Related papers: Deep Optical Observations of Compact Groups of Gal…

We present spectroscopic confirmation of nine moderate redshift galaxy groups and poor clusters selected from the ROSAT Deep Cluster Survey. The groups span the redshift range z=0.23-0.59 and have between 4 and 20 confirmed members. The…

Extending deep observations of the neutral atomic hydrogen (HI) to the environment around galaxy groups can reveal a complex history of group interactions which is invisible to studies that focus on the stellar component. Hickson Compact…

We present HST/ACS imaging of twenty-three very low surface brightness ($\mu_{e,V}$=25-27.5) galaxies detected in the fields of four nearby galaxy groups. These objects were selected from deep optical imaging obtained with the Dragonfly…

We study the formation and the evolution of galaxy groups in a critical universe, showing the importance of secondary infall for their dynamical evolution. Merging is only slightly accelerated if galaxies have massive halos, because the…

We present the largest publicly available catalogue of compact groups of galaxies identified using the original selection criteria of Hickson, selected from the Sixth Data Release (DR6) of the Sloan Digital Sky Survey (SDSS). We identify…

[Abridged] Over the years, several compact group catalogues have been built using different methods, but most of them are not deep enough to go beyond the very local universe with a high level of redshift completeness. We build…

A search for star forming objects belonging to tidal tails has been carried out in a sample of deep Halpha images of 16 compact groups of galaxies. A total of 36 objects with Halpha luminosity larger than 10^38 erg s-1 have been detected in…

In this work we present a lensing study of Compact Groups (CGs) using data obtained from the high quality Canada-France-Hawaii Telescope Stripe 82 Survey. Using stacking techniques we obtain the average density contrast profile. We analyse…

We present new Gemini spectra of 14 new objects found within the HI tails of Hickson Compact Groups 92 and 100. Nine of them are GALEX Far-UV (FUV) and Near-UV (NUV) sources. The spectra confirm that these objects are members of the compact…

Some indications for tension have long been identified between cosmological constraints obtained from galaxy clusters and primary CMB measurements. Typically, assuming the matter density and fluctuations, as parameterized with Omega_m and…

We examine the clustering properties of HI-selected galaxies through an analysis of the HI Parkes All-Sky Survey Catalogue (HICAT) two-point correlation function. Various sub-samples are extracted from this catalogue to study the overall…

Hickson compact groups (HCGs) offer an ideal environment for investigating galaxy transformation as a result of interactions. It has been established that the evolutionary sequence of HCGs is marked by an intermediate stage characterised by…

We identify compact groups of galaxies (CGs) in the IllustrisTNG-300 simulation using a Friends-of-Friends (FoF) algorithm. Our approach is designed to be comparable to systematic CG searches based on spectroscopic surveys, while avoiding…

We present the first results of a serendipitous search for clusters of galaxies in deep ROSAT-PSPC pointed observations at high galactic latitude. The survey is being carried out using a Wavelet based Detection Algorithm which is not biased…

We present the analysis of the spectra of 62 galaxies in 15 compact groups. The galaxies were classified in four activity classes: galaxies without emission, starburst nucleus galaxies (SBNGs), luminous AGNs and low-luminosity AGNs…

We obtain total galaxy X-ray luminosities, $L_X$, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected…

We used the HST WFPC2 to obtain I-band images of the centers of 81 brightest cluster galaxies (BCGs), drawn from a volume-limited sample of nearby BCGs. The images show a rich variety of morphological features, including multiple or double…

Hickson Compact Group (HCG) 16 is a prototypical compact group of galaxies, apparently in an intermediate stage of evolution, where its galaxies are losing gas to the intra-group medium (IGrM). The wide variety of ongoing process in HCG 16…

Numerical simulations as well as optical and X-ray observations over the last few years have shown that poor groups of galaxies can evolve to what is called a fossil group. Dynamical friction as the driving process leads to the coalescence…

We observed a group of galaxies, HCG 57, with ASCA. Regardless that their member galaxies are dominated by spiral galaxies, we detected extended thermal X-ray emission that is attributed to hot gas with a temperature of $1.04\pm0.10$ keV.…