CONSTRAINING DARK MATTER ANNIHILATION WITH NEUTRINOS AND GAMMA RAYS

2011 ◽  
Vol 01 ◽  
pp. 245-251
Author(s):  
NICOLE F. BELL
Keyword(s):  
Dark Matter ◽  
Total Cross Section ◽  
Cross Section ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Mass Range ◽  
Dark Matter Halo ◽  
Dark Matter Annihilation ◽  
Upper Limits ◽  
Wide Range

We examine dark matter annihilation in galaxy halos. By considering annihilation into all Standard Model particles we show that the least detectable final states, namely neutrinos, define a strong general upper bound on the total cross section. This limit is much stronger than the unitarity bound in the most interesting mass range and implies annihilation cannot significantly modify dark matter halo density profiles. We also calculate conservative upper limits on the self-annihilation cross section to monoenergetic gamma rays over a wide range of dark matter masses, using gamma-ray data from the Milky Way, Andromeda (M31), and the cosmic background. We compare gamma-ray-based and neutrino-based upper limits on the total cross section.

scholarly journals Constraints to Dark Matter Annihilation from High-Latitude HAWC Unidentified Sources

Galaxies ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 5
Author(s):  
Javier Coronado-Blázquez ◽  
Miguel A. Sánchez-Conde
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Gamma Rays ◽  
High Latitude ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Dark Matter Annihilation ◽  
Annihilation Channel ◽  
Dark Matter Search ◽  
Spatially Extended

The Λ CDM cosmological framework predicts the existence of thousands of subhalos in our own Galaxy not massive enough to retain baryons and become visible. Yet, some of them may outshine in gamma rays provided that the dark matter is made of weakly interacting massive particles (WIMPs), which would self-annihilate and would appear as unidentified gamma-ray sources (unIDs) in gamma-ray catalogs. Indeed, unIDs have proven to be competitive targets for dark matter searches with gamma rays. In this work, we focus on the three high-latitude ( | b | ≥ 10 ) sources present in the 2HWC catalog of the High Altitude Water Cherenkov (HAWC) observatory with no clear associations at other wavelengths. Indeed, only one of these sources, 2HWC J1040+308, is found to be above the HAWC detection threshold when considering 760 days of data, i.e., a factor 1.5 more exposure time than in the original 2HWC catalog. Other gamma-ray instruments, such as Fermi-LAT or VERITAS at lower energies, do not detect the source. Also, this unID is reported as spatially extended, making it even more interesting in a dark matter search context. While waiting for more data that may shed further light on the nature of this source, we set competitive upper limits on the annihilation cross section by comparing this HAWC unID to expectations based on state-of-the-art N-body cosmological simulations of the Galactic subhalo population. We find these constraints to be particularly competitive for heavy WIMPs, i.e., masses above ∼25 (40) TeV in the case of the b b ¯ ( τ + τ − ) annihilation channel, reaching velocity-averaged cross section values of 2 × 10 − 25 ( 5 × 10 − 25 ) cm 3 ·s − 1 . Although far from testing the thermal relic cross section value, the obtained limits are independent and nicely complementary to those from radically different DM analyses and targets, demonstrating once again the high potential of this DM search approach.

scholarly journals Separating astrophysical sources from indirect dark matter signals

2014 ◽  
Vol 112 (40) ◽  
pp. 12272-12277 ◽  
Author(s):  
Jennifer M. Siegal-Gaskins
Keyword(s):  
Dark Matter ◽  
Angular Distribution ◽  
Energy Spectrum ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Dark Matter Annihilation ◽  
Robust Identification ◽  
Analysis Methods ◽  
The Status

Indirect searches for products of dark matter annihilation and decay face the challenge of identifying an uncertain and subdominant signal in the presence of uncertain backgrounds. Two valuable approaches to this problem are (i) using analysis methods which take advantage of different features in the energy spectrum and angular distribution of the signal and backgrounds and (ii) more accurately characterizing backgrounds, which allows for more robust identification of possible signals. These two approaches are complementary and can be significantly strengthened when used together. I review the status of indirect searches with gamma rays using two promising targets, the Inner Galaxy and the isotropic gamma-ray background. For both targets, uncertainties in the properties of backgrounds are a major limitation to the sensitivity of indirect searches. I then highlight approaches which can enhance the sensitivity of indirect searches using these targets.

DARK MATTER ANNIHILATION IN THE LATE UNIVERSE

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1643-1648
Author(s):  
NICOLE F. BELL
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Galactic Halo ◽  
Atmospheric Neutrino ◽  
Mass Range ◽  
Annihilation Cross Section ◽  
Dark Matter Annihilation ◽  
Unitarity Bound ◽  
Dark Matter Mass ◽  
Positron Flux

We examine dark matter annihilation in the Universe today. We first discuss the suggestion that the Galactic positron flux, which is difficult to account for with astrophysical sources, is produced by the annihilation of dark matter in the Galactic halo. We show that the positrons produced would necessarily be accompanied by a flux of gamma rays which exceed observational constraints, unless the dark matter mass is very low. We shall also derive a very general bond on the dark matter annihilation cross section. By considering annihilation into all Standard Model particles, we show that the least detectable final states, namely neutrinos, define an upper bound on the total annihilation cross section. Calculating the cosmic diffuse neutrino signal, and comparing it to the measured terrestrial atmospheric neutrino background, we derive a robust limit that is much stronger than the unitarity bound in the most interesting mass range. We conclude that dark matter self-annihilation rates cannot be large enough to have a significant effect on the density profiles of dark matter halos.

scholarly journals Effect of turbulent reacceleration on electrons produced by dark matter annihilation in the Coma cluster

2019 ◽  
Vol 488 (1) ◽  
pp. 1401-1406 ◽  
Author(s):  
P Marchegiani
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Coma Cluster ◽  
Dark Matter Annihilation ◽  
Annihilation Channel ◽  
Radio Halo ◽  
Upper Limits ◽  
Astrophysical Objects ◽  
Conservative Values ◽  
Short Times

ABSTRACT In this paper, we study the effect of reacceleration provided by turbulences on electrons produced by dark matter (DM) annihilation in the Coma cluster. We use a simplified phenomenological model to describe the effect of the turbulences, and explore a limited subset of three possible DM models for neutralino particles with different mass and annihilation channel. We find that, for values of the annihilation cross-section of the order of the upper limits found with Fermi–LAT measurements in astrophysical objects, and for conservative values of the boosting factor due to DM substructures, the reacceleration due to turbulences can enhance the radio emission produced by DM-originated electrons up to the level of the observed flux of the radio halo in Coma, for moderate reacceleration intensity in relatively short times. Therefore, we conclude that, even if it is not possible to distinguish between the fits obtained in this paper because of the scattering present in the radio flux data, the electrons produced by DM annihilation can be possible seed electrons for the reacceleration, as well as secondary electrons of hadronic origin. A possible discriminant between these two classes of models is the flux produced in the gamma ray band, which in the case of DM-originated electrons should be more than two orders of magnitude smaller than the present Fermi–LAT upper limits, whereas in the hadronic case the expected gamma ray flux should be close to the value of present upper limits.

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