Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGamma-Ray Dark Matter Searches in Milky Way Satellites -- A Comparative Review of Data Analysis Methods and Current Results
45
0
0.0
(
0
)
Authors
Javier Rico
Ask ChatGPT about the research
No Arabic abstract
If dark matter is composed of weakly interacting particles with mass in the GeV-TeV range, their annihilation or decay may produce gamma rays that could be detected by gamma-ray telescopes. Observations of dwarf spheroidal satellite galaxies of the Milky Way (dSphs) benefit from the relatively accurate predictions of dSph dark matter content to produce robust constraints to the dark matter properties. The sensitivity of these observations for the search for dark matter signals can be optimized thanks to the use of advanced statistical techniques able to exploit the spectral and morphological peculiarities of the expected signal. In this paper, I review the status of the dark matter searches from observations of dSphs with the current generation of gamma-ray telescopes: Fermi-LAT, H.E.S.S, MAGIC, VERITAS and HAWC. I will describe in detail the general statistical analysis framework used by these instruments, putting in context the most recent experimental results and pointing out the most relevant differences among the different particular implementations. This~will facilitate the comparison of the current and future results, as well as their eventual integration in a multi-instrument and multi-target dark matter search.
rate research
Read More
The Fermi LAT collaboration has recently presented constraints on the gamma-ray signal from annihilating dark matter using separate analyses of a number of dwarf spheroidal galaxies. Since the expected annihilation signal has the same physical properties regardless of the target (except for a normalization scale), it is possible to enhance the constraining power using a combined analysis, the initial results of which will be presented here.
We analyze the possibility that the HESS gamma-ray source at the Galactic Center could be explained as the secondary flux produced by annihilation of TeV Dark Matter (TeVDM) particles with locally enhanced density, in a region spatially compatible with the HESS observations themselves. We study the inner 100 pc considering (i) the extrapolation of several density profiles from state-of-the-art N-body + Hydrodynamics simulations of Milky Way-like galaxies, (ii) the DM spike induced by the black hole, and (iii) the DM particles scattering off by bulge stars. We show that in some cases the DM spike may provide the enhancement in the flux required to explain the cut-off in the HESS J1745-290 gamma-ray spectra as TeVDM. In other cases, it may helps to describe the spatial tail reported by HESS II at angular scales < 0.54 degrees towards Sgr A.
Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 1e-26 cm^3 s^-1 at 5 GeV to about 5e-23 cm^3 s^-1 at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (~3e-26 cm^3 s^-1 for a purely s-wave cross section), without assuming additional boost factors.
Dwarf spheroidal galaxies have a large mass to light ratio and low astrophysical background, and are therefore considered one of the most promising targets for dark matter searches in the gamma-ray band. By applying a joint likelihood analysis, the power of resultant limits in case of no detection can be enhanced and robust constraints on the dark matter parameter space can be obtained. We present results from a combined analysis of 10 dwarf spheroidal galaxies using Fermi-LAT data. Different annihilation channels have been analyzed and uncertainties from astrophysical properties have been taken into account.
With 91 months of the publicly available Fermi-LAT Pass 8 data, we analyze the gamma-ray emission from the Milky Way satellites to search for potential line signals due to the annihilation of dark matter particles into double photons. The searched targets include a sample of dwarf spheroidal galaxies, the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). No significant line emission has been found neither in the stacked dwarf galaxy sample nor in the direction of LMC/SMC. The corresponding upper limits on the cross section of DM annihilation into two photons are derived. Compared with results of previous gamma-ray line searches with the Pass 7 data, the current constraints on the line emission from dwarf spheroidal galaxies has been significantly improved in a wide energy range. With the rapid increase of the sample of dwarf spheroidal galaxies (candidates), we expect that the sensitivity of gamma ray line searches will be significantly improved in the near future.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
