Summary: GALAXIES AT z = 2:
EXTENSIONS AROUND RADIO­QUIET QSOs
ITZIAR ARETXAGA, B.J. BOYLE, R.J. TERLEVICH
Royal Greenwich Observatory, Madingley Road, Cambridge CB3 OEZ, U.K.
Abstract
We have been conducting an imaging survey to detect host galaxies of radio­quiet QSOs at
high redshift (z ß 2), in order to compare them with those of radio­loud objects. Six QSOs were
observed in the R passband with the auxiliary port of the 4.2m WHT of the Observatorio de Roque
de los Muchachos in August 1994. The objects were selected to be bright (M B
! ¸ \Gamma28 mag) and
have bright stars in the field, which could enable us to define the point spread function (PSF)
accurately. The excellent seeing of La Palma (! 0:9 arcsec thoughout the run) allowed us to detect
extensions to the nuclear PSFs around three (one radio­loud and two radio­quiet) QSOs, out of
4 suitable targets. The extensions are most likely due to the host galaxies of these QSOs, with
luminosities of at least 3 \Gamma 7% of the QSO luminosity. The most likely values for the luminosity of
the host galaxies lie in the range 6 \Gamma 18% of the QSO luminosity. Our observations show that, if
the extensions we have detected are indeed galaxies, extraordinary massive and luminous galaxies
are not only a characteristic of radio­loud objects, but of QSOs as an entire class.
1. Analysis of the observations
For each QSO field, we defined a 2­dimensional PSF using the brightest of the closest stellar companion

Source: Aretxaga, Itziar - Instituto Nacional de Astrofísica Óptica y Electrónica

Collections: Physics