scholarly journals Stellar population synthesis: Application To Galactic Bulges

1993 ◽  
Vol 153 ◽  
pp. 133-150
Author(s):  
N. Arimoto
Keyword(s):  
Observational Data ◽  
Stellar Population ◽  
Stellar Populations ◽  
Population Synthesis ◽  
Firm Conclusion ◽  
Formation History ◽  
Stellar Population Synthesis ◽  
Central Regions ◽  
History Of ◽  
Metallicity Distribution

The stellar populations give traces of the formation history of the bulges. The metallicity distribution of K-giants in the Galactic bulge resembles to that of the giant ellipticals. There seems to be no conspicuous colour-magnitude relation intrinsic to the bulges. This can be explained if the bulges formed by the dissipative collapse of central regions of proto-galaxies followed by the supernova-driven bulge wind which was induced later than the dwarf ellipticals of the similar mass (the biased wind). Unfortunately, the observational data available at present of stellar populations of the bulges are not yet sufficient to get a firm conclusion on the origin of the bulges.

scholarly journals Effects of the selection function on metallicity trends in spectroscopic surveys of the Milky Way

2017 ◽  
Vol 606 ◽  
pp. A97 ◽  
Author(s):  
G. Nandakumar ◽  
M. Schultheis ◽  
M. Hayden ◽  
A. Rojas-Arriagada ◽  
G. Kordopatis ◽  
...  
Keyword(s):  
Stellar Population ◽  
Milky Way ◽  
Target Selection ◽  
Selection Function ◽  
Population Synthesis ◽  
Sample Distribution ◽  
Stellar Population Synthesis ◽  
Source Sample ◽  
Correction Terms ◽  
Metallicity Distribution

Context. Large spectroscopic Galactic surveys imply a selection function in the way they performed their target selection. Aims. We investigate here the effect of the selection function on the metallicity distribution function (MDF) and on the vertical metallicity gradient by studying similar lines of sight using four different spectroscopic surveys (APOGEE, LAMOST, RAVE, and Gaia-ESO), which have different targeting strategies and therefore different selection functions. Methods. We use common fields between the spectroscopic surveys of APOGEE, LAMOST, RAVE (ALR) and APOGEE, RAVE, Gaia-ESO (AGR) and use two stellar population synthesis models, GALAXIA and TRILEGAL, to create mock fields for each survey. We apply the selection function in the form of colour and magnitude cuts of the respective survey to the mock fields to replicate the observed source sample. We make a basic comparison between the models to check which best reproduces the observed sample distribution. We carry out a quantitative comparison between the synthetic MDF from the mock catalogues using both models to understand the effect of the selection function on the MDF and on the vertical metallicity gradient. Results. Using both models, we find a negligible effect of the selection function on the MDF for APOGEE, LAMOST, and RAVE. We find a negligible selection function effect on the vertical metallicity gradients as well, though GALAXIA and TRILEGAL have steeper and shallower slopes, respectively, than the observed gradient. After applying correction terms on the metallicities of RAVE and LAMOST with respect to our reference APOGEE sample, our observed vertical metallicity gradients between the four surveys are consistent within 1σ. We also find consistent gradient for the combined sample of all surveys in ALR and AGR. We estimated a mean vertical metallicity gradient of − 0.241 ± 0.028 dex kpc-1. There is a significant scatter in the estimated gradients in the literature, but our estimates are within their ranges. Conclusions. We have shown that there is a negligible selection function effect on the MDF and the vertical metallicity gradients for APOGEE, RAVE, and LAMOST using two stellar population synthesis models. Therefore, it is indeed possible to combine common fields of different surveys in studies using MDF and metallicity gradients provided their metallicities are brought to the same scale.

scholarly journals Applications of Stellar Population Synthesis in the Distant Universe

Galaxies ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 6 ◽  
Author(s):  
Elizabeth R. Stanway
Keyword(s):  
Physical Properties ◽  
Stellar Population ◽  
Stellar Populations ◽  
Population Synthesis ◽  
Signal To Noise ◽  
Distant Galaxies ◽  
Stellar Population Synthesis ◽  
Noise Data

Comparison with artificial galaxy models is essential for translating the incomplete and low signal-to-noise data we can obtain on astrophysical stellar populations to physical interpretations which describe their composition, physical properties, histories and internal conditions. In particular, this is true for distant galaxies, whose unresolved light embeds clues to their formations and evolutions, and their impacts on their wider environs. Stellar population synthesis models are now used as the foundation of analysis at all redshifts, but are not without their problems. Here we review the use of stellar population synthesis models, with a focus on applications in the distant Universe.

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.

Stellar population synthesis of jellyfish galaxies

2019 ◽  
Vol 15 (S359) ◽  
pp. 255-256
Author(s):  
Gabriel M. Azevedo ◽  
Ana L. Chies Santos ◽  
Rogério Riffel ◽  
Augusto Lassen ◽  
Marina Trevisan ◽  
...  
Keyword(s):  
Stellar Population ◽  
Stellar Populations ◽  
Population Synthesis ◽  
Data Cubes ◽  
Ram Pressure ◽  
Stellar Population Synthesis

AbstractJellyfish are the most extreme cases of galaxies undergoing ram-pressure stripping. In order to analyse the stellar populations distribution along these galaxies, we have performed stellar population synthesis in data cubes of jellyfish from the GASP programme, using both Starlight and FADO codes.

Stellar populations and ionised gas in central spheroidal galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 469-472
Author(s):  
Vanessa Lorenzoni ◽  
Sandro B. Rembold
Keyword(s):  
Stellar Population ◽  
Synthesis Method ◽  
Galactic Nuclei ◽  
Stellar Populations ◽  
High Mass ◽  
Population Synthesis ◽  
The Galaxy ◽  
History Of ◽  
Low Mass ◽  
Spheroidal Galaxies

We investigate the stellar populations and ionised gas properties of a sample of central spheroidal galaxies in order to better constrain their history of star formation and gas excitation mechanism. We select galaxies from Spheroids Panchromatic Investigation in Different Environmental Regions (SPIDER) catalogue and separate these galaxies in different regimes of halo and galaxy mass. To characterise the stellar population properties of these galaxies we use the stellar population synthesis method with the Starlight code, and the presence of ionised gas is identified by measurements of the Hα equivalent width. We analyse how these properties behave as a function of the galaxy stellar mass and the parent halo mass. A trend is observed in the sense of increased ionised gas emission for low-mass centrals in high-mass halos. We interpret this trend in a scenario of intracluster medium (ICM) cooling versus active galactic nuclei (AGN) feedback in a Bondi accretion context.

scholarly journals Stellar Populations in Mixed Pairs of Galaxies

1995 ◽  
Vol 164 ◽  
pp. 434-434 ◽  
Author(s):  
D.F. De Mello ◽  
W.C. Keel ◽  
J.W. Sulentic ◽  
R. Rampazzo
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Elliptical Galaxy ◽  
Star Formation History ◽  
Population Synthesis ◽  
Early Type ◽  
Stellar Content ◽  
Stellar Population Synthesis ◽  
History Of ◽  
Early Type Galaxy

The interpration of the interaction in galaxies is simplified in mixed pairs (E+S) because most or all of the cold gas can be traced to an origin in a single galaxy (S). We used spectroscopy, imaging, far–IR, and stellar population synthesis to study the stellar content and history of star formation in the nuclear region of the early–type galaxy in the mixed pair AM0327–285. We used the procedure for stellar population synthesis developed by Bica (1988) to estimate the star-formation history of the nucleus of the elliptical galaxy. The method uses a library of star clusters, and estimates the chemical evolution in a test population with two parameters: age and metallicity; no assumptions on gravity or details of stellar evolution are necessary, and the IMF is implicit in the cluster spectra. The procedure allows one to both determine the chemical enrichment and date successive generations of star formation. The result indicates that the dominant population is old and metal–rich ([Z/Z]⊙=0.3), while ~ 10% of the flux at 5870 Å arises from a young stellar population (age ≤ 5 × 108 yr), confirming that this early-type galaxy had recent star formation as suggested also by photometry and far–IR data (de Mello et al 1994). This age is close to several estimates of the characteristic timescale of the interaction, suggesting that the mass influx associated with this star formation occurred as a result of an earlier phase of the interaction and not as a result of the present geometry of the pair.

Stellar population synthesis of galaxies with chemical evolution model

2019 ◽  
Vol 15 (S341) ◽  
pp. 147-151
Author(s):  
Shiyin Shen ◽  
Jun Yin
Keyword(s):  
Chemical Evolution ◽  
Stellar Population ◽  
Local Group ◽  
Evolution Model ◽  
Star Formation History ◽  
Population Synthesis ◽  
Formation History ◽  
Fitting Algorithm ◽  
Stellar Population Synthesis ◽  
Chemical Evolution Model

AbstractThe derivation of accurate stellar populations of galaxies is a non-trivial task because of the well-known age-metallicity degeneracy. We aim to break this degeneracy by invoking a chemical evolution model (CEM) for isolated disk galaxy, where its metallicity enrichment history (MEH) is modelled to be tightly linked to its star formation history (SFH). Our CEM has been successfully tested on several local group dwarf galaxies whose SFHs and MEHs have been both independently measured from deep colour-magnitude diagrams of individual stars. By introducing the CEM into the stellar population fitting algorithm as a prior, we expect that the SFH of galaxies could be better constrained.

scholarly journals The effects of the selection function on metallicity trends in spectroscopic surveys of the Milky Way

2017 ◽  
Vol 13 (S334) ◽  
pp. 345-346
Author(s):  
G. Nandakumar ◽  
M. Schultheis ◽  
M. Hayden ◽  
A. Rojas-Arriagada ◽  
G. Kordopatis ◽  
...  
Keyword(s):  
Distribution Function ◽  
Stellar Population ◽  
Milky Way ◽  
Selection Function ◽  
Population Synthesis ◽  
Stellar Population Synthesis ◽  
Metallicity Distribution

AbstractWe investigate here the effect of the selection function on the metallicity distribution function (MDF) as well as on the vertical metallicity gradient by studying similar lines-of-sight using four different spectroscopic surveys (APOGEE, LAMOST, RAVE and Gaia-ESO) which have different targeting strategies and therefore different selection functions. We create mock fields for each survey using two stellar population synthesis models, GALAXIA and TRILEGAL. The effects of the selection function are studied in detail by applying the selection function to the two models and comparing the MDF as well as vertical metallicity gradients of the selected sources with that of the underlying sample. We find a negligible selection function effect on the MDF as well as on the vertical metallicity gradients for APOGEE, RAVE and LAMOST, and estimate a mean vertical metallicity gradient of -0.241±0.028 dex kpc−1.

scholarly journals Spectrophotometric Population Synthesis of Early Type Galaxies

1996 ◽  
Vol 171 ◽  
pp. 460-460
Author(s):  
A. Vazdekis ◽  
R. Peletier ◽  
E. Casuso ◽  
J. Beckman
Keyword(s):  
Absorption Line ◽  
Chemical Evolution ◽  
Stellar Population ◽  
Stellar Populations ◽  
Population Synthesis ◽  
Early Type ◽  
Evolutionary Scheme ◽  
Stellar Population Synthesis

We have developed a new stellar population synthesis model for calculating colours and absorption line indices in early type galaxies. This model can work either for single-age stellar populations or in an evolutionary scheme following the chemical evolution. The model is based on the isochrones of the Padova group and we have developed our own method of conversion to colours. Details can be found in Vazdekis A., Casuso E., Peletier R. & Beckman J. (submitted, 1995). To test the model we have obtained accurate observations in many colours and line indices of the three standard galaxies: NGC 3379, NGC 4472 and NGC 4594.

scholarly journals New results on the structure and stellar content of the outer regions of the SMC

1991 ◽  
Vol 148 ◽  
pp. 51-52
Author(s):  
L. T. Gardiner ◽  
M.R.S. Hawkins
Keyword(s):  
Evolutionary History ◽  
Large Scale ◽  
Stellar Population ◽  
Main Sequence ◽  
Population Synthesis ◽  
Stellar Content ◽  
Surface Distribution ◽  
Contour Maps ◽  
Stellar Population Synthesis ◽  
History Of

Surface distribution contour maps of the HB/clump population and the < 1 Gyr main sequence population for the outer regions of the Small Magellanic Cloud (SMC) are presented. Aspects of the stellar population synthesis, large-scale structure and evolutionary history of the SMC halo are discussed.

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