MSPs and the Radio/FIR Correlation

Observations over several decades have established a strong correlation between the far-infrared and non-thermal radio luminosities of star-forming galaxies. Because far-IR emission is produced primarily by massive stars, and non-thermal radio emission primarily by cosmic-ray electrons, this relationship is interpreted as observational evidence for the production of high-energy cosmic-rays by recent star-formation events. Intriguingly, this relation continues over more than four magnitudes in star-formation rate. Recent LOFAR observations, however, find an intriguing radio excess among galaxies with high stellar masses and low-star formation rates -- a result which apperas at odd with star-formation models of the cosmic-ray population. We propose that millisecond pulsars -- which evolve over Gyr timescales and thus trace historic star-formation, can contribute to, or even dominate, the radio flux from these dead galaxies. Such an observation has important implications for our understanding of stellar evolution, as well as cosmic-ray production within the bulge of the Milky Way and other nearby galaxies.

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Full Publication List:

5. Millisecond Pulsars Modify the Radio-SFR Correlation in Quiescent Galaxies
Takahiro Sudoh, Tim Linden, John Beacom
Physical Review D 103 083017

4. Cluster Mergers and the Origin of the ARCADE-2 Excess
Ke Fang, Tim Linden
Journal of Cosmology and Astroparticle Physics 1610 10 004

3. Challenges in Explaining the Galactic Center Gamma-Ray Excess with Millisecond Pulsars
Ilias Cholis, Dan Hooper, Tim Linden
Journal of Cosmology and Astroparticle Physics, 06 043 (2015)

2. The Circular Polarization of Pulsar Wind Nebulae and the Cosmic-Ray Positron Excess
Tim Linden
The Astrophysical Journal 799 200 (2015)

1. Testing the WMAP-Planck Haze with Spiral Galaxies
Eric Carlson, Dan Hooper, Tim Linden, Stefano Profumo
Journal of Cosmology and Astroparticle Physics, 1307 026 (2013)

Tim Linden

Assistant Professor, Stockholm University