Astronomical instrumentation

Abstract:

We are using adaptive optics on Keck and the VLT to probe the dynamics and star formation in Seyfert and QSO nuclei, obtaining spatial resolutions better than 0.1" in the H- and K-bands. The dynamics are traced via the 2.12um H_2 1-0S(1) line, while the stellar cluster is traced through the CO 2-0 and 6-3 absorption bandheads at 2.29um and 1.62um respectively. Matching disk models to the H_2 rotation curves allows us to study nuclear rings, bars, and warps; and to constrain the mass of the central black hole. The spatial extent and equivalent width of the stellar absorption permits us to estimate the mass of stars in the nucleus and their contribution to the emission. Here we report on new data for I Zwicky 1, Markarian 231, and NGC 7469.

Abstract:

We describe an instrument concept that will provide simultaneous spectra for a million spatial samples on the sky. With the proposed field of view and spectral resolution, it will be able to measure redshifts and line strengths for around 2-4000 z~3-7 galaxies in a 16 night campaign. The main science driver is to obtain a complete census of the star formation properties of galaxies with 2.5

Abstract:

We have calculated the two-point correlation functions in redshift space, Ζ (σ, π), for galaxies of different spectral types in the 2dF Galaxy Redshift Survey. Using these correlation functions, we are able to estimate values of the linear redshift-space distortion parameter, β ≡ Ωm^0.6/b, the pairwise velocity dispersion, a, and the real-space correlation function, Ζ(r), for galaxies with both relatively low star formation rates (for which the present rate of star formation is less than 10 per cent of its past averaged value) and galaxies with higher current star formation activity. At small separations, the real-space clustering of passive galaxies is very much stronger than that of the more actively star-forming galaxies; the correlation-function slopes are, respectively, 1.93 and 1.50, and the relative bias between the two classes is a declining function of scale. On scales larger than 10 h^-1 Mpc, there is evidence that the relative bias tends to a constant, b passive/bactive ≃ 1. This consistent with the similar degrees of redshift-space distortions seen in the correlation functions of the two classes - the contours of Ζ(σ, π) require β active = 0.49 ± 0.13 and βpassive = 0-48 ± 0.14. The pairwise velocity dispersion is highly correlated with β. Despite this, a significant difference is seen between the two classes. Over the range 820 h^-1 Mpc, the pairwise velocity dispersion has mean values of 416 ± 76 and 612 ± 92 km s^-1 for the active and passive galaxy samples, respectively. This is consistent with the expectation from morphological segregation, in which passively evolving galaxies preferentially inhabit the cores of high-mass virialized regions.