2020/05/31 by Takahiro Sudoh, Tim Linden, John F. Beacom · 1 citation
Physics and Astronomy · #astro-ph.GA #astro-ph.HE #hep-ph
paper · pdf · doi:10.1103/physrevd.103.083017
published as Phys. Rev. D 103, 083017 (2021) · Main text 14 pages, 4 figures. Accepted in PRD
arxiv created 2021/04/12 · arxiv updated 2021/04/28
The observed correlation between the far-infrared and radio luminosities of galaxies illustrates the close connection between star formation and cosmic-ray production. Intriguingly, recent gamma-ray observations indicate that recycled/millisecond pulsars (MSPs), which do not trace recent star formation, may also efficiently accelerate cosmic-ray electrons. We study the contribution of MSPs to the galactic non-thermal radio emission, finding that they can dominate the emission from massive quiescent galaxies. This model can explain recent LOFAR observations that found a peculiar radio excess in galaxies with high stellar masses and low star-formation rates. We show that MSP-based models provide a significantly improved fit to LOFAR data. We discuss the implications for the radio-FIR correlation, the observation of radio excesses in nearby galaxies, and local electron and positron observations.