Gamma-ray image reconstruction of the Andromeda galaxy

Abstract

We analyze about 12 years of Fermi-LAT data in the direction of the Andromeda galaxy (M31). We robustly characterize its spectral and morphological properties against systematic uncertainties related to the modeling of the Galactic diffuse emission. We perform this work by adapting and exploiting the potential of the skyFACT adaptive template fitting algorithm. We reconstruct the gamma-ray image of M31 in a template-independent way, and we show that flat spatial models are preferred by data, indicating an extension of the $\gamma$-ray emission of about 0.3-0.4 degree for the bulge of M31. This study also suggests that a second component, extending to at least 1 degree, contributes to the observed total emission. We quantify systematic uncertainties related to mis-modeling of Galactic foreground emission at the level of 2.9%.

14 pages, 8 figures, 5 tables

References in corpus (8)

• Background model systematics for the Fermi GeV excess
• The long bar as seen by the VVV survey: I. Colour-magnitude diagrams
• Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33
• Evidence for a Massive, Extended Circumgalactic Medium Around the Andromeda Galaxy
• Observations of M31 and M33 with the Fermi Large Area Telescope: a galactic center excess in Andromeda?
• A Revised LCDM Mass Model For The Andromeda Galaxy
• Search for $\gamma$-ray emission from dark matter particle interactions from Andromeda and Triangulum Galaxies with the Fermi Large Area Telescope
• Fermi-LAT Observations of Gamma-Ray Emission Towards the Outer Halo of M31

Cited by in corpus (5)

• When models fail: an introduction to posterior predictive checks and model misspecification in gravitational-wave astronomy
• The Andromeda Gamma-Ray Excess: Background Systematics of the Millisecond Pulsars and Dark Matter Interpretations
• Exploring the MeV Sky with a Combined Coded Mask and Compton Telescope: The Galactic Explorer with a Coded Aperture Mask Compton Telescope (GECCO)
• Nature of M31 gamma-ray halo in relation to dark matter annihilation
• Prospects for annihilating dark matter from M31 and M33 observations with the Cherenkov Telescope Array