Most supermassive black hole growth is obscured by dust
Abstract
We present an alternative method to X-ray surveys for hunting down the high-redshift type-2 quasar population, using Spitzer and VLA data on the Spitzer First Look Survey. By demanding objects to be bright at 24 µm but faint at 3.6 µm, and combining this with a radio criterion, we find 21 type-2 radio-quiet quasar candidates at the epoch at which the quasar activity peaked. Optical spectroscopy with the WHT confirmed 10 of these objects to be type-2s with 1.4 ≤ z ≤ 4.2 while the rest are blank. There is no evidence for contamination in our sample, and we postulate that our 11 blank-spectrum candidates are obscured by kpc-scale dust as opposed to dust from a torus around the accretion disk. By carefully modelling our selection criteria, we conclude that, at high redshift, 50–80% of the supermassive black hole growth is obscured by dust.
Additional Information
© 2006 Wiley-VCH. Received 12 October 2005; accepted 15 November 2005; published online 20 February 2006. AMS, SR, ML, CS and MJJ would like to thank the organisers of the conference: Montse, Rosa, Enrique and Jose Luis for their kind hospitality. AMS would also like to thank the Council of the European Union for funding, and the Ministerio de Educaciόn y Ciencia for financial support for this conference. SR and CS would like to thank the UK PPARC for a Senior Research Fellowship and an Advanced Fellowship respectively.Additional details
- Eprint ID
- 24505
- Resolver ID
- CaltechAUTHORS:20110722-102417306
- European Research Council (ERC)
- Ministerio de Educación y Ciencia (MEC)
- Created
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2011-07-22Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field