We use measurements of 59/58 quasars (QSOs), over a redshift range $0.0041\leq z \leq 1.686$, to do comparative study the radius--luminosity ($R-L$) and X-ray$-$UV luminosity ($L_X-L_{UV}$) relations implication these for cosmological parameter estimation. By simultaneously determining $R-L$ or $L_X-L_{UV}$ relation parameters in six different models, we find that both are standardizable but pr...

For a sample of 25 dwarf irregular galaxies with distances D ∼ < 5 Mpc and measured oxygen abundances, we present results derived from galaxy luminosities at 4.5 μm and stellar masses from near-infrared imaging with IRAC on the Spitzer Space Telescope. We have constructed the appropriate luminosity-metallicity (L–Z) and mass-metallicity (M–Z) relations, and compared these relations with their c...

The virial mass (Mvir)–metallicity relation among the Local Group dwarf spheroidal galaxies (dSphs) is examined. Hirashita, Takeuchi, & Tamura showed that the dSphs can be divided into two distinct classes with respect to the relation between their virial masses and luminosities: low-mass (Mvir . 10M⊙) and highmass (Mvir & 10M⊙) groups. We see that both the mass–metallicity and the mass– lumino...

Using the conditional luminosity function (CLF) — the luminosity distribution of galaxies in a dark matter halo — as the fundamental building block, we present an empirical model for the galaxy distribution. The model predictions are compared with the published luminosity function and clustering statistics from Sloan Digital Sky Survey (SDSS) at low redshifts, and galaxy correlation functions f...

A new Monte-Carlo radiative-transfer code, Sunrise, is used to study the effects of dust in N-body/hydrodynamic simulations of interacting galaxies. Dust has a profound effect on the appearance of the simulated galaxies. At peak luminosities, ∼ 90% of the bolometric luminosity is absorbed, and the dust obscuration scales with luminosity in such a way that the brightness at UV/visual wavelengths...

We use a semianalytic galaxy catalogue constructed from the Millennium Simulation (MS) to study the satellites of isolated galaxies in the ΛCDM cosmogony. The large volume surveyed by the MS (500 hMpc), together with its unprecedented numerical resolution, enable the compilation of a large sample of ∼ 80, 000 bright (Mr < −20.5) primaries, surrounded by ∼ 178, 000 satellites down to the faint m...

We present the results of non-linear pulsation modelling of 20 bump Cepheids in the LMC. By obtaining a optimal fit to the observed V, R MACHO lightcurves we have placed tight constraints on stellar parameters of M , L, Teff and well as quantities of distance modulus and reddening. We describe the mass-luminosity relation for core-He burning for intermediate mass stars. The mass-luminosity rela...

We present deep spectroscopic data for a 24-object subsample of our full 41-object z ∼ 0.5 radio galaxy sample in order to investigate the evolution of the Fundamental Plane of radio galaxies.We find that the low-luminosity, FRI-type, radio galaxies in our sample are consistent with the local Fundamental Plane of radio galaxies defined by Bettoni et al. when corrected for simple passive evoluti...

We present the results of numerical experiments designed to evaluate the usefulness of near-infrared luminosity functions for constraining the Initial Mass Function (IMF) of young stellar populations. We test the sensitivity of the near-infrared K band luminosity function (KLF) of a young stellar cluster to variations in the underlying IMF, star forming history, and pre-main sequence mass-to-lu...

The relevance of galaxies of different luminosity and mass for the chemical enrichment of the intracluster medium (ICM) is analysed. For this purpose, I adopt the composite luminosity function of cluster galaxies from Trentham (1998), which exhibits a significant rise at the very faint end. The model – adopting a universal Salpeter IMF – is calibrated on reproducing the MFe/Ltot, MFe/M∗, and α/...