cold dark matter?

    SciTech Connect

    Zurek, W.H.; Bromley, B.C.; Warren, M.S.

    1994-12-31

    While the standard cold dark matter (CDM) model has received numerous marks against it on the basis of a variety of observational data, the prediction of high {Sigma}{Upsilon}, the pairwise-velocity dispersion between galaxies, on small (megaparsec) scales was reported as perhaps one of its greatest failings. Here, we reexamine the case of CDM and {Sigma}{Upsilon}, with high-resolution numerical simulations. The statistic was measured in simulations, in artificial galaxy catalogs, and in the CfA North Forty redshift survey. In our reanalysis of the CfA data, we found that {Sigma}{Upsilon} {approximately} 500 km/s, significantly higher than the original estimates of Davis & Peebles (1983). This new value, along with our estimate of the velocity bias, leads to a virial measure of the cosmological density parameter, {Omega} {approximately} 0.9. which is more than four times the traditionally cited CfA result. Analysis the simulations indicates that while the method of Davis and Peebles works well, the {Sigma}{Upsilon} statistic itself is not generally robust: there is large scatter from catalog to catalog and evidence that the recovered {Sigma}{Upsilon} value depends strongly on a small fraction of galaxies in the central regions of rare, massive clusters. Thus, at present the CDM model cannot be deemed incompatible with observed small-scale peculiar velocities.

  12. Big Bang synthesis of nuclear dark matter

    NASA Astrophysics Data System (ADS)

    Hardy, Edward; Lasenby, Robert; March-Russell, John; West, Stephen M.

    2015-06-01

    We investigate the physics of dark matter models featuring composite bound states carrying a large conserved dark "nucleon" number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. ≳ 108, may be synthesised, with the number distribution taking one of two characteristic forms. If small-nucleon-number fusions are sufficiently fast, the distribution of dark nuclei takes on a logarithmically-peaked, universal form, independent of many details of the initial conditions and small-number interactions. In the case of a substantial bottleneck to nucleosynthesis for small dark nuclei, we find the surprising result that even larger nuclei, with size ≫ 108, are often finally synthesised, again with a simple number distribution. We briefly discuss the constraints arising from the novel dark sector energetics, and the extended set of (often parametrically light) dark sector states that can occur in complete models of nuclear dark matter. The physics of the coherent enhancement of direct detection signals, the nature of the accompanying dark-sector form factors, and the possible modifications to astrophysical processes are discussed in detail in a companion paper.

  13. Twin Higgs WIMP dark matter

    NASA Astrophysics Data System (ADS)

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-01

    Dark matter (DM) without a matter asymmetry is studied in the context of twin Higgs (TH) theories in which the LHC naturalness problem is addressed. These possess a twin sector related to the Standard Model (SM) by a (broken) Z2 symmetry, and interacting with the SM via a specific Higgs portal. We focus on the minimal realization of the TH mechanism, the fraternal twin Higgs, with only a single generation of twin quarks and leptons, and the S U (3 )'×S U (2 )' gauge group. We show that a variety of natural twin-WIMP DM candidates are present (directly linked to the weak scale by naturalness), the simplest and most attractive being the τ' lepton with a mass mτ'>mHiggs/2 , although spin-1 W'± DM and multicomponent DM are also possible (twin baryons are strongly disfavored by tuning). We consider in detail the dynamics of the possibly (meta)stable glueballs in the twin sector, the nature of the twin QCD phase transition, and possible new contributions to the number of relativistic degrees of freedom, Δ Neff . Direct detection signals are below current bounds but accessible in near-future experiments. Indirect detection phenomenology is rich and requires detailed studies of twin hadronization and fragmentation to twin glueballs and quarkonia and their subsequent decay to SM, and possible light twin sector states.

  14. Ratcheting Up The Search for Dark Matter

    SciTech Connect

    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, I 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

  15. Di-photon excess illuminates dark matter

    NASA Astrophysics Data System (ADS)

    Backović, Mihailo; Mariotti, Alberto; Redigolo, Diego

    2016-03-01

    We propose a simplified model of dark matter with a scalar mediator to accommodate the di-photon excess recently observed by the ATLAS and CMS collaborations. Decays of the resonance into dark matter can easily account for a relatively large width of the scalar resonance, while the magnitude of the total width combined with the constraint on dark matter relic density leads to sharp predictions on the parameters of the Dark Sector. Under the assumption of a rather large width, the model predicts a signal consistent with ˜ 300 GeV dark matter particle and ˜ 750 GeV scalar mediator in channels with large missing energy. This prediction is not yet severely bounded by LHC Run I searches and will be accessible at the LHC Run II in the jet plus missing energy channel with more luminosity. Our analysis also considers astro-physical constraints, pointing out that future direct detection experiments will be sensitive to this scenario.

  16. Condensation of galactic cold dark matter

    NASA Astrophysics Data System (ADS)

    Visinelli, Luca

    2016-07-01

    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. Within the model proposed, we predict the mass of the cold dark matter particle to be of the order of Mχ c2 ≈ 10‑24 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.

  17. SOLAR CONSTRAINTS ON ASYMMETRIC DARK MATTER

    SciTech Connect

    Lopes, Ilidio; Silk, Joseph E-mail: silk@astro.ox.ac.uk

    2012-10-01

    The dark matter content of the universe is likely to be a mixture of matter and antimatter, perhaps comparable to the measured asymmetric mixture of baryons and antibaryons. During the early stages of the universe, the dark matter particles are produced in a process similar to baryogenesis, and dark matter freezeout depends on the dark matter asymmetry and the annihilation cross section (s-wave and p-wave annihilation channels) of particles and antiparticles. In these {eta}-parameterized asymmetric dark matter ({eta}ADM) models, the dark matter particles have an annihilation cross section close to the weak interaction cross section, and a value of dark matter asymmetry {eta} close to the baryon asymmetry {eta}{sub B}. Furthermore, we assume that dark matter scattering of baryons, namely, the spin-independent scattering cross section, is of the same order as the range of values suggested by several theoretical particle physics models used to explain the current unexplained events reported in the DAMA/LIBRA, CoGeNT, and CRESST experiments. Here, we constrain {eta}ADM by investigating the impact of such a type of dark matter on the evolution of the Sun, namely, the flux of solar neutrinos and helioseismology. We find that dark matter particles with a mass smaller than 15 GeV, a spin-independent scattering cross section on baryons of the order of a picobarn, and an {eta}-asymmetry with a value in the interval 10{sup -12}-10{sup -10}, would induce a change in solar neutrino fluxes in disagreement with current neutrino flux measurements. This result is also confirmed by helioseismology data. A natural consequence of this model is suppressed annihilation, thereby reducing the tension between indirect and direct dark matter detection experiments, but the model also allows a greatly enhanced annihilation cross section. All the cosmological {eta}ADM scenarios that we discuss have a relic dark matter density {Omega}h {sup 2} and baryon asymmetry {eta}{sub B} in agreement with

  18. Dynamics of dark energy in collapsing halo of dark matter

    NASA Astrophysics Data System (ADS)

    Tsizh, M.; Novosyadlyj, B.

    2015-09-01

    We investigate the non-linear evolution of spherical density and velocity perturbations of dark matter and dark energy in the expanding Universe. For this we have used the conservation and Einstein equations to describe the evolution of gravitationally coupled inhomogeneities of dark matter, dark energy and radiation from the linear stage in the early Universe to the non-linear stage at the current epoch. A simple method of numerical integration of the system of non-linear differential equations for evolution of the central part of halo is proposed. The results are presented for the halo of cluster (k=2 Mpc^{-1}) and supercluster scales (k=0.2 Mpc^{-1}) and show that a quintessential scalar field dark energy with a low value of effective speed of sound c_s<0.1 can have a notable impact on the formation of large-scale structures in the expanding Universe.

  19. Dark matter and dark energy in dwarf galaxy systems

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Teerikorpi, P.

    2014-01-01

    Quantitative estimates of themaximumallowed totalmasses and sizes of the dark-matter halos in groups and associations of dwarf galaxies—special types of metagalactic populations identified in recent astronomical observations with the Hubble Space Telescope—are presented. Dwarf-galaxy systems are formed of isolated dark-matter halos with a small number of dark galaxies embedded in them. Data on the sizes of these systems and the velocity dispersions of the embedded galaxies can be used to determine lower limits on the total dark-halo masses using the virial theorem. Upper limits follow from the conditions that the systems immersed in the cosmic dark-energy background be gravitationally bound. The median maximum masses are close to 1012 M ⊙ for both groups and associations of dwarf galaxies, although the median virial masses for these two types of systems differ by approximately a factor of ten.

  20. Phenomenological studies of dark matter

    NASA Astrophysics Data System (ADS)

    Gomez Ramirez, Miguel Alejandro

    It is common knowledge that eighty percent of the matter in our Universe consists of a mysterious substance called "dark matter'' (DM) which has only been detected through its gravitational interactions. The "Standard Model'' (SM) of particle physics, despite its extremely impressive successes, does not have a good candidate particle to fit the DM requirements. If DM is made up of a particle which interacts weakly and it has a mass on the same scale as other SM particles, it should be detectable. In this work, two different phenomenological studies of DM are performed. The first possibility is a weakly-interacting particle being detected when a high density of particles and enough energy is present. These conditions are met by objects called "active galactic nuclei'' (AGN). AGN are the extremely violent central regions of very large galaxies, and in these regions highly-energetic "jets'' of particles are accelerated. It was thought that the possibility the jet particles interact with the surrounding DM producing photons with very distinctive characteristics. A comparison of predicted values with current data is made and it is shown that the prospects for detecting DM in this way are promising in the near future. In the second approach instead of working with complicated fully developed models, only the minimal content needed to account for DM is added to the SM. The strength of these "simplified'' models is that they encompass the interactions and parameter spaces of well-motivated models such as supersymmetry. A simplified model of fermionic DM candidate which couples exclusively to the right handed top quark via a color-charged scalar is considered (motivated by EW symmetry breaking). It is shown that this model can account for the totality of DM and the chances of detection in the near future are very good.

  1. Light and dark matter in the universe

    SciTech Connect

    2010-01-01

    This simulation follows the growth of density perturbations in both gas and dark matter components in a volume 1 billion light years on a side beginning shortly after the Big Bang and evolved to half the present age of the universe. It calculates the gravitational clumping of intergalactic gas and dark matter modeled using a computational grid of 64 billion cells and 64 billion dark matter particles. The simulation uses a computational grid of 4096^3 cells and took over 4,000,000 CPU hours to complete. Read more: http://www.anl.gov/Media_Center/News/2010/news100104.html

  2. Axion dark matter detection using atomic transitions.

    PubMed

    Sikivie, P

    2014-11-14

    Dark matter axions may cause transitions between atomic states that differ in energy by an amount equal to the axion mass. Such energy differences are conveniently tuned using the Zeeman effect. It is proposed to search for dark matter axions by cooling a kilogram-sized sample to millikelvin temperatures and count axion induced transitions using laser techniques. This appears to be an appropriate approach to axion dark matter detection in the 10^{-4}  eV mass range. PMID:25432034

  3. Unraveling the mystery of Dark Matter

    NASA Astrophysics Data System (ADS)

    Arvanitaki, Asimina

    2016-05-01

    Dark Matter constitutes a significant component of the energy budget of our Universe and we have diagnosed its existence through its gravitational interaction with us. Our theories of Dark Matter though predict that this glue that is responsible for the existence of our Galaxy should also interact with us in non-trivial ways. After I review these ideas, I will discuss how we can learn more about the properties of Dark Matter in a variety of new experiments, ranging from atomic clocks to black holes and gravitational waves.

  4. Constraints on hadronically decaying dark matter

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Tran, David E-mail: alejandro.ibarra@ph.tum.de

    2012-08-01

    We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons. We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order.

  5. Quintessence with quadratic coupling to dark matter

    SciTech Connect

    Boehmer, Christian G.; Chan, Nyein; Caldera-Cabral, Gabriela; Lazkoz, Ruth; Maartens, Roy

    2010-04-15

    We introduce a new form of coupling between dark energy and dark matter that is quadratic in their energy densities. Then we investigate the background dynamics when dark energy is in the form of exponential quintessence. The three types of quadratic coupling all admit late-time accelerating critical points, but these are not scaling solutions. We also show that two types of coupling allow for a suitable matter era at early times and acceleration at late times, while the third type of coupling does not admit a suitable matter era.

  6. Cosmological explosions from cold dark matter perturbations

    NASA Technical Reports Server (NTRS)

    Scherrer, Robert J.

    1992-01-01

    The cosmological-explosion model is examined for a universe dominated by cold dark matter in which explosion seeds are produced from the growth of initial density perturbations of a given form. Fragmentation of the exploding shells is dominated by the dark-matter potential wells rather than the self-gravity of the shells, and particular conditions are required for the explosions to bootstrap up to very large scales. The final distribution of dark matter is strongly correlated with the baryons on small scales, but uncorrelated on large scales.

  7. Decaying hidden dark matter in warped compactification

    SciTech Connect

    Chen, Xingang

    2009-09-01

    The recent PAMELA and ATIC/Fermi/HESS experiments have observed an excess of electrons and positrons, but not anti-protons, in the high energy cosmic rays. To explain this result, we construct a decaying hidden dark matter model in string theory compactification that incorporates the following two ingredients, the hidden dark matter scenario in warped compactification and the phenomenological proposal of hidden light particles that decay to the Standard Model. In this model, on higher dimensional warped branes, various warped Kaluza-Klein particles and the zero-mode of gauge field play roles of the hidden dark matter or mediators to the Standard Model.

  8. Pursuing parameters for critical-density dark matter models

    NASA Astrophysics Data System (ADS)

    Liddle, Andrew R.; Lyth, David H.; Schaefer, R. K.; Shafi, Q.; Viana, Pedro T. P.

    1996-07-01

    We present an extensive comparison of models of structure formation with observations, based on linear and quasi-linear theory. We assume a critical matter density, and study both cold dark matter models and cold plus hot dark matter models. We explore a wide range of parameters, by varying the fraction of hot dark matter , the Hubble parameter h and the spectral index of density perturbations n, and allowing for the possibility of gravitational waves from inflation influencing large-angle microwave background anisotropies. New calculations are made of the transfer functions describing the linear power spectrum, with special emphasis on improving the accuracy on short scales where there are strong constraints. For assessing early object formation, the transfer functions are explicitly evaluated at the appropriate redshift. The observations considered are the four-year COBE observations of microwave background anisotropies, peculiar velocity flows, the galaxy correlation function, and the abundances of galaxy clusters, quasars and damped Lyman alpha systems. Each observation is interpreted in terms of the power spectrum filtered by a top-hat window function. We find that there remains a viable region of parameter space for critical-density models when all the dark matter is cold, though h must be less than 0.5 before any fit is found and n significantly below unity is preferred. Once a hot dark matter component is invoked, a wide parameter space is acceptable, including n 1. The allowed region is characterized by 0.35 and 0.60 n 1.25, at 95 per cent confidence on at least one piece of data. There is no useful lower bound on h, and for curious combinations of the other parameters it is possible to fit the data with h as high as 0.65.

  9. Quasar microlensing and dark matter

    NASA Technical Reports Server (NTRS)

    Rix, Hans-Walter; Hogan, Craig J.

    1988-01-01

    The amplification of quasar brightness due to gravitational lensing by foreground objects is discussed. It is shown that a recently published sample of X-ray-selected quasars behind foreground galaxies shows a statistically significant brightening compared to a control sample. Correlations with galaxy redshift and impact parameter predicted by microlensing are also demonstrated. A technique is described to measure the mean density of the lenses from a small number of identified cases of microlensing. It is shown that, in this sample, amplification bias is important in determining the mean intensity enhancement and must be included in the density estimate. Assuming that at least two of the four intrinsically brightest quasars behind galaxies are indeed microlensed, the present data yield a formal lower limit on the mean density parameter of lenses Omega(l) greater than 0.25 at 95 percent confidence. These data also imply that a considerable quantity of dark matter exists in macroscopic objects outside the visible parts of galaxies but is still highly correlated with them.

  10. Naturalness of MSSM dark matter

    NASA Astrophysics Data System (ADS)

    Cabrera, María Eugenia; Casas, J. Alberto; Delgado, Antonio; Robles, Sandra; de Austri, Roberto Ruiz

    2016-08-01

    There exists a vast literature examining the electroweak (EW) fine-tuning problem in supersymmetric scenarios, but little concerned with the dark matter (DM) one, which should be combined with the former. In this paper, we study this problem in an, as much as possible, exhaustive and rigorous way. We have considered the MSSM framework, assuming that the LSP is the lightest neutralino, χ 1 0 , and exploring the various possibilities for the mass and composition of χ 1 0 , as well as different mechanisms for annihilation of the DM particles in the early Universe (well-tempered neutralinos, funnels and co-annihilation scenarios). We also present a discussion about the statistical meaning of the fine-tuning and how it should be computed for the DM abundance, and combined with the EW fine-tuning. The results are very robust and model-independent and favour some scenarios (like the h-funnel when {M}_{χ_1^0} is not too close to m h /2) with respect to others (such as the pure wino case). These features should be taken into account when one explores "natural SUSY" scenarios and their possible signatures at the LHC and in DM detection experiments.

  11. Superdense cosmological dark matter clumps

    SciTech Connect

    Berezinsky, V.; Dokuchaev, V.; Eroshenko, Yu.; Kachelriess, M.; Solberg, M. Aa.

    2010-05-15

    The formation and evolution of superdense clumps (or subhalos) is studied. Such clumps of dark matter (DM) can be produced by many mechanisms, most notably by spiky features in the spectrum of inflationary perturbations and by cosmological phase transitions. Being produced very early during the radiation-dominated epoch, superdense clumps evolve as isolated objects. They do not belong to hierarchical structures for a long time after production, and therefore they are not destroyed by tidal interactions during the formation of larger structures. For DM particles with masses close to the electroweak mass scale, superdense clumps evolve towards a power-law density profile {rho}(r){proportional_to}r{sup -1.8} with a central core. Superdense clumps cannot be composed of standard neutralinos, since their annihilations would overproduce the diffuse gamma radiation. If the clumps are constituted of superheavy DM particles and develop a sufficiently large central density, the evolution of their central part can lead to a ''gravithermal catastrophe.'' In such a case, the initial density profile turns into an isothermal profile with {rho}{proportional_to}r{sup -2} and a new, much smaller core in the center. Superdense clumps can be observed by gamma radiation from DM annihilations and by gravitational wave detectors, while the production of primordial black holes and cascade nucleosynthesis constrain this scenario.

  12. Photonic dark matter portal revisited

    NASA Astrophysics Data System (ADS)

    Alavi, S. A.; Kazemian, F. S.

    2016-05-01

    In our previous paper, we studied a model of dark matter (DM) in which the hidden sector interacts with standard model particles via a hidden photonic portal (HP). We investigated the effects of this new interaction on the hydrogen atom and obtained an upper bound for the coupling of the model as f ≤ 10-12. In this work, we study the effects of HP on two interesting exotic atoms namely muonium and positronium. We obtain a tighter upper limit on the coupling as f ≤ 10-13. We also calculate the change (shift) in the Aharonov-Bohm phase due to HP and find that the phase shift is negligibly small (for DM particles mass in the GeV range). Recently a 3.5 keV X-ray line signal observed in the spectrum of 73 galaxy clusters, reported by the XXM-Newton X-ray observatory. Since in HP model the DM particles can decay directly into photons, so we finally calculate the value of the coupling constant f using the condition ΔEDM = 3.5 keV.

  13. New Efforts to Identify Dark Matter

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Could the dark matter in our universe be warm instead of cold? Recent observations have placed new constraints on the warm dark matter model.Whats the Deal with Cold/Warm/Hot Dark Matter?An example of cold dark matter: MACHOs, massive objects like black holes that are hiding in the halo of our galaxy. [Alain r]Nobody knows what dark matter is made of, but we have a few theories. The objects or particles that could make up dark matter fall into three broad categories cold, warm, and hot dark matter based on something called their free streaming length, or how far they moved due to random motions in the early universe.Neutrinos are an example of hot dark matter: very light particles with free streaming lengths much longer than the size of a typical galaxy. Cold dark matter could consist of objects like black holes or brown dwarfs, or particles like WIMPs all of which are very heavy and therefore have free streaming lengths much shorter than the size of a galaxy.Warm dark matter is whats in between: middle-mass particles with free streaming lengths roughly the size of a galaxy. There arent any known particles that fit this description, but there are theorized particles such as sterile neutrinos or gravitinos that do.Cumulative mass functions at z = 6 for different values of the warm dark matter particle mass mX. The shaded boxs on the left correspond to the observed number density of faint galaxies within different confidence levels. [Menci et al. 2016]Smoothing Out the UniverseThe widely favored model is lambda-CDM, in which cold dark matter makes up the missing matter in our universe. This model nicely explains much of what we observe, but it still has a few problems. The biggest issue with lambda-CDM is that it predicts that there should be many more small, dwarf galaxies than we observe.While this could just mean that we havent yet managed to see all the existing, faint dwarf galaxies, we should also consider alternative models the warm dark matter model chief

  14. New Efforts to Identify Dark Matter

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Could the dark matter in our universe be warm instead of cold? Recent observations have placed new constraints on the warm dark matter model.Whats the Deal with Cold/Warm/Hot Dark Matter?An example of cold dark matter: MACHOs, massive objects like black holes that are hiding in the halo of our galaxy. [Alain r]Nobody knows what dark matter is made of, but we have a few theories. The objects or particles that could make up dark matter fall into three broad categories cold, warm, and hot dark matter based on something called their free streaming length, or how far they moved due to random motions in the early universe.Neutrinos are an example of hot dark matter: very light particles with free streaming lengths much longer than the size of a typical galaxy. Cold dark matter could consist of objects like black holes or brown dwarfs, or particles like WIMPs all of which are very heavy and therefore have free streaming lengths much shorter than the size of a galaxy.Warm dark matter is whats in between: middle-mass particles with free streaming lengths roughly the size of a galaxy. There arent any known particles that fit this description, but there are theorized particles such as sterile neutrinos or gravitinos that do.Cumulative mass functions at z = 6 for different values of the warm dark matter particle mass mX. The shaded boxs on the left correspond to the observed number density of faint galaxies within different confidence levels. [Menci et al. 2016]Smoothing Out the UniverseThe widely favored model is lambda-CDM, in which cold dark matter makes up the missing matter in our universe. This model nicely explains much of what we observe, but it still has a few problems. The biggest issue with lambda-CDM is that it predicts that there should be many more small, dwarf galaxies than we observe.While this could just mean that we havent yet managed to see all the existing, faint dwarf galaxies, we should also consider alternative models the warm dark matter model chief

  15. Hidden SU (N ) glueball dark matter

    NASA Astrophysics Data System (ADS)

    Soni, Amarjit; Zhang, Yue

    2016-06-01

    We investigate the possibility that the dark matter candidate is from a pure non-Abelian gauge theory of the hidden sector, motivated in large part by its elegance and simplicity. The dark matter is the lightest bound state made of the confined gauge fields, the hidden glueball. We point out that this simple setup is capable of providing rich and novel phenomena in the dark sector, especially in the parameter space of large N . They include self-interacting and warm dark matter scenarios, Bose-Einstein condensation leading to massive dark stars possibly millions of times heavier than our sun giving rise to gravitational lensing effects, and indirect detections through higher dimensional operators as well as interesting collider signatures.

  16. Redshift space clustering of galaxies and cold dark matter model

    NASA Technical Reports Server (NTRS)

    Bahcall, Neta A.; Cen, Renyue; Gramann, Mirt

    1993-01-01

    The distorting effect of peculiar velocities on the power speturm and correlation function of IRAS and optical galaxies is studied. The observed redshift space power spectra and correlation functions of IRAS and optical the galaxies over the entire range of scales are directly compared with the corresponding redshift space distributions using large-scale computer simulations of cold dark matter (CDM) models in order to study the distortion effect of peculiar velocities on the power spectrum and correlation function of the galaxies. It is found that the observed power spectrum of IRAS and optical galaxies is consistent with the spectrum of an Omega = 1 CDM model. The problems that such a model currently faces may be related more to the high value of Omega in the model than to the shape of the spectrum. A low-density CDM model is also investigated and found to be consistent with the data.

  17. Dark-matter QCD-axion searches.

    PubMed

    Rosenberg, Leslie J

    2015-10-01

    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

  18. 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

  19. Detecting Dark Matter annihilation lines with Fermi

    SciTech Connect

    Ylinen, Tomi; Edmonds, Yvonne; Bloom, Elliott D.; Conrad, Jan; /Royal Inst. Tech., Stockholm /Kalmar U. /KIPAC, Menlo Park /SLAC /Stockholm U.

    2009-05-15

    Dark matter constitutes one of the most intriguing but so far unresolved issues in physics today. In many extensions of the Standard Model the existence of a stable Weakly Interacting Massive Particle (WIMP) is predicted. The WIMP is an excellent dark matter particle candidate and one of the most interesting scenarios include an annihilation of two WIMPs into two gamma-rays. If the WIMPs are assumed to be non-relativistic, the resulting photons will both have an energy equal to the mass of the WIMP and manifest themselves as a monochromatic spectral line in the energy spectrum. This type of signal would represent a 'smoking gun' for dark matter, since no other known astrophysical process should be able to produce it. In these proceedings we give an overview of the different approaches to a search for dark matter lines that the Fermi-LAT collaboration is pursuing and the various challenges involved.

  20. Disentangling Dark Matter Dynamics with Directional Detection

    SciTech Connect

    Lisanti, Mariangela; Wacker, Jay G.; /SLAC

    2009-12-16

    Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a non-minimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. While upcoming direct detection experiments will see strong signals from such models, they may not be able to unambiguously determine the presence of the subdominant elastic scattering from the recoil spectra alone. We show that directional detection experiments can separate elastic and inelastic scattering events and discover the underlying dynamics of dark matter models.

  1. Disentangling dark matter dynamics with directional detection

    SciTech Connect

    Lisanti, Mariangela; Wacker, Jay G.

    2010-05-01

    Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a nonminimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. While upcoming direct detection experiments will see strong signals from such models, they may not be able to unambiguously determine the presence of the subdominant elastic scattering from the recoil spectra alone. We show that directional detection experiments can separate elastic and inelastic scattering events and discover the underlying dynamics of dark matter models.

  2. Dark matter particles in the galactic halo

    SciTech Connect

    Bernabei, R. Belli, P.; Montecchia, F.; Nozzoli, F.; Cappella, F.; D'Angelo, A.; Incicchitti, A.; Prosperi, D.; Cerulli, R.; Dai, C. J.; He, H. L.; Kuang, H. H.; Ma, J. M.; Sheng, X. D.; Ye, Z. P.

    2009-12-15

    Arguments on the investigation of the DarkMatter particles in the galactic halo are addressed. Recent results obtained by exploiting the annual modulation signature are summarized and the perspectives are discussed.

  3. Vector dark matter at the LHC

    NASA Astrophysics Data System (ADS)

    Kumar, Jason; Marfatia, Danny; Yaylali, David

    2015-11-01

    We consider monojet searches at the Large Hadron Collider (LHC) for spin-1 dark matter that interacts with quarks through a contact operator. If the dark matter particles are produced with longitudinal polarizations, then the production matrix element is enhanced by factors of the energy. We show that this particularly effective search strategy can test models for which the energy suppression scale of the operator is as large as 105 TeV . As such, these searches can probe a large class of models for which the contact-operator approximation is valid. We find that for contact operators that permit velocity-independent dark matter-nucleon scattering, LHC monojet searches for spin-1 dark matter are competitive with or far surpass direct-detection searches depending on whether the scattering is spin independent or spin dependent, respectively.

  4. Shocking signals of dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Davis, Jonathan H.; Silk, Joseph; BÅ`hm, Céline; Kotera, Kumiko; Norman, Colin

    2016-05-01

    We examine whether charged particles injected by self-annihilating dark matter (DM) into regions undergoing diffuse shock acceleration can be accelerated to high energies. We consider three astrophysical sites where shock acceleration is supposed to occur, namely the Galactic center and galaxy cluster mergers. For the Milky Way, we find that the acceleration of cosmic rays injected by dark matter could lead to a bump in the cosmic ray spectrum provided that the product of the efficiency of the acceleration mechanism and the concentration of DM particles is high enough. Within the Galaxy, we find that the Fermi bubbles are a potentially more efficient accelerator than supernovae remnants. However, both could in principle accelerate electrons and protons injected by dark matter to very high energies. At the extragalactic level, the acceleration of dark matter annihilation products could be responsible for enhanced radio emission from colliding clusters.

  5. Dark matter direct detection with accelerometers

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Kaplan, David E.; Mardon, Jeremy; Rajendran, Surjeet; Terrano, William A.

    2016-04-01

    The mass of the dark matter particle is unknown, and may be as low as ˜1 0-22 eV . The lighter part of this range, below ˜eV , is relatively unexplored both theoretically and experimentally but contains an array of natural dark matter candidates. An example is the relaxion, a light boson predicted by cosmological solutions to the hierarchy problem. One of the few generic signals such light dark matter can produce is a time-oscillating, equivalence-principle-violating force. We propose searches for this using accelerometers, and consider in detail the examples of torsion balances, atom interferometry, and pulsar timing. These approaches have the potential to probe large parts of unexplored parameter space in the next several years. Thus such accelerometers provide radically new avenues for the direct detection of dark matter.

  6. Supernova cooling in a dark matter smog

    SciTech Connect

    Zhang, Yue

    2014-11-27

    A light hidden gauge boson with kinetic mixing with the usual photon is a popular setup in theories of dark matter. The supernova cooling via radiating the hidden boson is known to put an important constraint on the mixing. I consider the possible role dark matter, which under reasonable assumptions naturally exists inside supernova, can play in the cooling picture. Because the interaction between the hidden gauge boson and DM is likely unsuppressed, even a small number of dark matter compared to protons inside the supernova could dramatically shorten the free streaming length of the hidden boson. A picture of a dark matter “smog” inside the supernova, which substantially relaxes the cooling constraint, is discussed in detail.

  7. GRAVITATIONALLY FOCUSED DARK MATTER AROUND COMPACT STARS

    SciTech Connect

    Bromley, Benjamin C.

    2011-12-01

    If dark matter self-annihilates then it may produce an observable signal when its density is high. The details depend on the intrinsic properties of dark matter and how it clusters in space. For example, the density profile of some dark matter candidates may rise steeply enough toward the Galactic Center that self-annihilation may produce detectable {gamma}-ray emission. Here, we discuss the possibility that an annihilation signal arises near a compact object (e.g., neutron star or black hole) even when the density of dark matter in the neighborhood of the object is uniform. Gravitational focusing produces a local enhancement of density with a profile that falls off approximately as the inverse square-root of distance from the compact star. While geometric dilution may overwhelm the annihilation signal from this local enhancement, magnetic fields tied to the compact object can increase the signal's contrast relative to the background.

  8. Scalar dark matter: direct vs. indirect detection

    NASA Astrophysics Data System (ADS)

    Duerr, Michael; Pérez, Pavel Fileviez; Smirnov, Juri

    2016-06-01

    We revisit the simplest model for dark matter. In this context the dark matter candidate is a real scalar field which interacts with the Standard Model particles through the Higgs portal. We discuss the relic density constraints as well as the predictions for direct and indirect detection. The final state radiation processes are investigated in order to understand the visibility of the gamma lines from dark matter annihilation. We find two regions where one could observe the gamma lines at gamma-ray telescopes. We point out that the region where the dark matter mass is between 92 and 300 GeV can be tested in the near future at direct and indirect detection experiments.

  9. Dark matter particles in the galactic halo

    NASA Astrophysics Data System (ADS)

    Bernabei, R.; Belli, P.; Montecchia, F.; Nozzoli, F.; Cappella, F.; D'Angelo, A.; Incicchitti, A.; Prosperi, D.; Cerulli, R.; Dai, C. J.; He, H. L.; Kuang, H. H.; Ma, J. M.; Sheng, X. D.; Ye, Z. P.

    2009-12-01

    Arguments on the investigation of the DarkMatter particles in the galactic halo are addressed. Recent results obtained by exploiting the annual modulation signature are summarized and the perspectives are discussed.

  10. Astrophysical Constraints of Dark Matter Properties

    NASA Astrophysics Data System (ADS)

    Moustakas, Leonidas A.; Abel, Tom; Brooks, Alyson; Buckley, Matthew; Bullock, James; Collins, Michelle; Cyr-Racine, Francis-Yan; Dawson, William; Drlica-Wagner, Alex; Gaskins, Jennifer; Kaplinghat, Manoj; Keeton, Charles R.; Kim, Stacy; Peter, Annika; Read, Justin; Simon, Joshua D.; Somerville, Rachel S.; Tollerud, Erik Jon; Treu, Tommaso; Wechsler, Risa H.

    2016-01-01

    The nature of the dark matter that fills the universe remains a profound puzzle in physics and astrophysics. Modern astronomical observations have the potential to produce constraints or measurements on properties of dark matter that may have real power for insights into its particle nature. The key lies with understanding what those constraints may be in a way that is interpretable for both the astronomical and particle physics communities, and establishing a community consensus of how diverse astronomical paths can use a common language. The AAS Special Session on the "Astrophysical constraints of dark matter properties" focuses on framing these questions with concrete proposals for astronomical dark matter metrics and potentially figures of merit, and through a series of presentations that serve as points of departure for discussion, ultimately to reach a community consensus that will be useful for current and future pursuits on this topic.

  11. Supernova cooling in a dark matter smog

    SciTech Connect

    Zhang, Yue

    2014-11-01

    A light hidden gauge boson with kinetic mixing with the usual photon is a popular setup in theories of dark matter. The supernova cooling via radiating the hidden boson is known to put an important constraint on the mixing. I consider the possible role dark matter, which under reasonable assumptions naturally exists inside supernova, can play in the cooling picture. Because the interaction between the hidden gauge boson and DM is likely unsuppressed, even a small number of dark matter compared to protons inside the supernova could dramatically shorten the free streaming length of the hidden boson. A picture of a dark matter ''smog'' inside the supernova, which substantially relaxes the cooling constraint, is discussed in detail.

  12. Scalar Dark Matter From Theory Space

    SciTech Connect

    Birkedal-Hansen, Andreas; Wacker, Jay G.

    2003-12-26

    The scalar dark matter candidate in a prototypical theory space little Higgs model is investigated. We review all details of the model pertinent to a relic density calculation. We perform a thermal relic density calculation including couplings to the gauge and Higgs sectors of the model. We find two regions of parameter space that give acceptable dark matter abundances. The first region has a dark matter candidate with a mass {Omicron}(100 GeV), the second region has a candidate with a mass greater than {Omicron}(500 GeV). The dark matter candidate in either region is an admixture of an SU(2) triplet and an SU(2) singlet, thereby constituting a possible WIMP (weakly interacting massive particle).

  13. Antimatter signals of singlet scalar dark matter

    SciTech Connect

    Goudelis, A.; Mambrini, Y.; Yaguna, C. E-mail: yann.mambrini@th.u-psud.fr

    2009-12-01

    We consider the singlet scalar model of dark matter and study the expected antiproton and positron signals from dark matter annihilations. The regions of the viable parameter space of the model that are excluded by present data are determined, as well as those regions that will be probed by the forthcoming experiment AMS-02. In all cases, different propagation models are investigated, and the possible enhancement due to dark matter substructures is analyzed. We find that the antiproton signal is more easily detectable than the positron one over the whole parameter space. For a typical propagation model and without any boost factor, AMS-02 will be able to probe –via antiprotons– the singlet model of dark matter up to masses of 600 GeV. Antiprotons constitute, therefore, a promising signal to constraint or detect the singlet scalar model.

  14. Relativistic Dark Matter at the Galactic Center

    SciTech Connect

    Amin, Mustafa A.; Wizansky, Tommer; /SLAC

    2007-11-16

    In a large region of the supersymmetry parameter space, the annihilation cross section for neutralino dark matter is strongly dependent on the relative velocity of the incoming particles. We explore the consequences of this velocity dependence in the context of indirect detection of dark matter from the galactic center. We find that the increase in the annihilation cross section at high velocities leads to a flattening of the halo density profile near the galactic center and an enhancement of the annihilation signal.

  15. The C-4 Dark Matter Experiment

    SciTech Connect

    Bonicalzi, Ricco M.; Collar, J. I.; Colaresi, J.; Fast, James E.; Fields, N.; Fuller, Erin S.; Hai, M.; Hossbach, Todd W.; Kos, Marek S.; Orrell, John L.; Overman, Cory T.; Reid, Douglas J.; VanDevender, Brent A.; Wiseman, Clinton G.; Yocum, K. M.

    2013-02-18

    Abstract We describe the experimental design of C-4, an expansion of the CoGeNT dark matter search to four identical detectors each approximately three times the mass of the p-type point contact (PPC) germanium diode presently taking data at the Soudan Underground Laboratory. Expected reductions of radioactive backgrounds and energy threshold are discussed, including an estimate of the additional sensitivity to low-mass dark matter candidates to be obtained with this search.

  16. Status of the LUX Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Fiorucci, S.; Akerib, D. S.; Bedikian, S.; Bernstein, A.; Bolozdynya, A.; Bradley, A.; Carr, D.; Chapman, J.; Clark, K.; Classen, T.; Curioni, A.; Dahl, E.; Dazeley, S.; de Viveiros, L.; Druszkiewicz, E.; Gaitskell, R.; Hall, C.; Hernandez Faham, C.; Holbrook, B.; Kastens, L.; Kazkaz, K.; Lander, R.; Lesko, K.; Malling, D.; Mannino, R.; McKinsey, D.; Mei, D.; Mock, J.; Nikkel, J.; Phelps, P.; Schroeder, U.; Shutt, T.; Skulski, W.; Sorensen, P.; Spaans, J.; Stiegler, T.; Svoboda, R.; Sweany, M.; Thomson, J.; Toke, J.; Tripathi, M.; Walsh, N.; Webb, R.; White, J.; Wolfs, F.; Woods, M.; Zhang, C.

    2010-02-01

    The Large Underground Xenon (LUX) dark matter search experiment is currently being deployed at the Homestake Laboratory in South Dakota. We will highlight the main elements of design which make the experiment a very strong competitor in the field of direct detection, as well as an easily scalable concept. We will also present its potential reach for supersymmetric dark matter detection, within various timeframes ranging from 1 year to 5 years or more.

  17. A two measure model of dark energy and dark matter

    SciTech Connect

    Guendelman, Eduardo; Singleton, Douglas; Yongram, N. E-mail: dougs@csufresno.edu

    2012-11-01

    In this work we construct a unified model of dark energy and dark matter. This is done with the following three elements: a gravitating scalar field, φ with a non-conventional kinetic term, as in the string theory tachyon; an arbitrary potential, V(φ); two measures — a metric measure ((−g){sup 1/2}) and a non-metric measure (Φ). The model has two interesting features: (i) For potentials which are unstable and would give rise to tachyonic scalar field, this model can stabilize the scalar field. (ii) The form of the dark energy and dark matter that results from this model is fairly insensitive to the exact form of the scalar field potential.

  18. Vector dark matter from inflationary fluctuations

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Mardon, Jeremy; Rajendran, Surjeet

    2016-05-01

    We calculate the production of a massive vector boson by quantum fluctuations during inflation. This gives a novel dark-matter production mechanism quite distinct from misalignment or thermal production. While scalars and tensors are typically produced with a nearly scale-invariant spectrum, surprisingly the vector is produced with a power spectrum peaked at intermediate wavelengths. Thus dangerous, long-wavelength, isocurvature perturbations are suppressed. Further, at long wavelengths the vector inherits the usual adiabatic, nearly scale-invariant perturbations of the inflaton, allowing it to be a good dark-matter candidate. The final abundance can be calculated precisely from the mass and the Hubble scale of inflation, HI. Saturating the dark-matter abundance we find a prediction for the mass m ≈10-5 eV ×(1014 GeV /HI)4 . High-scale inflation, potentially observable in the cosmic microwave background, motivates an exciting mass range for recently proposed direct-detection experiments for hidden photon dark matter. Such experiments may be able to reconstruct the distinctive, peaked power spectrum, verifying that the dark matter was produced by quantum fluctuations during inflation and providing a direct measurement of the scale of inflation. Thus a detection would not only be the discovery of dark matter, it would also provide an unexpected probe of inflation itself.

  19. Wanted! Nuclear Data for Dark Matter Astrophysics

    SciTech Connect

    Gondolo, P.

    2014-06-15

    Astronomical observations from small galaxies to the largest scales in the universe can be consistently explained by the simple idea of dark matter. The nature of dark matter is however still unknown. Empirically it cannot be any of the known particles, and many theories postulate it as a new elementary particle. Searches for dark matter particles are under way: production at high-energy accelerators, direct detection through dark matter-nucleus scattering, indirect detection through cosmic rays, gamma rays, or effects on stars. Particle dark matter searches rely on observing an excess of events above background, and a lot of controversies have arisen over the origin of observed excesses. With the new high-quality cosmic ray measurements from the AMS-02 experiment, the major uncertainty in modeling cosmic ray fluxes is in the nuclear physics cross sections for spallation and fragmentation of cosmic rays off interstellar hydrogen and helium. The understanding of direct detection backgrounds is limited by poor knowledge of cosmic ray activation in detector materials, with order of magnitude differences between simulation codes. A scarcity of data on nucleon spin densities blurs the connection between dark matter theory and experiments. What is needed, ideally, are more and better measurements of spallation cross sections relevant to cosmic rays and cosmogenic activation, and data on the nucleon spin densities in nuclei.

  20. Model-Independent Studies of Dark Matter

    NASA Astrophysics Data System (ADS)

    Chen, Chuan-Ren

    The excess in cosmic-ray positrons and electrons observed by PAMELA, ATIC, PPB-BET and Fermi can be explained by dark matter decay or annihilation. On the other hand, the negative results from CDMS II and XENON direct detections of dark matter put an upper limit on the elastic-scattering cross section between dark matter and nucleon. We adopted model-independent approaches to study dark matter in cosmic-ray electrons, gamma-ray, relic density, direct detection experiments and LHC. We studied the distribution of the cosmic-ray electron flux observed at the Earth and found that it can reflect the initial energy spectrum of electrons generated from dark matter decay or annihilation even after propagation. We also derive constraints on the decay rate of dark matter into various two-body final states using Fermi and HESS gamma-ray data. We found that the μ+μ- or τ+τ- final state is favored in order to simultaneously explain electron excess and meet all gamma-ray constraints. Finally, we examined various tree-level induced operators of dimension six and constrain them using the current experimental data, including the WMAP data of the relic abundance and CDMS II direct detection of the spin-independent scattering. The implication of LHC search is also explored.

  1. Leptophilic dark matter in Galactic Center excess

    NASA Astrophysics Data System (ADS)

    Lu, Bo-Qiang; Zong, Hong-Shi

    2016-04-01

    Herein we explore the possibility of explaining a gamma-ray excess in the Galactic Center with the dark matter scenario. After taking into account the constraints from both the AMS-02 experiment and the gamma-ray observation on dwarf spheroidal satellite galaxies in Fermi-LAT, we find that the τ lepton channel is the only permissive channel for the interpretation of the Galaxy center excess. Tau leptophilic dark matter provides a well-motivated framework in which the dark matter can dominantly couple to τ lepton at tree-level. We describe the interactions with a general effective field theory approach by using higher-dimensional operators, and this approach provides for a model independent analysis. We consider the constraints from the measurement of the DM relic density in the Planck experiment and the AMS-02 cosmic rays experiment, and find that most of the interaction operators except O7 , O9 and O12 have been excluded. Due to the quantum fluctuations, even in such a scenario there are loop induced dark matter-nucleon interactions. We calculate the dark matter-nucleon scattering cross-section at loop-level, and if the limits on the dark matter-nucleon scattering cross-section from direct detection experiments are also taken into account, we find that the operators remaining available for accounting for the Galaxy center excess are O9 and O12.

  2. Identifying dark matter interactions in monojet searches

    DOE PAGESBeta

    Agrawal, Prateek; Rentala, Vikram

    2014-05-22

    We study the discrimination of quark-initiated jets from gluon-initiated jets in monojet searches for dark matter using the technique of averaged jet energy profiles. We demonstrate our results in the context of effective field theories of dark matter interactions with quarks and gluons, but our methods apply more generally to a wide class of models. Different effective theories of dark matter and the standard model backgrounds each have a characteristic quark/gluon fraction for the leading jet. When used in conjunction with the traditional cut-and-count monojet search, the jet energy profile can be used to set stronger bounds on contact interactionsmore » of dark matter. In the event of a discovery of a monojet excess at the 14 TeV LHC, contact interactions between dark matter with quarks or with gluons can be differentiated at the 95% confidence level. For a given rate at the LHC, signal predictions at direct detection experiments for different dark matter interactions can span five orders of magnitude. Lastly, the ability to identify these interactions allows us to make a tighter connection between LHC searches and direct detection experiments.« less

  3. Identifying dark matter interactions in monojet searches

    SciTech Connect

    Agrawal, Prateek; Rentala, Vikram

    2014-05-22

    We study the discrimination of quark-initiated jets from gluon-initiated jets in monojet searches for dark matter using the technique of averaged jet energy profiles. We demonstrate our results in the context of effective field theories of dark matter interactions with quarks and gluons, but our methods apply more generally to a wide class of models. Different effective theories of dark matter and the standard model backgrounds each have a characteristic quark/gluon fraction for the leading jet. When used in conjunction with the traditional cut-and-count monojet search, the jet energy profile can be used to set stronger bounds on contact interactions of dark matter. In the event of a discovery of a monojet excess at the 14 TeV LHC, contact interactions between dark matter with quarks or with gluons can be differentiated at the 95% confidence level. For a given rate at the LHC, signal predictions at direct detection experiments for different dark matter interactions can span five orders of magnitude. Lastly, the ability to identify these interactions allows us to make a tighter connection between LHC searches and direct detection experiments.

  4. Interaction between bosonic dark matter and stars

    NASA Astrophysics Data System (ADS)

    Brito, Richard; Cardoso, Vitor; Macedo, Caio F. B.; Okawa, Hirotada; Palenzuela, Carlos

    2016-02-01

    We provide a detailed analysis of how bosonic dark matter "condensates" interact with compact stars, extending significantly the results of a recent Letter [1]. We focus on bosonic fields with mass mB , such as axions, axion-like candidates and hidden photons. Self-gravitating bosonic fields generically form "breathing" configurations, where both the spacetime geometry and the field oscillate, and can interact and cluster at the center of stars. We construct stellar configurations formed by a perfect fluid and a bosonic condensate, and which may describe the late stages of dark matter accretion onto stars, in dark-matter-rich environments. These composite stars oscillate at a frequency which is a multiple of f =2.5 ×1014(mBc2/eV ) Hz . Using perturbative analysis and numerical relativity techniques, we show that these stars are generically stable, and we provide criteria for instability. Our results also indicate that the growth of the dark matter core is halted close to the Chandrasekhar limit. We thus dispel a myth concerning dark matter accretion by stars: dark matter accretion does not necessarily lead to the destruction of the star, nor to collapse to a black hole. Finally, we argue that stars with long-lived bosonic cores may also develop in other theories with effective mass couplings, such as (massless) scalar-tensor theories.

  5. Dark matter and dark energy from quark bag model

    SciTech Connect

    Brilenkov, Maxim; Eingorn, Maxim; Jenkovszky, Laszlo; Zhuk, Alexander E-mail: maxim.eingorn@gmail.com E-mail: ai.zhuk2@gmail.com

    2013-08-01

    We calculate the present expansion of our Universe endowed with relict colored objects — quarks and gluons — that survived hadronization either as isolated islands of quark-gluon ''nuggets'' or spread uniformly in the Universe. In the first scenario, the QNs can play the role of dark matter. In the second scenario, we demonstrate that uniform colored objects can play the role of dark energy providing the late-time accelerating expansion of the Universe.

  6. Thermodynamics of dark energy interacting with dark matter and radiation

    SciTech Connect

    Jamil, Mubasher; Saridakis, Emmanuel N.; Setare, M. R.

    2010-01-15

    We investigate the validity of the generalized second law of thermodynamics, in the cosmological scenario where dark energy interacts with both dark matter and radiation. Calculating separately the entropy variation for each fluid component and for the apparent horizon itself, we show that the generalized second law is always and generally valid, independently of the specific interaction form, of the fluids equation-of-state parameters and of the background geometry.

  7. The second coming of cold dark matter?

    SciTech Connect

    Zurek, W.H.; Bromley, B.C.; Warren, M.S.

    1995-07-01

    While the standard cold dark matter (CDM) model has received numerous marks against it on the basis of a variety of observational data, the prediction of high {sigma}{sub {ital v}}, the pairwise-velocity dispersion between galaxies, on small (megaparsec) scales was reported as perhaps one of its greatest failings. Here, we reexamine the case of CDM and {sigma}{sub {ital v}} with high-resolution numerical simulations. The {sigma}{sub {ital v}} statistic was measured in simulations, in artificial galaxy catalogs, and the CfA North Forty redshift survey. In our reanalysis of the CfA data, we found that {sigma}{sub {ital v}}{similar_to}500 km/s, significantly higher than the original estimates of Davis & Peebles (1983). This new value, along with our estimate of the velocity bias, leads to a virial measure of the cosmological density parameter, {Omega}{similar_to}0.9, which is more than four times the traditionally cited CfA result. Analysis of the simulations indicates that while the method of Davis and Peebles works well, the {sigma}{sub {ital v}} statistic itself is not generally robust: there is large scatter from catalog to catalog and evidence that the recovered {sigma}{sub {ital v}} value depends strongly on a small fraction of galaxies in the central regions of rare, massive clusters. Thus, at present the CDM model cannot be deemed incompatible with observed small-scale peculiar velocities. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  8. On baryogenesis from dark matter annihilation

    SciTech Connect

    Bernal, Nicolás; Colucci, Stefano; Ubaldi, Lorenzo; Josse-Michaux, François-Xavier; Racker, J. E-mail: colucci@th.physik.uni-bonn.de E-mail: racker@ific.uv.es

    2013-10-01

    We study in detail the conditions to generate the baryon asymmetry of the universe from the annihilation of dark matter. This scenario requires a low energy mechanism for thermal baryogenesis, hence we first discuss some of these mechanisms together with the specific constraints due to the connection with the dark matter sector. Then we show that, contrary to what stated in previous studies, it is possible to generate the cosmological asymmetry without adding a light sterile dark sector, both in models with violation and with conservation of B−L. In addition, one of the models we propose yields some connection to neutrino masses.

  9. Halos of unified dark matter scalar field

    SciTech Connect

    Bertacca, Daniele; Bartolo, Nicola; Matarrese, Sabino E-mail: nicola.bartolo@pd.infn.it

    2008-05-15

    We investigate the static and spherically symmetric solutions of Einstein's equations for a scalar field with a non-canonical kinetic term, assumed to provide both the dark matter and dark energy components of the Universe. In particular, we give a prescription to obtain solutions (dark halos) whose rotation curve v{sub c}(r) is in good agreement with observational data. We show that there exist suitable scalar field Lagrangians that allow us to describe the cosmological background evolution and the static solutions with a single dark fluid.

  10. Cold dark matter as compact composite objects

    NASA Astrophysics Data System (ADS)

    Zhitnitsky, Ariel

    2006-08-01

    Dark matter (DM) being the vital ingredient in the cosmos, still remains a mystery. The standard assumption is that the collisionless cold dark matter (CCDM) particles are represented by some weakly interacting fundamental fields which cannot be associated with any standard quarks or leptons. However, recent analyses of structure on galactic and subgalactic scales have suggested discrepancies and stimulated numerous alternative proposals including, e.g. self-interacting dark matter, self-annihilating dark matter, decaying dark matter, to name just a few. We propose the alternative to the standard assumption about the nature of DM particles (which are typically assumed to be weakly interacting fundamental pointlike particles, yet to be discovered). Our proposal is based on the idea that DM particles are strongly interacting composite macroscopically large objects which made of well-known light quarks (or even antiquarks). The required weakness of the DM particle interactions is guaranteed by a small geometrical factor γ˜(area)/(volume)˜B-1/3≪1 of the composite objects with a large baryon charge B≫1, rather than by a weak coupling constant of a new field. We argue that the interaction between hadronic matter and composite dark objects does not spoil the desired properties of the latter as cold matter. We also argue that such a scenario does not contradict to the current observational data. Rather, it has natural explanations of many observed data, such as ΩDM/ΩB˜1 or 511 KeV line from the bulge of our galaxy. We also suggest that composite dark matter may modify the dynamics of structure formation in the central overdense regions of galaxies. We also present a number of other cosmological/astrophysical observations which indirectly support the novel concept of DM nature.

  11. Dark matter directional detection in non-relativistic effective theories

    SciTech Connect

    Catena, Riccardo

    2015-07-20

    We extend the formalism of dark matter directional detection to arbitrary one-body dark matter-nucleon interactions. The new theoretical framework generalizes the one currently used, which is based on 2 types of dark matter-nucleon interaction only. It includes 14 dark matter-nucleon interaction operators, 8 isotope-dependent nuclear response functions, and the Radon transform of the first 2 moments of the dark matter velocity distribution. We calculate the recoil energy spectra at dark matter directional detectors made of CF{sub 4}, CS{sub 2} and {sup 3}He for the 14 dark matter-nucleon interactions, using nuclear response functions recently obtained through numerical nuclear structure calculations. We highlight the new features of the proposed theoretical framework, and present our results for a spherical dark matter halo and for a stream of dark matter particles. This study lays the foundations for model independent analyses of dark matter directional detection experiments.

  12. Fermionic semi-annihilating dark matter

    NASA Astrophysics Data System (ADS)

    Cai, Yi; Spray, Andrew

    2016-01-01

    Semi-annihilation is a generic feature of dark matter theories with symmetries larger than Z_2 . We investigate two examples with multi-component dark sectors comprised of an SU(2) L singlet or triplet fermion besides a scalar singlet. These are respectively the minimal fermionic semi-annihilating model, and the minimal case for a gauge-charged fermion. We study the relevant dark matter phenomenology, including the interplay of semi-annihilation and the Sommerfeld effect. We demonstrate that semi-annihilation in the singlet model can explain the gamma ray excess from the galactic center. For the triplet model we scan the parameter space, and explore how signals and constraints are modified by semi-annihilation. We find that the entire region where the model comprises all the observed dark matter is accessible to current and planned direct and indirect searches.

  13. How clustering dark energy affects matter perturbations

    NASA Astrophysics Data System (ADS)

    Mehrabi, A.; Basilakos, S.; Pace, F.

    2015-09-01

    The rate of structure formation in the Universe is different in homogeneous and clustered dark energy models. The degree of dark energy clustering depends on the magnitude of its effective sound speed c2_eff and for c2_eff=0 dark energy clusters in a similar fashion to dark matter while for c2_eff=1 it stays (approximately) homogeneous. In this paper we consider two distinct equations of state for the dark energy component, wd = const and w_d=w_0+w_1(z/1+z) with c2_eff as a free parameter and we try to constrain the dark energy effective sound speed using current available data including Type Ia supernovae, baryon acoustic oscillation, cosmic microwave background shift parameter (Planck and WMAP), Hubble parameter, big bang nucleosynthesis and the growth rate of structures fσ8(z). At first we derive the most general form of the equations governing dark matter and dark energy clustering under the assumption that c2_eff=const. Finally, performing an overall likelihood analysis we find that the likelihood function peaks at c2_eff=0; however, the dark energy sound speed is degenerate with respect to the cosmological parameters, namely Ωm and wd.

  14. Radiative neutrino mass, dark matter, and leptogenesis

    SciTech Connect

    Gu Peihong; Sarkar, Utpal

    2008-05-15

    We propose an extension of the standard model, in which neutrinos are Dirac particles and their tiny masses originate from a one-loop radiative diagram. The new fields required by the neutrino mass generation also accommodate the explanation for the matter-antimatter asymmetry and dark matter in the Universe.

  15. Wave Dark Matter and Dwarf Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Parry, Alan R.

    We explore a model of dark matter called wave dark matter (also known as scalar field dark matter and boson stars) which has recently been motivated by a new geometric perspective by Bray. Wave dark matter describes dark matter as a scalar field which satisfies the Einstein-Klein-Gordon equations. These equations rely on a fundamental constant Upsilon (also known as the "mass term'' of the Klein-Gordon equation). Specifically, in this dissertation, we study spherically symmetric wave dark matter and compare these results with observations of dwarf spheroidal galaxies as a first attempt to compare the implications of the theory of wave dark matter with actual observations of dark matter. This includes finding a first estimate of the fundamental constant Upsilon. In the introductory Chapter 1, we present some preliminary background material to define and motivate the study of wave dark matter and describe some of the properties of dwarf spheroidal galaxies. In Chapter 2, we present several different ways of describing a spherically symmetric spacetime and the resulting metrics. We then focus our discussion on an especially useful form of the metric of a spherically symmetric spacetime in polar-areal coordinates and its properties. In particular, we show how the metric component functions chosen are extremely compatible with notions in Newtonian mechanics. We also show the monotonicity of the Hawking mass in these coordinates. Finally, we discuss how these coordinates and the metric can be used to solve the spherically symmetric Einstein-Klein-Gordon equations. In Chapter 3, we explore spherically symmetric solutions to the Einstein-Klein-Gordon equations, the defining equations of wave dark matter, where the scalar field is of the form f(t, r) = eiotF(r) for some constant o ∈ R and complex-valued function F(r). We show that the corresponding metric is static if and only if F( r) = h(r)eia for some constant alpha ∈ R and real-valued function h(r). We describe the

  16. Searching for Dark-Matter Axions

    NASA Astrophysics Data System (ADS)

    Rosenberg, Leslie

    2016-03-01

    The axion is a hypothetical elementary particle arising in the 1970's from an elegant solution to the Strong CP problem in Quantum Chromo Dynamics. Light QCD axions (masses <10-3 eV/c2) would have extraordinarily feeble interactions with normal matter and radiation, and these axions have the properties of an ideal dark-matter candidate. Axions have been searched for since their inception. However, light axions constituting dark matter are so feebly coupled that it is only recently that detection technology has advanced to where such axions might be detected. Several large searches are in the construction and commissioning phase, with new projects in the development phase. There are also concepts for new detector technologies aimed at improving the sensitivity and axion mass-reach. These searches would have the potential to detect even the more pessimistically-coupled dark-matter axions should they contribute a fraction of the local Milky Way dark-matter halo. This talk discusses the dark-matter axion experimental landscape and the prospects for their discovery. Supported by the U.S. Department of Energy, Office of High Energy Physics.

  17. Colloquium: Annual modulation of dark matter

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; Lisanti, Mariangela; Savage, Christopher

    2013-10-01

    Direct detection experiments, which are designed to detect the scattering of dark matter off nuclei in detectors, are a critical component in the search for the Universe’s missing matter. This Colloquium begins with a review of the physics of direct detection of dark matter, discussing the roles of both the particle physics and astrophysics in the expected signals. The count rate in these experiments should experience an annual modulation due to the relative motion of the Earth around the Sun. This modulation, not present for most known background sources, is critical for solidifying the origin of a potential signal as dark matter. The focus is on the physics of annual modulation, discussing the practical formulas needed to interpret a modulating signal. The dependence of the modulation spectrum on the particle and astrophysics models for the dark matter is illustrated. For standard assumptions, the count rate has a cosine dependence with time, with a maximum in June and a minimum in December. Well-motivated generalizations of these models, however, can affect both the phase and amplitude of the modulation. Shown is how a measurement of an annually modulating signal could teach us about the presence of substructure in the galactic halo or about the interactions between dark and baryonic matter. Although primarily a theoretical review, the current experimental situation for annual modulation and future experimental directions is briefly discussed.

  18. Beyond minimal lepton-flavored Dark Matter

    NASA Astrophysics Data System (ADS)

    Chen, Mu-Chun; Huang, Jinrui; Takhistov, Volodymyr

    2016-02-01

    We consider a class of flavored dark matter (DM) theories where dark matter interacts with the Standard Model lepton fields at the renormalizable level. We allow for a general coupling matrix between the dark matter and leptons whose structure is beyond the one permitted by the minimal flavor violation (MFV) assumption. It is assumed that this is the only new source of flavor violation in addition to the Standard Model (SM) Yukawa interactions. The setup can be described by augmenting the SM flavor symmetry by an additional SU(3) χ , under which the dark matter χ transforms. This framework is especially phenomenologically rich, due to possible novel flavor-changing interactions which are not present within the more restrictive MFV framework. As a representative case study of this setting, which we call "beyond MFV" (BMFV), we consider Dirac fermion dark matter which transforms as a singlet under the SM gauge group and a triplet under SU(3) χ . The DM fermion couples to the SM lepton sector through a scalar mediator ϕ. Unlike the case of quark-flavored DM, we show that there is no {{Z}}_3 symmetry within either the MFV or BMFV settings which automatically stabilizes the lepton-flavored DM. We discuss constraints on this setup from flavor-changing processes, DM relic abundance as well as direct and indirect detections. We find that relatively large flavor-changing couplings are possible, while the dark matter mass is still within the phenomenologically interesting region below the TeV scale. Collider signatures which can be potentially searched for at the lepton and hadron colliders are discussed. Finally, we discuss the implications for decaying dark matter, which can appear if an additional stabilizing symmetry is not imposed.

  19. Working Group Report: Dark Matter Complementarity (Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond)

    SciTech Connect

    Arrenberg, Sebastian; et al.,

    2013-10-31

    In this Report we discuss the four complementary searches for the identity of dark matter: direct detection experiments that look for dark matter interacting in the lab, indirect detection experiments that connect lab signals to dark matter in our own and other galaxies, collider experiments that elucidate the particle properties of dark matter, and astrophysical probes sensitive to non-gravitational interactions of dark matter. The complementarity among the different dark matter searches is discussed qualitatively and illustrated quantitatively in several theoretical scenarios. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program based on all four of those approaches.

  20. Sub-horizon evolution of cold dark matter perturbations through dark matter-dark energy equivalence epoch

    SciTech Connect

    Piattella, O.F.; Martins, D.L.A.; Casarini, L. E-mail: denilsonluizm@gmail.com

    2014-10-01

    We consider a cosmological model of the late universe constituted by standard cold dark matter plus a dark energy component with constant equation of state w and constant effective speed of sound. By neglecting fluctuations in the dark energy component, we obtain an equation describing the evolution of sub-horizon cold dark matter perturbations through the epoch of dark matter-dark energy equality. We explore its analytic solutions and calculate an exact w-dependent correction for the dark matter growth function, logarithmic growth function and growth index parameter through the epoch considered. We test our analytic approximation with the numerical solution and find that the discrepancy is less than 1% for 0k = during the cosmic evolution up to a = 100.

  1. Direct detection constraints on superheavy dark matter.

    PubMed

    Albuquerque, Ivone F M; Baudis, Laura

    2003-06-01

    The dark matter in the Universe might be composed of superheavy particles (mass greater, similar 10(10) GeV). These particles can be detected via nuclear recoils produced in elastic scatterings from nuclei. We estimate the observable rate of strongly interacting supermassive particles (simpzillas) in direct dark matter search experiments. The simpzilla energy loss in Earth and in the experimental shields is taken into account. The most natural scenarios for simpzillas are ruled out based on recent EDELWEISS and CDMS results. The dark matter can be composed of superheavy particles only if these interact weakly with normal matter or if their mass is above 10(15) GeV. PMID:12857302

  2. Dark matter and dark energy via nonperturbative (flavor) vacua

    NASA Astrophysics Data System (ADS)

    Tarantino, Walter

    2012-02-01

    A nonperturbative field theoretical approach to flavor physics (Blasone-Vitiello formalism) has been shown to imply a highly nontrivial vacuum state. Although still far from representing a satisfactory framework for a coherent and complete characterization of flavor states, in recent years the formalism has received attention for its possible implications at cosmological scales. In a previous work, we implemented the approach on a simple supersymmetric model (free Wess-Zumino), with flavor mixing, which was regarded as a model for free neutrinos and sneutrinos. The resulting effective vacuum (called flavor vacuum) was found to be characterized by a strong supersymmetry breaking. In this paper we explore the phenomenology of the model and we argue that the flavor vacuum is a consistent source for both dark energy (thanks to the bosonic sector of the model) and dark matter (via the fermionic one). Quite remarkably, besides the parameters connected with neutrino physics, in this model no other parameters have been introduced, possibly leading to a predictive theory of dark energy/matter. Despite its oversimplification, such a toy model already seems capable to shed some light on the observed energy hierarchy between neutrino physics, dark energy and dark matter. Furthermore, we move a step forth in the construction of a more realistic theory, by presenting a novel approach for calculating relevant quantities and hence extending some results to interactive theories, in a completely nonperturbative way.

  3. [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. PMID:16463572

  4. Quark matter and fermionic dark matter compact stars

    NASA Astrophysics Data System (ADS)

    Samanta, Chhanda; Mukhopadhyay, Somenath; Basu, Devasish Narayan

    2016-03-01

    Compact stars, made of quark matter and fermionic dark matter with arbitrary masses and interaction strengths, are studied by solving the Tolman-Oppenheimer-Volkoff equation of general relativity. The mass-radius relation for quark matter compact stars is obtained from the MIT bag model equation of state (EoS) with thin crust for different bag constants. The EoS of non-self-annihilating dark matter for an interacting Fermi gas with dark matter particle of 1-100 GeV mass is studied. For sufficiently strong interactions, the maximum stable mass of compact stars and its radius are controlled by the parameter of the interaction, both increasing linearly with the interaction strength. The mass-radius relation for compact stars made of strongly interacting fermions shows that the radius remains approximately constant for a wide range of compact stars.

  5. Dark Matter and Dark Energy - Fact or Fantasy?

    NASA Astrophysics Data System (ADS)

    Mannheim, Philip

    We show that the origin of the dark matter and dark energy problems originates in the assumption of standard Einstein gravity that Newton's constant is fundamental. We discuss an alternate, conformal invariant, metric theory of gravity in which Newton's constant is induced dynamically, with the global induced one which is effective for cosmology being altogether weaker than the local induced one needed for the solar system. We find that in the theory dark matter is no longer needed, and that the accelerating universe data can be fitted without fine-tuning using a cosmological constant as large as particle physics suggests. In the conformal theory then it is not the cosmological constant which is quenched but rather the amount of gravity that it produces.

  6. Direct Search for Dark Matter with DarkSide

    NASA Astrophysics Data System (ADS)

    Agnes, P.; Alexander, T.; Alton, A.; Arisaka, K.; Back, H. O.; Baldin, B.; Biery, K.; Bonfini, G.; Bossa, M.; Brigatti, A.; Brodsky, J.; Budano, F.; Cadonati, L.; Calaprice, F.; Canci, N.; Candela, A.; Cao, H.; Cariello, M.; Cavalcante, P.; Chavarria, A.; Chepurnov, A.; Cocco, A. G.; Crippa, L.; D'Angelo, D.; D'Incecco, M.; Davini, S.; De Deo, M.; Derbin, A.; Devoto, A.; Di Eusanio, F.; Di Pietro, G.; Edkins, E.; Empl, A.; Fan, A.; Fiorillo, G.; Fomenko, K.; Forster, G.; Franco, D.; Gabriele, F.; Galbiati, C.; Goretti, A.; Grandi, L.; Gromov, M.; Guan, M. Y.; Guardincerri, Y.; Hackett, B.; Herner, K.; Hungerford, E. V.; Ianni, Al; Ianni, An; Jollet, C.; Keeter, K.; Kendziora, C.; Kidner, S.; Kobychev, V.; Koh, G.; Korablev, D.; Korga, G.; Kurlej, A.; Li, P. X.; Loer, B.; Lombardi, P.; Love, C.; Ludhova, L.; Luitz, S.; Ma, Y. Q.; Machulin, I.; Mandarano, A.; Mari, S.; Maricic, J.; Marini, L.; Martoff, C. J.; Meregaglia, A.; Meroni, E.; Meyers, P. D.; Milincic, R.; Montanari, D.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B.; Muratova, V.; Musico, P.; Nelson, A.; Odrowski, S.; Okounkova, M.; Orsini, M.; Ortica, F.; Pagani, L.; Pallavicini, M.; Pantic, E.; Papp, L.; Parmeggiano, S.; Parsells, R.; Pelczar, K.; Pelliccia, N.; Perasso, S.; Pocar, A.; Pordes, S.; Pugachev, D.; Qian, H.; Randle, K.; Ranucci, G.; Razeto, A.; Reinhold, B.; Renshaw, A.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Sablone, D.; Saggese, P.; Saldanha, R.; Sands, W.; Sangiorgio, S.; Segreto, E.; Semenov, D.; Shields, E.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Stanford, C.; Suvorov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Tonazzo, A.; Unzhakov, E.; Vogelaar, R. B.; Wada, M.; Walker, S.; Wang, H.; Wang, Y.; Watson, A.; Westerdale, S.; Wojcik, M.; Wright, A.; Xiang, X.; Xu, J.; Yang, C. G.; Yoo, J.; Zavatarelli, S.; Zec, A.; Zhu, C.; Zuzel, G.

    2015-11-01

    The DarkSide experiment is designed for the direct detection of Dark Matter with a double phase liquid Argon TPC operating underground at Laboratori Nazionali del Gran Sasso. The TPC is placed inside a 30 tons liquid organic scintillator sphere, acting as a neutron veto, which is in turn installed inside a 1 kt water Cherenkov detector. The current detector is running since November 2013 with a 50 kg atmospheric Argon fill and we report here the first null results of a Dark Matter search for a (1422 ± 67) kg.d exposure. This result correspond to a 90% CL upper limit on the WIMP-nucleon cross section of 6.1 × 10-44 cm2 (for a WIMP mass of 100 GeV/c2) and it's currently the most sensitive limit obtained with an Argon target.

  7. Direct search for dark matter with DarkSide

    SciTech Connect

    Agnes, P.

    2015-11-16

    Here, the DarkSide experiment is designed for the direct detection of Dark Matter with a double phase liquid Argon TPC operating underground at Laboratori Nazionali del Gran Sasso. The TPC is placed inside a 30 tons liquid organic scintillator sphere, acting as a neutron veto, which is in turn installed inside a 1 kt water Cherenkov detector. The current detector is running since November 2013 with a 50 kg atmospheric Argon fill and we report here the first null results of a Dark Matter search for a (1422 ± 67) kg.d exposure. This result correspond to a 90% CL upper limit on the WIMP-nucleon cross section of 6.1 × 10-44 cm2 (for a WIMP mass of 100 GeV/c2) and it's currently the most sensitive limit obtained with an Argon target.

  8. Direct search for dark matter with DarkSide

    DOE PAGESBeta

    Agnes, P.

    2015-11-16

    Here, the DarkSide experiment is designed for the direct detection of Dark Matter with a double phase liquid Argon TPC operating underground at Laboratori Nazionali del Gran Sasso. The TPC is placed inside a 30 tons liquid organic scintillator sphere, acting as a neutron veto, which is in turn installed inside a 1 kt water Cherenkov detector. The current detector is running since November 2013 with a 50 kg atmospheric Argon fill and we report here the first null results of a Dark Matter search for a (1422 ± 67) kg.d exposure. This result correspond to a 90% CL uppermore » limit on the WIMP-nucleon cross section of 6.1 × 10-44 cm2 (for a WIMP mass of 100 GeV/c2) and it's currently the most sensitive limit obtained with an Argon target.« less

  9. The vacuum's dark particles behave like dark matter and dark energy

    NASA Astrophysics Data System (ADS)

    Haller, John

    2015-04-01

    Building on the governing hypothesis that self-information is equal to action, I solve for the time step of the vacuum. The resulting equations (both quantum diffusion and Friedmann's equations) argue that a dark particle, or special black hole, exists at hbar or twice the reduced Planck mass where the Hawking temperature breaks down. It is hypothesized that if neutral hydrogen is nearby the dark particles are able to couple with the background field and thus have a density that looks like dark matter. If hydrogen is not around, the dark particles become frozen leading to a constant density of black body radiation similar to dark energy. If the Universe's dark particles (away from neutral hydrogen) became frozen during the re-ionization of the Universe's history, its BBR density is well within confidence ranges for the cosmological constant. This hypothesis can also explain the recent observations that dark matter decays into dark energy.

  10. Nonthermal dark matter models and signals

    NASA Astrophysics Data System (ADS)

    Okada, Hiroshi; Orikasa, Yuta; Toma, Takashi

    2016-03-01

    Many experiments exploring weakly interacting massive particles (WIMPs) such as direct, indirect and collider searches have been carried out until now. However, a clear signal of a WIMP has not been found yet and it makes us to suspect that WIMPs are questionable as a dark matter candidate. Taking into account this situation, we propose two models in which dark matter relic density is produced by decay of a metastable particle. In the first model, the metastable particle is a feebly interacting massive particle, which is the so-called FIMP, produced by freeze-in mechanism in the early universe. In the second model, the decaying particle is thermally produced the same as the usual WIMP. However decay of the particle into dark matter is led by a higher dimensional operator. As a phenomenologically interesting feature of nonthermal dark matter discussed in this paper, a strong sharp gamma-ray emission as an indirect detection signal occurs due to internal bremsstrahlung, although some parameter space has already been ruled out by this process. Moreover combining other experimental and theoretical constraints such as dark matter relic density, big bang nucleosynthesis, collider, gamma-rays and perturbativity of couplings, we discuss the two nonthermal DM models.

  11. Dimensionless constants, cosmology, and other dark matters

    SciTech Connect

    Tegmark, Max; Aguirre, Anthony; Rees, Martin J.; Wilczek, Frank

    2006-01-15

    We identify 31 dimensionless physical constants required by particle physics and cosmology, and emphasize that both microphysical constraints and selection effects might help elucidate their origin. Axion cosmology provides an instructive example, in which these two kinds of arguments must both be taken into account, and work well together. If a Peccei-Quinn phase transition occurred before or during inflation, then the axion dark matter density will vary from place to place with a probability distribution. By calculating the net dark matter halo formation rate as a function of all four relevant cosmological parameters and assessing other constraints, we find that this probability distribution, computed at stable solar systems, is arguably peaked near the observed dark matter density. If cosmologically relevant weakly interacting massive particle (WIMP) dark matter is discovered, then one naturally expects comparable densities of WIMPs and axions, making it important to follow up with precision measurements to determine whether WIMPs account for all of the dark matter or merely part of it.

  12. Neutrinos from Inert Doublet dark matter

    SciTech Connect

    Andreas, Sarah; Tytgat, Michel H.G.; Swillens, Quentin E-mail: mtytgat@ulb.ac.be

    2009-04-15

    We investigate the signatures of neutrinos produced in the annihilation of WIMP dark matter in the Earth, the Sun and at the Galactic centre within the framework of the Inert Doublet Model and extensions. We consider a dark matter candidate, that we take to be one of the neutral components of an extra Higgs doublet, in three distinct mass ranges, which have all been shown previously to be consistent with both WMAP abundance and direct detection experiments exclusion limits. Specifically, we consider a light WIMP with mass between 4 and 8 GeV (low), a WIMP with mass around 60-70 GeV (middle) and a heavy WIMP with mass above 500 GeV (high). In the first case, we show that capture in the Sun may be constrained using Super-Kamiokande data. In the last two cases, we argue that indirect detection through neutrinos is challenging but not altogether excluded. For middle masses, we try to make the most benefit of the proximity of the so-called 'iron resonance' that might enhance the capture of the dark matter candidate by the Earth. The signal from the Earth is further enhanced if light right-handed Majorana neutrinos are introduced, in which case the scalar dark matter candidate may annihilate into pairs of mono-energetic neutrinos. In the case of high masses, detection of neutrinos from the Galactic centre might be possible, provided the dark matter abundance is substantially boosted.

  13. Missing dark matter in dwarf galaxies?

    NASA Astrophysics Data System (ADS)

    Oman, Kyle A.; Navarro, Julio F.; Sales, Laura V.; Fattahi, Azadeh; Frenk, Carlos S.; Sawala, Till; Schaller, Matthieu; White, Simon D. M.

    2016-08-01

    We use cosmological hydrodynamical simulations of the APOSTLE project to examine the fraction of baryons in $\\Lambda$CDM haloes that collect into galaxies. This `galaxy formation efficiency' correlates strongly and with little scatter with halo mass, dropping steadily towards dwarf galaxies. The baryonic mass of a galaxy may thus be used to place a lower limit on total halo mass and, consequently, on its asymptotic maximum circular velocity. A number of dwarfs seem to violate this constraint, having baryonic masses up to ten times higher than expected from their rotation speeds, or, alternatively, rotating at only half the speed expected for their mass. Taking the data at face value, either these systems have formed galaxies with extraordinary efficiency - highly unlikely given their shallow potential wells - or they inhabit haloes with extreme deficits in their dark matter content. This `missing dark matter' is reminiscent of the inner mass deficits of galaxies with slowly-rising rotation curves, but extends to regions larger than the luminous galaxies themselves, disfavouring explanations based on star formation-induced `cores' in the dark matter. An alternative could be that galaxy inclination errors have been underestimated, and that these are just systems where inferred mass profiles have been compromised by systematic uncertainties in interpreting the velocity field. This should be investigated further, since it might provide a simple explanation not only for missing-dark-matter galaxies but also for other challenges to our understanding of the inner structure of cold dark matter haloes.

  14. Can dark matter be a scalar field?

    NASA Astrophysics Data System (ADS)

    Jesus, J. F.; Pereira, S. H.; Malatrasi, J. L. G.; Andrade-Oliveira, F.

    2016-08-01

    In this paper we study a real scalar field as a possible candidate to explain the dark matter in the universe. In the context of a free scalar field with quadratic potential, we have used Union 2.1 SN Ia observational data jointly with a Planck prior over the dark matter density parameter to set a lower limit on the dark matter mass as m>=0.12H0‑1 eV (c=hbar=1). For the recent value of the Hubble constant indicated by the Hubble Space Telescope, namely H0=73±1.8 km s‑1Mpc‑1, this leads to m>=1.56×10‑33 eV at 99.7% c.l. Such value is much smaller than m~ 10‑22 eV previously estimated for some models. Nevertheless, it is still in agreement with them once we have not found evidences for a upper limit on the scalar field dark matter mass from SN Ia analysis. In practice, it confirms free real scalar field as a viable candidate for dark matter in agreement with previous studies in the context of density perturbations, which include scalar field self interaction.

  15. Dynamical dark matter: A new framework for dark-matter physics

    NASA Astrophysics Data System (ADS)

    Dienes, Keith R.; Thomas, Brooks

    2013-05-01

    Although much remains unknown about the dark matter of the universe, one property is normally considered sacrosanct: dark matter must be stable well beyond cosmological time scales. However, a new framework for dark-matter physics has recently been proposed which challenges this assumption. In the "dynamical dark matter" (DDM) framework, the dark sector consists of a vast ensemble of individual dark-matter components with differing masses, lifetimes, and cosmological abundances. Moreover, the usual requirement of stability is replaced by a delicate balancing between lifetimes and cosmological abundances across the ensemble as a whole. As a result, it is possible for the DDM ensemble to remain consistent with all experimental and observational bounds on dark matter while nevertheless giving rise to collective behaviors which transcend those normally associated with traditional dark-matter candidates. These include a new, non-trivial darkmatter equation of state as well as potentially distinctive signatures in collider and direct-detection experiments. In this review article, we provide a self-contained introduction to the DDM framework and summarize some of the work which has recently been done in this area. We also present an explicit model within the DDM framework, and outline a number of ideas for future investigation.

  16. 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

  17. Antimatter signatures of gravitino dark matter decay

    SciTech Connect

    Ibarra, Alejandro; Tran, David E-mail: david.tran@desy.de

    2008-07-15

    The scenario of gravitino dark matter with broken R-parity naturally reconciles three paradigms that, albeit very well motivated separately, seem to be in mutual conflict: supersymmetric dark matter, thermal leptogenesis and standard big bang nucleosynthesis. Interestingly, the products of the gravitino decay could be observed, opening the possibility of indirect detection of gravitino dark matter. In this paper, we compute the positron and the antiproton fluxes from gravitino decay. We find that a gravitino with a mass of m{sub 3/2}{approx}150 GeV and a lifetime of {tau}{sub 3/2}{approx}10{sup 26} s could simultaneously explain the EGRET anomaly in the extragalactic diffuse gamma ray background and the HEAT excess in the positron fraction. However, the predicted antiproton flux tends to be too large, although the prediction suffers from large uncertainties and might be compatible with present observations for certain choices of propagation parameters.

  18. Cold Positrons from Decaying Dark Matter

    SciTech Connect

    Boubekeur, Lotfi; Dodelson, Scott; Vives, Oscar

    2012-11-01

    Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often heavier particles decay into the lightest dark matter particle as the Universe evolves. Here we explore the possibilities that arise if one of the products in a (Heavy Particle) $\\rightarrow$ (Dark Matter) decay is a positron, and the lifetime is shorter than the age of the Universe. The positrons cool down by scattering off the cosmic microwave background and eventually annihilate when they fall into Galactic potential wells. The resulting 511 keV flux not only places constraints on this class of models but might even be consistent with that observed by the INTEGRAL satellite.

  19. Dark matter search project PICO-LON

    NASA Astrophysics Data System (ADS)

    Fushimi, K.; Ejiri, H.; Hazama, R.; Ikeda, H.; Imagawa, K.; Inoue, K.; Kanzaki, G.; Kozlov, A.; Orito, R.; Shima, T.; Takemoto, Y.; Teraoka, Y.; Umehara, S.; Yasuda, K.; Yoshida, S.; PICO-LON Collaboration

    2016-05-01

    The PICO-LON project aims at search for cold dark matter by means of highly radio-pure and large volume NaI(Tl) scintillator. The NaI powder was purified by chemical processing to remove lead isotopes and selecting a high purity graphite crucible. The concentrations of radioactive impurities of 226Ra and 228Th were effectively reduced to 58 ± 4 µBq/kg and 1.5 ± 1.9 µBq/kg, respectively. It should be remarked that the concentration of 210Pb, which is crucial for the sensitivity to dark matter, was reduced to 24 ± 2 µBq/kg. The total background rate at 10 keVee was as low as 8 keV‑1kg‑1day‑1, which was sufficiently low to search for dark matter. Further purification of NaI(Tl) ingot and future prospect of PICO-LON project is discussed.

  20. Antiproton limits on decaying gravitino dark matter

    SciTech Connect

    Delahaye, Timur; Grefe, Michael E-mail: michael.grefe@uam.es

    2013-12-01

    We derive 95 % CL lower limits on the lifetime of decaying dark matter in the channels Zν, Wℓ and hν using measurements of the cosmic-ray antiproton flux by the PAMELA experiment. Performing a scan over the allowed range of cosmic-ray propagation parameters we find lifetime limits in the range of 8 × 10{sup 28} s to 5 × 10{sup 25} s for dark matter masses from roughly 100 GeV to 10 TeV. We apply these limits to the well-motivated case of gravitino dark matter in scenarios with bilinear violation of R-parity and find a similar range of lifetime limits for the same range of gravitino masses. Converting the lifetime limits to constraints on the size of the R-parity violating coupling we find upper limits in the range of 10{sup −8} to 8 × 10{sup −13}.

  1. Constraining condensate dark matter in galaxy clusters

    NASA Astrophysics Data System (ADS)

    de Souza, J. C. C.; Ujevic, M.

    2015-09-01

    We constrain scattering length parameters in a Bose-Einstein condensate dark matter model by using galaxy clusters radii, with the implementation of a method previously applied to galaxies. At the present work, we use a sample of 114 clusters radii in order to obtain the scattering lengths associated with a dark matter particle mass in the range - eV. We obtain scattering lengths that are five orders of magnitude larger than the ones found in the galactic case, even when taking into account the cosmological expansion in the cluster scale by means of the introduction of a small cosmological constant. We also construct and compare curves for the orbital velocity of a test particle in the vicinity of a dark matter cluster in both the expanding and the non-expanding cases.

  2. Chromo-Rayleigh interactions of dark matter

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Osborne, James

    2015-11-01

    For a wide range of models, dark matter can interact with QCD gluons via chromo-Rayleigh interactions. We point out that the Large Hadron Collider (LHC), as a gluon machine, provides a superb probe of such interactions. In this paper, we introduce simplified models to UV-complete two effective dark matter chromo-Rayleigh interactions and identify the corresponding collider signatures, including four jets or a pair of di-jet resonances plus missing transverse energy. After performing collider studies for both the 8 TeV and 14 TeV LHC, we find that the LHC can be more sensitive to dark matter chromo-Rayleigh interactions than direct detection experiments and thus provides the best opportunity for future discovery of this class of models.

  3. Solitonic axion condensates modeling dark matter halos

    SciTech Connect

    Castañeda Valle, David Mielke, Eckehard W.

    2013-09-15

    Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose–Einstein type condensates could provide a viable soliton type interpretation of the DM ‘bullets’ observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein–Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two ‘lump’ type solitons. -- Highlights: •An axion model of dark matter is considered. •Collision of axion type solitons are studied in a two dimensional toy model. •Relations to dark matter collisions in galaxy clusters are proposed.

  4. Accretion of dark matter by stars.

    PubMed

    Brito, Richard; Cardoso, Vitor; Okawa, Hirotada

    2015-09-11

    Searches for dark matter imprints are one of the most active areas of current research. We focus here on light fields with mass m_{B}, such as axions and axionlike candidates. Using perturbative techniques and full-blown nonlinear numerical relativity methods, we show the following. (i) Dark matter can pile up in the center of stars, leading to configurations and geometries oscillating with a frequency that is a multiple of f=2.5×10^{14}(m_{B}c^{2}/eV)  Hz. These configurations are stable throughout most of the parameter space, and arise out of credible mechanisms for dark-matter capture. Stars with bosonic cores may also develop in other theories with effective mass couplings, such as (massless) scalar-tensor theories. We also show that (ii) collapse of the host star to a black hole is avoided by efficient gravitational cooling mechanisms. PMID:26406817

  5. Seeded hot dark matter models with inflation

    NASA Technical Reports Server (NTRS)

    Gratsias, John; Scherrer, Robert J.; Steigman, Gary; Villumsen, Jens V.

    1993-01-01

    We examine massive neutrino (hot dark matter) models for large-scale structure in which the density perturbations are produced by randomly distributed relic seeds and by inflation. Power spectra, streaming velocities, and the Sachs-Wolfe quadrupole fluctuation are derived for this model. We find that the pure seeded hot dark matter model without inflation produces Sachs-Wolfe fluctuations far smaller than those seen by COBE. With the addition of inflationary perturbations, fluctuations consistent with COBE can be produced. The COBE results set the normalization of the inflationary component, which determines the large-scale (about 50/h Mpc) streaming velocities. The normalization of the seed power spectrum is a free parameter, which can be adjusted to obtain the desired fluctuations on small scales. The power spectra produced are very similar to those seen in mixed hot and cold dark matter models.

  6. Sources and distributions of dark matter

    SciTech Connect

    Sikivie, P. |

    1995-12-31

    In the first section, the author tries to convey a sense of the variety of observational inputs that tell about the existence and the spatial distribution of dark matter in the universe. In the second section, he briefly reviews the four main dark matter candidates, taking note of each candidate`s status in the world of particle physics, its production in the early universe, its effect upon large scale structure formation and the means by which it may be detected. Section 3 concerns the energy spectrum of (cold) dark matter particles on earth as may be observed some day in a direct detection experiment. It is a brief account of work done in collaboration with J. Ipser and, more recently, with I. Tkachev and Y. Wang.

  7. Rotating drops of axion dark matter

    NASA Astrophysics Data System (ADS)

    Davidson, Sacha; Schwetz, Thomas

    2016-06-01

    We consider how QCD axions produced by the misalignment mechanism could form galactic dark matter halos. We recall that stationary, gravitationally stable axion field configurations have the size of an asteroid with masses of order 10-13M⊙ (because gradient pressure is insufficient to support a larger object). We call such field configurations "drops." We explore whether rotating drops could be larger, and find that their mass could increase by a factor ˜10 . This mass is comparable to the mass of miniclusters generated from misalignment axions in the scenario where the axion is born after inflation. We speculate that misalignment axions today are in the form of drops, contributing to dark matter like a distribution of asteroids (and not as a coherent oscillating background field). We consider some observational signatures of the drops, which seem consistent with a galactic halo made of axion dark matter.

  8. Probing the Dark Sector with Dark Matter Bound States

    NASA Astrophysics Data System (ADS)

    An, Haipeng; Echenard, Bertrand; Pospelov, Maxim; Zhang, Yue

    2016-04-01

    A model of the dark sector where O (few GeV ) mass dark matter particles χ couple to a lighter dark force mediator V , mV≪mχ, is motivated by the recently discovered mismatch between simulated and observed shapes of galactic halos. Such models, in general, provide a challenge for direct detection efforts and collider searches. We show that for a large range of coupling constants and masses, the production and decay of the bound states of χ , such as 0-+ and 1-- states, ηD and ϒD, is an important search channel. We show that e+e-→ηD+V or ϒD+γ production at B factories for αD>0.1 is sufficiently strong to result in multiple pairs of charged leptons and pions via ηD→2 V →2 (l+l-) and ϒD→3 V →3 (l+l-) (l =e ,μ ,π ). The absence of such final states in the existing searches performed at BABAR and Belle sets new constraints on the parameter space of the model. We also show that a search for multiple bremsstrahlung of dark force mediators, e+e-→χ χ ¯+n V , resulting in missing energy and multiple leptons, will further improve the sensitivity to self-interacting dark matter.

  9. Probing the Dark Sector with Dark Matter Bound States.

    PubMed

    An, Haipeng; Echenard, Bertrand; Pospelov, Maxim; Zhang, Yue

    2016-04-15

    A model of the dark sector where O(few  GeV) mass dark matter particles χ couple to a lighter dark force mediator V, m_{V}≪m_{χ}, is motivated by the recently discovered mismatch between simulated and observed shapes of galactic halos. Such models, in general, provide a challenge for direct detection efforts and collider searches. We show that for a large range of coupling constants and masses, the production and decay of the bound states of χ, such as 0^{-+} and 1^{--} states, η_{D} and ϒ_{D}, is an important search channel. We show that e^{+}e^{-}→η_{D}+V or ϒ_{D}+γ production at B factories for α_{D}>0.1 is sufficiently strong to result in multiple pairs of charged leptons and pions via η_{D}→2V→2(l^{+}l^{-}) and ϒ_{D}→3V→3(l^{+}l^{-}) (l=e,μ,π). The absence of such final states in the existing searches performed at BABAR and Belle sets new constraints on the parameter space of the model. We also show that a search for multiple bremsstrahlung of dark force mediators, e^{+}e^{-}→χχ[over ¯]+nV, resulting in missing energy and multiple leptons, will further improve the sensitivity to self-interacting dark matter. PMID:27127956

  10. Description of dark energy and dark matter by vector fields

    NASA Astrophysics Data System (ADS)

    Meierovich, Boris E.

    A simple Lagrangian (with squared covariant divergence of a vector field as a kinetic term) turned out an adequate tool for oscopic description of dark sector. The zero-mass field acts as the dark energy. Its energy-momentum tensor is a simple additive to the cosmological constant. Space-like and time-like massive vector fields describe two different forms of dark matter. The space-like field is attractive. It is responsible for the observed plateau in galaxy rotation curves. The time-like massive field displays repulsive elasticity. In balance with dark energy and ordinary matter it provides a four-parametric diversity of regular solutions of the Einstein equations describing different possible cosmological and oscillating non-singular scenarios of evolution of the Universe. In particular, the singular "big bang" turns into a regular inflation-like transition from contraction to expansion with accelerated expansion at late times. The fine-tuned Friedman-Robertson-Walker singular solution is a particular limiting case at the boundary of existence of regular oscillating solutions (in the absence of vector fields). The simplicity of the general covariant expression for the energy-momentum tensor allows analyzing the main properties of the dark sector analytically, avoiding unnecessary model assumptions.

  11. Dark and visible matter in spiral galaxies

    NASA Technical Reports Server (NTRS)

    Persic, M.; Salucci, P.

    1988-01-01

    Rotation-curve profiles are used to determine the dark-to-luminous mass ratio within the disk size for 43 spiral galaxies. It is noted that faint galaxies are halo-dominated and that bright galaxies are disk-dominated in the disk regions. The luminosity sequence is shown to be a dark-to-luminous sequence. By removing the dark-matter contribution from the velocity at the disk edge, the dispersion affecting the luminosity-kinematics relation is found to decrease in comparison with the conventional Tully-Fisher correlation.

  12. 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.

  13. Directional dark matter searches with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Capparelli, L. M.; Cavoto, G.; Mazzilli, D.; Polosa, A. D.

    2015-09-01

    A new solution to the problem of dark matter directional detection might come from the use of large arrays of aligned carbon nanotubes. We calculate the expected rate of carbon ions channeled in single-wall nanotubes once extracted by the scattering with a massive dark matter particle. Depending on its initial kinematic conditions, the ejected carbon ion may be channeled in the nanotube array or stop in the bulk. The orientation of the array with respect to the direction of motion of the Sun has an appreciable effect on the channeling probability. This provides the required anisotropic response for a directional detector.

  14. Supersymmetry, dark matter and new particles

    SciTech Connect

    Fayet, Pierre

    2010-06-23

    Supersymmetric theories introduce superpartners with an odd R-parity which makes the lightest neutralino stable, leading to a missing energy signature and a natural dark matter candidate. They require new charged and neutral Higgs bosons and may also include, beyond the minimal model (MSSM), an extra singlet coupled through a {lambda}H{sub 1}H{sub 2}S superpotential (N/nMSSM), with possibly an extra U(1) gauge symmetry (USSM). New light neutral particles very weakly coupled to ordinary ones, such as a light U boson or light dark matter particles, may also exist.

  15. Dark matter complementarity in the phenomenological MSSM

    SciTech Connect

    Ismail, Ahmed

    2014-06-24

    The lightest neutralino of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation is one of the most well-studied dark matter (DM) candidates. Using a set of models in the 19-parameter phenomenological MSSM (pMSSM), we examine the abilities of XENON100/1T, LUX-ZEPLIN, Fermi, CTA, IceCube/DeepCore, and the LHC to study neutralino dark matter. We find that direct detection, indirect detection, neutrino telescope, and collider searches for minimal supersymmetry often fulfill concomitant roles.

  16. Black holes and local dark matter

    NASA Technical Reports Server (NTRS)

    Hegyi, D. J.; Kolb, E. W.; Olive, K. A.

    1986-01-01

    Two independent constraints are placed on the amount of dark matter in black holes contained in the galactic disk. First, gas accretion by black holes leads to X-ray emission which cannot exceed the observed soft X-ray background. Second, metals produced in stellar processes that lead to black hole formation cannot exceed the observed disk metal abundance. Based on these constraints, it appears unlikely that the missing disk mass could be contained in black holes. A consequence of this conclusion is that at least two different types of dark matter are needed to solve the various missing mass problems.

  17. Can cosmic structure form without dark matter?

    PubMed

    Dodelson, Scott; Liguori, Michele

    2006-12-01

    One of the prime pieces of evidence for dark matter is the observation of large overdense regions in the Universe. To account for this observation, perturbations had to have grown since recombination by a factor greater than (1+z*) approximately 1180 where z* is the epoch of recombination. This enhanced growth does not happen in general relativity, and so dark matter is needed in the standard theory. We show here that enhanced growth can occur in alternatives to general relativity, in particular, in Bekenstein's relativistic version of modified Newtonian dynamics. PMID:17280192

  18. Universal properties of dark matter halos.

    PubMed

    Boyarsky, A; Neronov, A; Ruchayskiy, O; Tkachev, I

    2010-05-14

    We discuss the universal relation between density and size of observed dark matter halos that was recently shown to hold on a wide range of scales, from dwarf galaxies to galaxy clusters. Predictions of cold dark matter (ΛCDM) N-body simulations are consistent with this relation. We demonstrate that this property of ΛCDM can be understood analytically in the secondary infall model. Qualitative understanding given by this model provides a new way to predict which deviations from ΛCDM or large-scale modifications of gravity can affect universal behavior and, therefore, to constrain them observationally. PMID:20866958

  19. Dark matter and the equivalence principle

    NASA Technical Reports Server (NTRS)

    Frieman, Joshua A.; Gradwohl, Ben-Ami

    1991-01-01

    If the dark matter in galaxies and clusters is nonbaryonic, it can interact with additional long-range fields that are invisible to experimental tests of the equivalence principle. The astrophysical and cosmological implications of a long-range force coupled only to the dark matter are discussed and rather tight constraints on its strength are found. If the force is repulsive (attractive), the masses of galaxy groups and clusters (and the mean density of the universe inferred from them) have been systematically underestimated (overestimated). Such an interaction also has unusual implications for the growth of large-scale structure.

  20. Composite Higgs models, Dark Matter and {lambda}

    SciTech Connect

    Diaz Cruz, J. Lorenzo

    2009-04-20

    We suggest that dark matter can be identified with a stable composite fermion X{sup 0}, that arises within the holographic AdS/CFT models, where the Higgs boson emerges as a composite pseudo-goldstone boson. The predicted properties of X{sup 0} satisfies the cosmological bounds, with m{sub X{sup 0}}{approx}4{pi}f{approx_equal}O(TeV). Thus, through a deeper understanding of the mechanism of electroweak symmetry breaking, a resolution of the Dark Matter enigma is found. Furthermore, by proposing a discrete structure of the Higgs vacuum, one can get a distinct approach to the cosmological constant problem.

  1. Minimal decaying Dark Matter and the LHC

    SciTech Connect

    Arcadi, Giorgio; Covi, Laura E-mail: covi@theorie.physik.uni-goettingen.de

    2013-08-01

    We consider a minimal Dark Matter model with just two additional states, a Dark Matter Majorana fermion and a colored or electroweakly charged scalar, without introducing any symmetry to stabilize the DM state. We identify the parameter region where an indirect DM signal would be within the reach of future observations and the DM relic density generated fits the observations. We find in this way two possible regions in the parameter space, corresponding to a FIMP/SuperWIMP or a WIMP DM. We point out the different collider signals of this scenario and how it will be possible to measure the different couplings in case of a combined detection.

  2. Cold positrons from decaying dark matter

    NASA Astrophysics Data System (ADS)

    Boubekeur, Lotfi; Dodelson, Scott; Vives, Oscar

    2012-11-01

    Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often, heavier particles decay into the lightest dark matter particle as the Universe evolves. Here, we explore the possibilities which arise if one of the products in a (heavyparticle)→(darkmatter) decay is a positron, and the lifetime is shorter than the age of the Universe. The positrons cool down by scattering off the cosmic microwave background and eventually annihilate when they fall into Galactic potential wells. The resulting 511 keV flux not only places constraints on this class of models, but might even be consistent with that observed by the INTEGRAL satellite.

  3. Results from the DRIFT Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Ayad, R.; Hyatt, M.; Hanson-Hart, Z.; Katz-Hyman, M.; Martoff, C. J.; Kirkpatrick, J.; Snowden-Ifft, D. P.; Lawson, T. B.; Lightfoot, P. K.; Morgan, B.; Paling, S. M.; Robinson, M.; Spooner, N. J. C.

    2004-05-01

    DRIFT [1] is the only direction-sensitive WIMP Dark Matter search experiment now running underground. It employs a novel detector invented for this purpose: the Negative Ion TPC (NITPC). Data is collected in the form of digitized time-records of signals received on each active anode wire of the NITPC endcap. New Results from 2002 data taking will be presented, especially on underground neutron calibration and background. [1] Low Pressure Negative Ion TPC for Dark Matter Search. D. P.Snowden-Ifft, C. J. Martoff, J. M. Burwell, Phys Rev. D. Rapid Comm. 61,101301 (2000).

  4. The LUX direct dark matter search

    NASA Astrophysics Data System (ADS)

    Murphy, A. St. J.

    2016-06-01

    As evidenced by the numerous contributions on the topic at this meeting, the IX International Conference on Interconnections between Particle Physics and Cosmology (PPC2015), the direct detection of dark matter remains as one of the highest priorities in both particle physics and cosmology. In 2013 the LUX direct dark matter search collaboration reported the most stringent constraints to-date on the spin-independent WIMP-nucleon interaction cross section. Here we present a summary of that work, describe recent technical improvements, and results from new calibrations. Prospects for the future of the LUX scientific program are reported, together with the outlook for its successor project, LZ.

  5. A cosmological solution to mimetic dark matter

    NASA Astrophysics Data System (ADS)

    Saadi, Hassan

    2016-01-01

    In this paper, a cosmological solution to Mimetic Dark Matter (MDM) for an exponential potential is provided. Then a solution for the 0-i perturbed Einstein differential equation of MDM is obtained based on an exponential potential that satisfies inflation for some initial conditions. Another general potential is suggested that incorporates inflation too. Then quantum perturbations are included. The constants in the model can be tuned to be in agreement with the fluctuation amplitude of the cosmic microwave background (CMB) radiation. Finally, the spectral index is calculated for the suggested potentials. Moreover, MDM is shown to be a viable model to produce dark matter, inflation, and CMB's fluctuation.

  6. Dark matter detection in the BMSSM

    SciTech Connect

    Bernal, Nicolás; Goudelis, Andreas E-mail: andreas.goudelis@th.u-psud.fr

    2010-03-01

    The addition of non-renormalizable terms involving the Higgs fields to the MSSM (BMSSM) ameliorates the little hierarchy problem of the MSSM. For neutralino dark matter, new regions for which the relic abundance of the LSP is consistent with WMAP (as the bulk region and the stop coannihilation region) are now permitted. In this framework, we analyze in detail the direct dark matter detection prospects in a XENON-like experiment. On the other hand, we study the capability of detecting gamma-rays, antiprotons and positrons produced in the annihilation of neutralino LSPs in the Fermi and oncoming AMS-02 experiments.

  7. Search for pseudoscalar cold dark matter

    SciTech Connect

    van Bibber, K.; Stoeffl, W.; LLNL Collaborators

    1992-05-29

    AH dynamical evidence points to the conclusion that the predominant form of matter in the universe is in a non-luminous form. Furthermore, large scale deviations from uniform Hubble flow, and the recent COBE reports of inhomogeneities in the cosmic microwave background strongly suggest that we live in an exactly closed universe. If this is true, then ordinary baryonic matter could only be a minority component (10% at most) of the missing mass, and that what constitutes the majority of the dark matter must involve new physics. The axion is one of very few well motivated candidates which may comprise the dark matter. Additionally it is a `cold` dark-matter candidate which is preferred by the COBE data. We propose to construct and operate an experiment to search for axions which may constitute the dark matter of our own galaxy. As proposed by Sikivie, dark-matter axions may be detected by their stimulated conversion into monochromatic microwave photons in a tunable high-Q cavity inside a strong magnetic field. Our ability to mount an experiment quickly and take data within one year is due to a confluence of three factors. The first is the availability of a compact high field superconducting magnet and a local industrial partner, Wang NMR, who can make a very thermally efficient and economical cryostat for it. The second is an ongoing joint venture with the Institute for Nuclear Research of the Russian Academy of Sciences to do R&D on metalized precision-formed ceramic microwave cavities for the axion search, and INR has commited to providing all the microwave cavity arrays for this experiment, should this proposal be approved. The third is a commitment of very substantial startup capital monies from MIT for all of the state-of-the-art ultra-low noise microwave electronics, to one of our outstanding young collaborators who is joining their faculty.

  8. Mystery of the Hidden Cosmos [Complex Dark Matter

    SciTech Connect

    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 are under way to search for evidence of such a dark sector.

  9. Earth's stopping effect in directional dark matter detectors

    NASA Astrophysics Data System (ADS)

    Kouvaris, Chris

    2016-02-01

    We explore the stopping effect that results from interactions between dark matter and nuclei as the dark matter particles travel underground towards the detector. Although this effect is negligible for heavy dark matter particles, there is parameter phase space where the underground interactions of the dark matter particles with the nuclei can create observable differences in the spectrum. Dark matter particles that arrive on the detector from below can have less energy from the ones arriving from above. These differences can be potentially detectable by upcoming directional detectors. This can unveil a large amount of information regarding the type and strength of interactions between nuclei and light dark matter candidates.

  10. Indirect Signatures of Gravitino Dark Matter

    SciTech Connect

    Ibarra, Alejandro

    2008-11-23

    Supersymmetric models provide very interesting scenarios to account for the dark matter of the Universe. In this talk we discuss scenarios with gravitino dark matter in R-parity breaking vacua, which not only reproduce very naturally the observed dark matter relic density, but also lead to a thermal history of the Universe consistent with the observed abundances of primordial elements and the observed matter-antimatter asymmetry. In this class of scenarios the dark matter gravitinos are no longer stable, but decay with very long lifetimes into Standard Model particles, thus opening the possibility of their indirect detection. We have computed the expected contribution from gravitino decay to the primary cosmic rays and we have found that a gravitino with a mass of m{sub 2/3}{approx}150 GeV and a lifetime of {tau}{sub 3/2}{approx}10{sup 26} s could simultaneously explain the EGRET anomaly in the extragalactic gamma-ray background and the HEAT excess in the positron fraction.

  11. Indirect and direct search for dark matter

    NASA Astrophysics Data System (ADS)

    Klasen, M.; Pohl, M.; Sigl, G.

    2015-11-01

    The majority of the matter in the universe is still unidentified and under investigation by both direct and indirect means. Many experiments searching for the recoil of dark-matter particles off target nuclei in underground laboratories have established increasingly strong constraints on the mass and scattering cross sections of weakly interacting particles, and some have even seen hints at a possible signal. Other experiments search for a possible mixing of photons with light scalar or pseudo-scalar particles that could also constitute dark matter. Furthermore, annihilation or decay of dark matter can contribute to charged cosmic rays, photons at all energies, and neutrinos. Many existing and future ground-based and satellite experiments are sensitive to such signals. Finally, data from the Large Hadron Collider at CERN are scrutinized for missing energy as a signature of new weakly interacting particles that may be related to dark matter. In this review article we summarize the status of the field with an emphasis on the complementarity between direct detection in dedicated laboratory experiments, indirect detection in the cosmic radiation, and searches at particle accelerators.

  12. Impact of semi-annihilations on dark matter phenomenology. An example of ZN symmetric scalar dark matter

    NASA Astrophysics Data System (ADS)

    Bélanger, Geneviève; Kannike, Kristjan; Pukhov, Alexander; Raidal, Martti

    2012-04-01

    We study the impact of semi-annihilations xixjleftrightarrowxkX and dark matter conversion xixjleftrightarrowxkxl, where xi is any dark matter and X is any standard model particle, on dark matter phenomenology. We formulate minimal scalar dark matter models with an extra doublet and a complex singlet that predict non-trivial dark matter phenomenology with semi-annihilation processes for different discrete Abelian symmetries ZN, N > 2. We implement two such example models with Z3 and Z4 symmetry in micrOMEGAs and work out their phenomenology. We show that both semi-annihilations and dark matter conversion significantly modify the dark matter relic abundance in this type of models. In the Z4 model, there are two stable neutral particles and therefore multi-component dark matter. We also study the possibility of dark matter direct detection in XENON100 in those models.

  13. 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.

  14. 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.

  15. Dark matter and dark energy: approaches and constraints

    NASA Astrophysics Data System (ADS)

    Zakharov, Alexander

    We will introduce problems of Dark Matter (DM) and Dark Energy (DE), namely we will describe a development of these concepts and their present status. We will demonstrate ap-proaches to these problems. As specific issues we will discuss limits on DM concentration near the black hole at the Galactic Center and ways to solve DE problem introducing alternative theories of gravity such as f (R)-theories. The existence of dark matter (DM) at scales of few pc down to 10-5 pc around the centers of galaxies and in particular in the Galactic Center region has been considered in the literature. Under the assumption that such a DM clump, principally constituted by non-baryonic matter (like WIMPs) does exist at the center of our galaxy, the study of the γ-ray emission from the Galactic Center region allows us to constrain both the mass and the size of this DM sphere. Moreover, if a DM cusp does exist around the Galactic Center it could modify the trajectories of stars moving around it in a sensible way depending on the DM mass distribution. Here, we discuss the constraints that can be obtained with the orbit analysis of stars (as S2 and S16) moving inside the DM concentration with present and next generations of large telescopes. In particular, consideration of the S2 star apoastron shift may allow improving limits on the DM mass and size. We will describe severe constraints from Solar system data on parameters f (R) = Rn theories, where n = 1 corresponds to the standard general relativistic case. 1. A. F. Zakharov, A.A. Nucita, F. De Paolis, G. Ingrosso: Solar system constraints on Rn gravity, Phys. Rev. D 74, 107101, (2006). 2. A. F. Zakharov, A.A. Nucita, F. De Paolis, G. Ingrosso: Apoastron shift constraints on dark matter distribution at the Galactic Center, Phys. Rev. D 76, 062001, (2007). 3. A.F. Zakharov, S. Capozziello, F. De Paolis, G. Ingrosso, A.A. Nucita, The Role of Dark Matter and Dark Energy in Cosmological Models: Theoretical Overview, Space Sci. Rev. 148

  16. Gravitational lenses and dark matter - Theory

    NASA Technical Reports Server (NTRS)

    Gott, J. Richard, III

    1987-01-01

    Theoretical models are presented for guiding the application of gravitational lenses to probe the characteristics of dark matter in the universe. Analytical techniques are defined for quantifying the mass associated with lensing galaxies (in terms of the image separation), determining the quantity of dark mass of the lensing bodies, and estimating the mass density of the lenses. The possibility that heavy halos are made of low mass stars is considered, along with the swallowing of central images of black holes or cusps in galactic nuclei and the effects produced on a lensed quasar image by nonbaryonic halos. The observable effects of dense groups and clusters and the characteristics of dark matter strings are discussed, and various types of images which are possible due to lensing phenomena and position are described.

  17. Halo cold dark matter and microlensing

    SciTech Connect

    Gates, Evalyn; Turner, Michael S.

    1993-12-01

    There is good evidence that most of the baryons in the Universe are dark and some evidence that most of the matter in the Universe is nonbaryonic with cold dark matter (cdm) being a promising possibility. We discuss expectations for the abundance of baryons and cdm in the halo of our galaxy and locally. We show that in plausible cdm models the local density of cdm is at least $10^{-25}\\gcmm3$. We also discuss what one can learn about the the local cdm density from microlensing of stars in the LMC by dark stars in the halo and, based upon a suite of reasonable two-component halo models, conclude that microlensing is not a sensitive probe of the local cdm density.

  18. Shedding light on baryonic dark matter

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1991-01-01

    Halo dark matter, if it is baryonic, may plausibly consist of compact stellar remnants. Jeans mass clouds containing 10 to the 6th to 10 to the 8th solar masses could have efficiently formed stars in the early universe and could plausibly have generated, for a suitably top-heavy stellar initial mass function, a high abundance of neutron stars as well as a small admixture of long-lived low mass stars. Within the resulting clusters of dark remnants, which eventually are tidally disrupted when halos eventually form, captures of neutron stars by nondegenerate stars resulted in formation of close binaries. These evolve to produce, by the present epoch, an observable X-ray signal associated with dark matter aggregations in galaxy cluster cores.

  19. Neutralino Dark Matter in Gauge Messenger Models

    SciTech Connect

    Bae, Kyu Jung

    2008-11-23

    The lightest neutralino is one of the best candidate for dark matter. In gauge messenger models, It is generic that bino and wino masses are almostly degenerate. Because of this, neutralino annihilation becomes more efficient. Also, gauge messenger models have squeezed mass spectrum so that there are many resonance and co-annihilation regions, and can give correct amount of neutralino relic density.

  20. Electroweak fragmentation functions for dark matter annihilation

    SciTech Connect

    Cavasonza, Leila Ali; Krämer, Michael; Pellen, Mathieu

    2015-02-18

    Electroweak corrections can play a crucial role in dark matter annihilation. The emission of gauge bosons, in particular, leads to a secondary flux consisting of all Standard Model particles, and may be described by electroweak fragmentation functions. To assess the quality of the fragmentation function approximation to electroweak radiation in dark matter annihilation, we have calculated the flux of secondary particles from gauge-boson emission in models with Majorana fermion and vector dark matter, respectively. For both models, we have compared cross sections and energy spectra of positrons and antiprotons after propagation through the galactic halo in the fragmentation function approximation and in the full calculation. Fragmentation functions fail to describe the particle fluxes in the case of Majorana fermion annihilation into light fermions: the helicity suppression of the lowest-order cross section in such models cannot be lifted by the leading logarithmic contributions included in the fragmentation function approach. However, for other classes of models like vector dark matter, where the lowest-order cross section is not suppressed, electroweak fragmentation functions provide a simple, model-independent and accurate description of secondary particle fluxes.

  1. PICO-LON Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Fushimi, K.; Nakayama, S.; Orito, R.; Sugawara, R.; Awatani, Y.; Ejiri, H.; Shima, T.; Hazama, R.; Inoue, K.; Ikeda, H.; Kozlov, A.

    2013-12-01

    It is an important task to find an annual modulation of WIMPs signal for identifying dark matter signal. To search for annual modulation signal by means of inorganic scintillators, a large mass and a highly radiopure detector is needed. PICO-LON (Planar Inorganic Crystal Observatory for LOw background Neutr(al)inos) is a dark matter search project with multi-array NaI(Tl) scintillators. The test module of PICO-LON whose dimension is 15cm×15cm×0.1cm gives enough performance, energy resolution and low energy threshold, for dark matter search. The highly radiopure NaI(Tl) crystal is indispensable to start a large mass experiment. We have developed highly radiopure NaI(Tl) scintillator. The U and Th chain impurities were precisely measured by meand of pulse shape analysis for NaI(Tl) scintillators. The future plan of KamLAND-PICO dark matter search project is proposed.

  2. Missing dark matter in the local universe

    NASA Astrophysics Data System (ADS)

    Karachentsev, I. D.

    2012-04-01

    A sample of 11 thousand galaxies with radial velocities V LG < 3500 km/s is used to study the features of the local distribution of luminous (stellar) and dark matter within a sphere of radius of around 50 Mpc around us. The average density of matter in this volume, Ω m,loc = 0.08 ± 0.02, turns out to be much lower than the global cosmic density Ω m,glob = 0.28 ± 0.03. We discuss three possible explanations of this paradox: 1) galaxy groups and clusters are surrounded by extended dark halos, the major part of the mass of which is located outside their virial radii; 2) the considered local volume of the Universe is not representative, being situated inside a giant void; and 3) the bulk of matter in the Universe is not related to clusters and groups, but is rather distributed between them in the form of massive dark clumps. Some arguments in favor of the latter assumption are presented. Besides the two well-known inconsistencies of modern cosmological models with the observational data: the problem of missing satellites of normal galaxies and the problem of missing baryons, there arises another one—the issue of missing dark matter.

  3. Dark matter balls help supernovae to explode

    NASA Astrophysics Data System (ADS)

    Froggatt, C. D.; Nielsen, H. B.

    2015-10-01

    As a solution to the well-known problem that the shock wave potentially responsible for the explosion of a supernova actually tends to stall, we propose a new energy source arising from our model for dark matter. Our earlier model proposed that dark matter should consist of cm-large white dwarf-like objects kept together by a skin separating two different sorts of vacua. These dark matter balls or pearls will collect in the middle of any star throughout its lifetime. At some stage during the development of a supernova, the balls will begin to take in neutrons and then other surrounding material. By passing into a ball nucleons fall through a potential of order 10 MeV, causing a severe production of heat — of order 10 foe for a solar mass of material eaten by the balls. The temperature in the iron core will thereby be raised, splitting up the iron into smaller nuclei. This provides a mechanism for reviving the shock wave when it arrives and making the supernova explosion really occur. The onset of the heating due to the dark matter balls would at first stop the collapse of the supernova progenitor. This opens up the possibility of there being two collapses giving two neutrino outbursts, as apparently seen in the supernova SN1987A — one in Mont Blanc and one 4 h 43 min later in both IMB and Kamiokande.

  4. Sterile neutrinos as subdominant warm dark matter

    SciTech Connect

    Palazzo, A.; Cumberbatch, D.; Slosar, A.; Silk, J.

    2007-11-15

    In light of recent findings which seem to disfavor a scenario with (warm) dark matter entirely constituted of sterile neutrinos produced via the Dodelson-Widrow mechanism, we investigate the constraints attainable for this mechanism by relaxing the usual hypothesis that the relic neutrino abundance must necessarily account for all of the dark matter. We first study how to reinterpret the limits attainable from x-ray nondetection and Lyman-{alpha} forest measurements in the case that sterile neutrinos constitute only a fraction f{sub s} of the total amount of dark matter. Then, assuming that sterile neutrinos are generated in the early universe solely through the Dodelson-Widrow mechanism, we show how the x-ray and Lyman-{alpha} results jointly constrain the mass-mixing parameters governing their production. Furthermore, we show how the same data allow us to set a robust upper limit f{sub s} < or approx. 0.7 at the 2{sigma} level, rejecting the case of dominant dark matter (f{sub s}=1) at the {approx}3{sigma} level.

  5. Nonthermal dark matter from cosmic strings

    SciTech Connect

    Cui Yanou; Morrissey, David E.

    2009-04-15

    Cosmic strings can be created in the early universe during symmetry-breaking phase transitions, such as might arise if the gauge structure of the standard model is extended by additional U(1) factors at high energies. Cosmic strings presented in the early universe form a network of long horizon-length segments, as well as a population of closed string loops. The closed loops are unstable against decay, and can be a source of nonthermal particle production. In this work we compute the density of weakly-interacting massive particle dark matter formed by the decay of gauge theory cosmic string loops derived from a network of long strings in the scaling regime or under the influence of frictional forces. We find that for symmetry-breaking scales larger than 10{sup 10} GeV, this mechanism has the potential to account for the observed relic density of dark matter. For symmetry-breaking scales lower than this, the density of dark matter created by loop decays from a scaling string network lies below the observed value. In particular, the cosmic strings originating from a U(1) gauge symmetry broken near the electroweak scale, that could lead to a massive Z{sup '} gauge boson observable at the LHC, produces a negligibly small dark matter relic density by this mechanism.

  6. Review of dark-matter axion experiments

    SciTech Connect

    van Bibber, K; Kinion, D

    2000-08-30

    We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a 'second-generation' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.

  7. Axino LSP baryogenesis and dark matter

    SciTech Connect

    Monteux, Angelo; Shin, Chang Sub

    2015-05-20

    We discuss a new mechanism for baryogenesis, in which the baryon asymmetry is generated by the lightest supersymmetric particle (LSP) decay via baryonic R-parity-violating interactions. As a specific example, we use a supersymmetric axion model with an axino LSP. This scenario predicts large R-parity violation for the stop, and an upper limit on the squark masses between 15 and 130 TeV, for different choices of the Peccei-Quinn scale and the soft X{sub t} terms. We discuss the implications for the nature of dark matter in light of the axino baryogenesis mechanism, and find that both the axion and a metastable gravitino can provide the correct dark matter density. In the axion dark matter scenario, the initial misalignment angle is restricted to be O(1). On the other hand, the reheating temperature is linked to the PQ scale and should be higher than 10{sup 4}–10{sup 5} GeV in the gravitino dark matter scenario.

  8. Dark Matter Ignition of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8 σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10 Myr old pulsars at the center of the Milky Way.

  9. A couplet from flavored dark matter

    SciTech Connect

    Agrawal, Prateek; Chacko, Zackaria; Kilic, Can; Verhaaren, Christopher B.

    2015-08-17

    We show that a couplet, a pair of closely spaced photon lines, in the X-ray spectrum is a distinctive feature of lepton flavored dark matter models for which the mass spectrum is dictated by Minimal Flavor Violation. In this scenario, mass splittings between different dark matter flavors are determined by Standard Model Yukawa couplings and can naturally be small, allowing all three flavors to be long-lived and contribute to the observed abundance. Then, in the presence of a tiny source of flavor violation, heavier dark matter flavors can decay via a dipole transition on cosmological timescales, giving rise to three photon lines. Two of these lines are closely spaced, and constitute the couplet. Provided the flavor violation is sufficiently small, the ratios of the line energies are determined in terms of the charged lepton masses, and constitute a prediction of this framework. Furthermore, for dark matter masses of order the weak scale, the couplet lies in the keV-MeV region, with a much weaker line in the eV-keV region. This scenario constitutes a potential explanation for the recent claim of the observation of a 3.5 keV line. As a result, the next generation of X-ray telescopes may have the necessary resolution to resolve the double line structure of such a couplet.

  10. A couplet from flavored dark matter

    DOE PAGESBeta

    Agrawal, Prateek; Chacko, Zackaria; Kilic, Can; Verhaaren, Christopher B.

    2015-08-17

    We show that a couplet, a pair of closely spaced photon lines, in the X-ray spectrum is a distinctive feature of lepton flavored dark matter models for which the mass spectrum is dictated by Minimal Flavor Violation. In this scenario, mass splittings between different dark matter flavors are determined by Standard Model Yukawa couplings and can naturally be small, allowing all three flavors to be long-lived and contribute to the observed abundance. Then, in the presence of a tiny source of flavor violation, heavier dark matter flavors can decay via a dipole transition on cosmological timescales, giving rise to threemore » photon lines. Two of these lines are closely spaced, and constitute the couplet. Provided the flavor violation is sufficiently small, the ratios of the line energies are determined in terms of the charged lepton masses, and constitute a prediction of this framework. Furthermore, for dark matter masses of order the weak scale, the couplet lies in the keV-MeV region, with a much weaker line in the eV-keV region. This scenario constitutes a potential explanation for the recent claim of the observation of a 3.5 keV line. As a result, the next generation of X-ray telescopes may have the necessary resolution to resolve the double line structure of such a couplet.« less

  11. Dark Matter Ignition of Type Ia Supernovae.

    PubMed

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way. PMID:26551803

  12. Determining Supersymmetric Parameters With Dark Matter Experiments

    SciTech Connect

    Hooper, Dan; Taylor, Andrew M.; /Oxford U.

    2006-07-01

    In this article, we explore the ability of direct and indirect dark matter experiments to not only detect neutralino dark matter, but to constrain and measure the parameters of supersymmetry. In particular, we explore the relationship between the phenomenological quantities relevant to dark matter experiments, such as the neutralino annihilation and elastic scattering cross sections, and the underlying characteristics of the supersymmetric model, such as the values of {mu} (and the composition of the lightest neutralino), m{sub A} and tan {beta}. We explore a broad range of supersymmetric models and then focus on a smaller set of benchmark models. We find that by combining astrophysical observations with collider measurements, {mu} can often be constrained far more tightly than it can be from LHC data alone. In models in the A-funnel region of parameter space, we find that dark matter experiments can potentially determine m{sub A} to roughly {+-}100 GeV, even when heavy neutral MSSM Higgs bosons (A, H{sub 1}) cannot be observed at the LHC. The information provided by astrophysical experiments is often highly complementary to the information most easily ascertained at colliders.

  13. Constraints on dissipative unified dark matter

    SciTech Connect

    Velten, Hermano; Schwarz, Dominik J. E-mail: dschwarz@physik.uni-bielefeld.de

    2011-09-01

    Modern cosmology suggests that the Universe contains two dark components — dark matter and dark energy — both unkown in laboratory physics and both lacking direct evidence. Alternatively, a unified dark sector, described by a single fluid, has been proposed. Dissipation is a common phenomenon in nature and it thus seems natural to consider models dominated by a viscous dark fluid. We focus on the study of bulk viscosity, as isotropy and homogeneity at large scales implies the suppression of shear viscosity, heat flow and diffusion. The generic ansatz ξ∝ρ{sup ν} for the coefficient of bulk viscosity (ρ denotes the mass/energy density), which for ν = −1/2 mimics the ΛCDM background evolution, offers excellent fits to supernova and H(z) data. We show that viscous dark fluids suffer from large contributions to the integrated Sachs-Wolfe effect (generalising a previous study by Li and Barrow) and a suppression of structure growth at small-scales (as seen from a generalized Meszaros equation). Based on recent observations, we conclude that viscous dark fluid models (with ξ∝ρ{sup ν} and neglecting baryons) are strongly challenged.

  14. On the capture of dark matter by neutron stars

    SciTech Connect

    Güver, Tolga; Erkoca, Arif Emre; Sarcevic, Ina; Reno, Mary Hall E-mail: aeerkoca@gmail.com E-mail: ina@physics.arizona.edu

    2014-05-01

    We calculate the number of dark matter particles that a neutron star accumulates over its lifetime as it rotates around the center of a galaxy, when the dark matter particle is a self-interacting boson but does not self-annihilate. We take into account dark matter interactions with baryonic matter and the time evolution of the dark matter sphere as it collapses within the neutron star. We show that dark matter self-interactions play an important role in the rapid accumulation of dark matter in the core of the neutron star. We consider the possibility of determining an exclusion region of the parameter space for dark matter mass and dark matter interaction cross section with the nucleons as well as dark matter self-interaction cross section, based on the observation of old neutron stars. We show that for a dark matter density of 10{sup 3} GeV/cm{sup 3}and dark matter mass m{sub χ} ∼< 10 GeV, there is a potential exclusion region for dark matter interactions with nucleons that is three orders of magnitude more stringent than without self-interactions. The potential exclusion region for dark matter self-interaction cross sections is many orders of magnitude stronger than the current Bullet Cluster limit. For example, for high dark matter density regions, we find that for m{sub χ} ∼ 10 GeV when the dark matter interaction cross section with the nucleons ranges from σ{sub χn} ∼ 10{sup −52} cm{sup 2} to σ{sub χn} ∼ 10{sup −57} cm{sup 2}, the dark matter self-interaction cross section limit is σ{sub χχ} ∼< 10{sup −33} cm{sup 2}, which is about ten orders of magnitude stronger than the Bullet Cluster limit.

  15. A hydrodynamic approach to cosmology - Texture-seeded cold dark matter and hot dark matter cosmogonies

    NASA Technical Reports Server (NTRS)

    Cen, R. Y.; Ostriker, J. P.; Spergel, D. N.; Turok, N.

    1991-01-01

    Hydrodynamical simulations of galaxy formation in a texture-seeded cosmology are presented, with attention given to Omega = 1 galaxies dominated by both hot dark matter (HDM) and cold dark matter (CDM). The simulations include both gravitational and hydrodynamical physics with a detailed treatment of collisional and radiative thermal processes, and use a cooling criterion to estimate galaxy formation. Background radiation fields and Zel'dovich-Sunyaev fluctuations are explicitly computed. The derived galaxy mass function is well fitted by the observed Schechter luminosity function for a baryonic M/L of 3 and total M/L of 60 in galaxies. In both HDM and CDM texture scenarios, the 'galaxies' and 'clusters' are significantly more strongly correlated than the dark matter due to physical bias processes. The slope of the correlation function in both cases is consistent with observations. In contrast to Gaussian models, peaks in the dark matter density distributrion are less correlated than average.

  16. On physical scales of dark matter halos

    SciTech Connect

    Zemp, Marcel

    2014-09-10

    It is common practice to describe formal size and mass scales of dark matter halos as spherical overdensities with respect to an evolving density threshold. Here, we critically investigate the evolutionary effects of several such commonly used definitions and compare them to the halo evolution within fixed physical scales as well as to the evolution of other intrinsic physical properties of dark matter halos. It is shown that, in general, the traditional way of characterizing sizes and masses of halos dramatically overpredicts the degree of evolution in the last 10 Gyr, especially for low-mass halos. This pseudo-evolution leads to the illusion of growth even though there are no major changes within fixed physical scales. Such formal size definitions also serve as proxies for the virialized region of a halo in the literature. In general, those spherical overdensity scales do not coincide with the virialized region. A physically more precise nomenclature would be to simply characterize them by their very definition instead of calling such formal size and mass definitions 'virial'. In general, we find a discrepancy between the evolution of the underlying physical structure of dark matter halos seen in cosmological structure formation simulations and pseudo-evolving formal virial quantities. We question the importance of the role of formal virial quantities currently ubiquitously used in descriptions, models, and relations that involve properties of dark matter structures. Concepts and relations based on pseudo-evolving formal virial quantities do not properly reflect the actual evolution of dark matter halos and lead to an inaccurate picture of the physical evolution of our universe.

  17. Dark matter cores all the way down

    NASA Astrophysics Data System (ADS)

    Read, J. I.; Agertz, O.; Collins, M. L. M.

    2016-07-01

    We use high-resolution simulations of isolated dwarf galaxies to study the physics of dark matter cusp-core transformations at the edge of galaxy formation: M200 = 107-109 M⊙. We work at a resolution (˜4 pc minimum cell size; ˜250 M⊙ per particle) at which the impact from individual supernovae explosions can be resolved, becoming insensitive to even large changes in our numerical `sub-grid' parameters. We find that our dwarf galaxies give a remarkable match to the stellar light profile; star formation history; metallicity distribution function; and star/gas kinematics of isolated dwarf irregular galaxies. Our key result is that dark matter cores of size comparable to the stellar half-mass radius r1/2 always form if star formation proceeds for long enough. Cores fully form in less than 4 Gyr for the M200 = 108 M⊙ and ˜14 Gyr for the 109 M⊙ dwarf. We provide a convenient two parameter `CORENFW' fitting function that captures this dark matter core growth as a function of star formation time and the projected stellar half-mass radius. Our results have several implications: (i) we make a strong prediction that if Λcold dark matter is correct, then `pristine' dark matter cusps will be found either in systems that have truncated star formation and/or at radii r > r1/2; (ii) complete core formation lowers the projected velocity dispersion at r1/2 by a factor of ˜2, which is sufficient to fully explain the `too-big-to-fail problem'; and (iii) cored dwarfs will be much more susceptible to tides, leading to a dramatic scouring of the sub-halo mass function inside galaxies and groups.

  18. In The Light of The Dark Matter

    NASA Astrophysics Data System (ADS)

    Thakur, Sunil

    2007-04-01

    Dark matter and Higgs field are two of the biggest mysteries the world of physics. However, dark matter and Higgs field are not the only mysteries that have troubled the physicists. Mechanism of creation of universe, expansion of universe, loss of energy, wave-particle duality, concept of gravity and gravitational waves, pioneer anomaly are some of the problems that need to be resolved. Higgs field is a theoretical necessity but there are no evidences of its existence and yet almost all of our theories of physics are directly or indirectly based on its predicted existence. Presence of dark matter on the other hand can be theoretically derived from the observed phenomenon and yet none of our theories take into account its existence. Since total mass and total energy in the universe has already been accounted for, existence of Higgs field is automatically ruled out. This paper attempts to resolve these issues by explaining that the dark matter forms the Higgs field. Higgs field absorbs most of the energy and converts this energy into Higgs particle that results in the expansion of the Higgs field. Expanse of the Higgs field is the expanse of our universe. Almost homogenous distribution of dark matter cancels the gravitational pull exerted by it except at the places where it gets distorted due to presence of substance and energy. This theory explains in detail the structure of the Higgs field and how the information flows in the Higgs field. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NES07.B1.8

  19. Dark matter searches using superheated liquids

    NASA Astrophysics Data System (ADS)

    Manuel, Bou-Cabo; Miguel, Ardid; Ivan, Felis

    2016-07-01

    Direct detection of dark matter is one of the most important topics in modern physics. It is estimated that 22% of universe matter is composed by dark matter in front of 0.4% of ordinary matter like stars, galaxies planets and all kind of known astrophysical objects. Several kinds of experiments are nowadays involved in detection of one of the more accepted particle candidates to be dark matter: WIMPs (Weakly Interacting Massive Particles). These detectors, using several kinds of techniques: Cryogenic semiconductors, scintillation materials like I Na or noble gas chambers among others, are reporting very interesting but inconclusive results. In this paper a review of detectors that are using the superheated liquid technique in bubble chambers in order to detect WIMPs is reported. Basically, we will report about Coupp (Chicagoland observatory for underground particle physics), PICO that is composed by Coupp and Picasso researchers having the aim to build a ton experiment and also about a new detector named MOSCAB (Materia oscura a bolle) that recently published a first results of a test chamber that uses also superheated liquid technique but as a Geyser chamber.

  20. Constraining decaying dark matter with neutron stars

    NASA Astrophysics Data System (ADS)

    Pérez-García, M. Ángeles; Silk, Joseph

    2015-05-01

    The amount of decaying dark matter, accumulated in the central regions in neutron stars together with the energy deposition rate from decays, may set a limit on the neutron star survival rate against transitions to more compact objects provided nuclear matter is not the ultimate stable state of matter and that dark matter indeed is unstable. More generally, this limit sets constraints on the dark matter particle decay time, τχ. We find that in the range of uncertainties intrinsic to such a scenario, masses (mχ /TeV) ≳ 9 ×10-4 or (mχ /TeV) ≳ 5 ×10-2 and lifetimes τχ ≲1055 s and τχ ≲1053 s can be excluded in the bosonic or fermionic decay cases, respectively, in an optimistic estimate, while more conservatively, it decreases τχ by a factor ≳1020. We discuss the validity under which these results may improve with other current constraints.

  1. Dark matter superfluidity and galactic dynamics

    NASA Astrophysics Data System (ADS)

    Berezhiani, Lasha; Khoury, Justin

    2016-02-01

    We propose a unified framework that reconciles the stunning success of MOND on galactic scales with the triumph of the ΛCDM model on cosmological scales. This is achieved through the physics of superfluidity. Dark matter consists of self-interacting axion-like particles that thermalize and condense to form a superfluid in galaxies, with ∼mK critical temperature. The superfluid phonons mediate a MOND acceleration on baryonic matter. Our framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not): dark matter has a higher temperature in clusters, and hence is in a mixture of superfluid and normal phase. The rich and well-studied physics of superfluidity leads to a number of striking observational signatures.

  2. Gamma-rays from Dark Matter Annihilation in the Central Region of the Galaxy

    SciTech Connect

    Serpico, Pasquale Dario; Hooper, Dan; /Fermilab /Chicago U., Astron. Astrophys. Ctr.

    2009-02-01

    In this article, we review the prospects for the FERMI satellite (formerly known as GLAST) to detect gamma-rays from dark matter annihilations in the Central Region of the Milky Way, in light of the recent observations and discoveries of Imaging Atmospheric Cherenkov Telescopes. While the existence of significant astrophysical backgrounds in this part of the sky limits FERMI's discovery potential to some degree, this can be mitigated by exploiting the peculiar energy spectrum and angular distribution of the dark matter annihilation signal relative to those of astrophysical backgrounds.

  3. 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.

  4. Dark radiation constraints on mixed Axion/Neutralino dark matter

    SciTech Connect

    Bae, Kyu Jung; Baer, Howard; Lessa, Andre E-mail: baer@nhn.ou.edu

    2013-04-01

    Recent analyses of CMB data combined with the measurement of BAO and H{sub 0} show that dark radiation — parametrized by the apparent number of additional neutrinos ΔN{sub eff} contributing to the cosmic expansion — is bounded from above by about ΔN{sub eff}∼<1.6 at 95% CL. We consider the mixed axion/neutralino cold dark matter scenario which arises in R-parity conserving supersymmetric (SUSY) models wherein the strong CP problem is solved by hadronic axions with a concommitant axion(a)/saxion(s)/axino(ã) supermultiplet. Our new results include improved calculations of thermal axion and saxion production and include effects of saxion decay to axinos and axions. We show that the above bound on ΔN{sub eff} is easily satisfied if saxions are mainly thermally produced and m{sub LSP} < m{sub ã}∼dark matter are highly constrained by combined CMB, BBN and Xe-100 constraints. In particular, supersymmetric models with a standard overabundance of neutralino dark matter are excluded for all values of the Peccei-Quinn breaking scale. Next generation WIMP direct detection experiments may be able to discover or exclude mixed axion-neutralino CDM scenarios where s → aa is the dominant saxion decay mode.

  5. New Light on Dark Matter

    SciTech Connect

    Freedman, Wendy L., Dr.

    2008-11-22

    Under this proposal, we have been undertaking a calibration of rate of change of the expansion rate of the Universe as a function of cosmic look-back time using the high-precision standard candles, Type Ia supernovae, as observed in their rest-frame near-infrared wavelengths. The apparent acceleration of the Universe, as discovered earlier using these same types of supernovae, was both unanticipated and extremely profound in its implications. Not only does the acceleration mean that the Universe is unbound, but it also implies the existence of a new constituent of the Universe (so-called 'dark energy') that is many orders of magnitude stronger than what physicists can easily accommodate in their standard theories of particle physics. A result with such wide-ranging and important implications must be checked, and all sources of systematic error and uncertainty must be evaluated and accounted for. At increasingly higher redshifts the objects being observed are seen at earlier cosmic times and the radiation that reaches Earth is shifted to longer and longer wavelengths. What leaves a supernova event at one time in the past as an optical photon is downgraded by cosmic expansion into a red or infrared photon by the time it is detected here. Optical images of distant supernovae seen now, began their lives as ultraviolet photons. The ultraviolet properties of nearby supernovae are not well understood, so comparing supernova across time and space becomes complicated and uncertain. Moreover it is well known that the systematic effects of interstellar dust are larger and more variable from place to place in the ultraviolet than they are at longer wavelengths. To mitigate both the uncertainty of the ultraviolet calibration and the certainty of variable dust extinction along the line of sight, the Carnegie Supernova Program (CSP) has been observing the distant supernovae at groundbased infrared wavelengths that more closely match restframe (emitted) optical wavelengths at the

  6. Dark Matter and Cosmic Web Story

    NASA Astrophysics Data System (ADS)

    Einasto, Jaan

    2014-01-01

    The development of concepts of dark matter and cosmic web are described as paradigm changes in cosmology. As characteristic in paradigm shifts, there is no single discovery; the new concepts were developed step-by-step by many scientists. The book describes the classical cosmological paradigm, elaborated in the first half of the 20th century. Next the book describes problems in the classical picture, and steps to solve the discrepancies, which eventually led to the formation of the modern cosmological paradigm. The new paradigm tells that the Universe is dominated by dark matter and dark energy, that it has the structure in the form of the cosmic web, and that it has evolved through an inflationary initial stage. The story is told from the perspective of one of the participants of events. The book concentrates to the path of the research, difficulties encountered, and discussions in favour or against new concepts. A special flavour gives to the story the description of difficulties of doing revolutionary research in an occupied country behind the Iron Curtain -- as well as convincing scientists in the West -- and the development of Estonia towards a free country. The book is accompanied by a website (http://www.aai.ee/~einasto/DarkMatter) which contains additional material: copies of originals of some crucial papers, astronomical movies, and also movies which show the private life of the author.

  7. 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

  8. 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

  9. Cold dark matter: Controversies on small scales.

    PubMed

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

    2015-10-01

    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

  10. Dark Energy, Dark Matter and Science with Constellation-X

    NASA Technical Reports Server (NTRS)

    Cardiff, Ann Hornschemeier

    2005-01-01

    Constellation-X, with more than 100 times the collecting area of any previous spectroscopic mission operating in the 0.25-40 keV bandpass, will enable highthroughput, high spectral resolution studies of sources ranging from the most luminous accreting supermassive black holes in the Universe to the disks around young stars where planets form. This talk will review the updated Constellation-X science case, released in booklet form during summer 2005. The science areas where Constellation-X will have major impact include the exploration of the space-time geometry of black holes spanning nine orders of magnitude in mass and the nature of the dark energy and dark matter which govern the expansion and ultimate fate of the Universe. Constellation-X will also explore processes referred to as "cosmic feedback" whereby mechanical energy, radiation, and chemical elements from star formation and black holes are returned to interstellar and intergalactic medium, profoundly affecting the development of structure in the Universe, and will also probe all the important life cycles of matter, from stellar and planetary birth to stellar death via supernova to stellar endpoints in the form of accreting binaries and supernova remnants. This talk will touch upon all these areas, with particular emphasis on Constellation-X's role in the study of Dark Energy.

  11. Light Dark Matter from Forbidden Channels.

    PubMed

    D'Agnolo, Raffaele Tito; Ruderman, Joshua T

    2015-08-01

    Dark matter (DM) may be a thermal relic that annihilates into heavier states in the early universe. This forbidden DM framework accommodates a wide range of DM masses from keV to weak scales. An exponential hierarchy between the DM mass and the weak scale follows from the exponential suppression of the thermally averaged cross section. Stringent constraints from the cosmic microwave background are evaded because annihilations turn off at late times. We provide an example where DM annihilates into dark photons, which is testable through large DM self-interactions and direct detection. PMID:26296106

  12. Distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter dominated universe

    SciTech Connect

    Ryu, D.; Vishniac, E.T.; Chiang, W.H.

    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 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.

  13. Dissipative dark matter and the rotation curves of dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Foot, R.

    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 interaction 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 Hα 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.

  14. Dark matter dispersion tensor in perturbation theory

    NASA Astrophysics Data System (ADS)

    Aviles, Alejandro

    2016-03-01

    We compute the dark matter velocity dispersion tensor up to third order in perturbation theory using the Lagrangian formalism, revealing growing solutions at the third and higher orders. Our results are general and can be used for any other perturbative formalism. As an application, corrections to the matter power spectrum are calculated, and we find that some of them have the same structure as those in the effective field theory of large-scale structure, with "EFT-like" coefficients that grow quadratically with the linear growth function and are further suppressed by powers of the logarithmic linear growth factor f ; other corrections present additional k dependence. Due to the velocity dispersions, there exists a free-streaming scale that suppresses the whole 1-loop power spectrum. Furthermore, we find that as a consequence of the nonlinear evolution, the free-streaming length is shifted towards larger scales, wiping out more structure than that expected in linear theory. Therefore, we argue that the formalism developed here is better suited for a perturbation treatment of warm dark matter or neutrino clustering, where the velocity dispersion effects are well known to be important. We discuss implications related to the nature of dark matter.

  15. The bestiary of dark matter species

    NASA Astrophysics Data System (ADS)

    Salati, P.

    Large amounts of invisible matter have been discovered back in 1933 when the Swiss astronomer Fritz Zwicky measured for the first time the velocity dispersion of individual galaxies inside the Coma cluster. Since then, this pioneering observation has been confirmed on scales ranging from galactic radii to cosmological distances. The existence of the so-called astronomical dark matter is now well established. The puzzle lies in the fact that this essential component of the universe is not made of ordinary atoms and electrons. The astronomical dark matter is indeed non-baryonic. Its nature is still an unresolved issue. Many theoretical ideas and proposals have flourished in the past thirty years and yet none of them provides a definite answer. I have the challenging task to introduce the cohort of these dark matter candidates to you. They make up a bestiary of exotic species which have been recently proliferating. Instead of a liste à la Prévert, I will present a tentative classification of the various models.

  16. Updates from the DMTPC Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Lopez, Jeremy

    2013-04-01

    The motion of Earth through the galactic dark matter halo combined with the rotation of Earth around its axis is expected to create a large daily modulation in the typical directions of WIMP dark matter induced nuclear recoils. This modulation, if found, would provide strong evidence for WIMP interactions with normal matter. To search for this signal, the Dark Matter Time Projection Chamber (DMTPC) collaboration is developing gas TPCs that can measure the directions of low energy nuclear recoils in low pressure CF4 gas. DMTPC detectors use a mesh-based amplification region to measure the ionization profiles of recoils on a two-dimensional readout plane. CCD cameras are used to achieve sub-millimeter spatial resolution for a typical nuclear recoil range of one to several millimeters. This talk will discuss the commissioning and calibration of a prototype DMTPC detector in a surface laboratory at MIT. This detector, the 4-shooter, is testing several new features necessary for a planned 1 m^3 fiducial volume detector currently being designed. Upon completion of surface calibrations in early 2013, the 4-shooter detector will be installed underground at the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico.

  17. Diluted equilibrium sterile neutrino dark matter

    NASA Astrophysics Data System (ADS)

    Patwardhan, Amol V.; Fuller, George M.; Kishimoto, Chad T.; Kusenko, Alexander

    2015-11-01

    We present a model where sterile neutrinos with rest masses in the range ˜keV to ˜MeV can be the dark matter and be consistent with all laboratory, cosmological, and large-scale structure, as well as x-ray constraints. These sterile neutrinos are assumed to freeze out of thermal and chemical equilibrium with matter and radiation in the very early Universe, prior to an epoch of prodigious entropy generation ("dilution") from out-of-equilibrium decay of heavy particles. In this work, we consider heavy, entropy-producing particles in the ˜TeV to ˜EeV rest-mass range, possibly associated with new physics at high-energy scales. The process of dilution can give the sterile neutrinos the appropriate relic densities, but it also alters their energy spectra so that they could act like cold dark matter, despite relatively low rest masses as compared to conventional dark matter candidates. Moreover, since the model does not rely on active-sterile mixing for producing the relic density, the mixing angles can be small enough to evade current x-ray or lifetime constraints. Nevertheless, we discuss how future x-ray observations, future lepton number constraints, and future observations and sophisticated simulations of large-scale structure could, in conjunction, provide evidence for this model and/or constrain and probe its parameters.

  18. Dark radiation alleviates problems with dark matter halos.

    PubMed

    Chu, Xiaoyong; Dasgupta, Basudeb

    2014-10-17

    We show that a scalar and a fermion charged under a global U(1) symmetry can not only explain the existence and abundance of dark matter (DM) and dark radiation (DR), but can also imbue DM with improved scattering properties at galactic scales, while remaining consistent with all other observations. Delayed DM-DR kinetic decoupling eases the missing satellites problem, while scalar-mediated self-interactions of DM ease the cusp versus core and too big to fail problems. In this scenario, DM is expected to be pseudo-Dirac and have a mass 100 keV ≲ m(χ) ≲ 10 GeV. The predicted DR may be measurable using the primordial elemental abundances from big bang nucleosynthesis, and using the cosmic microwave background. PMID:25361246

  19. Dark Radiation Alleviates Problems with Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Chu, Xiaoyong; Dasgupta, Basudeb

    2014-10-01

    We show that a scalar and a fermion charged under a global U(1) symmetry can not only explain the existence and abundance of dark matter (DM) and dark radiation (DR), but can also imbue DM with improved scattering properties at galactic scales, while remaining consistent with all other observations. Delayed DM-DR kinetic decoupling eases the missing satellites problem, while scalar-mediated self-interactions of DM ease the cusp versus core and too big to fail problems. In this scenario, DM is expected to be pseudo-Dirac and have a mass 100 keV≲mχ≲10 GeV. The predicted DR may be measurable using the primordial elemental abundances from big bang nucleosynthesis, and using the cosmic microwave background.

  20. Gravity Resonance Spectroscopy Constrains Dark Energy and Dark Matter Scenarios

    NASA Astrophysics Data System (ADS)

    Jenke, T.; Cronenberg, G.; Burgdörfer, J.; Chizhova, L. A.; Geltenbort, P.; Ivanov, A. N.; Lauer, T.; Lins, T.; Rotter, S.; Saul, H.; Schmidt, U.; Abele, H.

    2014-04-01

    We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate that Newton's inverse square law of gravity is understood at micron distances on an energy scale of 10-14 eV. At this level of precision, we are able to provide constraints on any possible gravitylike interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant β >5.8×108 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axionlike spin-mass coupling is excluded for the coupling strength gsgp>3.7×10-16 (5.3×10-16) at a Yukawa length of λ =20 μm (95% C.L.).

  1. Observing Dark Worlds: A crowdsourcing experiment for dark matter mapping

    NASA Astrophysics Data System (ADS)

    Harvey, D.; Kitching, T. D.; Noah-Vanhoucke, J.; Hamner, B.; Salimans, T.; Pires, A. M.

    2014-07-01

    We present the results and conclusions from the citizen science competition 'Observing Dark Worlds', where we asked participants to calculate the positions of dark matter halos from 120 catalogues of simulated weak lensing galaxy data, using computational methods. In partnership with Kaggle (http://www.kaggle.com), 357 users participated in the competition which saw 2278 downloads of the data and 3358 submissions. We found that the best algorithms improved on the benchmark code, LENSTOOL by >30% and could measure the positions of >3×1014M⊙ halos to <5″ and <1014M⊙ to within 1‧. In this paper, we present a brief overview of the winning algorithms with links to available code.

  2. Generalized models of unification of dark matter and dark energy

    NASA Astrophysics Data System (ADS)

    Čaplar, Neven; Štefančić, Hrvoje

    2013-01-01

    A model of unification of dark matter and dark energy based on the modeling of the speed of sound as a function of the parameter of the equation of state is introduced. It is found that the model in which the speed of sound depends on the power of the parameter of the equation of state, cs2=α(-w)γ, contains the generalized Chaplygin gas models as its subclass. An effective scalar field description of the model is obtained in a parametric form which in some cases can be translated into a closed form solution for the scalar field potential. A constraint on model parameters is obtained using the observational data on the Hubble parameter at different redshifts.

  3. Acquired scaling relations in dark matter turbulence

    NASA Astrophysics Data System (ADS)

    Nakamichi, Akika; Morikawa, Masahiro

    2010-01-01

    Variety of scaling relations are observed in astronomical objects. We study a consistent understanding of them from a simple proposal that the collision-less dark matter fluid terns into a turbulent state, i.e. cosmic dark turbulence. This happens most likely when the density fluctuations cross the caustic surface toward the non-linear regime. Collision-less dark turbulence may not be eddy-dominant. We first derive Kolmogorov scaling laws from the gravitational Navier-Stokes equation by the method similar to the case in Smoluchowski coagulation equation. Then we apply this to several observations such as the scale-dependent velocity dispersion, mass-luminosity ratio, magnetic fields, and mass-angular momentum relation, power spectrum of density fluctuations. They all conclude a single value for a constant energy flow per mass: 0.3cm2/sec3. This value may deeply related with the speed of the hierarchical coalescence process in the cosmic structure formation.

  4. Axion cold dark matter in nonstandard cosmologies

    SciTech Connect

    Visinelli, Luca; Gondolo, Paolo

    2010-03-15

    We study the parameter space of cold dark matter axions in two cosmological scenarios with nonstandard thermal histories before big bang nucleosynthesis: the low-temperature reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmology. We show that the axion velocity dispersion may be used to distinguish some of these nonstandard cosmologies. Thus, axion cold dark matter may be a good probe of the history of the Universe before big bang nucleosynthesis.

  5. `HERON` as a dark matter detector?

    SciTech Connect

    Adams, J.S.; Bandler, S.R.; Brouer, S.M.; Enss, C.; Lanou, R.E.; Maris, H.J.; More, T.; Seidel, G.M.

    1996-10-01

    ``{bold HERON}``, which is the acronym for `` {bold He}lium: {bold Ro}ton detection of {bold N}eutrinos``, is a project whose principal goal is a next generation detector of solar neutrinos from the p-p and {sup 7}Be branches. It will utilize superfluid helium as the target material and employ event energy transport out of the target by phonon and roton processes unique to helium. Many of the challenges presented for dark matter detection are very similar to those for low energy solar neutrinos. We present new results from our feasibility studies for {bold HERON} which indicate an asymmetry in the roton emission distribution from stopping particles and the ability to detect simultaneously the ultraviolet fluorescence photons also emitted. These features are potentially valuable for solar neutrino detection and the question is explored as to whether or not the same helium technique could be valuable for WIMP dark matter detection.

  6. Light Dark Matter in the NO$\

    SciTech Connect

    Hatzikoutelis, Athanasios

    2015-01-01

    The neutrino oscillations experiment NOA is the agship of Fermi National Laboratory. The neutrino source NuMI is delivering record numbers of protons-on-target surpassing the most stringent dark matter production upper limits of current models in the under-10 GeV mass range. We take advantage of the sophisticated particle identication algorithms of the experiment to interrogate the data from the 300-ton, o-axis, low-Z, Near Detector of NOvA during the rst physics runs. We search for signatures of sub-GeV or Light Dark Matter (LDM), Axion-like-particles, and Heavy or Sterile Neutrinos that may scatter or decay in the volume of the detector.

  7. Can Cosmic Structure form without Dark Matter?

    SciTech Connect

    Dodelson, Scott; Liguori, Michele; /Fermilab /Padua U. /INFN, Padua

    2006-08-01

    One of the prime pieces of evidence for dark matter is the observation of large overdense regions in the universe. Since we know from the cosmic microwave background that the regions that contained the most baryons when the universe was {approx} 400, 000 years old were overdense by only one part in ten thousand, perturbations had to have grown since then by a factor greater than (1 + z{sub *}) {approx_equal} 1180 where z{sub *} is the epoch of recombination. This enhanced growth does not happen in general relativity, so dark matter is needed in the standard theory. We show here that enhanced growth can occur in alternatives to general relativity, in particular in Bekenstein's relativistic version of Modified Newtonian Dynamics (MOND). The vector field introduced in that theory for a completely different reason plays a key role in generating the instability that produces large cosmic structures today.

  8. Axions as hot and cold dark matter

    SciTech Connect

    Jeong, Kwang Sik; Kawasaki, Masahiro; Takahashi, Fuminobu E-mail: kawasaki@icrr.u-tokyo.ac.jp

    2014-02-01

    The presence of a hot dark matter component has been hinted at 3σ by a combination of the results from different cosmological observations. We examine a possibility that pseudo Nambu-Goldstone bosons account for both hot and cold dark matter components. We show that the QCD axions can do the job for the axion decay constant f{sub a}∼

  9. Constraints on dark matter from intergalactic radiation

    NASA Technical Reports Server (NTRS)

    Overduin, J. M.; Wesson, P. S.

    1992-01-01

    Several of the dark matter candidates that have been proposed are believed to be unstable to decay, which would contribute photons to the radiation field between galaxies. The main candidates of this type are light neutrinos and axions, primordial mini-black holes, and a nonzero 'vacuum' energy. All of these can be constrained in nature by observational data on the extragalactic background light and the microwave background radiation. Black holes and the vacuum can be ruled out as significant contributors to the 'missing mass'. Light axions are also unlikely candidates; however, those with extremely small rest energies (the so-called 'invisible' axions) remain feasible. Light neutrinos, like those proposed by Sciama, are marginally viable. In general, we believe that the intergalactic radiation field is an important way of constraining all types of dark matter.

  10. Detection of Galactic Dark Matter by GLAST

    SciTech Connect

    Bloom, Elliott D

    1999-07-07

    The mysterious dark matter has been a subject of special interest to high energy physicists, astrophysicists and cosmologists for many years. According to theoretical models, it can make up a significant fraction of the mass of the Universe. One possible form of galactic dark matter, Weakly Interacting Massive Particles (WIMPs), could be detected by their annihilation into monoenergetic gamma-ray line(s). This paper will demonstrate that the Gamma-ray Large Area Space Telescope (GLAST), scheduled for launch in 2005 by NASA, will be capable of searching for these gamma-ray lines in the energy range from 20 GeV to {approx}500 GeV and will be sufficiently sensitive to test a number of models. The required instrument performance and its capability to reject backgrounds to the required levels are explicitly discussed.

  11. Axion dark matter: strings and their cores

    NASA Astrophysics Data System (ADS)

    Fleury, Leesa; Moore, Guy D.

    2016-01-01

    Axions constitute a well-motivated dark matter candidate, and if PQ symmetry breaking occurred after inflation, it should be possible to make a clean prediction for the relation between the axion mass and the axion dark matter density. We show that axion (or other global) string networks in 3D have a network density that depends logarithmically on the string separation-to-core ratio. This logarithm would be about 10 times larger in axion cosmology than what we can achieve in numerical simulations. We simulate axion production in the early Universe, finding that, for the separation-to-core ratios we can achieve, the changing density of the network has little impact on the axion production efficiency.

  12. Dark matter constraints from stellar evolution

    NASA Astrophysics Data System (ADS)

    Ayala, A.; Domínguez, I.; Straniero, O.

    2016-01-01

    The study of dark matter constraints from its effect on star evolution has been discussed in recent years. We propose a star evolution simulation approach to determine those costraints from properties related to star evolutionary stages and propose globular cluster observables in order to check those constraints. My work in progress (my PhD project research) employs FRANEC code to simulate complete star evolution from pre-main sequence to AGB phase, and regards several DM candidates like axions or WIMPs, motivated by different unsolved physical problems. Detailed energy production or energy loss due to DM particles are included, taking into account the expected interaction between dark matter particles and stellar plasma within different models.

  13. Dark matter in view of recent experiments

    SciTech Connect

    Zurek, Kathryn M.; /Fermilab

    2009-07-01

    We discuss new models of dark matter (DM) developed recently in light of the anomalous signals from DAMA, INTEGRAL, AMS, PAMELA, ATIC and Fermi. If the results of any of the experiments are the result of DM interactions with ordinary matter, whether through scattering or annihilation, the DM must have properties atypical of an ordinary Weakly Interacting Massive Particle (WIMP) from the Minimal Supersymmetric Standard Model (MSSM). Many of these new models of DM developed to explain these signals involve low mass hidden sectors with complex dynamics. We outline features required by the new models to be phenomenologically viable.

  14. Bounds on dark matter in solar orbit

    SciTech Connect

    Anderson, J.D.; Lau, E.L.; Taylor, A.H.; Dicus, D.A.; Teplitz, D.C.; Texas Univ., Austin; Maryland Univ., College Park )

    1989-07-01

    The possibility is considered that a spherical distribution of dark matter (DM), matter not visible with current instruments, is trapped in the sun's gravitational field. Bounds are placed from the motion of Uranus and Neptune, on the amount of DM that could be so trapped within the radius of those planets' orbits, as follows: from the Voyager 2, Uranus-flyby data new, more accurate ephemeris values are generated. Trapped DM mass is bounded by noting that such a distribution would increase the effective mass of the sun as seen by the outer planets and by using the new ephemeris values to bound such an increase. 34 refs.

  15. Sommerfeld enhancements for thermal relic dark matter

    NASA Astrophysics Data System (ADS)

    Feng, Jonathan L.; Kaplinghat, Manoj; Yu, Hai-Bo

    2010-10-01

    The annihilation cross section of thermal relic dark matter determines both its relic density and indirect detection signals. We determine how large indirect signals may be in scenarios with Sommerfeld-enhanced annihilation, subject to the constraint that the dark matter has the correct relic density. This work refines our previous analysis through detailed treatments of resonant Sommerfeld enhancement and the effect of Sommerfeld enhancement on freeze out. Sommerfeld enhancements raise many interesting issues in the freeze out calculation, and we find that the cutoff of resonant enhancement, the equilibration of force carriers, the temperature of kinetic decoupling, and the efficiency of self-interactions for preserving thermal velocity distributions all play a role. These effects may have striking consequences; for example, for resonantly-enhanced Sommerfeld annihilation, dark matter freezes out but may then chemically recouple, implying highly suppressed indirect signals, in contrast to naive expectations. In the minimal scenario with standard astrophysical assumptions, and tuning all parameters to maximize the signal, we find that, for force-carrier mass mϕ=250MeV and dark matter masses mX=0.1, 0.3, and 1 TeV, the maximal Sommerfeld enhancement factors are Seff=7, 30, and 90, respectively. Such boosts are too small to explain both the PAMELA and Fermi excesses. Nonminimal models may require smaller boosts, but the bounds on Seff could also be more stringent, and dedicated freeze out analyses are required. For concreteness, we focus on 4μ final states, but we also discuss 4e and other modes, deviations from standard astrophysical assumptions and nonminimal particle physics models, and we outline the steps required to determine if such considerations may lead to a self-consistent explanation of the PAMELA or Fermi excesses.

  16. A tilted cold dark matter cosmological scenario

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Gnedin, Nickolay Y.; Kofman, Lev A.; Ostriker, Jeremiah P.

    1992-01-01

    A new cosmological scenario based on CDM but with a power spectrum index of about 0.7-0.8 is suggested. This model is predicted by various inflationary models with no fine tuning. This tilted CDM model, if normalized to COBE, alleviates many problems of the standard CDM model related to both small-scale and large-scale power. A physical bias of galaxies over dark matter of about two is required to fit spatial observations.

  17. Planet Nine, dark matter and MOND

    NASA Astrophysics Data System (ADS)

    Sivaram, C.; Kenath, Arun; Kiren, O. V.

    2016-07-01

    Here we propose the possibility that the recently postulated Neptune-sized planet with an orbital period of 15,000 years could be a gravitationally condensed dark matter (DM) object. The observed mass of Planet Nine fits with the theoretical mass predicted for such DM objects formed by 60 GeV DM particles, which is the currently favoured DM particles. This object could also provide us with a testing ground for modification of Newtonian dynamics.

  18. Detecting dark matter with scintillating bubble chambers

    NASA Astrophysics Data System (ADS)

    Zhang, Jianjie; Dahl, C. Eric; Jin, Miaotianzi; Baxter, Daniel

    2016-03-01

    Threshold based direct WIMP dark matter detectors such as the superheated bubble chambers developed by the PICO experiment have demonstrated excellent electron-recoil and alpha discrimination, excellent scalability, ease of change of target fluid, and low cost. However, the nuclear-recoil like backgrounds have been a limiting factor in their dark matter sensitivity. We present a new type of detector, the scintillating bubble chamber, which reads out the scintillation pulse of the scattering events as well as the pressure, temperature, acoustic traces, and bubble images as a conventional bubble chamber does. The event energy provides additional handle to discriminate against the nuclear-recoil like backgrounds. Liquid xenon is chosen as the target fluid in our prototyping detector for its high scintillation yield and suitable vapor pressure which simplifies detector complexity. The detector can be used as an R&D tool to study the backgrounds present in the current PICO bubble chambers or as a prototype for standalone dark matter detectors in the future. Supported by DOE Grant DE-SC0012161.

  19. Dark-matter harmonics beyond annual modulation

    SciTech Connect

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

    2013-11-01

    The count rate at dark-matter direct-detection experiments should modulate annually due to the motion of the Earth around the Sun. We show that higher-frequency modulations, including daily modulation, are also present and in some cases are nearly as strong as the annual modulation. These higher-order modes are particularly relevant if (i) the dark matter is light, O(10) GeV, (ii) the scattering is inelastic, or (iii) velocity substructure is present; for these cases, the higher-frequency modes are potentially observable at current and ton-scale detectors. We derive simple expressions for the harmonic modes as functions of the astrophysical and geophysical parameters describing the Earth's orbit, using an updated expression for the Earth's velocity that corrects a common error in the literature. For an isotropic halo velocity distribution, certain ratios of the modes are approximately constant as a function of nuclear recoil energy. Anisotropic distributions can also leave observable features in the harmonic spectrum. Consequently, the higher-order harmonic modes are a powerful tool for identifying a potential signal from interactions with the Galactic dark-matter halo.

  20. Neutrino signature of Inert Doublet Dark Matter

    NASA Astrophysics Data System (ADS)

    Andreas, Sarah

    2010-06-01

    In the framework of the Inert Doublet Model and extensions, the signature of neutrinos from dark matter annihilation in the Earth, the Sun and at the Galactic centre is presented. The model contains an extra Higgs doublet, a neutral component of which is chosen as dark matter candidate. There are three distinct mass ranges for which consistency both with WMAP abundance and direct searches can be obtained: a low (4-8 GeV), a middle (60-70 GeV) and a high (500-1500 GeV) WIMP mass range. The first case is of interest as we showed that the model can at the same time give the correct WMAP abundance and account for the positive DAMA results without contradicting other direct searches. We present how capture in the Sun can further constrain this scenario using Super-Kamiokande data. Indirect detection through neutrinos is challenging for the middle and high mass ranges. For the former, the presence of the so-called `iron resonance' gives rise to larger neutrino fluxes for WIMP masses around 60-70 GeV since capture by the Earth is enhanced. The addition of light right-handed Majo-rana neutrinos to the particle content of the model further increases the signal since it opens a direct annihilation channel into mono-energetic neutrinos. Neutrinos from the Galactic centre might be detected for heavy WIMPs if the dark matter density at the Galactic centre is substantially boosted.

  1. Elementary Goldstone Higgs boson and dark matter

    NASA Astrophysics Data System (ADS)

    Alanne, Tommi; Gertov, Helene; Sannino, Francesco; Tuominen, Kimmo

    2015-05-01

    We investigate a perturbative extension of the Standard Model featuring elementary pseudo-Goldstone Higgs and dark matter particles. These are two of the five Goldstone bosons parametrizing the SU(4)/Sp(4) coset space. They acquire masses, and therefore become pseudo-Goldstone bosons, due to the embedding of the Yukawa and the electroweak gauge interactions that do not preserve the full SU(4) symmetry. At the one-loop order, the top corrections dominate and align the vacuum in the direction where the Higgs is mostly a pseudo-Goldstone boson. Because of the perturbative and elementary nature of the theory, the quantum corrections are precisely calculable. The remaining pseudo-Goldstone boson is identified with the dark matter candidate because it is neutral with respect to the Standard Model and stable. By a direct comparison with the Large Hadron Collider experiments, the model is found to be phenomenologically viable. Furthermore the dark matter particle leads to the observed thermal relic density while respecting the most stringent current experimental constraints.

  2. The baryonic self similarity of dark matter

    SciTech Connect

    Alard, C.

    2014-06-20

    The cosmological simulations indicates that dark matter halos have specific self-similar properties. However, the halo similarity is affected by the baryonic feedback. By using momentum-driven winds as a model to represent the baryon feedback, an equilibrium condition is derived which directly implies the emergence of a new type of similarity. The new self-similar solution has constant acceleration at a reference radius for both dark matter and baryons. This model receives strong support from the observations of galaxies. The new self-similar properties imply that the total acceleration at larger distances is scale-free, the transition between the dark matter and baryons dominated regime occurs at a constant acceleration, and the maximum amplitude of the velocity curve at larger distances is proportional to M {sup 1/4}. These results demonstrate that this self-similar model is consistent with the basics of modified Newtonian dynamics (MOND) phenomenology. In agreement with the observations, the coincidence between the self-similar model and MOND breaks at the scale of clusters of galaxies. Some numerical experiments show that the behavior of the density near the origin is closely approximated by a Einasto profile.

  3. Decaying majoron dark matter and neutrino masses

    SciTech Connect

    Lattanzi, Massimiliano

    2008-01-03

    We review our recent proposal of the majoron as a suitable warm dark matter candidate. The majoron is the Goldstone boson associated to the spontaneous breaking of ungauged lepton number, one of the mechanisms proposed to give rise to neutrino masses. The majoron can acquire a mass through quantum gravity effects, and can possibly account for the observed dark matter component of the Universe. We present constraints on the majoron lifetime, mass and abundance obtained by the analysis of the cosmic microwave background data. We find that, in the case of thermal production, the limits for the majoron mass read 0.12 keV or approx. 250 Gyr. We also apply this results to a given seesaw model for the generation of neutrino masses, and find that this constraints the energy scale for the lepton number breaking phase transition to be > or approx. 10{sup 6} GeV. We thus find that the majoron decaying dark matter (DDM) scenario fits nicely in models where neutrino masses arise a la seesaw, and may lead to other possible cosmological implications.

  4. Geometrical aspects on the dark matter problem

    SciTech Connect

    Capistrano, A.J.S.; Cabral, L.A.

    2014-09-15

    In the present paper we apply Nash’s theory of perturbative geometry to the study of dark matter gravity in a higher-dimensional space–time. It is shown that the dark matter gravitational perturbations at local scale can be explained by the extrinsic curvature of the standard cosmology. In order to test our model, we use a spherically symmetric metric embedded in a five-dimensional bulk. As a result, considering a sample of 10 low surface brightness and 6 high surface brightness galaxies, we find a very good agreement with the observed rotation curves of smooth hybrid alpha-HI measurements. - Highlights: • The metric perturbation and the embedding lead naturally to a “brane-world”-like higher dimensional structure. • Nash’s theorem as a cornerstone of the formation of geometrical structures. • The dark matter gravitational perturbations at local scale can be explained by the extrinsic curvature. • A good agreement was found with the observed rotation curves of smooth hybrid alpha-HI measurements.

  5. Axino dark matter with low reheating temperature

    NASA Astrophysics Data System (ADS)

    Roszkowski, L.; Trojanowski, S.; Turzyński, K.

    2015-11-01

    We examine axino dark matter in the regime of a low reheating temperature, T R , after inflation and taking into account that reheating is a non-instantaneous process. This can have a significant effect on the dark matter abundance, mainly due to entropy production in inflaton decays. We study both thermal and non-thermal production of axinos in the framework of the MSSM with ten free parameters. We identify the ranges of the axino mass and the reheating temperature allowed by the LHC and other particle physics data in different models of axino interactions. We confront these limits with cosmological constraints coming the observed dark matter density, large structures formation and big bang nucleosynthesis. We find a number of differences in the phenomenologically acceptable values of the axino mass m ã and the reheating temperature relative to previous studies. In particular, an upper bound on m ã becomes dependent on T R , reaching a maximum value at T R ≃ 102 GeV. If the lightest ordinary supersymmetric particle is a wino or a higgsino, we obtain a lower limit of approximately 10 GeV for the reheating temperature. We demonstrate also that entropy production during reheating affects the maximum allowed axino mass and lowest values of the reheating temperature.

  6. Minimal model for dark matter and unification

    SciTech Connect

    Mahbubani, Rakhi; Senatore, Leonardo

    2006-02-15

    Gauge coupling unification and the success of TeV-scale weakly-interacting dark matter are usually taken as evidence of low-energy supersymmetry (SUSY). However, if we assume that the tuning of the Higgs can be explained in some unnatural way, from environmental considerations for example, SUSY is no longer a necessary component of any beyond the standard model theory. In this paper we study the minimal model with a dark matter candidate and gauge coupling unification. This consists of the standard model plus fermions with the quantum numbers of SUSY Higgsinos, and a singlet. It predicts thermal dark matter with a mass that can range from 100 GeV to around 2 TeV and generically gives rise to an electric dipole moment (EDM) that is just beyond current experimental limits, with a large portion of its allowed parameter space accessible to next-generation EDM and direct detection experiments. We study precision unification in this model by embedding it in a 5D orbifold GUT where certain large threshold corrections are calculable, achieving gauge coupling and b-{tau} unification, and predicting a rate of proton decay just beyond current limits.

  7. Direct Dark Matter search with XENON100

    NASA Astrophysics Data System (ADS)

    Orrigo, S. E. A.

    2016-07-01

    The XENON100 experiment is the second phase of the XENON program for the direct detection of the dark matter in the universe. The XENON100 detector is a two-phase Time Projection Chamber filled with 161 kg of ultra pure liquid xenon. The results from 224.6 live days of dark matter search with XENON100 are presented. No evidence for dark matter in the form of WIMPs is found, excluding spin-independent WIMP-nucleon scattering cross sections above 2 × 10-45 cm2 for a 55 GeV/c2 WIMP at 90% confidence level (C.L.). The most stringent limit is established on the spin-dependent WIMP-neutron interaction for WIMP masses above 6 GeV/c2, with a minimum cross section of 3.5 × 10-40 cm2 (90% C.L.) for a 45 GeV/c2 WIMP. The same dataset is used to search for axions and axion-like-particles. The best limits to date are set on the axion-electron coupling constant for solar axions, gAe < 7.7 × 10-12 (90% C.L.), and for axion-like-particles, gAe < 1 × 10-12 (90% C.L.) for masses between 5 and 10 keV/c2.

  8. Gravitational effects of condensate dark matter on compact stellar objects

    SciTech Connect

    Li, X.Y.; Wang, F.Y.; Cheng, K.S. E-mail: fayinwang@gmail.com

    2012-10-01

    We study the gravitational effect of non-self-annihilating dark matter on compact stellar objects. The self-interaction of condensate dark matter can give high accretion rate of dark matter onto stars. Phase transition to condensation state takes place when the dark matter density exceeds the critical value. A compact degenerate dark matter core is developed and alter the structure and stability of the stellar objects. Condensate dark matter admixed neutron stars is studied through the two-fluid TOV equation. The existence of condensate dark matter deforms the mass-radius relation of neutron stars and lower their maximum baryonic masses and radii. The possible effects on the Gamma-ray Burst rate in high redshift are discussed.

  9. Dark matter as the trigger of strong electroweak phase transition

    SciTech Connect

    Chowdhury, Talal Ahmed; Nemevšek, Miha; Senjanović, Goran; Zhang, Yue E-mail: miha@ictp.it E-mail: yuezhang@ictp.it

    2012-02-01

    In this paper, we propose a new possible connection between dark matter relic density and baryon asymmetry of the universe. The portal between standard model sector and dark matter not only controls the relic density and detections of dark matter, but also allows the dark matter to trigger the first order electroweak phase transition. We discuss systematically possible scalar dark matter candidates, starting from a real singlet to arbitrary high representations. We show that the simplest realization is provided by a doublet, and that strong first-order electroweak phase transition implies a lower bound on the dark matter direct detection rate. The mass of dark matter lies between 45 and 80 GeV, allowing for an appreciable invisible decay width of the Standard Model Higgs boson, which is constrained to be lighter than 130 GeV for the sake of the strong phase transition.

  10. Constraining Dark Matter and Dark Energy Models using Astrophysical Surveys

    NASA Astrophysics Data System (ADS)

    Cieplak, Agnieszka M.

    This thesis addresses astrophysical probes to constrain dark matter (DM) and dark energy models. Primordial black holes (PBHs) remain one of the few DM candidates within the Standard Model of Particle Physics. This thesis presents a new probe of this PBH DM, using the microlensing of the source stars monitored by the already existing Kepler satellite. With its photometric precision and the large projected cross section of the nearby stars, it is found that previous constraints on PBH DM could theoretically be extended by two orders of magnitude. Correcting a well-known microlensing formula, a limb-darkening analysis is included, and a new approximation is calculated for future star selection. A preliminary prediction is calculated for the planned Wide-Field Infrared Survey Telescope. A preliminary study of the first two years of publicly available Kepler data is presented. The investigation yields many new sources of background error not predicted in the theoretical calculations, such as stellar flares and comets in the field of view. Since no PBH candidates are detected, an efficiency of detection is therefore calculated by running a Monte Carlo with fake limb-darkened finite-source microlensing events. It is found that with just the first 8 quarters of data, a full order of magnitude of the PBH mass range can be already constrained. Finally, one of the astrophysical probes of dark energy is also addressed - specifically, the baryon acoustic oscillations (BAO) measurement in the gas distribution, as detected in quasar absorption lines. This unique measurement of dark energy at intermediate redshifts is being measured by current telescope surveys. The last part of this thesis therefore focuses on understanding the systematic effects in such a detection. Since the bias between the underlying dark matter distribution and the measured gas flux distribution is based on gas physics, hydrodynamic simulations are used to understand the evolution of neutral hydrogen over

  11. Polytropic dark matter flows illuminate dark energy and accelerated expansion

    NASA Astrophysics Data System (ADS)

    Kleidis, K.; Spyrou, N. K.

    2015-04-01

    Currently, a large amount of data implies that the matter constituents of the cosmological dark sector might be collisional. An attractive feature of such a possibility is that, it can reconcile dark matter (DM) and dark energy (DE) in terms of a single component, accommodated in the context of a polytropic-DM fluid. In fact, polytropic processes in a DM fluid have been most successfully used in modeling dark galactic haloes, thus significantly improving the velocity dispersion profiles of galaxies. Motivated by such results, we explore the time evolution and the dynamical characteristics of a spatially-flat cosmological model, in which, in principle, there is no DE at all. Instead, in this model, the DM itself possesses some sort of fluidlike properties, i.e., the fundamental units of the Universe matter-energy content are the volume elements of a DM fluid, performing polytropic flows. In this case, together with all the other physical characteristics, we also take the energy of this fluid's internal motions into account as a source of the universal gravitational field. This form of energy can compensate for the extra energy, needed to compromise spatial flatness, namely, to justify that, today, the total energy density parameter is exactly unity. The polytropic cosmological model, depends on only one free parameter, the corresponding (polytropic) exponent, Γ. We find this model particularly interesting, because for Γ ≤ 0.541, without the need for either any exotic DE or the cosmological constant, the conventional pressure becomes negative enough so that the Universe accelerates its expansion at cosmological redshifts below a transition value. In fact, several physical reasons, e.g., the cosmological requirement for cold DM (CDM) and a positive velocity-of-sound square, impose further constraints on the value of Γ, which is eventually settled down to the range -0.089 < Γ ≤ 0. This cosmological model does not suffer either from the age problem or from the

  12. 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.

  13. Local dark matter from a carefully selected sample

    NASA Astrophysics Data System (ADS)

    Bahcall, John N.; Flynn, Chris; Gould, Andrew

    1992-04-01

    The precise data obtained by Flynn and Freeman (1991) on K giants at the south Galactic pole are used to analyze the amount of local dark matter in which the systematic effects can be modeled easily and evaluated accurately. The method of Bahcall (1984) is employed to solve the self-consistent equations for the distribution of dark matter. The K-giant survey is found to provide significant evidence for disk dark matter. Taking into account all recognized sources of error using a statistical test devised by Gould (1989, 1990), a model with no dark matter is inconsistent with the data at the 86-percent confidence level. The best-fit P-model (in which dark matter is distributed proportionally to known matter) has 53 percent more dark matter than visible matter.

  14. WMAP haze: Directly observing dark matter?

    SciTech Connect

    Forbes, Michael McNeil; Zhitnitsky, Ariel R.

    2008-10-15

    In this paper, we show that dark matter in the form of dense matter/antimatter nuggets could provide a natural and unified explanation for several distinct bands of diffuse radiation from the core of the Galaxy spanning over 13 orders of magnitude in frequency. We fix all of the phenomenological properties of this model by matching to x-ray observations in the keV band, and then calculate the unambiguously predicted thermal emission in the microwave band, at frequencies smaller by 11 orders of magnitude. Remarkably, the intensity and spectrum of the emitted thermal radiation are consistent with - and could entirely explain - the so-called 'WMAP haze': a diffuse microwave excess observed from the core of our Galaxy by the Wilkinson Microwave Anisotropy Probe (WMAP). This provides another strong constraint of our proposal, and a remarkable nontrivial validation. If correct, our proposal identifies the nature of the dark matter, explains baryogenesis, and provides a means to directly probe the matter distribution in our Galaxy by analyzing several different types of diffuse emissions.

  15. The puzzles of dark matter searches

    SciTech Connect

    Khlopov, Maxim Yu.

    2010-06-23

    Positive results of dark matter searches in DAMA/NaI and DAMA/LIBRA experiments, being put together with negative results of other groups, imply nontrivial particle physics solutions for cosmological dark matter. Stable particles with charge -2 bind with primordial helium in O-helium 'atoms' (OHe), representing a specific Warmer than Cold nuclear-interacting form of dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground Dark matter detection like those used in CDMS experiment, but its reactions with nuclei can lead to annual variations of energy release in the interval of energy 2-6 keV in DAMA/NaI and DAMA/LIBRA experiments. Schrodinger equation for system of nucleus and OHe is considered and reduced to an equation of relative motion in a spherically symmetrical potential well, formed by the Yukawa tail of nuclear scalar isoscalar attraction potential, acting on He beyond the nucleus, and dipole Coulomb repulsion between the nucleus and OHe at distances from the nuclear surface, smaller than the size of OHe. The values of coupling strength and mass of meson, mediating scalar isoscalar nuclear potential, are rather uncertain. Within these uncertainties we find a narrow window of these parameters, at which the sodium and/or iodine nuclei have a few keV binding energy with OHe. The concentration of OHe in the matter of underground detectors is adjusted to the incoming flux of cosmic O-helium at the timescale less than few minutes. Therefore the rate of radiative capture of Na and/or I by OHe should experience annual modulations. Transitions to more energetic levels of Na+OHe (I+OHe) system imply tunneling through dipole Coulomb barrier that leads to suppression of annual modulation of events with MeV-tens MeV energy release in the correspondence with the results of DAMA experiments. The proposed explanation inevitably leads to prediction of abundance of anomalous Na (and/or I) corresponding to the signal, observed by DAMA

  16. The puzzles of dark matter searches

    NASA Astrophysics Data System (ADS)

    Khlopov, Maxim Yu.

    2010-06-01

    Positive results of dark matter searches in DAMA/NaI and DAMA/LIBRA experiments, being put together with negative results of other groups, imply nontrivial particle physics solutions for cosmological dark matter. Stable particles with charge -2 bind with primordial helium in O-helium ``atoms'' (OHe), representing a specific Warmer than Cold nuclear-interacting form of dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground Dark matter detection like those used in CDMS experiment, but its reactions with nuclei can lead to annual variations of energy release in the interval of energy 2-6 keV in DAMA/NaI and DAMA/LIBRA experiments. Schrodinger equation for system of nucleus and OHe is considered and reduced to an equation of relative motion in a spherically symmetrical potential well, formed by the Yukawa tail of nuclear scalar isoscalar attraction potential, acting on He beyond the nucleus, and dipole Coulomb repulsion between the nucleus and OHe at distances from the nuclear surface, smaller than the size of OHe. The values of coupling strength and mass of meson, mediating scalar isoscalar nuclear potential, are rather uncertain. Within these uncertainties we find a narrow window of these parameters, at which the sodium and/or iodine nuclei have a few keV binding energy with OHe. The concentration of OHe in the matter of underground detectors is adjusted to the incoming flux of cosmic O-helium at the timescale less than few minutes. Therefore the rate of radiative capture of Na and/or I by OHe should experience annual modulations. Transitions to more energetic levels of Na+OHe (I+OHe) system imply tunneling through dipole Coulomb barrier that leads to suppression of annual modulation of events with MeV-tens MeV energy release in the correspondence with the results of DAMA experiments. The proposed explanation inevitably leads to prediction of abundance of anomalous Na (and/or I) corresponding to the signal, observed by

  17. Vector Dark Matter through a radiative Higgs portal

    DOE PAGESBeta

    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

  18. Vector Dark Matter through a radiative Higgs Portal

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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) W × U (1) Y and under the dark gauge group, U (1)', generate an effective interaction between the Higgs and the dark matter at one loop. 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.

  19. Effects of bound states on dark matter annihilation

    NASA Astrophysics Data System (ADS)

    An, Haipeng; Wise, Mark B.; Zhang, Yue

    2016-06-01

    We study the impact of bound state formation on dark matter annihilation rates in models where dark matter interacts via a light mediator, the dark photon. We derive the general cross section for radiative capture into all possible bound states, and point out its nontrivial dependence on the dark matter velocity and the dark photon mass. For indirect detection, our result shows that dark matter annihilation inside bound states can play an important role in enhancing signal rates over the rate for direct dark matter annihilation with Sommerfeld enhancement. The effects are strongest for large dark gauge coupling and when the dark photon mass is smaller than the typical momentum of dark matter in the Galaxy. As an example, we show that for thermal dark matter the Fermi gamma ray constraint is substantially increased once bound state effects are taken into account. We also find that bound state effects are not important for dark matter annihilation during the freeze-out and recombination epochs.

  20. The offsets between galaxies and their dark matter in Λ cold dark matter

    NASA Astrophysics Data System (ADS)

    Schaller, Matthieu; Robertson, Andrew; Massey, Richard; Bower, Richard G.; Eke, Vincent R.

    2015-10-01

    We use the `Evolution and Assembly of GaLaxies and their Environments' (EAGLE) suite of hydrodynamical cosmological simulations to measure offsets between the centres of stellar and dark matter components of galaxies. We find that the vast majority (>95 per cent) of the simulated galaxies display an offset smaller than the gravitational softening length of the simulations (Plummer-equivalent ɛ = 700 pc), both for field galaxies and satellites in clusters and groups. We also find no systematic trailing or leading of the dark matter along a galaxy's direction of motion. The offsets are consistent with being randomly drawn from a Maxwellian distribution with σ ≤ 196 pc. Since astrophysical effects produce no feasible analogues for the 1.62^{+0.47}_{-0.49} kpc offset recently observed in Abell 3827, the observational result is in tension with the collisionless cold dark matter model assumed in our simulations.

  1. Effective theories for dark matter nucleon scattering

    NASA Astrophysics Data System (ADS)

    Hisano, Junji; Nagai, Ryo; Nagata, Natsumi

    2015-05-01

    We reformulate the calculation of the dark matter-nucleon scattering cross sections based on the method of effective field theories. We assume that the scatterings are induced by the exchange of colored mediators, and construct the effective theories by integrating out the colored particles. All of the leading order matching conditions as well as the renormalization group equations are presented. We consider a Majorana fermion, and real scalar and vector bosons for the dark matter and show the results for each case. The treatment for the twist-2 operators is discussed in detail, and it is shown that the scale of evaluating their nucleon matrix elements does not have to be the hadronic scale. The effects of the QCD corrections are evaluated on the assumption that the masses of the colored mediators are much heavier than the electroweak scale. Our formulation is systematic and model-independent, and thus suitable to be implemented in numerical packages, such as micrOMEGAs and DarkSUSY.

  2. Matter-antimatter asymmetry and dark matter from torsion

    SciTech Connect

    Poplawski, Nikodem J.

    2011-04-15

    We propose a simple scenario which explains the observed matter-antimatter imbalance and the origin of dark matter in the Universe. We use the Einstein-Cartan-Sciama-Kibble theory of gravity which naturally extends general relativity to include the intrinsic spin of matter. Spacetime torsion produced by spin generates, in the classical Dirac equation, the Hehl-Datta term which is cubic in spinor fields. We show that under a charge-conjugation transformation this term changes sign relative to the mass term. A classical Dirac spinor and its charge conjugate therefore satisfy different field equations. Fermions in the presence of torsion have higher energy levels than antifermions, which leads to their decay asymmetry. Such a difference is significant only at extremely high densities that existed in the very early Universe. We propose that this difference caused a mechanism, according to which heavy fermions existing in such a Universe and carrying the baryon number decayed mostly to normal matter, whereas their antiparticles decayed mostly to hidden antimatter which forms dark matter. The conserved total baryon number of the Universe remained zero.

  3. Matter-antimatter asymmetry and dark matter from torsion

    NASA Astrophysics Data System (ADS)

    Popławski, Nikodem J.

    2011-04-01

    We propose a simple scenario which explains the observed matter-antimatter imbalance and the origin of dark matter in the Universe. We use the Einstein-Cartan-Sciama-Kibble theory of gravity which naturally extends general relativity to include the intrinsic spin of matter. Spacetime torsion produced by spin generates, in the classical Dirac equation, the Hehl-Datta term which is cubic in spinor fields. We show that under a charge-conjugation transformation this term changes sign relative to the mass term. A classical Dirac spinor and its charge conjugate therefore satisfy different field equations. Fermions in the presence of torsion have higher energy levels than antifermions, which leads to their decay asymmetry. Such a difference is significant only at extremely high densities that existed in the very early Universe. We propose that this difference caused a mechanism, according to which heavy fermions existing in such a Universe and carrying the baryon number decayed mostly to normal matter, whereas their antiparticles decayed mostly to hidden antimatter which forms dark matter. The conserved total baryon number of the Universe remained zero.

  4. Hierarchical Structure in Dark Matter Distributions

    NASA Astrophysics Data System (ADS)

    Makishima, K.

    Galaxy observers argue for the dark halo surrounding each galaxy, while cluster investigators discuss the domiance of dark matter (DM) in the intra-cluster space. Then, what is the relation between the galaxy DM and the cluster DM? Some believe that the galaxy DM is nothing but a local portion of the cluster DM, while others claim that the cluster DM is merely a sum of the galaxy DM. ASCA studies of the Fornax, Centaurus, Hydra-A, and A1795 clusters have shown that neither is correct: in reality, while a cluster has a massive dark halo, the cD galaxy also has its own smaller-scale dark halo, thus making a halo-in-halo hierarchical structure. The narrower of the two DM concentrations produces a potential dimple at the cluster center, as suggested by gravitational lensing measurements. This dimple in turn produces the central X-ray brightness excess, which was previously thought to arise from cooling flows. Such a nested potential structure has also been discovered around several X-ray bright non-cD elliptical galaxies, including NGC 4636 in particular. These studies will provide us with an understanding of spatial Fourier power-density spectrum of the DM distribution.

  5. Massive gravitons as dark matter and gravitational waves

    NASA Astrophysics Data System (ADS)

    Aoki, Katsuki; Mukohyama, Shinji

    2016-07-01

    We consider the possibility that the massive graviton is a viable candidate for dark matter in the context of bimetric gravity. We first derive the energy-momentum tensor of the massive graviton and show that it indeed behaves as that of dark matter fluid. We then discuss a production mechanism and the present abundance of massive gravitons as dark matter. Since the metric to which ordinary matter fields couple is a linear combination of the two mass eigenstates of bigravity, production of massive gravitons, i.e., the dark matter particles, is inevitably accompanied by generation of massless gravitons, i.e., the gravitational waves. Therefore, in this scenario some information about dark matter in our Universe is encoded in gravitational waves. For instance, if LIGO detects gravitational waves generated by the preheating after inflation, then the massive graviton with the mass of ˜0.01 GeV is a candidate for dark matter.

  6. 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.

  7. Detecting Dark Matter with Imploding Pulsars in the Galactic Center

    NASA Astrophysics Data System (ADS)

    Bramante, Joseph; Linden, Tim

    2014-11-01

    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.

  8. Detecting dark matter with imploding pulsars in the galactic center.

    PubMed

    Bramante, Joseph; Linden, Tim

    2014-11-01

    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. PMID:25415895

  9. LHC bounds on interactions of dark matter

    SciTech Connect

    Rajaraman, Arvind; Shepherd, William; Tait, Tim M. P.; Wijangco, Alexander M.

    2011-11-01

    We derive limits on the interactions of dark matter with quarks from ATLAS null searches for jets+missing energy based on {approx}1 fb{sup -1} of integrated luminosity, using a model-insensitive effective theory framework. We find that the new limits from the LHC significantly extend limits previously derived from CDF data at the Tevatron. Translated into the parameter space of direct searches, these limits are particularly effective for {approx} GeV mass weakly interacting massive particles. Our limits indicate tension with isospin-violating models satisfying minimal flavor violation which attempt to reconcile the purported CoGeNT excess with Xenon-100, indicating that either a light mediator or nontrivial flavor structure for the dark sector is necessary for a viable reconciliation of CoGeNT with Xenon.

  10. Photonic dark matter portal and quantum physics

    NASA Astrophysics Data System (ADS)

    Alavi, S. A.; Kazemian, F. S.

    2016-02-01

    We study a model of dark matter in which the hidden sector interacts with standard model particles via a hidden photonic portal. We investigate the effects of this new interaction on the hydrogen atom, including the Stark, Zeeman and hyperfine effects. Using the accuracy of the measurement of energy, we obtain an upper bound for the coupling constant of the model as f ⩽ 10-12. We also calculate the contribution from the hidden photonic portal to the anomalous magnetic moment of the muon as aμ ⩽ 2.2 × 10-23 (for the dark particle mass scale 100 MeV), which provides an important probe of physics beyond the standard model.

  11. Exploring dark matter with Milky Way substructure.

    PubMed

    Kuhlen, Michael; Madau, Piero; Silk, Joseph

    2009-08-21

    The unambiguous detection of dark matter annihilation in our Galaxy would unravel one of the most outstanding puzzles in particle physics and cosmology. Recent observations have motivated models in which the annihilation rate is boosted by the Sommerfeld effect, a nonperturbative enhancement arising from a long-range attractive force. We applied the Sommerfeld correction to Via Lactea II, a high-resolution N-body simulation of a Milky Way-sized galaxy, to investigate the phase-space structure of the galactic halo. We found that the annihilation luminosity from kinematically cold substructure could be enhanced by orders of magnitude relative to previous calculations, leading to the prediction of gamma-ray fluxes from as many as several hundred dark clumps that should be detectable by the Fermi satellite. PMID:19608862

  12. Simplified Models for Dark Matter Model Building

    NASA Astrophysics Data System (ADS)

    DiFranzo, Anthony Paul

    The largest mass component of the universe is a longstanding mystery to the physics community. As a glaring source of new physics beyond the Standard Model, there is a large effort to uncover the quantum nature of dark matter. Many probes have been formed to search for this elusive matter; cultivating a rich environment for a phenomenologist. In addition to the primary probes---colliders, direct detection, and indirect detection---each with their own complexities, there is a plethora of prospects to illuminate our unanswered questions. In this work, phenomenological techniques for studying dark matter and other possible hints of new physics will be discussed. This work primarily focuses on the use of Simplified Models, which are intended to be a compromise between generality and validity of the theoretical description. They are often used to parameterize a particular search, develop a well-defined sense of complementarity between searches, or motivate new search strategies. Explicit examples of such models and how they may be used will be the highlight of each chapter.

  13. The Logotropic Dark Fluid as a unification of dark matter and dark energy

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri

    2016-07-01

    We propose a heuristic unification of dark matter and dark energy in terms of a single "dark fluid" with a logotropic equation of state P = Aln ⁡ (ρ /ρP), where ρ is the rest-mass density, ρP = 5.16 ×1099gm-3 is the Planck density, and A is the logotropic temperature. The energy density ɛ is the sum of a rest-mass energy term ρc2 ∝a-3 mimicking dark matter and an internal energy term u (ρ) = - P (ρ) - A = 3 Aln ⁡ a + C mimicking dark energy (a is the scale factor). The logotropic temperature is approximately given by A ≃ρΛc2 / ln ⁡ (ρP /ρΛ) ≃ρΛc2 / [ 123 ln ⁡ (10) ], where ρΛ = 6.72 ×10-24gm-3 is the cosmological density and 123 is the famous number appearing in the ratio ρP /ρΛ ∼10123 between the Planck density and the cosmological density. More precisely, we obtain A = 2.13 ×10-9gm-1s-2 that we interpret as a fundamental constant. At the cosmological scale, our model fulfills the same observational constraints as the ΛCDM model (they will differ in about 25 Gyrs when the logotropic universe becomes phantom). However, the logotropic dark fluid has a nonzero speed of sound and a nonzero Jeans length which, at the beginning of the matter era, is about λJ = 40.4pc, in agreement with the minimum size of the dark matter halos observed in the universe. The existence of a nonzero Jeans length may solve the missing satellite problem. At the galactic scale, the logotropic pressure balances the gravitational attraction, providing halo cores instead of cusps. This may solve the cusp problem. The logotropic equation of state generates a universal rotation curve that agrees with the empirical Burkert profile of dark matter halos up to the halo radius. In addition, it implies that all the dark matter halos have the same surface density Σ0 =ρ0rh = 141M⊙ /pc2 and that the mass of dwarf galaxies enclosed within a sphere of fixed radius ru = 300pc has the same value M300 = 1.93 ×107M⊙, in remarkable agreement with the observations

  14. The Shape of Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Olling, Robert Paul

    1995-01-01

    After reviewing our current knowledge of dark matter (DM) in spiral galaxies (Chapter 1), I present a new method of deriving the shape of these dark halos (Chapter 2). Such information, if obtained for a large number of systems, can provide important boundary conditions for theories of the formation of galaxies (Chapter 5). The halo-shape determination method relies on the comparison of model predictions of the thickness of the gas layer with observations of this flaring. Calculating the model gas layer widths from the observed gaseous velocity dispersion and the potential due to the total mass distribution of the galaxy we learn the following: (a) beyond the optical disk the thickness of the gas layer is sensitive to the shape of the DM halo, (b) the thickness of the gas layer is proportional to the ratio of the gaseous velocity dispersion and the rotation speed, (c) the self-gravity of the gas contributes significantly to the vertical force, (d) the derived shape of the DM halo is independent of the dark matter's radial density distribution, and is independent of the mass-to-light ratio of the stellar disk (f). In Chapter 3 I present a new method (usable for inclinations larger than 60^circ) to determine the thickness of the gas layer of spiral galaxies from high resolution H sc I observations. I use VLA H sc I observations of the almost edge-on Scd galaxy NGC 4244 to determine the gaseous velocity dispersion, and the flaring and rotation curves. From the Keplerian decline of the rotation curve beyond the stellar disks it follows that the dark-to-luminous mass ratio is at most two and a half. Combining the model predictions for the radial variation of the thickness of the gas layer with the measured flaring curve I find that the dark matter halo of NGC 4244 is highly flattened. The best fit occurs for a halo with an E8 shape (with a mass one-eight of an E0 halo), while the uncertainty (E5-E9) is dominated by the errors in the gaseous velocity dispersion: a round

  15. Asymmetric capture of Dirac dark matter by the Sun

    SciTech Connect

    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 and 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.

  16. Direct and indirect detection of dissipative dark matter

    SciTech Connect

    Fan, JiJi; Katz, Andrey; Shelton, Jessie E-mail: katz.andrey@gmail.com

    2014-06-01

    We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics allow this subdominant dark matter component to cool, resulting in its partial or total collapse into a smaller volume inside the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion compared to that of normal cold dark matter. We first show that these features considerably relax the limits from direct detection experiments on the couplings between standard model (SM) particles and dissipative dark matter. On the other hand, indirect detection of the annihilation of the symmetric dissipative dark matter component inside the Sun sets stringent and robust constraints on the properties of the dissipative dark matter. In particular, IceCube observations force dissipative dark matter particles with mass above 50 GeV to either have a small coupling to the SM or a low local density in the solar system, or to have a nearly asymmetric relic abundance. Possible helioseismology signals associated with purely asymmetric dissipative dark matter are discussed, with no present constraints.

  17. Self Interacting Dark Matter and Baryons

    NASA Astrophysics Data System (ADS)

    Fry, Alexander B.; Governato, Fabio; Pontzen, Andrew; Quinn, Thomas R.

    2015-01-01

    Self Interacting Dark Matter (SIDM) is a cosmologically consistent alternative theory to Cold Dark Matter (CDM). SIDM is motivated as a solution to solve problems of the CDM model on small scales including the core/cusp problem, the missing satellites, and halo triaxiality. Each of these problems has secular astrophysical solutions, however taken together and along with suggestions from dark matter (DM) particle physics it is interesting to place constraints on how strong a self interaction would have to be for us to observe it and conversely the null hypothesis of whether we can rule out SIDM. We use high resolution cosmological simulations to compare evolution of stellar populations and (DM) components of dwarf galaxies. Our advanced smooth particle hydrodynamics N-body simulations combine SIDM with baryon physics including star formation, feedback recipes, metal line cooling, UV background, and thermal diffusion that eliminates artificial surface gas tension. We find for a constant SIDM cross section of 2 cm2 g-1 that DM interactions alone are not significant enough to create cores in dwarf galaxies and for low mass (Vpeak= 25 km s-1) galaxies the introduction of SIDM fails to decrease the DM central density. Our simulations with star formation feedback are in good agreement with observational estimates of Local Group dwarfs. The lower mass (below 108 M⊙) halos have inefficient SF, late formation time, and less DM interactions thus small field halos in CDM and SIDM remain cuspy. We conclude that constant cross section SIDM of 2 cm2 g-1 would be close to unobservable in dwarf galaxies and yet at the same time this cross section is already larger than some observational constraints found in larger (higher velocity) systems. We conclude that to differentiate between SIDM and CDM in an observationally detectable and astrophysically consistent manner a velocity dependent cross section that peaks for halos with small peak velocities will be necessary.

  18. An Effective Theory of Dirac Dark Matter

    SciTech Connect

    Harnik, Roni; Kribs, Graham D.; /Oregon U.

    2010-06-11

    A stable Dirac fermion with four-fermion interactions to leptons suppressed by a scale {Lambda} {approx} 1 TeV is shown to provide a viable candidate for dark matter. The thermal relic abundance matches cosmology, while nuclear recoil direct detection bounds are automatically avoided in the absence of (large) couplings to quarks. The annihilation cross section in the early Universe is the same as the annihilation in our galactic neighborhood. This allows Dirac fermion dark matter to naturally explain the positron ratio excess observed by PAMELA with a minimal boost factor, given present astrophysical uncertainties. We use the Galprop program for propagation of signal and background; we discuss in detail the uncertainties resulting from the propagation parameters and, more importantly, the injected spectra. Fermi/GLAST has an opportunity to see a feature in the gamma-ray spectrum at the mass of the Dirac fermion. The excess observed by ATIC/PPB-BETS may also be explained with Dirac dark matter that is heavy. A supersymmetric model with a Dirac bino provides a viable UV model of the effective theory. The dominance of the leptonic operators, and thus the observation of an excess in positrons and not in anti-protons, is naturally explained by the large hypercharge and low mass of sleptons as compared with squarks. Minimizing the boost factor implies the right-handed selectron is the lightest slepton, which is characteristic of our model. Selectrons (or sleptons) with mass less than a few hundred GeV are an inescapable consequence awaiting discovery at the LHC.

  19. Simulating Gravity: Dark Matter and Gravitational Lensing in the Classroom

    ERIC Educational Resources Information Center

    Ford, Jes; Stang, Jared; Anderson, Catherine

    2015-01-01

    Dark matter makes up most of the matter in the universe but very little of a standard introductory physics curriculum. Here we present our construction and use of a spandex sheet-style gravity simulator to qualitatively demonstrate two aspects of modern physics related to dark matter. First, we describe an activity in which students explore the…

  20. Gravity resonance spectroscopy constrains dark energy and dark matter scenarios.

    PubMed

    Jenke, T; Cronenberg, G; Burgdörfer, J; Chizhova, L A; Geltenbort, P; Ivanov, A N; Lauer, T; Lins, T; Rotter, S; Saul, H; Schmidt, U; Abele, H

    2014-04-18

    We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate that Newton's inverse square law of gravity is understood at micron distances on an energy scale of 10-14  eV. At this level of precision, we are able to provide constraints on any possible gravitylike interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant β>5.8×108 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axionlike spin-mass coupling is excluded for the coupling strength gsgp>3.7×10-16 (5.3×10-16) at a Yukawa length of λ=20  μm (95% C.L.). PMID:24785025

  1. Dark Energy and Dark Matter from the same Vacuum Condensate

    NASA Astrophysics Data System (ADS)

    Sarfatti, Jack

    2003-04-01

    The micro-quantum Dirac negative energy electron Fermi sphere with Planck scale cutoff is unstable to the formation of off-mass-shell Cooper pairs of virtual electrons and positrons from their static Coulomb attraction. The resulting virtual BEC complex macro-quantum coherent local order parameter (0|e+e-|0) gives rise to both spin 2 gravity guv and spin 0 quintessence / from the Goldstone and Higgs oscillations respectively, Susskind's "world hologram" conjecture replaces the Planck scale Lp with Lp^2/3L^1/3 at scale L. Hagen Kleinert's strain tensor for the "world crystal" is Einstein's geometrodynamic field: guv = nuv + Lp^4/3L^2/3Du,Dvarg(0|e+e-|0)/2 nuv = Minkowski metric, = anti-commutator Du = ,u + TaAu^a is the spin 1 gauge covariant derivative for Lie group P with Lie algebra [Ta,Tb] = Cab^cTc / = Lp-4/3L-2/3[1 - Lp^2L|(0|e+e-|0)|^2] When L = size of visible universe 10^28 cm, Lp^2/3L^1/3 1 fermi / > 0 is anti-gravitating zero point vacuum dark energy, i.e. Kip Thorne's "exotic matter" for traversable wormhole time machines. / < 0 is gravitating zero point vacuum dark matter The non-perturbative BCS energy gap equation for a basic vacuum polarization closed loop with one virtual photon Feynman diagram is: z^2 = ge^-(1/gz) z = (Lp/L)^1/3 and the dimensionless coupling vertex is g^1/2 http://stardrive.org/Jack/nambu.pdf http://stardrive.org/Jack/Lambda1.pdf

  2. Dark Matter research with the PAMELA Mission

    NASA Astrophysics Data System (ADS)

    Picozza, P.; Malvezzi, V.

    The PAMELA satellite-borne experiment was launched from the Baikonur launch site on the 15th of June 2006. Since July 2006 it is daily delivering to ground 16GBytes of data. The instrument is composed by a magnetic spectrometer, a time-of-flight system, a silicon-tungsten electromagnetic calorimeter, a neutron detector and anticoincidence scintillators. The primary scientific goal is to searching for evidence of dark matter particle annihilations studying antiparticles fluxes. Preliminary results concerning antiproton-proton and positron-electron ratios are presented.

  3. Dark Matter from Binary Tetrahedral Flavor Symmetry

    NASA Astrophysics Data System (ADS)

    Eby, David; Frampton, Paul

    2012-03-01

    Binary Tetrahedral Flavor Symmetry, originally developed as a quark family symmetry and later adapted to leptons, has proved both resilient and versatile over the past decade. In 2008 a minimal T' model was developed to accommodate quark and lepton masses and mixings using a family symmetry of (T'xZ2). We examine an expansion of this earlier model using an additional Z2 group that facilitates predictions of WIMP dark matter, the Cabibbo angle, and deviations from Tribimaximal Mixing, while giving hints at the nature of leptogenesis.

  4. Solitonic axion condensates modeling dark matter halos

    NASA Astrophysics Data System (ADS)

    Castañeda Valle, David; Mielke, Eckehard W.

    2013-09-01

    Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose-Einstein type condensates could provide a viable soliton type interpretation of the DM 'bullets' observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein-Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two 'lump' type solitons.

  5. Excluding Light Asymmetric Bosonic Dark Matter

    NASA Astrophysics Data System (ADS)

    Kouvaris, Chris; Tinyakov, Peter

    2011-08-01

    We argue that current neutron star observations exclude asymmetric bosonic noninteracting dark matter in the range from 2 keV to 16 GeV, including the 5-15 GeV range favored by DAMA and CoGeNT. If bosonic weakly interacting massive particles (WIMPs) are composite of fermions, the same limits apply provided the compositeness scale is higher than ˜1012GeV (for WIMP mass ˜1GeV). In the case of repulsive self-interactions, we exclude the large range of WIMP masses and interaction cross sections which complements the constraints imposed by observations of the Bullet Cluster.

  6. Dark matter as residual of topological changes

    NASA Astrophysics Data System (ADS)

    Barbachoux, Cécile; Kouneiher, Joseph

    2016-01-01

    We investigate in this paper the possibilities that the observed cold dark matter density can be generated by decays of a heavy scalar field which dominate the universe at the quantum regime. Indeed, we present two approaches based on an extension of quantum field theory to the case when spacetime topology fluctuates (spacetime foam, at the quantum regime). In this extension the number of bosonic fields becomes a variable and the ground state is characterized by a finite particle number density. In the second approach it is the gauge-group parameters which became dynamical. This is tributary on the Centrally Extended Group and Cohomology.

  7. Re-ionization and decaying dark matter

    NASA Technical Reports Server (NTRS)

    Dodelson, Scott; Jubas, Jay M.

    1991-01-01

    Gunn-Peterson tests suggest that the Universe was reionized after the standard recombination epoch. A systematic treatment is presented of the ionization process by deriving the Boltzmann equations appropriate to this regime. A compact solution for the photon spectrum is found in terms of the ionization ratio. These equations are then solved numerically for the Decaying Dark Matter scenario, wherein neutrinos with mass of order 30 eV radiatively decay producing photons which ionize the intergalactic medium. It was found that the neutrino mass and lifetime are severely constrained by Gunn-Peterson tests, observations of the diffuse photon spectrum in the ultraviolet regime, and the Hubble parameter.

  8. KIMS : Dark Matter Search Experiment in Korea

    SciTech Connect

    Kim, Sun Kee

    2005-12-02

    KIMS is an experimental group searching for dark matter in an underground laboratory in Korea. Major effort of KIMS has been devoted for the development of low background CsI(Tl) crystal detectors with low threshold for the direct WIMP search. An underground laboratory utilizing the space in a tunnel of Yangyang Pumped Storage Power Plant is established. We present the first result obtained with one crystal detector and the future prospect of WIMP search as well as other research activities carried out by KIMS.

  9. KIMS : Dark Matter Search Experiment in Korea

    NASA Astrophysics Data System (ADS)

    Kim, Sun Kee

    2005-12-01

    KIMS is an experimental group searching for dark matter in an underground laboratory in Korea. Major effort of KIMS has been devoted for the development of low background CsI(Tl) crystal detectors with low threshold for the direct WIMP search. An underground laboratory utilizing the space in a tunnel of Yangyang Pumped Storage Power Plant is established. We present the first result obtained with one crystal detector and the future prospect of WIMP search as well as other research activities carried out by KIMS.

  10. The Future of Astronomical Dark Matter Probes

    NASA Astrophysics Data System (ADS)

    Peter, Annika; Kim, Stacy; Cyr-Racine, Francis-Yan; Drlica-Wagner, Alex

    2016-01-01

    As we map the local and distant universe ever more comprehensively, including in the time domain, there will be many new ways to identify and exploit the impact of the distribution and evolution of dark matter on many scales. These will come from GAIA, JWST, LSST, and WFIRST, as well as other dedicated approaches. We present and evaluate the potential of a broad set of measurements that may be possible in the near future, and discuss the key challenges and potential solutions, for each.

  11. Antideuterons from decaying gravitino dark matter

    SciTech Connect

    Delahaye, Timur; Grefe, Michael

    2015-07-08

    We study the possibility of improving the constraints on the lifetime of gravitino dark matter in scenarios with bilinear R-parity violation by estimating the amount of cosmic-ray antideuterons that can be produced in gravitino decays. Taking into account all different sources of theoretical uncertainties, we find that the margin of improvement beyond the limits already set by cosmic-ray antiproton data are quite narrow and unachievable for the next generation of experiments. However, we also identify more promising energy ranges for future experiments.

  12. Axion dark matter and cosmological parameters.

    PubMed

    Erken, O; Sikivie, P; Tam, H; Yang, Q

    2012-02-10

    We observe that photon cooling after big bang nucleosynthesis but before recombination can remove the conflict between the observed and theoretically predicted value of the primordial abundance of ^{7}Li. Such cooling is ordinarily difficult to achieve. However, the recent realization that dark matter axions form a Bose-Einstein condensate provides a possible mechanism because the much colder axions may reach thermal contact with the photons. This proposal predicts a high effective number of neutrinos as measured by the cosmic microwave anisotropy spectrum. PMID:22401054

  13. EDELWEISS experiment: Direct search for dark matter

    SciTech Connect

    Lubashevskiy, A. V. Yakushev, E. A.

    2008-07-15

    The EDELWEISS experiment is aimed at direct searches for nonbaryonic cold dark matter by means of cryogenic germanium detectors. It is deployed at the LSM underground laboratory in the Frejus tunnel, which connects France and Italy. The results of the experimentmade it possible to set a limit on the spin-independent cross section for the scattering of weak-interacting massive particles (WIMP) at a level of 10{sup -6} pb. Data from 21 detectors of total mass about 7 kg are being accumulated at the present time.

  14. Taming astrophysical bias in direct dark matter searches

    SciTech Connect

    Pato, Miguel; Strigari, Louis E.; Trotta, Roberto; Bertone, Gianfranco E-mail: strigari@stanford.edu E-mail: gf.bertone@gmail.com

    2013-02-01

    We explore systematic biases in the identification of dark matter in future direct detection experiments and compare the reconstructed dark matter properties when assuming a self-consistent dark matter distribution function and the standard Maxwellian velocity distribution. We find that the systematic bias on the dark matter mass and cross-section determination arising from wrong assumptions for its distribution function is of order ∼ 1σ. A much larger systematic bias can arise if wrong assumptions are made on the underlying Milky Way mass model. However, in both cases the bias is substantially mitigated by marginalizing over galactic model parameters. We additionally show that the velocity distribution can be reconstructed in an unbiased manner for typical dark matter parameters. Our results highlight both the robustness of the dark matter mass and cross-section determination using the standard Maxwellian velocity distribution and the importance of accounting for astrophysical uncertainties in a statistically consistent fashion.

  15. Growth of black holes and dark matter accretion

    NASA Astrophysics Data System (ADS)

    Munyaneza, Faustin; Biermann, Peter L.

    2006-12-01

    We investigate the distribution of fermion dark matter in the Milky Way galaxy and find that dark matter could gravitationally condensate in a degenerate core of mass of 3 × 106Mdot o embedded in a dark matter halo of 3 × 1012Mdot o with a size of about 200 kpc. We then show that the galactic black hole of mass of about 3 × 106Mdot o might have grown from a stellar seed black hole by mainly accreting dark matter from the compact degenerate fermion core. This leads to a lower limit on the mass of the fermion dark matter of about (6 10) keV. It is then argued that the constrained dark matter could be a sterile neutrino.

  16. Mystery of the Hidden Cosmos [Complex Dark Matter

    DOE PAGESBeta

    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

  17. Dark matter distribution and annihilation at the Galactic center

    NASA Astrophysics Data System (ADS)

    Dokuchaev, V. I.; Eroshenko, Yu N.

    2016-02-01

    We describe a promising method for measuring the total dark matter mass near a supermassive black hole at the Galactic center based on observations of nonrelativistic precession of the orbits of fast S0 stars. An analytical expression for the precession angle has been obtained under the assumption of a power-law profile of the dark matter density. The awaited weighing of the dark matter at the Galactic center provides the strong constraints on the annihilation signal from the neuralino dark matter particle candidate. The mass of the dark matter necessary for the explanation of the observed excess of gamma-radiation owing to the annihilation of the dark matter particles has been calculated with allowance for the Sommerfeld effect.

  18. Directional detection of dark matter in universal bound states

    SciTech Connect

    Laha, Ranjan

    2015-10-01

    It has been suggested that several small-scale structure anomalies in 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 angular recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. 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.

  19. Directional detection of dark matter in universal bound states

    SciTech Connect

    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 angular 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.

  20. Gravity-mediated (or composite) Dark Matter confronts astrophysical data

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Min; Park, Myeonghun; Sanz, Verónica

    2014-05-01

    We consider the astrophysical bounds on a new form of dark matter, the so called Gravity-mediated Dark Matter. In this scenario, dark matter communicates with us through a mediator sector composed of gravitational resonances, namely a new scalar (radion) and a massive spin-two resonance (massive graviton). We consider specific models motivated by natural electroweak symmetry breaking or weak-scale dark matter in the context of models in warped extra-dimensions and their composite duals. The main Dark Matter annihilation mechanism is due to the interactions of KK gravitons to gauge bosons that propagate in bulk. We impose the bounds on monochromatic or continuum photons from Fermi-LAT and HESS. We also explore scenarios in which the Fermi gamma-ray line could be a manifestation of Gravity-mediated Dark Matter.