Leauthaud, Alexie and Benson, Andrew J. and Civano, Francesca and Coil, Alison L. and Bundy, Kevin and Massey, Richard and Schramm, Malte and Schulze, Andreas and Capak, Peter and Elvis, Martin and Kulier, Andrea and Rhodes, Jason (2015) The Dark Matter Halos of Moderate Luminosity X-ray AGN as Determined fromWeak Gravitational Lensing and Host Stellar Masses. Monthly Notices of the Royal Astronomical Society, 446 (2). pp. 1874-1888. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20141203-090456560
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Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter haloes in which they reside is key to constraining how black hole fuelling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modelling. In practice, these approaches remain uncertain because AGN, no matter how they are identified, potentially live a wide range of halo masses with an occupation function whose general shape and normalization are poorly known. In this work, we show that better constraints can be achieved through a rigorous comparison of the clustering, lensing, and cross-correlation signals of AGN hosts to the fiducial stellar-to-halo mass relation (SHMR) derived for all galaxies, irrespective of nuclear activity. Our technique exploits the fact that the global SHMR can be measured with much higher accuracy than any statistic derived from AGN samples alone. Using 382 moderate luminosity X-ray AGN at z < 1 from the COSMOS field, we report the first measurements of weak gravitational lensing from an X-ray-selected sample. Comparing this signal to predictions from the global SHMR, we find that, contrary to previous results, most X-ray AGN do not live in medium size groups – nearly half reside in relatively low mass haloes with M_(200b) ∼ 10^(12.5) M_⊙. The AGN occupation function is well described by the same form derived for all galaxies but with a lower normalization – the fraction of haloes with AGN in our sample is a few per cent. The number of AGN satellite galaxies scales as a power law with host halo mass with a power-law index α = 1. By highlighting the relatively ‘normal’ way in which moderate luminosity X-ray AGN hosts occupy haloes, our results suggest that the environmental signature of distinct fuelling modes for luminous quasars compared to moderate luminosity X-ray AGN is less obvious than previously claimed.
|Additional Information:||© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 October 21. Received 2014 September 30. In original form 2014 August 10. First published online November 21, 2014. We thank Phil Hopkins, Surhud More, and John Silverman for insightful discussions while preparing this paper. We also thank Ed Turner for valuable discussions related to statistical methods. We are grateful to Ian Harnett for editing this manuscript. We also thank Nikos Fanidakis for clarifications regarding halo mass values in Fanidakis et al. (2013). This work was supported by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. AK is supported by the National Science Foundation Graduate Research Fellowship, grant no. DGE-1148900. FC acknowledges financial support by the NASA grant AR1-12012X. RM is supported by a Royal Society University Research Fellowship. JR was supported by JPL, which is run by Caltech under a contract for NASA. ALC acknowledge support from NSF CAREER award AST-1055081.|
|Group:||COSMOS, Infrared Processing and Analysis Center (IPAC)|
|Subject Keywords:||galaxies: abundances galaxies: active galaxies: haloes galaxies: Seyfert galaxies: stellar content|
|Official Citation:||Alexie Leauthaud, Andrew J. Benson, Francesca Civano, Alison L. Coil, Kevin Bundy, Richard Massey, Malte Schramm, Andreas Schulze, Peter Capak, Martin Elvis, Andrea Kulier, and Jason Rhodes The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses MNRAS (January 11, 2015) Vol. 446 1874-1888 doi:10.1093/mnras/stu2210 First published online November 21, 2014|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||03 Dec 2014 20:53|
|Last Modified:||09 Nov 2016 22:02|
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