Ivison, R. J. and Alexander, David M. and Biggs, Andy D. and Brandt, W. N. and Chapin, Edward L. and Coppin, Kristen E. K. and Devlin, Mark J. and Dickinson, Mark and Dunlop, James and Dye, Simon and Eales, Stephen A. and Frayer, David T. and Halpern, Mark and Hughes, David H. and Ibar, Edo and Kovács, A. and Marsden, Gaelen and Moncelsi, L. and Netterfield, Calvin B. and Pascale, Enzo and Patanchon, Guillaume and Rafferty, D. A. and Rex, Marie and Schinnerer, Eva and Scott, Douglas and Semisch, C. and Smail, Ian and Swinbank, A. M. and Truch, Matthew D. P. and Tucker, Gregory S. and Viero, Marco P. and Walter, Fabian and Weiß, Axel and Wiebe, Donald V. and Xue, Y. Q. (2010) BLAST: the far-infrared/radio correlation in distant galaxies. Monthly Notices of the Royal Astronomical Society, 402 (1). pp. 245-258. ISSN 0035-8711 http://resolver.caltech.edu/CaltechAUTHORS:20100304-100106920
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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.|
|Subject Keywords:||galaxies: evolution; infrared: galaxies; radio continuum: galaxies|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||04 Mar 2010 21:11|
|Last Modified:||26 Dec 2012 11:49|
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