27 research outputs found
The Violent Youth of Bright and Massive Cluster Galaxies and their Maturation over 7 Billion Years
In this study we investigate the formation and evolution mechanisms of the
brightest cluster galaxies (BCGs) over cosmic time. At high redshift
(), we selected BCGs and most massive cluster galaxies (MMCGs) from
the Cl1604 supercluster and compared them to low-redshift ()
counterparts drawn from the MCXC meta-catalog, supplemented by SDSS imaging and
spectroscopy. We observed striking differences in the morphological, color,
spectral, and stellar mass properties of the BCGs/MMCGs in the two samples.
High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies,
with blue broadband colors, properties largely absent amongst the low-redshift
BCGs/MMCGs. The stellar mass of BCGs was found to increase by an average factor
of from to . Through this and other
comparisons we conclude that a combination of major merging (mainly wet or
mixed) and \emph{in situ} star formation are the main mechanisms which build
stellar mass in BCGs/MMCGs. The stellar mass growth of the BCGs/MMCGs also
appears to grow in lockstep with both the stellar baryonic and total mass of
the cluster. Additionally, BCGs/MMCGs were found to grow in size, on average, a
factor of , while their average S\'ersic index increased by 0.45
from to , also supporting a scenario involving major
merging, though some adiabatic expansion is required. These observational
results are compared to both models and simulations to further explore the
implications on processes which shape and evolve BCGs/MMCGs over the past
7 Gyr.Comment: Accepted for publication in MNRA
The Properties of Radio Galaxies and the Effect of Environment in Large Scale Structures at
In this study we investigate 89 radio galaxies that are
spectroscopically-confirmed to be members of five large scale structures in the
redshift range of . Based on a two-stage classification
scheme, the radio galaxies are classified into three sub-classes: active
galactic nucleus (AGN), hybrid, and star-forming galaxy (SFG). We study the
properties of the three radio sub-classes and their global and local
environmental preferences. We find AGN hosts are the most massive population
and exhibit quiescence in their star-formation activity. The SFG population has
a comparable stellar mass to those hosting a radio AGN but are unequivocally
powered by star formation. Hybrids, though selected as an intermediate
population in our classification scheme, were found in almost all analyses to
be a unique type of radio galaxies rather than a mixture of AGN and SFGs. They
are dominated by a high-excitation radio galaxy (HERG) population. We discuss
environmental effects and scenarios for each sub-class. AGN tend to be
preferentially located in locally dense environments and in the cores of
clusters/groups, with these preferences persisting when comparing to galaxies
of similar colour and stellar mass, suggesting that their activity may be
ignited in the cluster/group virialized core regions. Conversely, SFGs exhibit
a strong preference for intermediate-density global environments, suggesting
that dusty starbursting activity in LSSs is largely driven by galaxy-galaxy
interactions and merging.Comment: 28 pages, 10 figures, accepted to MNRA
Star Formation Quenching in High-redshift Large-scale Structure: Post-starburst Galaxies in the Cl1604 Supercluster at
The Cl1604 supercluster at is one of the most extensively
studied high redshift large scale structures, with more than 500
spectroscopically confirmed members. It consists of 8 clusters and groups, with
members numbering from a dozen to nearly a hundred, providing a broad range of
environments for investigating the large scale environmental effects on galaxy
evolution. Here we examine the properties of 48 post-starburst galaxies in
Cl1604, comparing them to other galaxy populations in the same supercluster.
Incorporating photometry from ground-based optical and near-infrared imaging,
along with mid-infrared observations, we derive stellar masses for
all Cl1604 members. The colors and stellar masses of the K+A galaxies support
the idea that they are progenitors of red sequence galaxies. Their
morphologies, residual star-formation rates, and spatial distributions suggest
galaxy mergers may be the principal mechanism producing post-starburst
galaxies. Interaction between galaxies and the dense intra-cluster medium is
also effective, but only in the cores of dynamically evolved clusters. The
prevalence of post-starburst galaxies in clusters correlates with the dynamical
state of the host cluster, as both galaxy mergers and the dense intra-cluster
medium produce post-starburst galaxies. We also investigate the incompleteness
and contamination of K+A samples selected by means of H and [OII]
equivalent widths. K+A samples may be up to incomplete due to the
presence of LINER/Seyferts and up to of K+A galaxies could have
substantial star formation activity.Comment: 19 pages, 13 figures, accepted by Ap
Star Formation Quenching in High-Redshift Large-Scale Structure: Post-Starburst Galaxies in the CI 1604 Supercluster at \u3cem\u3ez\u3c/em\u3e ~ 0.9
The Cl 1604 supercluster at z ~ 0.9 is one of the most extensively studied high-redshift large-scale structures, with more than 500 spectroscopically confirmed members. It consists of eight clusters and groups, with members numbering from a dozen to nearly a hundred, providing a broad range of environments for investigating the large-scale environmental effects on galaxy evolution. Here we examine the properties of 48 post-starburst galaxies in Cl 1604, comparing them to other galaxy populations in the same supercluster. Incorporating photometry from ground-based optical and near-infrared imaging, along with Spitzer mid-infrared observations, we derive stellar masses for all Cl 1604 members. The colors and stellar masses of the K+A galaxies support the idea that they are progenitors of red sequence galaxies. Their morphologies, residual star formation rates, and spatial distributions suggest that galaxy mergers may be the principal mechanism producing post-starburst galaxies. Interaction between galaxies and the dense intracluster medium (ICM) is also effective, but only in the cores of dynamically evolved clusters. The prevalence of post-starburst galaxies in clusters correlates with the dynamical state of the host cluster, as both galaxy mergers and the dense ICM produce post-starburst galaxies. We also investigate the incompleteness and contamination of K+A samples selected by means of Hδ and [O II] equivalent widths. K+A samples may be up to ~50% incomplete due to the presence of LINERs/Seyferts, and up to ~30% of K+A galaxies could have substantial star formation activity
Star Formation Quenching in High-redshift Large-scale Structure: Post-starburst Galaxies in the Cl 1604 Supercluster at z∼0.9
The Cl 1604 supercluster at z ~ 0.9 is one of the most extensively studied high-redshift large-scale structures, with more than 500 spectroscopically confirmed members. It consists of eight clusters and groups, with members numbering from a dozen to nearly a hundred, providing a broad range of environments for investigating the large-scale environmental effects on galaxy evolution. Here we examine the properties of 48 post-starburst galaxies in Cl 1604, comparing them to other galaxy populations in the same supercluster. Incorporating photometry from ground-based optical and near-infrared imaging, along with Spitzer mid-infrared observations, we derive stellar masses for all Cl 1604 members. The colors and stellar masses of the K+A galaxies support the idea that they are progenitors of red sequence galaxies. Their morphologies, residual star formation rates, and spatial distributions suggest that galaxy mergers may be the principal mechanism producing post-starburst galaxies. Interaction between galaxies and the dense intracluster medium (ICM) is also effective, but only in the cores of dynamically evolved clusters. The prevalence of post-starburst galaxies in clusters correlates with the dynamical state of the host cluster, as both galaxy mergers and the dense ICM produce post-starburst galaxies. We also investigate the incompleteness and contamination of K+A samples selected by means of Hδ and [O II] equivalent widths. K+A samples may be up to ~50% incomplete due to the presence of LINERs/Seyferts, and up to ~30% of K+A galaxies could have substantial star formation activity
Endogenous Syngap1 Alpha Splice Forms Promote Cognitive Function and Seizure Protection
Altres ajuts: NIH grants from the National Institute of Mental Health (MH096847, MH108408, MH115005, MH113949, MH105400); National Institute for Neurological Disorders and Stroke (NS064079); Eunice Kennedy Shriver National Institute of Child Health and Human Development (HD089491); National Institute for Drug Abuse (DA034116, DA036376); Autism Speaks Weatherstone Pre-Doctoral fellowship (10646); Training fellowship from the Leon and Friends Charitable Foundation.Loss-of-function variants in SYNGAP1 cause a developmental encephalopathy defined by cognitive impairment, autistic features, and epilepsy. SYNGAP1 splicing leads to expression of distinct functional protein isoforms. Splicing imparts multiple cellular functions of SynGAP proteins through coding of distinct C-terminal motifs. However, it remains unknown how these different splice sequences function in vivo to regulate neuronal function and behavior. Reduced expression of SynGAP-α1/2 C-terminal splice variants in mice caused severe phenotypes, including reduced survival, impaired learning, and reduced seizure latency. In contrast, upregulation of α1/2 expression improved learning and increased seizure latency. Mice expressing α1-specific mutations, which disrupted SynGAP cellular functions without altering protein expression, promoted seizure, disrupted synapse plasticity, and impaired learning. These findings demonstrate that endogenous SynGAP isoforms with α1/2 spliced sequences promote cognitive function and impart seizure protection. Regulation of SynGAP-α expression or function may be a viable therapeutic strategy to broadly improve cognitive function and mitigate seizure
Glimpsing the imprint of local environment on the galaxy stellar mass function
International audienc