Breaking the Radio - Gamma-Ray Connection in Arp 220
arXiv:1901.04564 · doi:10.1093/mnras/stz223
Abstract
Recent analyses of the gamma-ray spectrum from the ultra-luminous infrared galaxy Arp 220 have revealed a discrepancy in the cosmic ray energy injection rates derived from the gamma-rays versus the radio emission. While the observed radio emission is consistent with the star formation rate inferred from infrared observations, a significantly higher cosmic ray population is necessary to accurately model the measured gamma-ray flux. To resolve this discrepancy between the radio and gamma-ray observations, we find that we must increase the cosmic ray energy injection rate and account for an infrared optical depth greater than unity. Raising the energy injection rate naturally raises the total gamma-ray flux but also raises the radio flux unless there is also an increase in the energy loss rate for cosmic ray leptons. A optically thick medium results in an increase in energy losses via inverse Compton for cosmic ray leptons and preserves agreement with submillimeter, millimeter, and infrared wavelength observations.
17 pages, 11 figures, 4 tables, submitted to MNRAS
References in corpus (13)
- Magnetic Fields in Starburst Galaxies and The Origin of the FIR-Radio Correlation
- The Starburst Contribution to the Extra-Galactic Gamma-Ray Background
- Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33
- Winds, Clumps, and Interacting Cosmic Rays in M82
- High-Resolution Radio Continuum Measurements of the Nuclear Disks of Arp 220
- Extreme dust disks in Arp 220 as revealed by ALMA
- Simulating Gamma-ray Emission in Star-forming Galaxies
- Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz: A kpc-scale star forming disk surrounding nuclei with shocked outflows
- Discovery of GeV emission from the direction of the luminous infrared galaxy NGC 2146
- Resolved Structure of Arp 220 Nuclei at λ~3 mm
- Search for gamma-ray emission from star-forming galaxies with Fermi LAT
- The Cosmic Ray Population of the Galactic Central Molecular Zone
- Parsec-scale magnetic fields in Arp 220
Cited by in corpus (6)
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- High-energy Neutrinos from the Inner Circumnuclear Region of NGC 1068
- No evidence of AGN features in the nuclei of Arp 220 from JWST/NIRSpec IFS
- Gamma-ray emission from spectrally resolved cosmic rays in galaxies
- JWST/NIRSpec insights into the circumnuclear region of Arp 220: A detailed kinematic study
- CONGRuENTS (COsmic-ray, Neutrino, Gamma-ray and Radio Non-Thermal Spectra). I. A predictive model for galactic non-thermal emission