Hae
Aineistot 41-50 / 447
Evolution and role of mergers in the BCG-cluster alignment. A view from cosmological hydrosimulations
Contradictory results have been reported on the time evolution of the alignment between clusters and their brightest cluster galaxy (BCG). We study this topic by analysing cosmological hydrosimulations of 24 massive clusters ...
On the accretion of a new group of galaxies on to Virgo: I. Internal kinematics of nine in-falling dEs
Galaxy environment has been shown to play an important role in transforming late-type, star-forming galaxies to quiescent spheroids. This transformation is expected to be more severe for low-mass galaxies (M < 10(10) ...
UV SEDs of early-type cluster galaxies: a new look at the UV upturn
Using GALEX, Ultraviolet Optical Telescope (UVOT), and optical photometry, we explore the prevalence and strength of the Ultraviolet (UV) upturn in the spectra of quiescent early-type galaxies in several nearby clusters. ...
Brightest group galaxies – II: the relative contribution of BGGs to the total baryon content of groups at z < 1.3
<p>We performed a detailed study of the evolution of the star formation rate (SFR) and stellar mass of the brightest group galaxies (BGGs) and their relative contribution to the total baryon budget within R<sub>200</sub> (</p><div>f BGG b,200 fb,200BGG</div><p>
). The sample comprises 407 BGGs selected from X-ray groups (M<sub>200</sub> = 10<sup>12.8</sup>–10<sup>14</sup> M<sub>⊙</sub>) out to z ∼ 1.3 identified in the Cosmic Evolution Survey (COSMOS), XMM Large-Scale Structure survey (XMM-LSS), and the All-Wavelength Extended Groth strip International Survey (AEGIS) fields. We find that BGGs constitute two distinct populations of quiescent and star-forming galaxies and their mean SFR is ∼2 dex higher than the median SFR at z < 1.3. Both the mean and the median SFRs decline with time by >2 dex. We take into account the halo mass growth of groups in selecting the sample of BGGs and find that the mean (median) stellar mass of BGGs has grown by 0.3 dex since z = 1.3 to the present day. We show that up to ∼ 45 per cent of the stellar mass growth in a star-forming BGG can be due to its star formation activity. With respect to </p><p></p><div>f BGG b,200 fb,200BGG</div><p>
</p><p>, we find it to increase with decreasing redshift by ∼0.35 dex, while decreasing with halo mass in a redshift-dependent manner. We show that the slope of the relation between </p><p></p><div>f BGG b,200 fb,200BGG</div><p>
</p><p> and halo mass increases negatively with decreasing redshift. This trend is driven by an insufficient star formation in BGGs, compared to the halo growth rate. We separately show the BGGs with the 20 per cent highest </p><p></p><div>f BGG b,200 fb,200BGG</div><p>
</p><p> are generally non-star-forming galaxies and grow in mass by processes not related to star formation (e.g. dry mergers and tidal striping). We present the M<sub>⋆</sub>–M<sub>h</sub> and M<sub>⋆</sub>/M<sub>h</sub>–M<sub>h</sub> relations and compare them with semi-analytic model predictions and a number of results from the literature. We quantify the intrinsic scatter in stellar mass of BGGs at fixed halo mass (</p><p></p><div>σ logM ⋆ σlogM⋆</div><p>
</p><p>) and find that </p><p></p><div>σ logM ⋆ σlogM⋆</div><p>
</p><p> increases from 0.3 dex at z ∼ 0.2–0.5 dex at z ∼ 1.0 due to the bimodal distribution of stellar mass.<br /></p>...
Signatures of quenching in dwarf galaxies in local galaxy clusters: A comparison of the galaxy populations in the Virgo and Fornax clusters
<div><p><i>Context.</i> The transformation of late-type galaxies has been suggested as the origin of early-type dwarf galaxies (typically <i>M</i><sub>⋆</sub> ≤ 10<sup>9</sup> <i>M</i><sub>⊙</sub>) in galaxy clusters. Based ...
The lowest-metallicity type II supernova from the highest-mass red supergiant progenitor
Red supergiants have been confirmed as the progenitor stars of the majority of hydrogen-rich type II supernovae(1). However, while such stars are observed with masses > 25 M-circle dot (ref. (2)), detections of > 18 M-circle ...
Circum-Galactic Medium in the Halo of Quasars
The properties of circum-galactic gas in the halo of quasar host galaxies are investigated analyzing Mg II 2800 and C IV 1540 absorption-line systems along the line of sight close to quasars. We used optical spectroscopy ...
A new precise mass for the progenitor of the Type IIP SN 2008bk
<p>
The progenitor of the Type IIP supernova (SN) 2008bk was discovered in pre-explosion g'r'i'IYJHK(s) images, acquired with European Southern Observatory Very Large Telescope FOcal Reducer and low dispersion ...
Galaxy And Mass Assembly (GAMA): Defining passive galaxy samples and searching for the UV upturn
We use data from the GAMA and GALEX surveys to demonstrate that the UV upturn, an unexpected excess of ultraviolet flux from a hot stellar component, seen in the spectra of many early-type galaxies, arises from processes ...