gamma-Ray emission from Arp 220: indications of an active galactic nucleus
Artikel i vetenskaplig tidskrift, 2017

Extragalactic cosmic ray populations are important diagnostic tools for tracking the distribution of energy in nuclei and for distinguishing between activity powered by star formation versus active galactic nuclei (AGNs). Here, we compare different diagnostics of the cosmic ray populations of the nuclei of Arp 220 based on radio synchrotron observations and the recent gamma-ray detection. We find the gamma-ray and radio emission to be incompatible; a joint solution requires at minimum a factor of 4-8 times more energy coming from supernovae and a factor of 40-70 more mass in molecular gas than that is observed. We conclude that this excess of the gamma-ray flux in comparison to all other diagnostics of star-forming activity indicates that there is an AGN present that is providing the extra cosmic rays, likely in the western nucleus.

galaxies: individual: (Arp 220)

galaxies: star-burst

Galaxies

Supermassive Black-Holes

gamma rays: galaxies

Continuum

Coevolution

galaxies: active

Array

Resolution

Arp-220

cosmic rays

Fermi-Lat

Författare

T. M. Yoast-Hull

J. S. Gallagher III

Susanne Aalto

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Eskil Varenius

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 469 1 L89-L93

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1093/mnrasl/slx054