CaltechAUTHORS
Published February 11, 2010 | Version Published
Journal Article Open

BLAST: the far-infrared/radio correlation in distant galaxies

Creators

  • 1. ROR icon UK Astronomy Technology Centre
  • 2. ROR icon University of Edinburgh
  • 3. ROR icon Durham University
  • 4. ROR icon European Southern Observatory
  • 5. ROR icon Pennsylvania State University
  • 6. ROR icon University of British Columbia
  • 7. ROR icon University of Pennsylvania
  • 8. ROR icon NOIRLab
  • 9. ROR icon Cardiff University
  • 10. ROR icon California Institute of Technology
  • 11. ROR icon National Institute of Astrophysics, Optics and Electronics
  • 12. ROR icon Max Planck Institute for Mathematics
  • 13. ROR icon University of Toronto
  • 14. ROR icon Astroparticle and Cosmology Laboratory
  • 15. ROR icon Max Planck Institute for Astronomy
  • 16. ROR icon Brown University

Abstract

We investigate the correlation between far-infrared (FIR) and radio luminosities in distant galaxies, a lynchpin of modern astronomy. We use data from the Balloon-borne Large Aperture Submillimetre Telescope (BLAST), Spitzer, the Large Apex BOlometer CamerA (LABOCA), the Very Large Array and the Giant Metre-wave Radio Telescope (GMRT) in the Extended Chandra Deep Field South (ECDFS). For a catalogue of BLAST 250-μm-selected galaxies, we remeasure the 70–870-μm flux densities at the positions of their most likely 24-μm counterparts, which have a median [interquartile] redshift of 0.74 [0.25, 1.57]. From these, we determine the monochromatic flux density ratio, q_(250)(= log_(10) [ S_(250 μm)/S_(1400 MHz)]), and the bolometric equivalent, q_(IR). At z ≈ 0.6 , where our 250-μm filter probes rest-frame 160-μm emission, we find no evolution relative to q_(160) for local galaxies. We also stack the FIR and submm images at the positions of 24-μm- and radio-selected galaxies. The difference between q_(IR) seen for 250-μm- and radio-selected galaxies suggests that star formation provides most of the IR luminosity in ≲100-μJy radio galaxies, but rather less for those in the mJy regime. For the 24-μm sample, the radio spectral index is constant across 0 < z < 3 , but q_(IR) exhibits tentative evidence of a steady decline such that q_(IR) ∝ (1 +z)^(−0.15±0.03) – significant evolution, spanning the epoch of galaxy formation, with major implications for techniques that rely on the FIR/radio correlation. We compare with model predictions and speculate that we may be seeing the increase in radio activity that gives rise to the radio background.

Additional Information

© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 October 22. Received 2009 October 19; in original form 2009 July 14. We thank John Peacock for his patient and good-natured assistance. We acknowledge the support of the UK Science and Technology Facilities Council (STFC), NASA through grant numbers NAG5-12785, NAG5-13301, and NNGO-6GI11G, the NSF Office of Polar Programs, the Canadian Space Agency, and the Natural Sciences and Engineering Research Council (NSERC) of Canada.

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Additional details

Identifiers

Eprint ID
17661
Resolver ID
CaltechAUTHORS:20100304-100106920

Funding

Science and Technology Facilities Council (STFC)
NASA
NAG5-12785
NASA
NAG5-13301
NASA
NNGO-6GI11G
NSF
Canadian Space Agency (CSA)
Natural Sciences and Engineering Research Council of Canada (NSERC)

Dates

Created
2010-03-04
Created from EPrint's datestamp field
Updated
2021-11-08
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Caltech Custom Metadata

Caltech groups
Infrared Processing and Analysis Center (IPAC) , Physics Department