Recent progress in constraining the massive accretions (>1:10) experienced by Milky Way (MW) and Andromeda galaxy (M31) offers an opportunity to understand dwarf population of Local Group. Using zoom-in dark matter-only simulations MW-mass haloes concentrating on subhaloes that are thought be capable hosting galaxies, we demonstrate infall a progenitor is accompanied with accretion destruction ...

We study the properties of the fossil cluster RX J1416.4+2315 through g’ and i’-band imaging and spectroscopy of 25 member galaxies. The system is at a mean redshift of 0.137 and has a velocity dispersion of 584 km s−1. Superimposed onto one quadrant of the cluster field there is a group of five galaxies at a mean redshift of 0.131, which, if included as part of the cluster, increases the veloc...

We have used STIS aboard HST to search for Lyα absorption lines in the outer regions of eight nearby galaxies using background QSOs and AGN as probes. Lyα lines are detected within a few hundred km s−1 of the systemic velocity of the galaxy in all cases. We conclude that a background line of sight which passes within 26 − 200 h−1 kpc of a foreground galaxy is likely to intercept low column dens...

We have used STIS aboard HST to search for Lyα absorption lines in the outer regions of eight nearby galaxies using background QSOs and AGN as probes. Lyα lines are detected within a few hundred km s−1 of the systemic velocity of the galaxy in all cases. We conclude that a background line of sight which passes within 26 − 200 h−1 kpc of a foreground galaxy is likely to intercept low column dens...

Low-resolution LAMOST and Keck spectra of blue supergiant stars distributed over the disks Local Group spiral galaxies M 31 33 are analyzed to determine stellar effective temperatures, gravities, metallicities, reddening. Logarithmic metallicities at center (in solar units) $0.30\pm0.09$ $0.11\pm0.04$ metallicity gradients $-0.37\pm0.13$ dex/$R_{25}$ $-0.36\pm0.16$ measured for 33, respectively...

With the success of the Chandra and XMM missions and the maturation of gravitational lensing techniques, powerful constraints on the orbital structure of cluster dark matter halos are possible. I show that the X-ray emissivity and mass of a galaxy cluster uniquely specify the anisotropy and velocity dispersion profiles of its dark matter halo. I consider hydrostatic as well as cooling flow scen...

We present the first interferometric evidence of CO (1–0) emission in the intragroup starburst (IGS) region of HCG 92 (Stephan’s Quintet). BIMA’s large primary beam fully covers both the IGS region and the dominant group member Seyfert galaxy NGC 7319, as well as partially covering the intruder galaxy NGC 7318B. CO emission of *4 j is detected in all of them. The detection of the CO emission as...

Over the next few years the new radio telescopes, such as the Low Frequency Array (LOFAR) will greatly enhance our knowledge of the active history of the Universe. Large-area surveys with these new telescopes will no longer be dominated by the powerful active galactic nuclei, but by radio-quiet quasars and star-forming galaxies over all cosmic epochs. Further in the future (∼ 2014) the Square K...

We present a study of a faint fuzzy star cluster system in the nearby SB0 galaxy NGC 5195 interacting with the famous spiral galaxy NGC 5194 (M51), based on HST ACS BV I mosaic images taken by the Hubble Heritage Team. We have found about 50 faint fuzzy star clusters around NGC 5195 which are larger than typical globular clusters with effective radii reff > 7 pc and red with (V − I) > 1.0. They...