GENIE observations of small scale astrophysical processes in star forming regions and quasars

The VLTI/GENIE configuration will operate using at least 4 of the VLTI telescopes (and possibly with one or more of the AT telescopes in the future if adaptive optics become available on them). GENIE effectively can be thought of as a 'smart' coronagraph, enabling high dynamic range imaging to be achieved at moderate spatial resolution, with high rejection of the emission of a central bright point source. However, but this bright source rejection may only provide a rather moderate image quality (due to the few baselines and transfer function on the sky). Operated in this way, only limited image reconstruction is possible since classical radio and millimeter wavelength interferometry techniques are not directly applicable to the outputs of optical interferometers because the absolute phases are generally not measured. However, measurements of visibility and closure phase could lead to situations where image reconstruction becomes possible. This paper addresses the issue of whether there are areas outside of the exoplanet search where it might be able to make a useful impact on astronomy.Comment: Proceedings of the Genie-Darwin Workshop - Hunting for Planet

QSO environments at intermediate redshifts

We have made a survey of quasar environments at 0.5 < z < 0.8, using a sample of both radio-loud and radio-quiet quasars matched in B-band luminosity. Our observations include images of background control fields to provide a good determination of the field galaxy counts. About 10 per cent of the quasars appear to live in rich clusters, whereas approximately 45 per cent live in environments similar to that of field galaxies. The richness of galaxies within a 0.5 Mpc radius around the radio-quiet quasars is found to be indistinguishable from the richness around the radio-loud quasars, corresponding on average to groups or poorer clusters of galaxies. Comparing the galaxy richness in the radio-loud quasar fields with quasar fields in the literature, we find no evidence of an evolution in the environment with epoch. Instead, a weak, but significant correlation between quasar radio luminosity and environmental richness is present. It is thus possible that the environments of quasars, at least the powerful ones, do not evolve much between the present epoch and z \approx 0.8.Comment: 6 pages, 4 figures, to appear in the proc. of the workshop `QSO hosts and their environments', IAA, Granada 10-12 Jan, 200

<i>AKARI</i>/IRC source catalogues and source counts for the IRAC Dark Field, ELAIS North and the <i>AKARI</i> Deep Field South

We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimized data analysis toolkit specifically for the processing of extragalactic point sources. The InfaRed Camera (IRC) on AKARI complements the SpitzerSpace Telescope via its comprehensive coverage between 8–24 μm filling the gap between the Spitzer/IRAC and MIPS instruments. Source counts in the AKARI bands at 3.2, 4.1, 7, 11, 15 and 18 μm are presented. At near-infrared wavelengths, our source counts are consistent with counts made in other AKARI fields and in general with SpitzerIRAC (except at 3.2 μm where our counts lie above). In the mid-infrared (11 – 18 μm), we find our counts are consistent with both previous surveys by AKARI and the Spitzer peak-up imaging survey with the InfraRed Spectrograph (IRS). Using our counts to constrain contemporary evolutionary models, we find that although the models and counts are in agreement at mid-infrared wavelengths there are inconsistencies at wavelengths shortward of 7 μm, suggesting either a problem with stellar subtraction or indicating the need for refinement of the stellar population models. We have also investigated the AKARI/IRC filters, and find an active galactic nucleus selection criteria out to z AKARI 4.1, 11, 15 and 18 μm colours

Radio-quiet quasar environments at 0.5 < z < 0.8

We have quantified the galaxy environments around a sample of 0.5 < z < 0.8 radio-quiet quasars using the amplitude of the spatial galaxy--quasar correlation function, B_gq. The quasars exist in a wide variety of environments, some sources are located in clusters as rich as Abell class 1--2 clusters, whereas others exist in environments comparable to the field. We find that on average, the quasars prefer poorer clusters of approximately Abell class 0, which suggests that quasars are biased tracers of mass compared to galaxies. The mean B_gq for the sample is found to be indistinguishable from the mean amplitude for a sample of radio-loud quasars matched in redshift and optical luminosity. These observations are consistent with recent studies of the hosts of radio-quiet quasars at low to intermediate redshifts, and suggest that the mechanism for the production of powerful radio jets in radio-loud quasars is controlled by processes deep within the active galactic nucleus itself, and is unrelated to the nature of the hosts or their environments.Comment: 19 pages, 8 figures, accepted for publication in MNRA

Clustering of galaxies around radio quasars at 0.5 < z < 0.8

We have observed the galaxy environments around a sample of 21 radio-loud, steep-spectrum quasars at 0.5<z<0.82, spanning several orders of magnitude in radio luminosity. The observations also include background control fields used to obtain the excess number of galaxies in each quasar field. The galaxy excess was quantified using the spatial galaxy-quasar correlation amplitude, B_gq, and an Abell-type measurement, N_0.5 (Hill & Lilly 1991). A few quasars are found in relatively rich clusters, but on average, they seem to prefer galaxy groups or clusters of approximately Abell class 0. We have combined our sample with literature samples extending down to z=0.2 and covering the same range in radio luminosity. By using Spearman statistic to disentangle redshift and luminosity dependences, we detect a weak, but significant, positive correlation between the richness of the quasar environment and the quasar's radio luminosity. However, we do not find any epoch dependence in B_gq, as has previously been reported for radio quasars and galaxies. We discuss the radio luminosity-cluster richness link and possible explanations for the weak correlation that is seen.Comment: 18 pages, 9 figures, submitted to MNRA

The Radio-Optical Correlation in Steep-Spectrum Quasars

Using complete samples of steep-spectrum quasars, we present evidence for a correlation between radio and optical luminosity which is not caused by selection effects, nor caused by an orientation dependence (such as relativistic beaming), nor a byproduct of cosmic evolution. We argue that this rules out models of jet formation in which there are no parameters in common with the production of the optical continuum. This is arguably the most direct evidence to date for a close link between accretion onto a black hole and the fuelling of relativistic jets. The correlation also provides a natural explanation for the presence of aligned optical/radio structures in only the most radio luminous high-redshift galaxies.Comment: MNRAS in press. Uses BoxedEPS (included

A 12um ISOCAM Survey of the ESO-Sculptor Field: Data Reduction and Analysis

We present a detailed reduction of a mid-infrared 12um (LW10 filter) ISOCAM open time observation performed on the ESO-Sculptor Survey field (Arnouts et al. 1997). A complete catalogue of 142 sources (120 galaxies and 22 stars), detected with high significance (equivalent to 5sigma), is presented above an integrated flux density of 0.24mJy. Star/galaxy separation is performed by a detailed study of colour-colour diagrams. The catalogue is complete to 1mJy and below this flux density the incompleteness is corrected using two independent methods. The first method uses stars and the second uses optical counterparts of the ISOCAM galaxies; these methods yield consistent results. We also apply an empirical flux density calibration using stars in the field. For each star, the 12um flux density is derived by fitting optical colours from a multi-band chi^2 to stellar templates (BaSel-2.0) and using empirical optical-IR colour-colour relations. This article is a companion analysis to Rocca-Volmerange 2007 et al. where the 12um faint galaxy counts are presented and analysed by galaxy type with the evolutionary code PEGASE.3.Comment: 12 pages, 7 figures, figure 1 modified from journal version for size, accepted for publication in A&A, includes psfig.st