Evolution of photoionization and star formation in starbursts and H1214 II galaxies

Moy, E.; Rocca‐Volmerange, B.; Fioc, Michel

doi:10.1051/0004-6361:20000045

Cited by 53 publications

(65 citation statements)

References 64 publications

(110 reference statements)

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“…In this respect our approach is similar to that of Pérez-González et al (2003a,b) who also use observed line ratios for their sample of strong H α emitting UCM survey galaxies. It differs from those of Charlot & Longhetti (2001), Moy et al (2001), or Zackrisson et al (2001, who assume electron densities and temperatures for the gas at low metallicities and couple a photoionisation code to their evolutionary synthesis model.…”

Section: Gaseous Emissionmentioning

confidence: 99%

Spectral and photometric evolution of young stellar populations: The impact of gaseous emission at various metallicities

Anders¹,

Alvensleben²

2003

A&A

347

444

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Abstract. We include gaseous continuum and line emission into our  models for the spectral and photometric evolution of Simple Stellar Populations (SSPs) for various metallicities in the range 0.02 ≤ Z/Z ≤ 2.5. This allows to extend them to significantly younger ages than before. They now cover the age range from 4 Myr all through 14 Gyr. We point out the very important contributions of gaseous emission to broad band fluxes and their strong metallicity dependence during very early evolutionary stages of star clusters, galaxies or subgalactic fragments with vigorous ongoing star formation. Emissionline contributions are commonly seen in these actively star-forming regions. Models without gaseous emission cannot explain their observed colors at all, or lead to wrong age estimates. We use up-to-date Lyman continuum (=Lyc) emission rates and decided to use recent empirical determinations of emission line ratios relative to H β for subsolar metallicities. We justify this approach for all situations where no or not enough spectral information is available to determine all the parameters required by photoionization models. The effects of gaseous line and continuum emission on broad band fluxes are shown for different metallicities and as a function of age. In addition to the many filter systems already included in our earlier models, we here also include the HST NICMOS and Advanced Camera for Surveys (=ACS) filter systems.

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Section: Gaseous Emissionmentioning

confidence: 99%

Spectral and photometric evolution of young stellar populations: The impact of gaseous emission at various metallicities

Anders¹,

Alvensleben²

2003

A&A

347

444

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“…[Nii]/Hα diagrams. This choice has been made by considering that these emission line ratios do not depend strongly on the age of the stellar population (Moy et al 2001;Stasińska & Izotov 2003;Stasińska et al 2006). (Figs.…”

Section: Comparison With Modelsmentioning

confidence: 99%

Classifying radio emitters from the Sloan Digital Sky Survey

Vitale

Zuther

García-Marín

et al. 2012

A&A

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Context. The Sloan Digital Sky Survey (SDSS) allows us to classify galaxies using optical low-ionization emission-line diagnostic diagrams. A cross-correlation of the SDSS data release 7 (DR7), containing spectroscopic data, with the Very Large Array (VLA) survey Faint Images of the Radio Sky at Twenty-centimeters (FIRST), makes it possible to conduct a joined multiwavelength statistical study of radio-optical galaxy properties on a very large number of sources. Aims. Our goal is to improve the study of the combined radio-optical data by investigating whether there is a correlation between the radio luminosity at 20 cm over the luminosity of the optical Hα line (L 20 cm /L Hα ) and line excitation ratios, where the latter provide the spectroscopic classification in Seyferts, low-ionization nuclear emission-line regions (LINERs), and star-forming galaxies. We search for a trend with z in the classification provided by classical and more recent optical emission-line diagnostic diagrams. Methods. We cross-matched the optical sources with the FIRST radio survey in order to obtain spectroscopic information of a selected sample of radio emitters with optical observed counterpart. We searched for an L 20 cm /L Hα threshold value above which the radio emitters start being classified as active galactic nuclei (AGNs) rather than star-forming galaxies (SFGs). We investigated the origin of emission-lines by using both photoionization and shock models. Results. The percentage of detected AGNs (Seyferts and LINERs) or composites is much higher in the optical-radio sample than in the optical sample alone. We find a progressive shift in the sources towards the AGN region of the diagram with increasing L 20 cm /L Hα , with an indication of different behavior for LINERs and Seyferts. The classification appears to slightly depend on the redshift. The diagnostic diagrams display a density peak in the star-forming or composite region for log (L 20 cm /L Hα ) < 0.716, while the distribution in the LINER region peaks above this threshold. A comparison with photoionization and shock models shows that the large fraction of LINERs identified in our study have emission lines that may be explained by shocks. Conclusions. Our results indicate that it is worthwhile to further explore the radio domain, probing the physical nature of LINERs, thanks to a combination of optical and radio information. The [Nii]/Hα vs. equivalent width of the Hα line (WHAN) diagram confirms the LINER classification for most of those that have been identified with the traditional diagnostic diagrams. The correlation between L 20 cm /L Hα and optical emission line ratios suggests the nuclear origin of the emission from the most powerful radio galaxies.

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“…Other hydrogen and metals lines are then rescaled in fixed proportions. Moy et al (2001) have improved the previous model by coupling the integrated spectrum with CLOUDY.…”

Section: Nebular Emission From a Star-forming Galaxymentioning

confidence: 99%

Dust and nebular emission

Panuzzo

Bressan

Granato

et al. 2003

A&A

121

184

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Abstract. We present a model for nebular emission in star forming galaxies, which takes into account the effects of dust reprocessing. The nebular emissions (continuum emission, 54 H and He recombination lines and 60 nebular lines from UV to IR) have been computed with CLOUDY and then included into GRASIL, our spectrophotometric code specifically developed for dusty galaxies. The interface between nebular emission and population synthesis is based on a set of pre-computed H  region emission models covering a wide range of physical quantities (metallicity, density, geometry and number of H , He  and O  ionizing photons). These quantities are fully adequate to describe the emission properties of the majority of starforming and starburst galaxies. Concerning the extinction properties of normal star forming galaxies, we are able to interpret the observed lack of correlation between the attenuation measured at Hα and in the UV band as a consequence of age selective extinction. We also find that, for these galaxies with modest SFR, the ratio FIR/UV provides the best constraints on the UV attenuation. The accurate treatment of lines and continuum in dusty galaxies also allows to deal with different SFR estimators in a consistent way, from the UV to radio wavelengths, and to discuss the uncertainties arising from the different physical conditions encountered in star forming galaxies. We provide our best estimates of SFR/luminosity calibrations, together with their expected range of variation. It results that SFR derived through Hα, even when corrected for extinction using the Balmer decrement, is affected by important uncertainties due to age selective extinction. Another remarkable result is that SFR from UV luminosity corrected by means of the ratio FIR/UV has a small uncertainty. Finally, our model provides a calibration of SFR from radio luminosity; its value differs from estimates from other works, but we are able to reproduce the observed FIR/radio ratio. These results are relevant to estimates of the contribution of disk galaxies to the cosmic SFR at z ≤ 1.

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Evolution of photoionization and star formation in starbursts and H1214 II galaxies

Cited by 53 publications

References 64 publications

Spectral and photometric evolution of young stellar populations: The impact of gaseous emission at various metallicities

Spectral and photometric evolution of young stellar populations: The impact of gaseous emission at various metallicities

Classifying radio emitters from the Sloan Digital Sky Survey

Dust and nebular emission

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