Astronomical instrumentation

Abstract:

To examine the evolution of the early-type galaxy population in the rich cluster Abell 2390 at z=0.23 we have gained spectroscopic data of 51 elliptical and lenticular galaxies with MOSCA at the 3.5 m telescope on Calar Alto Observatory. This investigation spans both a broad range in luminosity (-19.3>M_B>-22.3) and uses a wide field of view of 10'x10', therefore the environmental dependence of different formation scenarios can be analysed in detail as a function of radius from the cluster centre. Here we present results on the surface brightness modelling of galaxies where morphological and structural information is available in the F814W filter aboard the Hubble Space Telescope (HST) and investigate for this subsample the evolution of the Fundamental Plane.

Abstract:

We introduce the NOAO Fundamental Plane Survey (NFPS), a wide-field imaging/spectroscopic study of rich, low-redshift galaxy clusters. The survey targets X-ray-selected clusters at 0.010 < z < 0.067, distributed over the whole sky, with imaging and spectroscopic observations obtained for 93 clusters. This data set will be used in investigations of galaxy properties in the cluster environment and of large-scale velocity fields through the fundamental plane. In this paper, we present details of the cluster sample construction and the strategies employed to select early-type galaxy samples for spectroscopy. Details of the spectroscopic observations are reported. From observations of 5479 red galaxies, we present redshift measurements for 5388 objects and internal velocity dispersions for 4131. The velocity dispersions have a median estimated error ∼7%. The NFPS has ∼15% overlap with previously published velocity dispersion data sets. Comparisons to these external catalogs are presented and indicate typical external errors of ∼8%.

Abstract:

We present the result of a decomposition of the 2dF Galaxy Redshift Survey (2dFGRS) galaxy overdensity field into an orthonormal basis of spherical harmonics and spherical Bessel functions. Galaxies are expected to directly follow the bulk motion of the density field on large scales, so the absolute amplitude of the observed large-scale redshift-space distortions caused by this motion is expected to be independent of galaxy properties. By splitting the overdensity field into radial and angular components, we linearly model the observed distortion and obtain the cosmological constraint Ω m0.6σ8 = 0.46 ± 0.06. The amplitude of the linear redshift-space distortions relative to the galaxy overdensity field is dependent on galaxy properties and, for L* galaxies at redshift z = 0, we measure β(L*, 0) = 0.58 ± 0.08, and the amplitude of the overdensity fluctuations b(L *, 0)σ8 = 0.79 ± 0.03, marginalizing over the power spectrum shape parameters. Assuming a fixed power spectrum shape consistent with the full Fourier analysis produces very similar parameter constraints.