We present high-resolution mass reconstructions for five massive cluster-lenses spanning a redshift range from z = 0.18–0.57 utilizing archival Hubble Space Telescope (HST) data and applying galaxy-galaxy lensing techniques. These detailed mass models were obtained by combining constraints from the observed strong and weak lensing regimes. Quantifying the local weak distortions in the shear map...

AGN are elusive objects across that are visible across the electromagnetic spectrum. Currently, there is no complete picture of AGN formation and evolution in galaxy clusters. A general understanding of the AGN population has been impeded by cluster and selection biases and recent studies have shown that there is a large population of obscured or optically unremarkable AGN in galaxy clusters. T...

Passive spiral galaxies — unusual galaxies with spiral morphology without any sign of ongoing star formation — have recently been discovered to exist preferentially in cluster infalling regions (at about the virial radius, or at a local galaxy density of ∼ 1 Mpc). The discovery directly connects the passive spiral galaxies to the cluster galaxy evolution studies such as the Butcher-Oemler effec...

We develop a galaxy cluster finding algorithm based on spectral clustering technique to identify optical counterparts and estimate optical redshifts for X-ray selected cluster candidates. As an application, we run our algorithm on a sample of X-ray cluster candidates selected from the third XMM-Newton serendipitous source catalog (3XMM-DR5) that are located in the Stripe 82 of the Sloan Digital...

Galaxy clusters, the largest clearly defined objects in our Universe, are ideal laboratories to study in detail the cosmic evolution of the intergalactic intracluster medium (ICM) and the cluster galaxy population. For the ICM, which is heated to X-ray radiating temperatures, X-ray spectroscopy is the most important tool to obtain insight into the structure and astrophysics of galaxy clusters. ...

Measurements of galaxy cluster abundances, clustering properties, and massto-light ratios in current and future surveys can provide important cosmological constraints. Digital wide-field imaging surveys, the recently-demonstrated fidelity of red-sequence cluster detection techniques, and a new generation of realistic mock galaxy surveys provide the means for construction of large, cosmologicall...

We have performed fully self-consistent N -body simulations of star clusters near the Galactic center (GC). Such simulations have not been performed because it is the difficult to perform fast and accurate simulations of large-N systems using conventional methods. We used the Bridge code, which integrates the parent galaxy using the tree algorithm and the star cluster using the fourth-order Her...

We present follow-up spectroscopy of the galaxy cluster MS 1054–03 (z = 0.83) confirming that at least six of the nine merging galaxy pairs identified by van Dokkum et al. (1999) are indeed bound systems: they have projected separations of Rs < 10h −1 kpc and relative line-of sight velocities of ∆v < 165 km s. For the remaining three pairs, we were unable to obtain redshifts of both constituent...

Diffuse radio emission in galaxy clusters is known to be related to cluster mass and cluster dynamical state. We collect the observed fluxes of radio halos, relics, and mini-halos for a sample of galaxy clusters from the literature, and calculate their radio powers. We then obtain the values of cluster mass or mass proxies from previous observations, and also obtain the various dynamical parame...