Author: Michael DürrPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Gamma-ray Excess and the Minimal Dark Matter Model
Author: Michael DürrSimplified Dark Matter Models for the Galactic Center Gamma-Ray Excess
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 36
Book Description
Motivated by the gamma-ray excess observed from the region surrounding the Galactic Center, we explore particle dark matter models that could potentially account for the spectrum and normalization of this signal. Taking a model-independent approach, we consider an exhaustive list of tree-level diagrams for dark matter annihilation, and determine which could account for the observed gamma-ray emission while simultaneously predicting a thermal relic abundance equal to the measured cosmological dark matter density. We identify a wide variety of models that can meet these criteria without conflicting with existing constraints from direct detection experiments or the Large Hadron Collider (LHC). The prospects for detection in near future dark matter experiments and/or the upcoming 14 TeV LHC appear quite promising.
Searching for Dark Matter with Cosmic Gamma Rays
Author: Andrea AlbertPublisher: Morgan & Claypool Publishers
ISBN: 1681742691
Category : Science
Languages : en
Pages : 64
Book Description
Searching for Dark Matter with Cosmic Gamma Rays summarizes the evidence for dark matter and what we can learn about its particle nature using cosmic gamma rays. It has almost been 100 years since Fritz Zwicky first detected hints that most of the matter in the Universe that doesn't directly emit or reflect light. Since then, the observational evidence for dark matter has continued to grow. Dark matter may be a new kind of particle that is governed by physics beyond our Standard Model of particle physics. In many models, dark matter annihilation or decay produces gamma rays. There are a variety of instruments observing the gamma-ray sky from tens of MeV to hundreds of TeV. Some make deep, focused observations of small regions, while others provide coverage of the entire sky. Each experiment offers complementary sensitivity to dark matter searches in a variety of target sizes, locations, and dark matter mass scales. We review results from recent gamma-ray experiments including anomalies some have attributed to dark matter. We also discuss how our gamma-ray observations complement other dark matter searches and the prospects for future experiments.
Hidden Sector Dark Matter Models for the Galactic Center Gamma-Ray Excess
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The gamma-ray excess observed from the Galactic Center can be interpreted as dark matter particles annihilating into Standard Model fermions with a cross section near that expected for a thermal relic. Although many particle physics models have been shown to be able to account for this signal, the fact that this particle has not yet been observed in direct detection experiments somewhat restricts the nature of its interactions. One way to suppress the dark matter's elastic scattering cross section with nuclei is to consider models in which the dark matter is part of a hidden sector. In such models, the dark matter can annihilate into other hidden sector particles, which then decay into Standard Model fermions through a small degree of mixing with the photon, Z, or Higgs bosons. After discussing the gamma-ray signal from hidden sector dark matter in general terms, we consider two concrete realizations: a hidden photon model in which the dark matter annihilates into a pair of vector gauge bosons that decay through kinetic mixing with the photon, and a scenario within the generalized NMSSM in which the dark matter is a singlino-like neutralino that annihilates into a pair of singlet Higgs bosons, which decay through their mixing with the Higgs bosons of the MSSM.
Flavored Dark Matter and the Galactic Center Gamma-Ray Excess
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 5
Book Description
Thermal relic dark matter particles with a mass of 31-40 GeV and that dominantly annihilate to bottom quarks have been shown to provide an excellent description of the excess gamma rays observed from the center of the Milky Way. Flavored dark matter provides a well-motivated framework in which the dark matter can dominantly couple to bottom quarks in a flavor-safe manner. We propose a phenomenologically viable model of bottom flavored dark matter that can account for the spectral shape and normalization of the gamma-ray excess while naturally suppressing the elastic scattering cross sections probed by direct detection experiments. This model will be definitively tested with increased exposure at LUX and with data from the upcoming high-energy run of the Large Hadron Collider (LHC).
The Characterization of the Gamma-Ray Signal from the Central Milky Way
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Past studies have identified a spatially extended excess of ~1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. We revisit and scrutinize this signal with the intention of further constraining its characteristics and origin. By applying cuts to the Fermi event parameter CTBCORE, we suppress the tails of the point spread function and generate high resolution gamma-ray maps, enabling us to more easily separate the various gamma-ray components. Within these maps, we find the GeV excess to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. For example, the signal is very well fit by a 31-40 GeV dark matter particle annihilating to b quarks with an annihilation cross section of sigma v = (1.4-2.0) x 10^-26 cm^3/s (normalized to a local dark matter density of 0.3 GeV/cm^3). Furthermore, we confirm that the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within ~0.05 degrees of Sgr A*), showing no sign of elongation along or perpendicular to the Galactic Plane. The signal is observed to extend to at least 10 degrees from the Galactic Center, disfavoring the possibility that this emission originates from millisecond pulsars.
Supersymmetric Sub-Electroweak Scale Dark Matter, the Galactic Center Gamma-ray Excess, and Exotic Decays of the 125 GeV Higgs Boson
Author: Is The Gamma-Ray Source 3FGL J2212.5+0703 A Dark Matter Subhalo?
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In a previous paper, we pointed out that the gamma-ray source 3FGL J2212.5+0703 shows evidence of being spatially extended. If a gamma-ray source without detectable emission at other wavelengths were unambiguously determined to be spatially extended, it could not be explained by known astrophysics, and would constitute a smoking gun for dark matter particles annihilating in a nearby subhalo. With this prospect in mind, we scrutinize the gamma-ray emission from this source, finding that it prefers a spatially extended profile over that of a single point-like source with 5.1 sigma statistical significance. We also use a large sample of active galactic nuclei and other known gamma-rays sources as a control group, confirming, as expected, that statistically significant extension is rare among such objects. We argue that the most likely (non-dark matter) explanation for this apparent extension is a pair of bright gamma-ray sources that serendipitously lie very close to each other, and estimate that there is a chance probability of ~2% that such a pair would exist somewhere on the sky. In the case of 3FGL J2212.5+0703, a model with a second gamma-ray point source at the location of a known BZCAT/CRATES radio source yields fits that are comparable in quality to those obtained for a single extended source. If 3FGL J2212.5+0703 is a dark matter subhalo, it would imply that dark matter particles have a mass of ~18-33 GeV and an annihilation cross section on the order of sigma v ~ 10^-26 cm^3/s (for the representative case of annihilations to bb), similar to the values required to generate the Galactic Center gamma-ray excess.
Electroweak-Interacting Spin-1 Dark Matter and Its Phenomenology
Author: Motoko FujiwaraPublisher: Springer Nature
ISBN: 9819910358
Category : Science
Languages : en
Pages : 104
Book Description
This book offers construction of a renormalizable effective theory of electroweak-interacting spin-1 dark matter (DM). The effective theory realizes minimal but essential features of DM predicted in extra-dimension models, and enables to systematically treat non-perturbative corrections such as the Sommerfeld effects. Deriving an annihilation cross section including the Sommerfeld effects based on the effective theory, the author discusses the future sensitivity of observations to gamma-ray from the Galactic Center. As a result, the author explains the monochromatic gamma-ray signatures originate from two photons (γγ) or photon and Z boson (γZ) produced in the process of DM annihilations, and concludes a possible scenario that unstable neutral spin-1 particles (Z’) appear and results in a spectral peak in addition to the one caused by γγ and γZ channels in gamma-ray observations. If those two spectral peaks are observed, the masses of spin-1 DM and Z’ would be reconstructed.
Gamma Ray Lines from a Universal Extra Dimension
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 21
Book Description
Indirect Dark Matter searches are based on the observation of secondary particles produced by the annihilation or decay of Dark Matter. Among them, gamma-rays are perhaps the most promising messengers, as they do not suffer deflection or absorption on Galactic scales, so their observation would directly reveal the position and the energy spectrum of the emitting source. Here, we study the detailed gamma-ray energy spectrum of Kaluza--Klein Dark Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on the two body annihilation of Dark Matter particles into a photon and another particle, which produces monochromatic photons, resulting in a line in the energy spectrum of gamma rays. Previous calculations in the context of the five dimensional UED model have computed the line signal from annihilations into \gamma \gamma, but we extend these results to include \gamma Z and \gamma H final states. We find that these spectral lines are subdominant compared to the predicted \gamma \gamma signal, but they would be important as follow-up signals in the event of the observation of the \gamma \gamma line, in order to distinguish the 5d UED model from other theoretical scenarios.