Stellar population analysis of galaxies in SDSS and LAMOST Pilot Survey

2013 ◽  
Vol 9 (S298) ◽  
pp. 399-399
Author(s):  
Xiaoyan Chen ◽  
Ali Luo ◽  
Haifeng Yang
Keyword(s):  
Stellar Population ◽  
Population Analysis ◽  
Stellar Populations ◽  
Optical Spectra ◽  
Pilot Survey ◽  
Flux Calibration ◽  
Spectra Fitting

AbstractThe Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, i.e. Guoshoujing Telescope) has finished its pilot survey (from October 2011 to June 2012). With about 3000 galaxy spectra collected during the pilot survey, we are planning to analyze the stellar populations of these galaxies in two different ways respectively. One is Lick indices (such as Hβ, Mgb, 〈Fe〉 etc., Worthey et al. 1994), which are not sensitive to the flux calibration, and another one is the full optical spectra fitting (Chen et al. 2009, 2010). Then we can evaluate the affects of flux calibration errors on stellar population analysis by comparing the results of the two methods′. Here we briefly show the early experiments aiming to test the consistency and/or difference between the two methods.

scholarly journals Dynamical masses of brightest cluster galaxies – II. Constraints on the stellar IMF

2020 ◽  
Vol 500 (3) ◽  
pp. 4153-4165
Author(s):  
S I Loubser ◽  
H Hoekstra ◽  
A Babul ◽  
Y M Bahé ◽  
M Donahue
Keyword(s):  
Gravitational Lensing ◽  
Stellar Population ◽  
Population Analysis ◽  
Stellar Populations ◽  
Stellar Mass ◽  
Initial Mass Function ◽  
Dynamical Mass ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Mass Profiles

ABSTRACT We use stellar and dynamical mass profiles, combined with a stellar population analysis, of 32 brightest cluster galaxies (BCGs) at redshifts of 0.05 ≤$z$ ≤ 0.30, to place constraints on their stellar initial mass function (IMF). We measure the spatially resolved stellar population properties of the BCGs, and use it to derive their stellar mass-to-light ratios ($\Upsilon _{\star \rm POP}$). We find young stellar populations (<200 Myr) in the centres of 22 per cent of the sample, and constant $\Upsilon _{\star \rm POP}$ within 15 kpc for 60 per cent of the sample. We further use the stellar mass-to-light ratio from the dynamical mass profiles of the BCGs ($\Upsilon _{\star \rm DYN}$), modelled using a multi-Gaussian expansion and Jeans Anisotropic Method, with the dark matter contribution explicitly constrained from weak gravitational lensing measurements. We directly compare the stellar mass-to-light ratios derived from the two independent methods, $\Upsilon _{\star \rm POP}$ (assuming some IMF) to $\Upsilon _{\star \rm DYN}$ for the subsample of BCGs with no young stellar populations and constant $\Upsilon _{\star \rm POP}$. We find that for the majority of these BCGs, a Salpeter (or even more bottom-heavy) IMF is needed to reconcile the stellar population and dynamical modelling results although for a small number of BCGs, a Kroupa (or even lighter) IMF is preferred. For those BCGs better fit with a Salpeter IMF, we find that the mass-excess factor against velocity dispersion falls on an extrapolation (towards higher masses) of known literature correlations. We conclude that there is substantial scatter in the IMF amongst the highest mass galaxies.

Kinematics and stellar populations of the double-barred early-type galaxy NGC357

2007 ◽  
Vol 3 (S245) ◽  
pp. 137-138
Author(s):  
Adriana de Lorenzo-Cáceres ◽  
Alexandre Vazdekis ◽  
J. Alfonso L. Aguerri
Keyword(s):  
Radial Velocity ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Population Analysis ◽  
Stellar Populations ◽  
Abundance Ratio ◽  
Complete Characterization ◽  
Early Type ◽  
Early Type Galaxy

AbstractWe have carried out a kinematical and stellar population analysis of the double-barred galaxy NGC357 to provide a more complete characterization of these systems and their role in the formation of galaxy bulges. We clearly identify the presence of the inner bar in the radial velocity and velocity dispersion profiles. The age, metallicity and [Mg/Fe] abundance ratio estimates are very similar to those of ellipticals of equivalent central σ. The [Mg/Fe] value for the bulge of this galaxy suggests formation timescales shorter than 1Gyr.

Optical properties of CSS/GPS sources

2019 ◽  
Vol 15 (S359) ◽  
pp. 357-359
Author(s):  
Raquel S. Nascimento ◽  
Alberto Rodríguez-Ardila ◽  
Marcos F. Faria ◽  
Murilo Marinello ◽  
Luis G. Dahmer-Hahn
Keyword(s):  
Optical Properties ◽  
Strong Correlation ◽  
Stellar Population ◽  
Stellar Populations ◽  
Optical Spectra ◽  
Radio Sources ◽  
Population Synthesis ◽  
Stellar Population Synthesis ◽  
The Impact

AbstractIn this work, we study the optical properties of 58 CSS/GPS radio sources selected from the literature in order to determine the impact of the radio-jet in the circumnuclear environment of these objects. We obtained optical spectra for all sources from SDSS-DR12 and performed a stellar population synthesis using the Starlight code. Our results indicate that the sample is dominated by intermediate to old stellar populations and there is no strong correlation between optical and radio properties of these sources.

scholarly journals Stellar Populations of Galaxies in the LAMOST Spectral Survey

2021 ◽  
Vol 258 (1) ◽  
pp. 9
Author(s):  
Li-Li Wang ◽  
Shi-Yin Shen ◽  
A-Li Luo ◽  
Guang-Jun Yang ◽  
Ning Gai ◽  
...  
Keyword(s):  
Stellar Population ◽  
Signal To Noise Ratio ◽  
Stellar Populations ◽  
Sloan Digital Sky Survey ◽  
Small Scale ◽  
Scientific Application ◽  
Fitting Procedure ◽  
Sky Survey ◽  
Spectral Survey ◽  
Flux Calibration

Abstract We first derive the stellar population properties: age and metallicity for ∼43,000 low redshift galaxies in the DR7 of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, which have no spectroscopic observations in the Sloan Digital Sky Survey (SDSS). We employ a fitting procedure based on the small-scale features of galaxy spectra so as to avoid possible biases from the uncertain flux calibration of the LAMOST spectroscopy. We show that our algorithm can successfully recover the average age and metallicity of the stellar populations of galaxies down to signal-to-noise ratio ≥5 through testing on both mock galaxies and real galaxies comprising LAMOST and their SDSS counterparts. We provide a catalog of the age and metallicity for ∼43,000 LAMOST galaxies online. As a demonstration of the scientific application of this catalog, we present the Holmberg effect on both age and metallicity of a sample of galaxies in galaxy pairs.

scholarly journals Keck Cosmic Web Imager (KCWI) spectra of globular clusters and ultracompact dwarfs in the halo of M87

2020 ◽  
Vol 497 (1) ◽  
pp. 765-775
Author(s):  
Duncan A Forbes ◽  
Anna Ferré-Mateu ◽  
Mark Durré ◽  
Jean P Brodie ◽  
Aaron J Romanowsky
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Population Analysis ◽  
Stellar Populations ◽  
Element Abundances ◽  
Dispersion Profile ◽  
Self Consistent ◽  
First Time

ABSTRACT Using the Keck Cosmic Web Imager, we obtain spectra of several globular clusters (GCs), ultracompact dwarfs (UCDs), and the inner halo starlight of M87, at a similar projected galactocentric radius of ∼5 kpc. This enables us, for the first time, to apply the same stellar population analysis to the GCs, UCDs, and starlight consistently to derive ages, metallicities, and alpha-element abundances in M87. We find evidence for a dual stellar population in the M87 halo light, i.e. an ∼80 per cent component by mass that is old and metal-rich and a ∼20 per cent component that is old but metal-poor. Two red GCs share similar stellar populations to the halo light suggesting they may have formed contemporaneously with the dominant halo component. Three UCDs, and one blue GC, have similar stellar populations, with younger mean ages, lower metallicities, and near solar alpha-element abundances. Combined with literature data, our findings are consistent with the scenario that UCDs are the remnant nucleus of a stripped galaxy. We further investigate the discrepancy in the literature for M87’s kinematics at large radii, favouring a declining velocity dispersion profile. This work has highlighted the need for more self-consistent studies of galaxy haloes.

scholarly journals Shaping Disk Galaxy Stellar Populations via Internal and External Processes

2012 ◽  
Vol 10 (H16) ◽  
pp. 372-372
Author(s):  
Rok Roškar
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
Milky Way ◽  
Stellar Populations ◽  
Radial Migration ◽  
Disk Formation ◽  
Process Understanding ◽  
History Of ◽  
Nearby Galaxies ◽  
Gas Accretion

AbstractIn recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.

Stellar Population Analysis of Galaxies based on Genetic Algorithms

2005 ◽  
Vol 5 (4) ◽  
pp. 347-355 ◽  
Author(s):  
Abdel-Fattah Attia ◽  
H. A Ismail ◽  
I. M Selim ◽  
A. M Osman ◽  
I. A Isaa ◽  
...  
Keyword(s):  
Genetic Algorithms ◽  
Stellar Population ◽  
Population Analysis

scholarly journals 5.18. Molecular gas in the poststarburst galaxy NGC7331

1998 ◽  
Vol 184 ◽  
pp. 247-248
Author(s):  
T. Tosaki ◽  
Y. Shioya
Keyword(s):  
High Resolution ◽  
Spiral Galaxy ◽  
Stellar Populations ◽  
Optical Spectra ◽  
Molecular Gas ◽  
Early Type ◽  
Origin And Evolution ◽  
Co Observations

To understand the origin and evolution of starburst activity, we must study the full evolution of starburst; i.e., pre-, on-going, and post-starburst phases. It seems reasonable to suppose the numerous A-type stars indicate past starburst and they show strong Balmer absorption. NGC7331, nearby early-type spiral galaxy, is one of the poststarburst galaxies which show strong Balmer absorption. The optical spectra of NGC7331 were dominated by component of intermediate-age (5 × 109 years) stellar populations (Ohyama & Taniguchi 1996). We present the result of the high resolution CO observations of NGC7331 using Nobeyama Milimeter Array.

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