The Luminosity Function of QSO Host Galaxies

Abstract

We report on results from H band imaging observations of a complete sample of high-luminosity low-redshift QSOs. The luminosity function of QSO hosts is similar in shape to that of normal galaxies, although offset in normalisation by a factor of 10 −4 . This supports the hypothesis that the parent population of quasars is identical to the general population of early-type field galaxies. IntroductionIdentifying the parent population of QSO host galaxies is one of the fundamental problems linking the QSO phenomenon to galaxy evolution in general. While the most widely adopted approach is to compare morphological (and increasingly also spectral) properties of normal and active galaxies, we investigate here the statistical distribution of galaxy luminosities. This short report highlights some results which will be elaborated in more detail in a series of forthcoming papers. We adopt h = 0.5 and q 0 = 0.5 throughout. 2.H band imaging of a complete QSO sampleIn order to constrain the overall luminosity distribution of QSO hosts, the investigated targets must represent a fair sample of the QSO population. To obtain also the normalisation, the sample has furthermore to be complete (in the sense of comprising all QSOs within a given area that are brighter than a well-defined flux limit). Our sample has been selected from the Hamburg/ESO bright quasar survey , with the following additional criteria: Right ascension between 9 h and 16 h ; nuclear absolute magnitudes M B J < −23; and redshifts z < 0.3. The resulting sample consisted of 30 targets distributed over 2200 deg 2 , all of which were subsequently observed. Because of the op-1

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“…Secondly, it is clear that the AGNs and nearby inactive‐galaxy samples follow the same M bh – L bulge relation over >3 decades in black hole mass, and >2.5 decades in bulge luminosity. This second fact strongly supports the conclusions of Dunlop et al (2001) and Wisotzki et al (2001) that the host galaxies of powerful quasars are normal massive ellipticals drawn from the bright end of the elliptical galaxy luminosity function. Thirdly, there can be seen to be no systematic offset between the Seyfert 1 and quasar samples, reinforcing the findings of MD01 and Laor (2001) that, contrary to the results of Wandel (1999), the bulges of Seyfert galaxies and QSOs form a continuous sequence that ranges from M R (bulge)≃‐18 to M R (bulge)≃‐24.5.…”

Modelling the galaxy bimodality: shutdown above a critical halo mass

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Radio emission and the optical isophotal twist of radio-loud ellipticals

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