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%.

arXiv comment14 pages, 8 figures, 5 tables

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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