The far-infrared/radio correlation as probed by Herschel
Abstract
We set out to determine the ratio, q(IR), of rest-frame 8-1000um flux, S(IR), to monochromatic radio flux, S(1.4GHz), for galaxies selected at far-IR and radio wavelengths, to search for signs that the ratio evolves with redshift, luminosity or dust temperature, and to identify any far-IR-bright outliers - useful laboratories for exploring why the far-IR/radio correlation is generally so tight when the prevailing theory suggests variations are almost inevitable. We use flux-limited 250-um and 1.4-GHz samples, obtained in GOODS-N using Herschel (HerMES; PEP) and the VLA. We determine bolometric IR output using ten bands spanning 24-1250um, exploiting data from PACS and SPIRE, as well as Spitzer, SCUBA, AzTEC and MAMBO. We also explore the properties of an L(IR)-matched sample, designed to reveal evolution of q(IR) with z, spanning log L(IR) = 11-12 L(sun) and z=0-2, by stacking into the radio and far-IR images. For 1.4-GHz-selected galaxies, we see tentative evidence of a break in the flux ratio, q(IR), at L(1.4GHz) ~ 10^22.7 W/Hz, where AGN are starting to dominate the radio power density, and of weaker correlations with z and T(d). From our 250-um-selected sample we identify a small number of far-IR-bright outliers, and see trends of q(IR) with L(1.4GHz), L(IR), T(d) and z, noting that some of these are inter-related. For our L(IR)-matched sample, there is no evidence that q(IR) changes significantly as we move back into the epoch of galaxy formation: we find q(IR) goes as (1+z)^gamma, where gamma = -0.04 +/- 0.03 at z=0-2; however, discounting the least reliable data at z<0.5 we find gamma = -0.26 +/- 0.07, modest evolution which may be related to the radio background seen by ARCADE2, perhaps driven by <10uJy radio activity amongst ordinary star-forming galaxies at z>1.
Keywords
Cite
@article{arxiv.1005.1072,
title = {The far-infrared/radio correlation as probed by Herschel},
author = {R. J. Ivison and B. Magnelli and E. Ibar and P. Andreani and D. Elbaz and B. Altieri and A. Amblard and V. Arumugam and R. Auld and H. Aussel and T. Babbedge and S. Berta and A. Blain and J. Bock and A. Bongiovanni and A. Boselli and V. Buat and D. Burgarella and N. Castro and A. Cava and J. Cepa and P. Chanial and A. Cimatti and M. Cirasuolo and D. L. Clements and A. Conley and L. Conversi and A. Cooray and E. Daddi and H. Dominguez and C. D. Dowell and E. Dwek and S. Eales and D. Farrah and M. Fox and A. Franceschini and W. Gear and R. Genzel and J. Glenn and M. Griffin and C. Gruppioni and M. Halpern and E. Hatziminaoglou and K. Isaak and G. Lagache and L. Levenson and N. Lu and D. Lutz and S. Madden and B. Maffei and G. Magdis and G. Mainetti and R. Maiolino and L. Marchetti and G. E. Morrison and A. M. J. Mortier and H. T. Nguyen and R. Nordon and B. O'Halloran and S. J. Oliver and A. Omont and F. N. Owen and M. J. Page and P. Panuzzo and A. Papageorgiou and C. P. Pearson and A. and A. Poglitsch and M. Pohlen and P. Popesso and F. Pozzi and J. I. Rawlings and G. Raymond and D. Rigopoulou and L. Riguccini and D. Rizzo and G. Rodighiero and I. G. Roseboom and M. Rowan-Robinson and A. Saintonge and M. Sanchez Portal and P. Santini and B. Schulz and Douglas Scott and N. Seymour and L. Shao and D. L. Shupe and A. J. Smith and J. A. Stevens and E. Sturm and M. Symeonidis and L. Tacconi and M. Trichas and K. E. Tugwell and M. Vaccari and I. Valtchanov and J. Vieira and L. Vigroux and L. Wang and R. Ward and G. Wright and C. K. Xu and M. Zemcov},
journal= {arXiv preprint arXiv:1005.1072},
year = {2015}
}
Comments
A&A Herschel Special Issue, in press as a Letter. 5 pages