HerMES: Far-infrared properties of known AGN in the HerMES fields
Abstract
Nuclear and starburst activity are known to often occur concomitantly. Herschel-SPIRE provides sampling of the FIR SEDs of type 1 and type 2 AGN, allowing for the separation between the hot dust (torus) and cold dust (starburst) emission. We study large samples of spectroscopically confirmed type 1 and type 2 AGN lying within the Herschel Multi-tiered Extragalactic Survey (HerMES) fields observed during the science demonstration phase, aiming to understand their FIR colour distributions and constrain their starburst contributions. We find that one third of the spectroscopically confirmed AGN in the HerMES fields have 5-sigma detections at 250um, in agreement with previous (sub)mm AGN studies. Their combined Spitzer-MIPS and Herschel-SPIRE colours - specifically S(250)/S(70) vs. S(70)/S(24) - quite clearly separate them from the non-AGN, star-forming galaxy population, as their 24-um flux is dominated by the hot torus emission. However, their SPIRE colours alone do not differ from those of non-AGN galaxies. SED fitting shows that all those AGN need a starburst component to fully account for their FIR emission. For objects at z > 2, we find a correlation between the infrared luminosity attributed to the starburst component, L(SB), and the AGN accretion luminosity, L(acc), with L(SB) propto L(acc)^0.35. Type 2 AGN detected at 250um show on average higher L(SB) than type 1 objects but their number is still too low to establish whether this trend indicates stronger star-formation activity.
Cite
@article{arxiv.1005.2192,
title = {HerMES: Far-infrared properties of known AGN in the HerMES fields},
author = {E. Hatziminaoglou and A. Omont and J. A. Stevens and A. Amblard and V. Arumugam and R. Auld and H. Aussel and T. Babbedge and A. Blain and J. Bock and A. Boselli and V. Buat and D. Burgarella and N. Castro-Rodriguez and A. Cava and P. Chanial and D. L. Clements and A. Conley and L. Conversi and A. Cooray and C. D. Dowell and E. Dwek and S. Dye and S. Eales and D. Elbaz and D. Farrah and M. Fox and A. Franceschini and W. Gear and J. Glenn and E. A. Gonzalez Solares and M. Griffin and M. Halpern and E. Ibar and K. Isaak and R. J. Ivison and G. Lagache and L. Levenson and N. Lu and S. Madden and B. Maffei and G. Mainetti and L. Marchetti and A. M. J. Mortier and H. T. Nguyen and B. O'Halloran and S. J. Oliver and M. J. Page and P. Panuzzo and A. Papageorgiou and C. P. Pearson and I. Perez-Fournon and M. Pohlen and J. I. Rawlings and D. Rigopoulou and D. Rizzo and I. G. Roseboom and M. Rowan-Robinson and M. Sanchez Portal and B. Schulz and Douglas Scott and N. Seymour and D. L. Shupe and A. J. Smith and M. Symeonidis and M. Trichas and K. E. Tugwell and M. Vaccari and I. Valtchanov and L. Vigroux and L. Wang and R. Ward and G. Wright and C. K. Xu and M. Zemcov},
journal= {arXiv preprint arXiv:1005.2192},
year = {2015}
}
Comments
Astronomy and Astrophysics, Herschel Special Issue, in press as a Letter; 5 pages