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Published April 10, 2020 | Accepted Version + Published
Journal Article Open

Constraints on the Emission of Gamma-Rays from M31 with HAWC

Abstract

Cosmic rays, along with stellar radiation and magnetic fields, are known to make up a significant fraction of the energy density of galaxies such as the Milky Way. When cosmic rays interact in the interstellar medium, they produce gamma-ray emission which provides an important indication of how the cosmic rays propagate. Gamma-rays from the Andromeda galaxy (M31), located 785 kpc away, provide a unique opportunity to study cosmic-ray acceleration and diffusion in a galaxy with a structure and evolution very similar to the Milky Way. Using 33 months of data from the High Altitude Water Cherenkov Observatory, we search for teraelectronvolt gamma-rays from the galactic plane of M31. We also investigate past and present evidence of galactic activity in M31 by searching for Fermi bubble-like structures above and below the galactic nucleus. No significant gamma-ray emission is observed, so we use the null result to compute upper limits on the energy density of cosmic rays >10 TeV in M31.

Additional Information

© 2020 The American Astronomical Society. Received 2020 January 6; revised 2020 February 22; accepted 2020 February 23; published 2020 April 8. We acknowledge support from: the US National Science Foundation (NSF); the US Department of Energy Office of High-Energy Physics; the Laboratory Directed Research and Development (LDRD) program of Los Alamos National Laboratory; Consejo Nacional de Ciencia y Tecnología (CONACyT), México, grants 271051, 232656, 260378, 179588, 254964, 258865, 243290, 132197, A1-S-46288, A1-S-22784, cátedras 873, 1563, 341, 323, Red HAWC, México; DGAPA-UNAM grants AG100317, IN111315, IN111716-3, IN111419, IA102019, IN112218; VIEP-BUAP; PIFI 2012, 2013, PROFOCIE 2014, 2015; the University of Wisconsin Alumni Research Foundation; the Institute of Geophysics, Planetary Physics, and Signatures at Los Alamos National Laboratory; Polish Science Centre grant DEC-2018/31/B/ST9/01069, DEC-2017/27/B/ST9/02272; Coordinación de la Investigación Científica de la Universidad Michoacana; Royal Society—Newton Advanced Fellowship 180385. Thanks to Scott Delay, Luciano Díaz and Eduardo Murrieta for technical support. Software: threeML/hawc-hal (https://github.com/threeML), AERIE-LiFF (https://github.com/rjlauer/aerie-liff, HAWC Collaboration).

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Published - Albert_2020_ApJ_893_16.pdf

Accepted Version - 2001.04065.pdf

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Created:
August 19, 2023
Modified:
October 20, 2023