dc.contributor.author | Kukula, Marek | en_US |
dc.contributor.author | Dunlop, James | en_US |
dc.contributor.author | McClure, Ross | en_US |
dc.contributor.author | Miller, Lance | en_US |
dc.contributor.author | Percival, Will | en_US |
dc.contributor.author | Baum, Stefi | en_US |
dc.contributor.author | O'Dea, Christopher | en_US |
dc.date.accessioned | 2006-05-17T14:17:24Z | en_US |
dc.date.available | 2006-05-17T14:17:24Z | en_US |
dc.date.issued | 2001-10 | en_US |
dc.identifier.citation | Monthly Notices of the Royal Astronomical Society 326 (2001) 1533-1546 | en_US |
dc.identifier.issn | 1365-2966 | en_US |
dc.identifier.uri | http://hdl.handle.net/1850/1801 | en_US |
dc.description | RIT community members may access full-text via RIT Libraries licensed databases: http://library.rit.edu/databases/ | |
dc.description.abstract | We present the first results from a major Hubble Space Telescope programme designed
to investigate the cosmological evolution of quasar host galaxies from z~=2 to the
present day. Here we describe J and H-band NICMOS imaging of two quasar samples at redshifts of 0.9 and 1.9 respectively. Each sample contains equal numbers of radio-
loud and radio-quiet quasars, selected to lie within the same narrow range of optical
absolute magnitude (−24≥MV≥−25). Filter and target selection were designed to ensure that at each redshift the images sample the same part of the object’s rest-frame spectrum, longwards of 4000°A where starlight from the host galaxy is relatively
prominent, but avoiding potential contamination by [Oiii] 5007 and H-alpha emission lines. At z~=1 we have been able to establish host-galaxy luminosities and scalelengths with sufficient accuracy to demonstrate that the hosts of both radio-loud and radio-quiet quasars lie on the same Kormendy relation described by 3CR radio galaxies at comparable redshift (McLure & Dunlop 2000). Taken at face value the gap between the host luminosities of radio-loud and radio-quiet objects appears to have widened from only ~=0.4 mag. at z~=0.2 (Dunlop et al. 2001) to ~=1 mag. at z~=1, a difference that cannot be due to emission-line contamination given the design of our study. However, within current uncertainties, simple passive stellar evolution is sufficient to link these galaxies with the elliptical hosts of low-redshift quasars of comparable nuclear output,
implying that the hosts are virtually fully assembled by z~1. At z~=2 the hosts have proved harder to characterise accurately, and for only two of the nine z~=2 quasars observed has it proved possible to properly constrain the scalelength of the host galaxy. However, the data are of sufficient quality to yield host-galaxy luminosities accurate to within a factor ~=2. At this redshift the luminosity gap between radio-loud and radio-quiet quasars appears to have widened further to ~=1.5 mag. Thus while the hosts of radio-loud quasars remain consistent with a formation epoch of z>3, allowing for passive evolution implies that the hosts of radio-quiet
quasars are ~=2−4 times less massive at z~=2 than at z~=0.2. If the relationship between black-hole and spheroid mass is unchanged out to redshift z~=2, then our results rule out any model of quasar evolution which involves a substantial component of luminosity evolution (e.g. Kauffmann & Haehnelt 2000). Rather, this study indicates that at z~=2 there is a substantial increase in the number density of active black holes, along with a moderate increase in the fueling efficiency of a typical observed quasar. The fact that this latter effect is not displayed by the radio-loud objects in our sample might be explained by a selection effect arising from
the fact that powerful radio sources are only produced by the most massive black holes
(Dunlop et al. 2001; McLure & Dunlop 2000b) (Refer to PDF file for exact formulas). | en_US |
dc.description.sponsorship | The authors would like to thank the referee, D. Hines, for many useful comments and suggestions, and E. Bergeron for help with pedtherm. MJK, RJM & WJP acknowledge
PPARC funding. JSD acknowledges the enhanced research time afforded by the award of a PPARC Senior Fellowship. Support for this work was provided by NASA through grant numbers GO-06776.01-95A & GO-07447.01-
96A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based
on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute. This research has made use of the NASA/IPAC Extragalactic
Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. | en_US |
dc.format.extent | 433558 bytes | en_US |
dc.format.mimetype | application/pdf | en_US |
dc.language.iso | en_US | en_US |
dc.publisher | Blackwell Publishing | en_US |
dc.relation.ispartofseries | vol. 326 | en_US |
dc.relation.ispartofseries | no. 4 | en_US |
dc.subject | Galaxies-active | en_US |
dc.subject | Galaxies-evolution | en_US |
dc.subject | Quasars-general | en_US |
dc.title | A NICMOS imaging study of high-z quasar host galaxies | en_US |
dc.type | Article | en_US |
dc.identifier.url | http://dx.doi.org/10.1111/j.1365-2966.2001.04692.x | |