Bounds On Cross Sections And Lifetimes For Dark Matter Annihilation And Decay Into Charged Leptons From Gamma Ray Observations Of Dwarf Galaxies PDF Download
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Download Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and Decay Into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies Book in PDF, ePub and Kindle
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.
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Download Stringent Constraints on the Dark Matter Annihilation Cross Section From Subhalo Searches with the Fermi Gamma-Ray Space Telescope Book in PDF, ePub and Kindle
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.
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Total Pages | : 8 |
Release | : 2015 |
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Download Dark Matter Searches with the Fermi-LAT in the Direction of Dwarf Spheroidals Book in PDF, ePub and Kindle
Author | : Stefano Profumo |
Publisher | : Wspc (Europe) |
Total Pages | : 270 |
Release | : 2017 |
Genre | : Science |
ISBN | : 9781786340009 |
Download An Introduction to Particle Dark Matter Book in PDF, ePub and Kindle
Particle dark matter: the name of the game -- The thermal relic paradigm: zeroth-order lessons from cosmology -- The thermal relic paradigm: a closer look -- The art of WIMP direct detection -- Indirect dark matter searches -- Searching for dark matter with particle colliders -- Axions and axion-like particles as dark matter -- Sterile neutrinos as dark matter particles -- Bestiarium: a short, biased compendium of notable dark matter particle candidates and models
Author | : Scott Dodelson |
Publisher | : Academic Press |
Total Pages | : 462 |
Release | : 2003-03-13 |
Genre | : Science |
ISBN | : 0122191412 |
Download Modern Cosmology Book in PDF, ePub and Kindle
An advanced text for senior undergraduates, graduate students and physical scientists in fields outside cosmology. This is a self-contained book focusing on the linear theory of the evolution of density perturbations in the universe, and the anisotropiesin the cosmic microwave background.
Author | : Gianfranco Bertone |
Publisher | : Cambridge University Press |
Total Pages | : 763 |
Release | : 2010-01-07 |
Genre | : Science |
ISBN | : 0521763681 |
Download Particle Dark Matter Book in PDF, ePub and Kindle
Describes the dark matter problem in particle physics, astrophysics and cosmology for graduate students and researchers.
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Total Pages | : 21 |
Release | : 2010 |
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Download Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope Book in PDF, ePub and Kindle
Author | : Martin Bauer |
Publisher | : Springer |
Total Pages | : 180 |
Release | : 2019-06-11 |
Genre | : Science |
ISBN | : 3030162346 |
Download Yet Another Introduction to Dark Matter Book in PDF, ePub and Kindle
Dark matter is a frequently discussed topic in contemporary particle physics. Written strictly in the language of particle physics and quantum field theory, these course-based lecture notes focus on a set of standard calculations that students need in order to understand weakly interacting dark matter candidates. After introducing some general features of these dark matter agents and their main competitors, the Higgs portal scalar and supersymmetric neutralinos are introduced as our default models. In turn, this serves as a basis for exploring four experimental aspects: the dark matter relic density extracted from the cosmic microwave background; indirect detection including the Fermi galactic center excess; direct detection; and collider searches. Alternative approaches, like an effective theory of dark matter and simplified models, naturally follow from the discussions of these four experimental directions.
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Release | : 2015 |
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Download Multistep Cascade Annihilations of Dark Matter and the Galactic Center Excess Book in PDF, ePub and Kindle
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.
Author | : Georg G. Raffelt |
Publisher | : University of Chicago Press |
Total Pages | : 692 |
Release | : 1996-05 |
Genre | : Science |
ISBN | : 9780226702728 |
Download Stars as Laboratories for Fundamental Physics Book in PDF, ePub and Kindle
Much of what we know about neutrinos is revealed by astronomical observations, and the same applies to the axion, a conjectured new particle that is a favored candidate for the main component of the dark matter of the universe.