Quasars and their host galaxies

This review attempts to describe developments in the fields of quasar and quasar host galaxies in the past five. In this time period, the Sloan and 2dF quasar surveys have added several tens of thousands of quasars, with Sloan quasars being found to z>6. Obscured, or partially obscured quasars have begun to be found in significant numbers. Black hole mass estimates for quasars, and our confidence in them, have improved significantly, allowing a start on relating quasar properties such as radio jet power to fundamental parameters of the quasar such as black hole mass and accretion rate. Quasar host galaxy studies have allowed us to find and characterize the host galaxies of quasars to z>2. Despite these developments, many questions remain unresolved, in particular the origin of the close relationship between black hole mass and galaxy bulge mass/velocity dispersion seen in local galaxies.Comment: Review article, to appear in Astrophysics Update

Supermassive Binaries and Extragalactic Jets

Some quasars show Doppler shifted broad emission line peaks. I give new statistics of the occurrence of these peaks and show that, while the most spectacular cases are in quasars with strong radio jets inclined to the line of sight, they are also almost as common in radio-quiet quasars. Theories of the origin of the peaks are reviewed and it is argued that the displaced peaks are most likely produced by the supermassive binary model. The separations of the peaks in the 3C 390.3-type objects are consistent with orientation-dependent "unified models" of quasar activity. If the supermassive binary model is correct, all members of "the jet set" (astrophysical objects showing jets) could be binaries.Comment: 31 pages, PostScript, missing figure is in ApJ 464, L105 (see http://www.aas.org/ApJ/v464n2/5736/5736.html

Behaviour and activity patterns of the scuttle fly Megaselia oxybelorum Schmitz (Diptera : Phoridae) at nest aggregations of two host digger wasps (Hymenoptera : Crabronidae)

We report on a field study of the behavioural ecology of Megaselia oxybelorum Schmitz at nest aggregations of its hosts, the digger wasps Philanthus triangulum F. and Cerceris arenaria L. (Hymenoptera: Crabronidae). The flies flew across the P. triangulum nesting site both as single individuals and as females and males paired in copula, and the former case was recorded more than twice as often as the latter, while only single individuals were recorded at the C. arenaria site. Individuals both alone and in copula were seen at the P. triangulum site during the day roughly coinciding with the host provisioning activity, while at the C. arenaria site the fly's daily activity followed a bimodal trend in contrast to the normal distribution of the host provisioning. Visits of host nests were frequent at the P. triangulum site and null at the C. arenaria site. Single individuals spent less than 1 min inside a nest, while a female entering while still in copula spent generally 1-3 min inside, males exiting after 1-5 s, showing that only in this second case was an oviposition possible. The number of Megaselia oxybelorum increased with increasing host nest density and decreasing nearest neighbour distances of nests. Behavioural patterns of M. oxybelorum, when compared to other Megaselia spp. associated with fossorial Hymenoptera, showed differences possibly related to the biology of the hosts. In addition, some morphological variation within and between host sites are discussed