scholarly journals Age-density relation of Main galaxies at fixed parameters or for different galaxy families

Open Physics ◽  
2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Xin-Fa Deng ◽  
Jun Song ◽  
Yi-Qing Chen ◽  
Peng Jiang ◽  
Ying-Ping Ding
Keyword(s):  
Morphological Type ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Density Relation ◽  
Blue Galaxies ◽  
The One ◽  
Red Galaxies ◽  
Density Regime ◽  
Environmental Dependence

AbstractUsing two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), we examine the environmental dependence of galaxy age at fixed parameters or for different galaxy families. Statistical results show that the environmental dependence of galaxy age is stronger for late type galaxies, but can be still observed for the early types: the age of galaxies in the densest regime is preferentially older than that in the lowest density regime with the same morphological type. We also find that the environmental dependence of galaxy age for red galaxies and Low Stellar Mass (LSM) galaxies is stronger, while the one for blue galaxies and High Stellar Mass ( HSM ) galaxies is very weak.

scholarly journals The weak imprint of environment on the stellar populations of galaxies

2020 ◽  
Vol 500 (4) ◽  
pp. 4469-4490 ◽  
Author(s):  
James Trussler ◽  
Roberto Maiolino ◽  
Claudia Maraston ◽  
Yingjie Peng ◽  
Daniel Thomas ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Unique Feature ◽  
Stellar Populations ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Sky Survey ◽  
Satellite Galaxies ◽  
Projected Distance ◽  
Environmental Dependence

ABSTRACT We investigate the environmental dependence of the stellar populations of galaxies in Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Echoing earlier works, we find that satellites are both more metal-rich (<0.1 dex) and older (<2 Gyr) than centrals of the same stellar mass. However, after separating star-forming, green valley, and passive galaxies, we find that the true environmental dependence of both stellar metallicity (<0.03 dex) and age (<0.5 Gyr) is in fact much weaker. We show that the strong environmental effects found when galaxies are not differentiated result from a combination of selection effects brought about by the environmental dependence of the quenched fraction of galaxies, and thus we strongly advocate for the separation of star-forming, green valley, and passive galaxies when the environmental dependence of galaxy properties are investigated. We also study further environmental trends separately for both central and satellite galaxies. We find that star-forming galaxies show no environmental effects, neither for centrals nor for satellites. In contrast, the stellar metallicities of passive and green valley satellites increase weakly (<0.05 and <0.08 dex, respectively) with increasing halo mass, increasing local overdensity and decreasing projected distance from their central; this effect is interpreted in terms of moderate environmental starvation (‘strangulation’) contributing to the quenching of satellite galaxies. Finally, we find a unique feature in the stellar mass–stellar metallicity relation for passive centrals, where galaxies in more massive haloes have larger stellar mass (∼0.1 dex) at constant stellar metallicity; this effect is interpreted in terms of dry merging of passive central galaxies and/or progenitor bias.

scholarly journals A method for classification of red, blue, and green galaxies using fuzzy set theory

2020 ◽  
Vol 499 (1) ◽  
pp. L31-L35
Author(s):  
Biswajit Pandey
Keyword(s):  
Fuzzy Sets ◽  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Blue Galaxies ◽  
Boundary Sets ◽  
Red Galaxies

ABSTRACT Red and blue galaxies are traditionally classified using some specific cuts in colour or other galaxy properties, which are supported by empirical arguments. The vagueness associated with such cuts are likely to introduce a significant contamination in these samples. Fuzzy sets are vague boundary sets that can efficiently capture the classification uncertainty in the absence of any precise boundary. We propose a method for classification of galaxies according to their colours using fuzzy set theory. We use data from the Sloan Digital Sky Survey (SDSS) to construct a fuzzy set for red galaxies with its members having different degrees of ‘redness’. We show that the fuzzy sets for the blue and green galaxies can be obtained from it using different fuzzy operations. We also explore the possibility of using fuzzy relation to study the relationship between different galaxy properties and discuss its strengths and limitations.

scholarly journals How dark are filaments in the cosmic web?

2020 ◽  
Vol 498 (3) ◽  
pp. 3158-3170
Author(s):  
Tianyi Yang ◽  
Michael J Hudson ◽  
Niayesh Afshordi
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Sky Survey ◽  
Mass Fractions ◽  
The Masses ◽  
Red Galaxies

ABSTRACT The cold dark matter model predicts that dark matter haloes are connected by filaments. Direct measurements of the masses and structure of these filaments are difficult, but recently several studies have detected these dark-matter-dominated filaments using weak lensing. Here we study the efficiency of galaxy formation within the filaments by measuring their total mass-to-light ratios and stellar mass fractions. Specifically, we stack pairs of luminous red galaxies (LRGs) with a typical separation on the sky of 8 h−1 Mpc. We stack background galaxy shapes around pairs to obtain mass maps through weak lensing, and we stack galaxies from the Sloan Digital Sky Survey to obtain maps of light and stellar mass. To isolate the signal from the filament, we construct two matched catalogues of physical and non-physical (projected) LRG pairs, with the same distributions of redshift and separation. We then subtract the two stacked maps. Using LRG pair samples from the Baryon Oscillation Spectroscopic Survey at two different redshifts, we find that the evolution of the mass in filament is consistent with the predictions from perturbation theory. The filaments are not entirely dark: Their mass-to-light ratios (M/L = 351 ± 137 in solar units in the rband) and stellar mass fractions (Mstellar/M = 0.0073 ± 0.0030) are consistent with the cosmic values (and with their redshift evolutions).

scholarly journals Revealing galactic scale bars with the help of Galaxy Zoo

2012 ◽  
Vol 10 (H16) ◽  
pp. 324-324
Author(s):  
Karen L. Masters ◽  
Keyword(s):  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Gas Content ◽  
Barred Galaxies ◽  
Sky Survey ◽  
The Galaxy ◽  
Galaxy Sample ◽  
External Sources ◽  
Disc Galaxies ◽  
Environmental Dependence

AbstractWe use visual classifications of the brightest 250,000 galaxies in the Sloan Digital Sky Survey Main Galaxy Sample provided by citizen scientists via the Galaxy Zoo project (www.galaxyzoo.org, Lintott et al. 2008) to identify a sample of local disc galaxies with reliable bar identifications.These data, combined with information on the atomic gas content from the ALFALFA survey (Haynes et al. 2011) show that disc galaxies with higher gas content have lower bar fractions.We use a gas deficiency parameter to show that disc galaxies with more/less gas than expected for their stellar mass are less/more likely to host bars. Furthermore, we see that at a fixed gas content there is no residual correlation between bar fraction and stellar mass. We argue that this suggests previously observed correlations between galaxy colour/stellar mass and (strong) bar fraction (e.g. from the sample in Masters et al. 2011, and also see Nair & Abraham 2010) could be driven by the interaction between bars and the gas content of the disc, since more massive, optically redder disc galaxies are observed to have lower gas contents.Furthermore we see evidence that at a fixed gas content the global colours of barred galaxies are redder than those of unbarred galaxies. We suggest that this could be due to the exchange of angular momentum beyond co-rotation which might stop a replenishment of gas from external sources, and act as a source of feedback to temporarily halt or reduce the star formation in the outer parts of barred discs.These results (published as Masters et al. 2012) combined with those of Skibba et al. (2012), who use the same sample to show a clear (but subtle and complicated) environmental dependence of the bar fraction in disc galaxies, suggest that bars are intimately linked to the evolution of disc galaxies.

scholarly journals The Bimodal Color Distribution of Galaxies at Redshift of z=0-0.15 from the Sloan Digital Sky Survey (SDSS)

2019 ◽  
Vol 30 (2) ◽  
pp. 52
Author(s):  
Hareth Saad Mahdi
Keyword(s):  
Photometric Data ◽  
Sloan Digital Sky Survey ◽  
The Other ◽  
Efficient Tool ◽  
Color Distribution ◽  
Star Forming ◽  
Sky Survey ◽  
Blue Galaxies ◽  
Red Galaxies ◽  
Two Peaks

This work aims to use the color distribution of galaxies to differentiate between blue and red galaxies. The photometric data of 300000 galaxies at redshift of z = 0 – 0.15 were collected from the Sloan Digital Sky Survey (SDSS). Three redshift ranges were considered for the purpose of this work: 100000 galaxies at z = 0-0.05, 100000 galaxies at z = 0.05-0.1 and 100000 galaxies at z = 0.1-0.15. The color distributions for all redshift ranges were determined. The results have clearly shown that the color distributions for all redshift ranges are bimodal. One of the two peaks corresponds to the blue galaxies (young and star-forming galaxies), whereas the other peak corresponds to the red galaxies (old and non-star-forming galaxies). Therefore, the color distribution of galaxies can be considered as an efficient tool to distinguish between blue and red galaxies.

scholarly journals Exploring galaxy colour in different environments of the cosmic web with SDSS

2020 ◽  
Vol 498 (4) ◽  
pp. 6069-6082
Author(s):  
Biswajit Pandey ◽  
Suman Sarkar
Keyword(s):  
Local Density ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Local Dimension ◽  
Sky Survey ◽  
The Galaxy ◽  
Colour Distribution ◽  
The Mean ◽  
Red Galaxies

ABSTRACT We analyse a set of volume-limited samples from the Sloan Digital Sky Survey (SDSS) to study the dependence of galaxy colour on different environments of the cosmic web. We measure the local dimension of galaxies to determine the geometry of their embedding environments and find that filaments host a higher fraction of red galaxies than sheets at each luminosity. We repeat the analysis at a fixed density and recover the same trend, which shows that galaxy colours depend on geometry of environments besides local density. At a fixed luminosity, the fraction of red galaxies in filaments and sheets increases with the extent of these environments. This suggests that the bigger structures have a larger baryon reservoir favouring higher accretion and larger stellar mass. We find that the mean colour of the red and blue populations are systematically higher in the environments with smaller local dimension and increases monotonically in all the environments with luminosity. We observe that the bimodal nature of the galaxy colour distribution persists in all environments and all luminosities, which suggests that the transformation from blue to red galaxy can occur in all environments.

scholarly journals THE ENVIRONMENTAL DEPENDENCE OF GALAXY AGE AND STELLAR MASS IN THE REDSHIFT REGION 0.6 ≤ z ≤ 0.75

2019 ◽  
Vol 55 (2) ◽  
pp. 185-191
Author(s):  
Xin-Fa Deng
Keyword(s):  
Survey Data ◽  
Local Environment ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample ◽  
Environmental Dependence

In this work, I construct a LRG (Luminous Red Galaxy) sample with redshifts 0.6 ≤ z ≤ 0.75 from the Sloan Digital Sky Survey Data Release 15 (SDSS DR15), which contains 184172 CMASS LRGs and 27158 eBOSS LRGs, and examine the environmental dependence of galaxy age and stellar mass in this galaxy sample. I divide this LRG sample into subsamples with a redshift binning size of ∆z = 0.01, and analyze the environmental dependence of galaxy age and stellar mass for these subsamples in each redshift bin. Overall, galaxy age and stellar mass in the LRG sample with redshift 0.6 ≤ z ≤ 0.75 are very weakly correlated with the local environment, which shows that minimal environmental dependence of galaxy parameters can continue to larger redshifts.

Environmental dependence of stellar mass for SDSS-III/BOSS galaxies

2014 ◽  
Vol 92 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Xin-Fa Deng ◽  
Si-Yu Zou
Keyword(s):  
Selection Effect ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample ◽  
Environmental Dependence

Using the LOWZ (0.15 ≤ z ≤ 0.43) and CMASS (0.43 ≤ z ≤ 0.7) galaxy samples of the ninth data release from the Sloan Digital Sky Survey (SDSS) III Baryon Oscillation Spectroscopic Survey (BOSS), we investigate the environmental dependence of stellar mass of BOSS galaxies, and conclude that like the luminous red galaxy sample of the SDSS, the environmental dependence of stellar mass of BOSS galaxies is fairly weak. Results of this work also show that the CMASS sample with the redshift 0.43 ≤ z ≤ 0.7 used by many authors seriously suffers from the radial selection effect.

scholarly journals K-band luminosity–density relation at fixed parameters or for different galaxy families

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 290-301
Author(s):  
Xin-Fa Deng ◽  
Xiao-Qing Wen ◽  
Yong Xin ◽  
Xiao-Ping Qi ◽  
Ying-Ping Ding
Keyword(s):  
Survey Data ◽  
Sloan Digital Sky Survey ◽  
Apparent Magnitude ◽  
Substantial Influence ◽  
Sky Survey ◽  
Data Release ◽  
Density Relation ◽  
Galaxy Sample ◽  
Environmental Dependence ◽  
K Band

AbstractUsing the apparent magnitude-limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 10, we examine the K-band luminosity–density relation at fixed parameters or for different galaxy families. It is found that the limiting or fixing galaxy properties, such as galaxy morphology, stellar mass, and color, exert substantial influence on the environmental dependence of the K-band luminosity of galaxies, which suggests that the K-band luminosity–density relation is likely attributable to the relation between these galaxy properties and density.

scholarly journals Evolution of the distribution of stellar mass and light since redshift of unity

2012 ◽  
Vol 8 (S295) ◽  
pp. 121-124
Author(s):  
Cheng Li
Keyword(s):  
Dark Matter ◽  
Spatial Scale ◽  
Galaxy Formation ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Local Universe ◽  
Sky Survey ◽  
Fluctuation Amplitude ◽  
Better Than ◽  
Environmental Dependence

AbstractWe use data from the Sloan Digital Sky Survey (SDSS) and the DEEP2 survey to characterize the distribution of stellar mass and light of galaxies in the low-redshift and z = 1 Universe. We investigate the clustering bias of stellar mass and light by comparing these to projected autocorrelations of dark matter estimated from the Millennium Simulations (MS). All of the autocorrelation and bias functions show systematic trends with spatial scale and waveband, which are impressively similar at the two redshifts. This shows that the well-established environmental dependence of stellar populations in the local Universe is already in place at z = 1. The recent MS-based galaxy formation simulation of Guo et al. (2011) reproduces the scale-dependent clustering of luminosity to an accuracy better than 30% in all bands and at both redshifts, but substantially overpredicts mass autocorrelations at separations below ~ 2 Mpc. Further comparison of the shapes of our stellar mass bias functions with those predicted by the model suggests that both the SDSS and DEEP2 data prefer a fluctuation amplitude of σ8 ~ 0.8 rather than the σ8 = 0.9 assumed by the MS.

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