scholarly journals Galaxy properties from voids to clusters in the SDSS-DR4

2006 ◽  
Vol 2 (S235) ◽  
pp. 243-243
Author(s):  
G. Sorrentino ◽  
A. Rifatto ◽  
V. Antonuccio-Delogu
Keyword(s):  
Early Type ◽  
Late Type ◽  
Cluster Galaxies ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Environmental Dependence

AbstractWe investigate the environmental dependence of galaxy populations properties in the SDSS-DR4. Our aim is to search for systematic variations in the properties of galaxies with the local galaxy density in order to find hints that can be related to the presence of a void galaxy population. We find that galaxies in underdense regions (voids) are fainte and bluer than cluster galaxies. Moreover, the transition from underdense to overdense regions is smooth, as well as the percentage of late-type galaxies decreases while the percentage of early-type galaxies increases smoothly from underdense to dense environments.

scholarly journals An environmental dependence of the physical and structural properties in the Hydra cluster galaxies

2020 ◽  
Vol 500 (1) ◽  
pp. 1323-1339
Author(s):  
Ciria Lima-Dias ◽  
Antonela Monachesi ◽  
Sergio Torres-Flores ◽  
Arianna Cortesi ◽  
Daniel Hernández-Lang ◽  
...  
Keyword(s):  
Structural Properties ◽  
Clustering Algorithm ◽  
Spatial Clustering ◽  
Broad Band ◽  
Visible Region ◽  
Early Type ◽  
Cluster Galaxies ◽  
Using Data ◽  
Stellar Masses ◽  
Environmental Dependence

ABSTRACT The nearby Hydra cluster (∼50 Mpc) is an ideal laboratory to understand, in detail, the influence of the environment on the morphology and quenching of galaxies in dense environments. We study the Hydra cluster galaxies in the inner regions (1R200) of the cluster using data from the Southern Photometric Local Universe Survey, which uses 12 narrow and broad-band filters in the visible region of the spectrum. We analyse structural (Sérsic index, effective radius) and physical (colours, stellar masses, and star formation rates) properties. Based on this analysis, we find that ∼88 per cent of the Hydra cluster galaxies are quenched. Using the Dressler–Schectman test approach, we also find that the cluster shows possible substructures. Our analysis of the phase-space diagram together with density-based spatial clustering algorithm indicates that Hydra shows an additional substructure that appears to be in front of the cluster centre, which is still falling into it. Our results, thus, suggest that the Hydra cluster might not be relaxed. We analyse the median Sérsic index as a function of wavelength and find that for red [(u − r) ≥2.3] and early-type galaxies it displays a slight increase towards redder filters (13 and 18 per cent, for red and early type, respectively), whereas for blue + green [(u − r)<2.3] galaxies it remains constant. Late-type galaxies show a small decrease of the median Sérsic index towards redder filters. Also, the Sérsic index of galaxies, and thus their structural properties, do not significantly vary as a function of clustercentric distance and density within the cluster; and this is the case regardless of the filter.

scholarly journals Galaxies in most dense environments at redshift 1.4

2012 ◽  
Vol 8 (S295) ◽  
pp. 61-61
Author(s):  
V. Strazzullo
Keyword(s):  
Galaxy Evolution ◽  
Cosmic Time ◽  
Active Galaxy ◽  
Cluster Core ◽  
Host Galaxy ◽  
Early Type ◽  
X Ray ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Massive Cluster

AbstractAt a cosmic time when galaxy clusters start showing evidence of a still active galaxy population, the X-ray luminous, massive cluster XMMU J2235-2557 at z=1.39, already hosts massive, quiescent, early-type galaxies on a tight red sequence dominating the cluster core. XMMU J2235-2557 is among the most massive of the very distant clusters, which may explain the evolved status of the system itself, and of its host galaxy populations. It remains a unique laboratory to observe environment-biased galaxy evolution already 9 billion years ago.

scholarly journals Reconstructing Orbits of Galaxies in Extreme Regions (ROGER) II: reliability of projected phase-space in our understanding of galaxy populations

2021 ◽  
Author(s):  
Valeria Coenda ◽  
Martín de los Rios ◽  
Hernán Muriel ◽  
Sofía A Cora ◽  
Héctor J Martínez ◽  
...  
Keyword(s):  
Phase Space ◽  
Galaxy Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Cluster Galaxies ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
2D Data ◽  
Good Agreement

Abstract We connect galaxy properties with their orbital classification by analysing a sample of galaxies with stellar mass M⋆ ≥ 108.5h−1M⊙ residing in and around massive and isolated galaxy clusters with mass M200 > 1015h−1M⊙ at redshift z = 0. The galaxy population is generated by applying the semi-analytic model of galaxy formation sag on the cosmological simulation MultiDark Planck 2. We classify galaxies considering their real orbits (3D) and their projected phase-space position using the roger  code (2D). We define five categories: cluster galaxies, galaxies that have recently fallen into a cluster, backsplash galaxies, infalling galaxies, and interloper galaxies. For each class, we analyse the 0.1(g − r) colour, the specific star formation rate (sSFR), and the stellar age, as a function of the stellar mass. For the 3D classes, we find that cluster galaxies have the lowest sSFR, and are the reddest and the oldest, as expected from environmental effects. Backsplash galaxies have properties intermediate between the cluster and recent infaller galaxies. For each 2D class, we find an important contamination by other classes. We find it necessary to separate the galaxy populations in red and blue to perform a more realistic analysis of the 2D data. For the red population, the 2D results are in good agreement with the 3D predictions. Nevertheless, when the blue population is considered, the 2D analysis only provides reliable results for recent infallers, infalling galaxies and interloper galaxies.

scholarly journals Galaxy Environments in DEEP2: The Birth of the Red Sequence

2006 ◽  
Vol 2 (S235) ◽  
pp. 167-169
Author(s):  
Michael C. Cooper ◽  
Jeffrey A. Newman
Keyword(s):  
Star Formation ◽  
Evolutionary Trends ◽  
Early Type ◽  
Number Density ◽  
Late Type ◽  
Active Star ◽  
The Galaxy ◽  
Blue Galaxies ◽  
Galaxy Population ◽  
Red Sequence

The galaxy population at z ≲ 1 is effectively described as a combination of two distinct types: red, early-type galaxies lacking much star formation and blue, late-type galaxies with active star formation. For the red galaxy population, recent work by Bell et al. (2004) has shown that the number density of ~L* galaxies on the red sequence has risen by a factor of ~2 from z ~ 1 to z ~ 0. A variety of complementary observations suggests that the build-up of galaxies on the red sequence results from 2 distinct evolutionary trends: (1) the quenching of star formation in blue galaxies and their subsequent migration onto the red sequence and (2) the dissipationless or (“dry”) merging of red-sequence galaxies.

scholarly journals Galaxy Population in the Infall Regions of Intermediate Redshift Clusters

2006 ◽  
Vol 2 (S235) ◽  
pp. 254-254
Author(s):  
Miguel Verdugo ◽  
Bodo L. Ziegler
Keyword(s):  
Star Formation ◽  
X Ray ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Cluster Cores ◽  
Galaxy Population ◽  
Special Environment

AbstractWe investigate the galaxy populations in 6 clusters of different x-ray luminosities at intermediate redshifts (z ≈ 0.25) concentrating on their star formation activity. Our ~500 Calar Alto MOSCA spectra come from targets covering large fields out to 2–4 cluster virial radii. To probe this so-called infall region is important since here newly arriving galaxies from the surrounding field encounter the special environment of clusters for the first time. We selected 3 fields containing 2 clusters each from the X-ray Dark Cluster Survey (Gilbank et al. 2004). Results for one field were already published by Gerken et al. 2004.We find evidence that the process(es) that suppresses or truncates the star formation activity in cluster galaxies, sets in already at rather large distances from the cluster cores corresponding to low projected local galaxy densities. This changes the fraction of star forming galaxies rather quickly.

scholarly journals The Frequency of Anomalously Red Galaxies in SDSS Clusters

2014 ◽  
Vol 31 ◽  
Author(s):  
O. Shearman ◽  
K. A. Pimbblet
Keyword(s):  
Surface Brightness ◽  
Dust Content ◽  
Early Type ◽  
Late Type ◽  
Cluster Membership ◽  
Cluster Galaxies ◽  
Low Surface Brightness ◽  
Magnitude Diagram ◽  
Red Galaxies ◽  
Red Sequence

AbstractWe present a systematic photometric search for spectroscopically confirmed anomalously red galaxies members of 748 low redshift clusters between 0.03 z 0.17 from the SDSS-C4 cluster catalogue (Miller et al. 2005). For each cluster we spectroscopically determine cluster membership, construct a colour-magnitude diagram and fit the red sequence using a robust bi-weight fit. We define an “anomalously red galaxy” as having a (g - r) colour of greater than 3σ redward of the fitted cluster colour-magnitude relation. We find that of 7485 galaxies at r ≤ 17.77 in (g - r), 7 galaxies are anomalously red – 0.0935 per cent of all galaxies in our sample. We show that two of the red outliers are caused by red contamination from nearby sources and are therefore not intrinsically anomalous red. However, 5 have no underlying cause to be so red and we speculate that they may have a high internal dust content. These intrinsically red galaxies are rare – comprising no more than 0.0668 per cent of all cluster galaxies. Most are morphologically early type galaxies, with a few probable late type galaxies that are viewed edge-on and one low surface brightness late type. One of our anomalously red galaxies appears to be a dust-shrouded starburst and we speculate that this may be a unique galaxy amoungst this galaxy set.

scholarly journals Giant planets around AF and M stars

2013 ◽  
Vol 8 (S299) ◽  
pp. 64-65
Author(s):  
Julien Rameau ◽  
Gaël Chauvin ◽  
Anne-Marie Lagrange ◽  
Philippe Delorme ◽  
Justine Lannier
Keyword(s):  
Giant Planets ◽  
Early Type ◽  
Late Type ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Planetary Mass ◽  
Nearby Stars ◽  
Low Mass ◽  
M Stars ◽  
The One

AbstractWe present the results of two three-year surveys of young and nearby stars to search for wide orbit giant planets. On the one hand, we focus on early-type and massive, namely β Pictoris analogs. On the other hand, we observe late type and very low mass stars, i.e., M dwarfs. We report individual detections of new planetary mass objects. According to our deep detection performances, we derive the observed frequency of giant planets between these two classes of parent stars. We find frequency between 6 to 12% but we are not able to assess a/no correlation with the host-mass.

scholarly journals The Bimodality of Galaxy Populations Revisited Through Spectral Synthesis

2006 ◽  
Vol 2 (S235) ◽  
pp. 139-139
Author(s):  
L. Sodré ◽  
A. Mateus ◽  
R. Cid Fernandes ◽  
G. Stasińska ◽  
W. Schoenell ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Spectral Synthesis ◽  
Synthesis Method ◽  
Local Universe ◽  
Massive Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Stellar Masses

AbstractWe revisit the bimodality of the galaxy population seen in the local universe. We address this issue in terms of physical properties of galaxies, such as mean stellar ages and stellar masses, derived from the application of a spectral synthesis method to galaxy spectra from the SDSS. We show that the mean light-weighted stellar age of galaxies presents the best description of the bimodality seen in the galaxy population. The stellar mass has an additional role since most of the star-forming galaxies present in the local universe are low-mass galaxies. Our results give support to the existence of a ‘downsizing’ in galaxy formation, where nowadays massive galaxies tend to have stellar populations older than those found in less massive objects.

scholarly journals The early-type dwarf galaxy population of the Fornax cluster

2006 ◽  
Vol 463 (2) ◽  
pp. 503-512 ◽  
Author(s):  
S. Mieske ◽  
M. Hilker ◽  
L. Infante ◽  
C. Mendes de Oliveira
Keyword(s):  
Dwarf Galaxy ◽  
Early Type ◽  
Galaxy Population ◽  
Fornax Cluster
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