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GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3

Mullaney, J. R. and Hanish, D. J. (2012) GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3. Monthly Notices of the Royal Astronomical Society, 419 (1). pp. 95-115. ISSN 0035-8711. doi:10.1111/j.1365-2966.2011.19675.x.

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We present a study of the infrared properties of X-ray selected, moderate-luminosity (i.e. L_X= 10^(42)–10^(44) erg s^(−1)) active galactic nuclei (AGNs) up to z ≈ 3, in order to explore the links between star formation in galaxies and accretion on to their central black holes. We use 100 and 160 μ m fluxes from GOODS-Herschel – the deepest survey yet undertaken by the Herschel telescope – and show that in the vast majority of cases (i.e. >94 per cent) these fluxes are dominated by emission from the host galaxy. As such, these far-infrared bands provide an uncontaminated view of star formation in the AGN host galaxies. We find no evidence of any correlation between the X-ray and infrared luminosities of moderate AGNs at any redshift, suggesting that global star formation is decoupled from nuclear (i.e. AGN) activity in these galaxies. On the other hand, we confirm that the star formation rates of AGN hosts increase strongly with redshift, by a factor of 43^(+27)_(−18) from z < 0.1 to z = 2–3 for AGNs with the same range of X-ray luminosities. This increase is entirely consistent with the factor of 25–50 increase in the specific star formation rates (SSFRs) of normal, star-forming (i.e. main-sequence) galaxies over the same redshift range. Indeed, the average SSFRs of AGN hosts are only marginally (i.e. ≈20 per cent) lower than those of main-sequence galaxies at all surveyed redshifts, with this small deficit being due to a fraction of AGNs residing in quiescent (i.e. low SSFR) galaxies. We estimate that 79 ± 10 per cent of moderate-luminosity AGNs are hosted in main-sequence galaxies, 15 ± 7 per cent in quiescent galaxies and <10 per cent in strongly starbursting galaxies. We derive the fractions of all main-sequence galaxies at z < 2 that are experiencing a period of moderate nuclear activity, noting that it is strongly dependent on galaxy stellar mass (M_(stars)), rising from just a few per cent at M_(stars) ∼ 10^(10) M_⊙ to ≳20 per cent at M_(stars)≥ 10^(11) M_⊙. Our results indicate that it is galaxy stellar mass that is most important in dictating whether a galaxy hosts a moderate-luminosity AGN. We argue that the majority of moderate nuclear activity is fuelled by internal mechanisms rather than violent mergers, which suggests that high-redshift disc instabilities could be an important AGN feeding mechanism.

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Mullaney, J. R.0000-0002-3126-6712
Additional Information:© 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS. Accepted 2011 August 20. Received 2011 August 10; in original form 2011 June 20. Article first published online: 31 Oct. 2011. We are grateful to N. Drory for sharing the SED-fitting code used to estimate galaxy stellar masses. We thank V. Strazzullo and the anonymous referee for their useful comments. We acknowledge funding from a European FP7 Co-fund Fellowship (JRM) and the Science and Technology Funding Council (DMA). DE and MP acknowledge financial support from the French Agence Nationale de la Recherche (ANR) project HUGE, ANR-09-BLAN-0224. This research was supported by the ERC-StG grant UPGAL 240039 and by the French ANR under contract ANR-08-JCJC-0008. This work is based on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.
Funding AgencyGrant Number
Marie Curie FellowshipUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-09-BLAN-0224
European Research Council (ERC)UPGAL 240039
Agence Nationale pour la Recherche (ANR)ANR-08-JCJC-0008
Subject Keywords: galaxies; active; galaxies; high-redshift; galaxies; star formation; infrared; galaxies; X-rays; galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20120228-082439755
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Official Citation:Mullaney, J. R., Pannella, M., Daddi, E., Alexander, D. M., Elbaz, D., Hickox, R. C., Bournaud, F., Altieri, B., Aussel, H., Coia, D., Dannerbauer, H., Dasyra, K., Dickinson, M., Hwang, H. S., Kartaltepe, J., Leiton, R., Magdis, G., Magnelli, B., Popesso, P., Valtchanov, I., Bauer, F. E., Brandt, W. N., Del Moro, A., Hanish, D. J., Ivison, R. J., Juneau, S., Luo, B., Lutz, D., Sargent, M. T., Scott, D. and Xue, Y. Q. (2012), GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3. Monthly Notices of the Royal Astronomical Society, 419: 95–115. doi: 10.1111/j.1365-2966.2011.19675.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29499
Deposited By: Ruth Sustaita
Deposited On:28 Feb 2012 16:50
Last Modified:09 Nov 2021 17:07

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