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Probing star formation with galactic cosmic rays

Authors :
Yoel Rephaeli
Massimo Persic
Source :
Monthly Notices of the Royal Astronomical Society. 403:1569-1576
Publication Year :
2010
Publisher :
Oxford University Press (OUP), 2010.

Abstract

Cosmic-ray energy densities in central regions of starburst galaxies, as inferred from radio and gamma-ray measurements of, respectively, non-thermal synchrotron and neutral pion decay emission, are typically U_p = O(100)eV/cm3, i.e. typically at least an order of magnitude larger than near the Galactic center and in other non-very-actively star-forming galaxies. We first show that these very different energy-density levels reflect a similar disparity in the respective supernova rates in the two environments, which is not unexpected given the supernova origin of (Galactic) energetic particles. As a consequence of this correspondence, we then demonstrate that there is partial quantitative evidence that the stellar initial mass function (IMF) in starburst nuclei has a low-mass truncation at ~2M_sun, as predicted by theoretical models of turbulent media, in contrast with the much smaller value of 0.1M_sun that characterizes the low-mass cutoff of the stellar IMF in `normal' galactic environments.

Details

ISSN :
13652966 and 00358711
Volume :
403
Database :
OpenAIRE
Journal :
Monthly Notices of the Royal Astronomical Society
Accession number :
edsair.doi...........93d46815aa03d312143d0784c5d54bd4
Full Text :
https://doi.org/10.1111/j.1365-2966.2009.16218.x