arXiv subjects

V. Gammaldi

Publications and source records attributed to V. Gammaldi.

22 records · Page 2Linked to original sources

arXiv2013

Spectral Study of the HESS J1745-290 Gamma-Ray Source as Dark Matter Signal

We study the main spectral features of the gamma-ray fluxes observed by the High Energy Stereoscopic System (HESS) from the J1745-290 Galactic Center source during the years 2004, 2005 and 2006. In particular, we show that these data are well fitted as the secondary gamma-rays photons generated from dark matter annihilating into Standard Model particles in combination with a simple power law background. We present explicit analyses for annihilation in a single standard model particle-antiparticle pair. In this case, the best fits are obtained for the u and d quark-antiquark channels and for the WW and ZZ gauge bosons, with background spectral index compatible with the Fermi-Large Area Telescope (LAT) data from the same region. The fits return a heavy WIMP, with a mass above 10 TeV approximately, but well below the unitarity limit for thermal relic annihilation.

astro-ph.CO↗

arXiv2012

Dark matter origin of the gamma ray emission from the galactic center observed by HESS

We show that the gamma ray spectrum observed with the HESS array of Cherenkov telescopes coming from the Galactic Center (GC) region and identified with the source HESS J1745-290, is well fitted by the secondary photons coming from dark matter (DM) annihilation over a diffuse power-law background. The amount of photons and morphology of the signal localized within a region of few parsecs, require compressed DM profiles as those resulting from baryonic contraction, which offer $\sim 10^3$ enhancements in the signal over DM alone simulations. The fitted background from HESS data is consistent with recent Fermi-LAT observations of the same region.

hep-ph↗

arXiv2012

Indirect constraints to branon dark matter

If the present dark matter in the Universe annihilates into Standard Model particles, it must contribute to the gamma ray fluxes detected on the Earth. Here we briefly review the present constraints for the detection of gamma ray photons produced in the annihilation of branon dark matter. We show that observations of dwarf spheroidal galaxies and the galactic center by EGRET, Fermi-LAT or MAGIC are below the sensitivity limits for branon detection. However,future experiments such as CTA could be able to detect gamma-ray photons from annihilating branons of masses above 150 GeV.

astro-ph.CO↗

arXiv2011

Detection of branon dark matter with gamma ray telescopes

Branons are new degrees of freedom that appear in flexible brane-world models corresponding to brane fluctuations. These new fields can behave as standard weakly interacting massive particles (WIMPs) with a significant associated thermal relic density. We analyze the present constraints from their spontaneous annihilations into photons for EGRET, Fermi-LAT and MAGIC, and the prospects for detection in future Cherenkov telescopes. In particular, we focus on possible signals coming from the Galactic Center and different dwarf spheroidals, such as Draco, Sagittarius, Canis Major and SEGUE 1. We conclude that for those targets, present observations are below the sensitivity limits for branon detection by assuming standard dark matter distributions and no additional boost factors. However, future experiments such as CTA could be able to detect gamma-ray photons coming from the annihilation of branons with masses higher than 150 GeV.

astro-ph.CO↗