Very-high-energy emission from M 82

• Published in: Astronomy and astrophysics (Berlin) Vol. 486; no. 1; pp. 143 - 149
• Main Authors: Persic, M., Rephaeli, Y., Arieli, Y.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.07.2008
• Subjects: acceleration of particles; Astronomy; Earth, ocean, space; Exact sciences and technology; galaxies: general; galaxies: starburst; ISM: cosmic rays; radiation mechanisms: non-thermal; stars: formation; Energetics; Protons; radiation mechanisms: non-thermal; galaxies: starburst; galaxies: general; Starburst galaxies; Northern hemisphere; acceleration of particles; Relativistic electron; Particle acceleration; Cosmic radiation; Convection; Radio emission; stars: formation; Radiation mechanism; ISM: cosmic rays; Star formation; Pions neutral; Diffusion; Energy models; Very high energy; Synchrotron radiation
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:200809525

Spurred by the improved measurement sensitivity in the very-high-energy (VHE: ≥100 GeV) γ-ray band, we assess the feasibility of detection of the nearby starburst galaxy M 82. VHE emission is expected to be predominantly from the decay of neutral pions which are produced in energetic proton interactions with ambient protons. An estimate of VHE emission from this process is obtained by an approximate, semi-quantitative calculation, and also by a detailed numerical treatment based on a convection-diffusion model for energetic electron and proton propagation and energy losses. All relevant hadronic and leptonic processes are considered, gauged by the measured synchrotron radio emission from the inner disk region. We estimate an integrated flux $f($≥100 GeV) ~ 2 $\times$ 10-12 cm-2 s-1, possibly detectable by the current northern-hemisphere imaging air Cherenkov telescopes, MAGIC and VERITAS, and a good candidate for detection with the upcoming MAGIC II telescope. We also estimate $f($≥100 MeV) ~ 10-8 cm-2 s-1, a level of emission that can be detected by GLAST/LAT based on the projected sensitivity for a one-year observation.