The APM galaxy survey - V. Catalogues of galaxy clusters
Monthly Notices of the Royal Astronomical Society 289:2 (1997) 263-284
Abstract:
We describe the construction of catalogues of galaxy clusters from the APM Galaxy survey using an automated algorithm based on Abell-like selection criteria. We investigate the effects of varying several parameters in our selection algorithm, including the magnitude range and radius from the cluster centre used to estimate the cluster richnesses. We quantify the accuracy of the photometric distance estimates by comparing them with measured redshifts, and we investigate the stability and completeness of the resulting catalogues. We find that the angular correlation functions for different cluster catalogues are in good agreement with one another, and are also consistent with the observed amplitude of the spatial correlation function of rich clusters. © 1997 RAS.The nuclear stellar core, the hot dust source, and the location of the nucleus of NGC 1068
Astrophysical Journal 490:1 PART I (1997) 238-246
Abstract:
We present new near-infrared speckle and adaptive optics imaging and integral field spectroscopy of the nuclear region of NGC 1068. Ninety-four percent of the K-band light in the central 1" originates from a ≤30 milliarcsecond diameter source whose position we determine to coincide within ± 0''15 with the apex of the cone structure seen in the optical narrow emission lines, as well as the location of the flat spectrum radio component SI and the 12 μm emission peak. We interpret the compact source as hot dust near the sublimation temperature within ∼ 1 pc of the true nucleus of the galaxy. The remaining 6% of the light in the central 1″ comes from a moderately extincted stellar core centered on the nuclear position and of intrinsic size ∼50 pc. We show that this nuclear stellar core is probably 5-16 × 108 yr in age and contributes at least 7% of the total nuclear luminosity of ~1 × 1011 L⊙. © 1997. The American Astronomical Society. All rights reserved.X-ray QSO evolution from a very deep ROSAT survey
Monthly Notices of the Royal Astronomical Society 285:3 (1997) 547-560
Abstract:
In the deepest optically identified X-ray survey yet performed, we have identified 32 X-ray-selected QSOs to a flux limit of 2 × 10-15 erg cm-2 s-1 (0.5-2 keV). The survey, performed with the ROSAT Position Sensitive Proportional Counter (PSPC), has 89 per cent spectroscopic completeness. The QSO log(N)-log(S) relation is found to have a break to a flat slope at faint fluxes. The surface density of QSOs at the survey limit is 230 ± 40 per square degree, the largest so far of any QSO survey. We use this survey to measure the QSO X-ray luminosity function at low luminosities (LX<1044.5 erg s-1) and high redshifts (23D - A new generation imaging spectrometer
P SOC PHOTO-OPT INS 2871 (1997) 1179-1186
Abstract:
3D is a new type of a highly sensitive near-infrared integral field spectrometer developed at MPE. It has been designed to multiplex spectral as well as spatial information thus obtaining a full data cube in a single integration. At a spectral resolution between 1000 and 2000 and a field of view of 16 x 16 pixels, optimized for subarcsecond spatial resolution imaging spectroscopy, it has a much higher efficiency compared to conventional techniques. Outfitting one of the VLTs with a near-IR 3D type instrument will provide a powerful tool for diffraction-limited integral field spectroscopic research, in particular on faint high-z galaxies in the early universe. The basic design, recent upgrades as well as plans for a possible VLT-3D instrument are presented.GMOS: The GEMINI multiple object spectrographs
OPTICAL TELESCOPES OF TODAY AND TOMORROW: FOLLOWING IN THE DIRECTION OF TYCHO BRAHE 2871 (1997) 1099-1106