<i>ULySS</i>: a full spectrum fitting package

Koleva, M.; Prugniel, Ph.; Bouchard, Antoine; Wu, Yue

doi:10.1051/0004-6361/200811467

Cited by 473 publications

(543 citation statements)

References 51 publications

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“…The five galaxies below the line were not observed and/or analysed (as described in section 2), but we do not expect these to affect our conclusions as described in section 5. lar evolution theory is then used to calculate the integrated properties of these SSPs and predict a spectral energy distribution that can be compared to observations. We follow the methods of Koleva et al (2009), Loubser (2014 and Groenewald & Loubser (2014) to analyse the stellar populations of BCGs. We use the University of Lyon Spectroscopic analysis Software (ULySS) (Koleva et al 2009) to obtain a non-linear χ 2 -minimization against SSP (or a linear combination of more than one SSP) models convolved with the internal kinematics of the galaxy.…”

Section: Stellar Populationsmentioning

confidence: 99%

The regulation of star formation in cool-core clusters: imprints on the stellar populations of brightest cluster galaxies

Loubser

Babul

Hoekstra

et al. 2015

Mon. Not. R. Astron. Soc.

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A fraction of brightest cluster galaxies (BCGs) shows bright emission in the UV and the blue part of the optical spectrum, which has been interpreted as evidence of recent star formation. Most of these results are based on the analysis of broadband photometric data. Here, we study the optical spectra of a sample of 19 BCGs hosted by X-ray luminous galaxy clusters at 0.15 < z < 0.3, a subset from the Canadian Cluster Comparison Project (CCCP) sample. We identify plausible star formation histories of the galaxies by fitting Simple Stellar Populations (SSPs) as well as composite populations, consisting of a young stellar component superimposed on an intermediate/old stellar component, to accurately constrain their star formation histories. We detect prominent young (∼ 200 Myr) stellar populations in 4 of the 19 galaxies. Of the four, the BCG in Abell 1835 shows remarkable A-type stellar features indicating a relatively large population of young stars, which is extremely unusual even amongst star forming BCGs. We constrain the mass contribution of these young components to the total stellar mass to be typically between 1% to 3%, but rising to 7% in Abell 1835. We find that the four of the BCGs with strong evidence for recent star formation (and only these four galaxies) are found within a projected distance of 5 kpc of their host cluster's X-ray peak, and the diffuse, X-ray gas surrounding the BCGs exhibit a ratio of the radiative cooling-to-free-fall time (t c /t ff ) of ≤ 10. These are also some of the clusters with the lowest central entropy. Our results are consistent with the predictions of the precipitation-driven star formation and AGN feedback model, in which the radiatively cooling diffuse gas is subject to local thermal instabilities once the instability parameter t c /t ff falls below ∼ 10, leading to the condensation and precipitation of cold gas. The number of galaxies in our sample where the host cluster satisfies all the criteria for recent and ongoing star formation is small, but their stellar populations suggest a timescale for star formation to restart of the order of ∼ 200 Myrs.

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Section: Stellar Populationsmentioning

confidence: 99%

The regulation of star formation in cool-core clusters: imprints on the stellar populations of brightest cluster galaxies

Loubser

Babul

Hoekstra

et al. 2015

Mon. Not. R. Astron. Soc.

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“…Fernandes et al 2005;Fernandes & Delgado 2010;Koleva et al 2009;MacArthur et al 2009). This is achieved by a full spectrum fitting including the continuum shape and absorption features.…”

Section: Continuum S/n Optimized Testmentioning

confidence: 99%

Integrated spectra extraction based on signal-to-noise optimization using integral field spectroscopy

Rosales-Ortega

Arribas

Colina

2012

A&A

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Aims. We explore the potential of a method to extract high signal-to-noise (S/N) integrated spectra of particular physical and/or morphological regions of a two-dimensional field using integral field spectroscopy (IFS) observations by applying an optimization procedure based on either continuum (stellar) or line (nebular) emission features. Methods. The optimization method is applied to a set of IFS VLT-VIMOS observations of (U)LIRG galaxies. We describe the advantages of the optimization by comparing the results with a fixed-aperture, single-spectrum case, and by implementing some statistical tests. Results. We demonstrate that the S/N of the IFS optimized integrated spectra is significantly higher than for the single-aperture unprocessed case. In some cases, the optimization based on the emission lines allows to characterize some of the source properties more reliably than with standard integration methods. We are able to clearly retrieve the weak continuum features, hence more precisely constrain the properties of the unresolved stellar population. The most suitable method for integrating spectra over (part of) the field-of-view ultimately depends on the science case, and may involve a trade off among the different variables (e.g. S/N, probe area, spatial resolution, etc.). we therefore provide an iterative user-friendly and versatile IDL algorithm that, in addition to the above-mentioned method, allows the user to spatially integrate spectra following more standard procedures. Our procedure is made available to the community as part of the PINGSoft IFS software package.

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“…We speculate that the poor fit may also be caused by the way in which the continuum shape is fitted by Starlight. To check this point, we used yet another program, ULySS (Koleva et al 2009b), to perform similar fits, and we achieved superior fits around Hβ. However, this problem does not significantly affect our stellar population analysis.…”

Section: Star-forming Galaxiesmentioning

confidence: 99%

Comparing six evolutionary population synthesis models by performing spectral synthesis for galaxies

Chen

Liang

Hammer

et al. 2010

A&A

Self Cite

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Aims. We compare six popularly used evolutionary population synthesis (EPS) models by fitting the full optical spectra of six representative types of galaxies (star-forming and composite galaxies, Seyfert 2s, LINERs, E+A, and early-type galaxies) taken from the Sloan Digital Sky Survey (SDSS). We explore the dependence of stellar population synthesis results on the main ingredients of the EPS models and study whether there is an age sequence among these types of galaxies. Methods. We use the simple stellar populations (SSPs) of each EPS model and the software STARLIGHT to perform our fits. Firstly, we explore the dependence of stellar population synthesis on EPS models by fixing the age, metallicity, and initial mass function (IMF) to construct a standard SSP group. We then use the standard SSP group of each EPS model (BC03, CB07, Ma05, GALEV, GRASIL, and Vazdekis/Miles) to fit the spectra of star-forming and E+A galaxies. Secondly, we fix the IMF and alter the age and metallicity to construct eight additional SSP groups. We then use these SSP groups to fit the spectra of star-forming and E+A galaxies to verify the effects of age and metallicity on stellar populations. Finally, we study the effect of stellar evolution tracks and stellar spectral libraries on our results, and present a possible age sequence among these types of galaxies. Results. Using different EPS models, the numerical values of contributing light fractions obviously change, even though the dominant populations are unaltered. The stellar population synthesis does depend on the selection of age and metallicity, but does not depend significantly on the stellar evolution track. The importance of young populations decreases from star-forming, composite, Seyfert 2, LINER, to early-type galaxies, and the properties of E+A galaxies are between composite galaxies and Seyfert 2s in most cases. Conclusions. Different EPS models infer different stellar population parameters, so that it is not reasonable to directly compare stellar populations estimated from different EPS models. To obtain reliable results, we should use the same EPS model to derive the parameter values that we compare.

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ULySS: a full spectrum fitting package

Cited by 473 publications

References 51 publications

The regulation of star formation in cool-core clusters: imprints on the stellar populations of brightest cluster galaxies

The regulation of star formation in cool-core clusters: imprints on the stellar populations of brightest cluster galaxies

Integrated spectra extraction based on signal-to-noise optimization using integral field spectroscopy

Comparing six evolutionary population synthesis models by performing spectral synthesis for galaxies

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