Cosmology

Abstract:

With ~10000 QSO redshifts, the 2dF QSO Redshift Survey (2QZ) is already the biggest individual QSO survey. The aim for the survey is to have ~25000 QSO redshifts, providing an order of magnitude increase in QSO clustering statistics. We first describe the observational parameters of the 2dF QSO survey. We then describe several highlights of the survey so far; we present new estimates of the QSO luminosity function and the QSO correlation function. We also present the first estimate of the QSO power spectrum from the 2QZ catalogue, probing the form of the fluctuation power-spectrum out to the \~1000h-1Mpc scales only previously probed by COBE. We find a power spectrum which is steeper than the prediction of standard CDM and more consistent with the prediction of Lambda-CDM. The best-fit value for the power spectrum shape parameter for a range of cosmologies is Gamma=0.1+-0.1. Finally, we discuss how the complete QSO survey will be able to constrain the value of Omega_Lambda by combining results from the evolution of QSO clustering and from a geometric test of clustering isotropy.

Abstract:

We report the first wide-field mapping of the kinematics and stellar populations in the E3 galaxy NGC 4365. The velocity maps extend previous long-slit work. They show two independent kinematic subsystems: the central 300 pc × 700 pc rotates about the projected minor axis, and the main body of the galaxy, 3 kpc × 4 kpc, rotates almost at right angles to this. The line strength maps show that the metallicity of the stellar population decreases from a central value greater than solar to one-half solar at a radius of 2 kpc. The decoupled core and main body of the galaxy have the same luminosity-weighted age, ≈14 Gyr, and the same elevated magnesium-to-iron ratio. The two kinematically distinct components have thus shared a common star formation history. We infer that the galaxy underwent a sequence of mergers associated with dissipative star formation that ended ≳ 12 Gyr ago. The misalignment between the photometric and kinematic axes of the main body is unambiguous evidence of triaxiality. The similarity of the stellar populations in the two components suggests that the observed kinematic structure has not changed substantially in 12 Gyr.

Abstract:

We briefly describe the SAURON project, aimed at determining the intrinsic shape and internal dynamics of spheroids. We focus here on the ability of SAURON to identify gaseous and stellar disks and to measure their morphology and kinematics. We illustrate some of our results with complete maps of NGC3377, NGC3623, and NGC4365.