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A Critical Reevaluation Of Radio Constraints On Annihilating Dark Matter
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Book Synopsis A Critical Reevaluation of Radio Constraints on Annihilating Dark Matter by :
Download or read book A Critical Reevaluation of Radio Constraints on Annihilating Dark Matter written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of groups have employed radio observations of the Galactic center to derive stringent constraints on the annihilation cross section of weakly interacting dark matter. In this paper, we show that electron energy losses in this region are likely to be dominated by inverse Compton scattering on the interstellar radiation field, rather than by synchrotron, considerably relaxing the constraints on the dark matter annihilation cross section compared to previous works. Strong convective winds, which are well motivated by recent observations, may also significantly weaken synchrotron constraints. After taking these factors into account, we find that radio constraints on annihilating dark matter are orders of magnitude less stringent than previously reported, and are generally weaker than those derived from current gamma-ray observations.
Book Synopsis Prospects of Radio Observations of Dark Matter Annihilation by : Kathrin Böckmann
Download or read book Prospects of Radio Observations of Dark Matter Annihilation written by Kathrin Böckmann and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Isotropic Radio Background and Annihilating Dark Matter by :
Download or read book The Isotropic Radio Background and Annihilating Dark Matter written by and published by . This book was released on 2012 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations by ARCADE-2 and other telescopes sensitive to low frequency radiation have revealed the presence of an isotropic radio background with a hard spectral index. The intensity of this observed background is found to exceed the flux predicted from astrophysical sources by a factor of approximately 5-6. In this article, we consider the possibility that annihilating dark matter particles provide the primary contribution to the observed isotropic radio background through the emission of synchrotron radiation from electron and positron annihilation products. For reasonable estimates of the magnetic fields present in clusters and galaxies, we find that dark matter could potentially account for the observed radio excess, but only if it annihilates mostly to electrons and/or muons, and only if it possesses a mass in the range of approximately 5-50 GeV. For such models, the annihilation cross section required to normalize the synchrotron signal to the observed excess is sigma v ̃(0.4-30) x 10-̂26 cm3̂/s, similar to the value predicted for a simple thermal relic (sigma v ̃3 x 10-̂26 cm3̂/s). We find that in any scenario in which dark matter annihilations are responsible for the observed excess radio emission, a significant fraction of the isotropic gamma ray background observed by Fermi must result from dark matter as well.
Book Synopsis Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope by :
Download or read book Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope written by and published by . This book was released on 2012 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Constraints on Cosmological Dark Matter Annihilation from the Fermi-LAT Isotropic Diffuse Gamma-Ray Measurement by :
Download or read book Constraints on Cosmological Dark Matter Annihilation from the Fermi-LAT Isotropic Diffuse Gamma-Ray Measurement written by and published by . This book was released on 2013 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Stringent Constraints on the Dark Matter Annihilation Cross Section From Subhalo Searches with the Fermi Gamma-Ray Space Telescope by :
Download or read book Stringent Constraints on the Dark Matter Annihilation Cross Section From Subhalo Searches with the Fermi Gamma-Ray Space Telescope written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The dark matter halo of the Milky Way is predicted to contain a very large number of smaller subhalos. As a result of the dark matter annihilations taking place within such objects, the most nearby and massive subhalos could appear as point-like or spatially extended gamma-ray sources, without observable counterparts at other wavelengths. In this paper, we use the results of the Aquarius simulation to predict the distribution of nearby subhalos, and compare this to the characteristics of the unidentified gamma-ray sources observed by the Fermi Gamma-Ray Space Telescope. Focusing on the brightest high latitude sources, we use this comparison to derive limits on the dark matter annihilation cross section. For dark matter particles lighter than ~200 GeV, the resulting limits are the strongest obtained to date, being modestly more stringent than those derived from observations of dwarf galaxies or the Galactic Center. We also derive independent limits based on the lack of unidentified gamma-ray sources with discernible spatial extension, but these limits are a factor of ~2-10 weaker than those based on point-like subhalos. Lastly, we note that four of the ten brightest high-latitude sources exhibit a similar spectral shape, consistent with 30-60 GeV dark matter particles annihilating to b quarks with an annihilation cross section on the order of sigma v ~ (5-10) x 10^-27 cm^3/s, or 8-10 GeV dark matter particles annihilating to taus with sigma v ~ (2.0-2.5) x 10^-27 cm^3/s.
Book Synopsis Constraints on Galactic Dark Matter with Multi-annihilation Channels from Charged Cosmic-ray by : Yu Heng Chen
Download or read book Constraints on Galactic Dark Matter with Multi-annihilation Channels from Charged Cosmic-ray written by Yu Heng Chen and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis New Limits on Dark Matter Annihilation from AMS Cosmic Ray Positron Data by :
Download or read book New Limits on Dark Matter Annihilation from AMS Cosmic Ray Positron Data written by and published by . This book was released on 2013 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Sensitivity of Radio Emission from Galaxy Clusters and Dwarf Spheroidal Galaxies to Dark Matter Annihilation by : Jan-Erik Schönberg
Download or read book Sensitivity of Radio Emission from Galaxy Clusters and Dwarf Spheroidal Galaxies to Dark Matter Annihilation written by Jan-Erik Schönberg and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis BBN Constraints on the Annihilation of MeV-scale Dark Matter by : P. F. Depta
Download or read book BBN Constraints on the Annihilation of MeV-scale Dark Matter written by P. F. Depta and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Limits on Dark Matter Annihilation Signals from the Fermi LAT 4-year Measurement of the Isotropic Gamma-Ray Background by :
Download or read book Limits on Dark Matter Annihilation Signals from the Fermi LAT 4-year Measurement of the Isotropic Gamma-Ray Background written by and published by . This book was released on 2015 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Telescope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predictions compared to previous work. More specifically, we estimate the cosmologically-induced gamma-ray intensity to have an uncertainty of a factor ~ 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former on the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies. This is possible thanks to the new Fermi LAT IGRB measurement, which now extends up to an energy of 820 GeV. As a result, we quantify uncertainties in detail and show the potential this type of search offers for testing the WIMP paradigm with a complementary and truly cosmological probe of DM particle signals.
Book Synopsis The Effects of Dark Matter Annihilation on Cosmic Reionization by :
Download or read book The Effects of Dark Matter Annihilation on Cosmic Reionization written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We revisit the possibility of constraining the properties of dark matter (DM) by studying the epoch of cosmic reionization. Previous studies have shown that DM annihilation was unlikely to have provided a large fraction of the photons that ionized the universe, but instead played a subdominant role relative to stars and quasars. The DM, however, begins to efficiently annihilate with the formation of primordial microhalos at $z\sim100-200$, much earlier than the formation of the first stars. Therefore, if DM annihilation ionized the universe at even the percent level over the interval $z \sim 20-100$, it can leave a significant imprint on the global optical depth, $\tau$. Moreover, we show that cosmic microwave background (CMB) polarization data and future 21 cm measurements will enable us to more directly probe the DM contribution to the optical depth. In order to compute the annihilation rate throughout the epoch of reionization, we adopt the latest results from structure formation studies and explore the impact of various free parameters on our results. We show that future measurements could make it possible to place constraints on the dark matter's annihilation cross section that are at a level comparable to those obtained from the observations of dwarf galaxies, cosmic ray measurements, and studies of recombination.
Book Synopsis Constraints on Dark Matter Annihilations from Diffuse Gamma-ray Emission in the Galaxy by :
Download or read book Constraints on Dark Matter Annihilations from Diffuse Gamma-ray Emission in the Galaxy written by and published by . This book was released on 2013 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis What Does The PAMELA Antiproton Spectrum Tell Us About Dark Matter? by :
Download or read book What Does The PAMELA Antiproton Spectrum Tell Us About Dark Matter? written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the cosmic ray antiproton spectrum can be used to search for contributions from annihilating dark matter and to constrain the dark matter annihilation cross section. Depending on the assumptions made regarding cosmic ray propagation in the Galaxy, such constraints can be quite stringent. We revisit this topic, utilizing a set of propagation models fit to the cosmic ray boron, carbon, oxygen and beryllium data. We derive upper limits on the dark matter annihilation cross section and find that when the cosmic ray propagation parameters are treated as nuisance parameters (as we argue is appropriate), the resulting limits are significantly less stringent than have been previously reported. We also note (as have several previous groups) that simple GALPROP-like diffusion-reacceleration models predict a spectrum of cosmic ray antiprotons that is in good agreement with PAMELA's observations above ~ 5 GeV, but that significantly underpredict the flux at lower energies. Although the complexity of modeling cosmic ray propagation at GeV-scale energies makes it difficult to determine the origin of this discrepancy, we consider the possibility that the excess antiprotons are the result of annihilating dark matter. Suggestively, we find that this excess is best fit for mDM ~ 35 GeV and [sigma] v ~ 10$-$26 cm3/s (to $b\bar{_b}$), in good agreement with the mass and cross section previously shown to be required to generate the gamma-ray excess observed from the Galactic Center.
Book Synopsis Placing Limits on Experimental Signatures of Dark Matter Model Predictions by : Arjun Sharma
Download or read book Placing Limits on Experimental Signatures of Dark Matter Model Predictions written by Arjun Sharma and published by . This book was released on 2018 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, we consider two different models of dark matter and set limits on results of experiments. One is a dynamic dark matter scenario where we put limits on parameters observable by experiments DAMA and XMASS through nuclear recoil of detector atoms (direct detection). The second is a case of dark matter annihilation into positrons and electrons and the signal this would produce on measured values of positron flux and ratio of electron to positron (indirect detection). The values of these quantities as measured by FERMI and PAMELA experiments are observed and an explanation using a dark matter annihilation is presented vs astrophysical sources of particles.
Download or read book Neutrino Mass written by Guido Altarelli and published by Springer. This book was released on 2004-02-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews the current state of knowledge of neutrino masses and the related question of neutrino oscillations. After an overview of the theory of neutrino masses and mixings, detailed accounts are given of the laboratory limits on neutrino masses, astrophysical and cosmological constraints on those masses, experimental results on neutrino oscillations, the theoretical interpretation of those results, and theoretical models of neutrino masses and mixings. The book concludes with an examination of the potential of long-baseline experiments. This is an essential reference text for workers in elementary-particle physics, nuclear physics, and astrophysics.
Book Synopsis New Worlds, New Horizons in Astronomy and Astrophysics by : National Research Council
Download or read book New Worlds, New Horizons in Astronomy and Astrophysics written by National Research Council and published by National Academies Press. This book was released on 2011-02-04 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
