HerMES: SPIRE emission from radio-selected active galactic nuclei
journal contributionposted on 24.10.2012, 08:54 by M. Symeonidis, M. J. Page, A. Amblard, V. Arumugam, H. Aussel, A. Blain, J. Bock, A. Boselli, V. Buat, N. Castro-Rodriguez, A. Cava, P. Chanial, DL. Clements, A. Conley, L. Conversi, A. Cooray, C. D. Dowell, E. Dwek, S. Eales, D. Elbaz, A. Franceschini, J. Glenn, E. A. G. Solares, M. Griffin, E. Hatziminaoglou, E. Ibar, K. Isaak, R. J. Ivison, G. Lagache, L. Levenson, N. Lu, S. Madden, B. Maffei, G. Mainetti, L. Marchetti, H. T. Nguyen, B. O'Halloran, S. J. Oliver, A. Omont, P. Panuzzo, A. Papageorgiou, C. P. Pearson, I. Perez-Fournon, M. Pohlen, J. I. Rawlings, D. Rizzo, I. G. Roseboom, M. Rowan-Robinson, B. Schulz, D. Scott, D. L. Shupe, A. J. Smith, J. A. Stevens, M. Trichas, K. E. Tugwell, M. Vaccari, I. Valtchanov, L. Vigroux, L. Wang, G. Wright, C. K. Xu, M. Zemcov
We examine the rest-frame far-infrared emission from powerful radio sources with 1.4-GHz luminosity densities of 25 ≤ log(L1.4/W Hz−1) ≤ 26.5 in the extragalactic Spitzer First Look Survey field. We combine Herschel/SPIRE flux densities with Spitzer/Infrared Array Camera and Multiband Imaging Photometer for Spitzer infrared data to obtain total (Graphicm) infrared luminosities for these radio sources. We separate our sources into a moderate, 0.4 < z < 0.9, and a high, 1.2 < z < 3.0, redshift sub-sample and we use Spitzer observations of a z < 0.1 3CRR sample as a local comparison. By comparison to numbers from the Square Kilometre Array (SKA) Simulated Skies, we find that our moderate-redshift sample is complete and our high-redshift sample is 14 per cent complete. We constrain the ranges of mean star formation rates (SFRs) to be 3.4–4.2, 18–41 and 80–581 M⊙ yr−1 for the local, moderate- and high-redshift samples, respectively. Hence, we observe an increase in the mean SFR with increasing redshift which we can parametrize as ∼(1 + z)Q, where Q = 4.2 ± 0.8. However, we observe no trends of mean SFR with radio luminosity within the moderate- or high-redshift bins. We estimate that radio-loud active galactic nuclei (AGN) in the high-redshift sample contribute 0.1–0.5 per cent to the total SFR density at that epoch. Hence, if all luminous starbursts host radio-loud AGN we infer a radio-loud phase duty cycle of 0.001–0.005.