Francesca Calore

Background model systematics for the Fermi GeV excess

The possible gamma-ray excess in the inner Galaxy and the Galactic center (GC) suggested by Fermi-LAT observations has triggered a large number of studies. It has been interpreted as a variety of dierent phenomena such as a signal from WIMP dark matter annihilation, gamma-ray emission from a population of millisecond pulsars, or emission from cosmic rays injected in a sequence of burst-like events or continuously at the GC. We present the rst comprehensive study of model systematics coming from the Galactic diuse emission in the inner part of our Galaxy and their impact on the inferred properties of the excess emission at Galactic latitudes 2 < jbj < 20 and 300 MeV to 500 GeV. We study both theoretical and empirical model systematics, which we deduce from a large range of Galactic diuse emission models and a principal component analysis of residuals in numerous test regions along the Galactic plane. We show that the hypothesis of an extended spherical excess emission with a uniform energy spectrum is compatible with the Fermi-LAT data in our region of interest at 95% CL. Assuming that this excess is the extended counterpart of the one seen in the inner few degrees of the Galaxy, we derive a lower limit of 10:0 (95% CL) on its extension away from the GC. We show that, in light of the large correlated uncertainties that aect

A tale of tails: Dark matter interpretations of the Fermi GeV excess in light of background model systematics

Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. This excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular: (1) In the case of DM annihilation into (b) over barb, we find that even large DM masses up to m(chi) similar or equal to 74 GeV are allowed at p-value > 0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from mu(+)mu(-) with m(chi) similar to 60-70 GeV can also account for the excess at higher latitudes, vertical bar b vertical bar > 2 degrees, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.

The Galactic Center GeV excess from a series of leptonic cosmic-ray outbursts

It has been proposed that a recent outburst of cosmic-ray electrons could account for the excess of GeV-scale gamma rays observed from the region surrounding the Galactic Center. After studying this possibility in some detail, we identify scenarios in which a series of leptonic cosmic-ray outbursts could plausibly generate the observed excess. The morphology of the emission observed outside of

Diffuse γ-ray emission from galactic pulsars

\sim1^{\circ}-2^{\circ}

On the Relevance of Sharp Gamma-Ray Features for Indirect Dark Matter Searches

from the Galactic Center can be accommodated with two outbursts, one which took place approximately

Constraining dark matter annihilation with the isotropic γ-ray background: updated limits and future potential

\sim10^6

CMB bounds on disk-accreting massive primordial black holes

years ago, and another (injecting only about 10\% as much energy as the first) about

Conservative upper limits on WIMP annihilation cross section from Fermi-LAT γ-rays

\sim10^5

RADIO DETECTION PROSPECTS FOR A BULGE POPULATION OF MILLISECOND PULSARS AS SUGGESTED BY FERMI-LAT OBSERVATIONS OF THE INNER GALAXY

years ago. The emission observed from the innermost

γ-ray anisotropies from dark matter in the Milky Way: the role of the radial distribution

\sim1^{\circ}-2^{\circ}