Using well-defined selection criteria applied to the LEDA galaxy catalogue we have constructed a sample of elliptical galaxies that can be taken to lie in the field. Such criteria can easily be applied to theoretical simulations for direct comparison with observations. The variation of the number of ‘isolated’ ellipticals with selection criteria is also investigated. A preliminary study of the ...

I have assembled a diverse sample of galaxies from the literature with far-ultraviolet (FUV), optical, infrared (IR) and radio luminosities to explore the calibration of radio-derived and IR-derived star formation (SF) rates, and the origin of the radio-IR correlation. By comparing the 8–1000μm IR, which samples dust-reprocessed starlight, with direct stellar FUV emission, I show that the IR tr...

Data are presently available on the luminosities and half-light radii of 101 globular clusters associated with lowluminosity parent galaxies. The luminosity distribution of globulars embedded in dwarf galaxies havingMv > −16 is found to differ dramatically from that for globular clusters surrounding giant host galaxies with Mv < −16. The luminosity distribution of globular clusters in giant gal...

We use Chandra observations of 13 nearby groups of galaxies to investigate the hot gas content of their member galaxies. We find that a large fraction of nearIR bright, early-type galaxies in groups have extended X-ray emission, indicating that they retain significant hot gas halos even in these dense environments. In particular, we detect hot gas halos in ∼80% of LK > L∗ galaxies. We do not fi...

The role of the environment of an elliptical galaxy on its hot interstellar gas is discussed. In general, the X-ray halos of early-type galaxies tend to be smaller and fainter in denser environments, with the exception of group-central galaxies. X-ray observations show many examples of nearby galaxies which are undergoing gas stripping. On the other hand, most bright galaxies in clusters do man...

We present results of large-aperture (D1@) JK photometry and CCD BV RI photometry near the centers of three distant (0.111 z1 0.22), rich Abell clusters of galaxies. The colors of the integrated light are consistent with those of nearby E and S0 galaxies. The absence of anomalous reddening implies that no more than 2 h~1% (1 p limit) of the dark matter in these clusters can be in the form of lo...

We discuss some results of a morphological study of edge-on galaxies, based on optical and especially near-infrared surface photometry. We find that the vertical surface brightness distributions of galaxies are fitted very well by exponential profiles, much better than by isothermal distributions. We find that in general the vertical scale height increases when going outward. This increase is s...

Our Chandra X-ray Observatory archival study of intracluster entropy in a sample of 222 galaxy clusters shows that Hα and radio emission from the brightest cluster galaxy are much more pronounced when the cluster’s core gas entropy is . 30 keV cm2. The prevalence of Hα emission below this threshold indicates that it marks a dichotomy between clusters that can harbor multiphase gas and star form...

We investigate strong lensing of galaxies in the Hubble Deep Field by foreground groups and clusters of galaxies with masses from 10 to 10M⊙. Over this mass range, groups with the profile of Navarro, Frenk, & White (1995) are less efficient than singular isothermal spheres at producing multiple images of galaxies, by factors of 5× 10 to 10. This difference highlights the sensitivity of the lens...

Averaged spectral energy distributions (SEDs) of active and starburst galaxies from the 12μm sample in the Local Universe and quasars, from an optically selected sample at a mean redshift 〈z〉=0.7 are built from optical, near-IR and far-IR (IRAS and ISO) photometric observations. These SEDs are then used to predict at various redshifts the number of Seyfert type 1 and type 2, starburst, normal g...