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Multistep Cascade Annihilations Of Dark Matter And The Galactic Center Excess
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Book Synopsis Multistep Cascade Annihilations of Dark Matter and the Galactic Center Excess by :
Download or read book Multistep Cascade Annihilations of Dark Matter and the Galactic Center Excess written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: If dark matter is embedded in a non-trivial dark sector, it may annihilate and decay to lighter dark-sector states which subsequently decay to the Standard Model. Such scenarios - with annihilation followed by cascading dark-sector decays - can explain the apparent excess GeV gamma-rays identified in the central Milky Way, while evading bounds from dark matter direct detection experiments. Each 'step' in the cascade will modify the observable signatures of dark matter annihilation and decay, shifting the resulting photons and other final state particles to lower energies and broadening their spectra. We explore, in a model-independent way, the effect of multi-step dark-sector cascades on the preferred regions of parameter space to explain the GeV excess. We find that the broadening effects of multi-step cascades can admit final states dominated by particles that would usually produce too sharply peaked photon spectra; in general, if the cascades are hierarchical (each particle decays to substantially lighter particles), the preferred mass range for the dark matter is in all cases 20-150 GeV. Decay chains that have nearly-degenerate steps, where the products are close to half the mass of the progenitor, can admit much higher DM masses. We map out the region of mass/cross-section parameter space where cascades (degenerate, hierarchical or a combination) can fit the signal, for a range of final states. In the current paper, we study multi-step cascades in the context of explaining the GeV excess, but many aspects of our results are general and can be extended to other applications.
Book Synopsis Dark Matter Annihilation at the Galactic Center by :
Download or read book Dark Matter Annihilation at the Galactic Center written by and published by . This book was released on 2013 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 role of future telescopes in di erentiating a dark matter model from astrophysical emission.
Book Synopsis Search for Dark Matter Annihilation in the Galactic Center with IceCube-79 by :
Download or read book Search for Dark Matter Annihilation in the Galactic Center with IceCube-79 written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope by :
Download or read book Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope written by and published by . This book was released on 2010 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and Decay Into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies by :
Download or read book Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and Decay Into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies written by and published by . This book was released on 2009 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We provide conservative bounds on the dark matter cross-section and lifetime from final state radiation produced by annihilation or decay into charged leptons, either directly or via an intermediate particle [phi]. Our analysis utilizes the experimental gamma-ray flux upper limits from four Milky Way dwarf satellites: HESS observations of Sagittarius and VERITAS observations of Draco, Ursa Minor, and Willman 1. Using 90% confidence level lower limits on the integrals over the dark matter distributions, we find that these constraints are largely unable to rule out dark matter annihilations or decays as an explanation of the PAMELA and ATIC/PPB-BETS excesses. However, if there is an additional Sommerfeld enhancement in dwarfs, which have a velocity dispersion ≈ 10 to 20 times lower than that of the local Galactic halo, then the cross-sections for dark matter annihilating through [phi]'s required to explain the excesses are very close to the cross-section upper bounds from Willman 1. Dark matter annihilation directly into [tau]'s is also marginally ruled out by Willman 1 as an explanation of the excesses, and the required cross-section is only a factor of a few below the upper bound from Draco. Finally, we make predictions for the gamma-ray flux expected from the dwarf galaxy Segue 1 for the Fermi Gamma-ray Space Telescope. We find that for a sizeable fraction of the parameter space in which dark matter annihilation into charged leptons explains the PAMELA excess, Fermi has good prospects for detecting a gamma-ray signal from Segue 1 after one year of observation.
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 Time-dependent Models for Dark Matter at the Galactic Center by :
Download or read book Time-dependent Models for Dark Matter at the Galactic Center written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Adm Nasa Publisher :Independently Published ISBN 13 :9781728893440 Total Pages :36 pages Book Rating :4.8/5 (934 download)
Book Synopsis Rate for Annihilation of Galactic Dark Matter Into Two Photons by : National Aeronautics and Space Adm Nasa
Download or read book Rate for Annihilation of Galactic Dark Matter Into Two Photons written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-17 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A calculation of the cross section for neutralino-neutralino annihilation into two photons is performed and applied to dark matter in the galactic halo to find the counting rate in a large gamma ray detector such as EGRET (Energetic Gamma Ray Experiment Telescope) or ASTROGAM. Combining constraints from particle accelerators with the requirement that the neutralinos make up the dark matter, it is found that rates of over a few dozen events per year are unlikely. The assumptions that go into these conclusions are listed. Other particle dark matter candidates which could give larger and perhaps observable signals are suggested. Giudice, Gian F. and Griest, Kim Unspecified Center NAGW-1340
Book Synopsis Using the Dark to See by : Ranjan Laha
Download or read book Using the Dark to See written by Ranjan Laha and published by . This book was released on 2014 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss two important research avenues in astroparticle physics: dark matter and neutrinos. We discuss both direct and indirect detection of dark matter. We calculate the signatures of dark matter annihilation from galaxy clusters in neutri- nos. We show the constraints on dark matter annihilation from radio measurements near the Galactic Center. We consider the dark matter annihilation contribution to the isotropic diffuse gamma-ray background and show how to determine the mini- mum dark matter halo mass for a given dark matter mass and annihilation channel. Motivated by recent hints on dark matter self-interactions, we calculate the nuclear recoil spectrum from a bound state dark matter scattering with a nuclei at rest in a dark matter direct detection experiment. We discuss non-standard interactions of neutrinos and astrophysical neutrino detection in the second part of the thesis. We derive strong constraints on a light Abelian gauge boson coupling to Standard Model leptons. In light of the recent detection of high energy neutrinos in IceCube, we discuss the cascade detection of high energy astrophysical neutrinos in IceCube and point out the benefits of this detection channel. We propose a new method to detect supernova electron neutrino in gadolinium loaded Super-Kamiokande detector and show that it can be used to measure the supernova electron neutrino spectrum to ~ 20% accuracy.
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 Nota inzake de problematiek samenhangende met de structuur van de bureaus van de rijksaccountantsdienst in de directie Rotterdam by :
Download or read book Nota inzake de problematiek samenhangende met de structuur van de bureaus van de rijksaccountantsdienst in de directie Rotterdam written by and published by . This book was released on 1981 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Stellar Probe of Dark Matter Annihilation in Galactic Nuclei by : Pierre Salati
Download or read book A Stellar Probe of Dark Matter Annihilation in Galactic Nuclei written by Pierre Salati and published by . This book was released on 1987 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Search for Dark Matter Annihilation in the Galactic Halo Using IceCube by :
Download or read book Search for Dark Matter Annihilation in the Galactic Halo Using IceCube written by and published by . This book was released on 2016 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multi-wavelength Emissions from Dark Matter Annihilation Processes in Galaxy Clusters Using Cosmological Simulations by : Remudin Reshid Mekuria
Download or read book Multi-wavelength Emissions from Dark Matter Annihilation Processes in Galaxy Clusters Using Cosmological Simulations written by Remudin Reshid Mekuria and published by . This book was released on 2017 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Probing Dark Matter Decay and Annihilation with Fermi LAT Observations of Nearby Galaxy Clusters by : Xiaoyuan Huang
Download or read book Probing Dark Matter Decay and Annihilation with Fermi LAT Observations of Nearby Galaxy Clusters written by Xiaoyuan Huang and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
