Modeling the ionizing spectra of H II regions: individual stars versus stellar ensembles

Villaverde, M.; Cerviño, M.; Luridiana, V.

doi:10.1051/0004-6361/200912993

Cited by 11 publications

(13 citation statements)

References 46 publications

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“…There are alternative approaches to SPS modeling (e.g., Barbaro & Bertelli 1977;Cerviño et al 2000;Villaverde et al 2010 the IMF stochastic sampling effects. Cerviño et al (2002) constructed a statistical formalism to quantify the uncertainties due to IMF sampling errors and applied their results to model a starburst population from birth to 20 Myr.…”

Section: Imf Stochasticitymentioning

confidence: 99%

The Evolution and Properties of Rotating Massive Star Populations

Choi

Conroy

Byler

2017

ApJ

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We investigate the integrated properties of massive (> 10 M ), rotating, single-star stellar populations for a variety of initial rotation rates (v/v crit = 0.0, 0.2, 0.4, 0.5, and 0.6). We couple the new MESA Isochrone and Stellar Tracks (MIST) models to the Flexible Stellar Population Synthesis (FSPS) package, extending the stellar population synthesis models to include the contributions from very massive stars (> 100 M ), which can be significant in the first ∼ 4 Myr after a starburst. These models predict ionizing luminosities that are consistent with recent observations of young nuclear star clusters. We also construct composite stellar populations assuming a distribution of initial rotation rates. Even in low-metallicity environments where rotation has a significant effect on the evolution of massive stars, we find that stellar population models require a significant contribution from fast-rotating (v/v crit > 0.4) stars in order to sustain the production of ionizing photons beyond a few Myr following a starburst. These results have potentially important implications for cosmic reionization by massive stars and the interpretation of nebular emission lines in high-redshift star-forming galaxies.

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Section: Imf Stochasticitymentioning

confidence: 99%

The Evolution and Properties of Rotating Massive Star Populations

Choi

Conroy

Byler

2017

ApJ

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“…The effect that random sampling of the IMF has on observed stellar populations has been investigated by many authors (see e.g. Cerviño et al 2002; Cerviño & Valls‐Gabaud 2003; Villaverde, Cerviño & Luridiana 2010; Eldridge 2012; da Silva, Fumagalli & Krumholz 2012). When considering the formation of XBs, the parameter space of binary initial conditions is multidimensional, and the volume of that space which produces bright XBs is much smaller than the volume which leads to a massive star and an SN.…”

Section: The Importance Of Stochasticitymentioning

confidence: 99%

Another thread in the tapestry of stellar feedback: X-ray binaries

Justham

Schawinski

2012

Monthly Notices of the Royal Astronomical Society

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We consider X-ray binaries (XBs) as potential sources of stellar feedback. XBs observationally appear able to deposit a high fraction of their power output into their local interstellar medium, which may make them a non-negligible source of energy input. The formation rate of the most luminous XBs rises with decreasing metallicity, which should increase their significance during galaxy formation in the early universe. We also argue that stochastic effects are important to XB feedback (XBF) and may dominate the systematic changes due to metallicity in many cases. Large stochastic variation in the magnitude of XBF at low absolute star formation rates provides a natural reason for diversity in the evolution of dwarf galaxies which were initially almost identical, with several percent of such halos experiencing energy input from XBs roughly two orders of magnitude above the most likely value. These probability distributions suggest that the effect of XBF is most commonly significant for total stellar masses between ~10^7 and 10^8 Msun, which might resolve a current problem with modelling populations of such galaxies. We explain how XBs might inject energy before luminous supernovae (SNe) contribute significantly to feedback and how XBs can assist in keeping gas hot long after the last core-collapse SN has exploded. [...] XBF could be especially important to some dwarf galaxies, potentially heating gas without expelling it; the properties of XBF also match those previously derived as allowing episodic star formation. We also argue that the efficiency of SN feedback (SNF) might be reduced when XBF has had the opportunity to act first. In addition, we note that the effect of SNF is unlikely to be scale-free; galaxies smaller than ~100 pc might well experience less effective SNF. (Slightly abbreviated to fit arXiv size limit.)Comment: Very belatedly updated to include a note added in proof and additional reference. The definitive version is at: mnras.oxfordjournals.org/content/423/2/164

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“…The masses of these clusters are also described by their own cluster IMF (CIMF). Furthermore, fluctuations in the IMF of these clusters, especially if their mass is less than 10 4 M ⊙ , can provide large variation in the ionizing fluxes from the cluster (Cerviño et al 2003; Villaverde, Cerviño & Luridiana 2010a,b). The implication of stars forming in clusters is that the stellar IMF (SIMF) does not apply across an entire galaxy.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we examine recent observations (Lee et al 2009; Calzetti et al 2010; Lamb et al 2010) that may provide a firmer constraint on how nature selects the masses of stars in clusters and galaxies (Pflamm‐Altenburg et al 2007, 2009; Villaverde et al 2010b; Fumagalli, da Silva & Krumholz 2011; Weisz et al 2012). The novel feature of this work is that we are able to demonstrate how binary stars alter our population synthesis predictions.…”

Section: Introductionmentioning

confidence: 99%

Stochasticity, a variable stellar upper mass limit, binaries and star formation rate indicators

Eldridge¹

2012

Monthly Notices of the Royal Astronomical Society

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Using our Binary Population And Spectral Synthesis (BPASS) code we explore the effects on star formation rate indicators of stochastically sampling the stellar initial mass function (IMF), adding a cluster-mass-dependent stellar upper mass limit and including binary stars. We create synthetic spectra of young clusters and star-forming galaxies and compare these to observations of Hα emission from isolated clusters and the relation between Hα and farultraviolet (FUV) emission from nearby galaxies. We find that observations of clusters tend to favour a purely stochastic sampling of the IMF for clusters less than 100 M , rather than the maximum stellar mass being dependent on the total cluster mass. It is more difficult to determine whether the same is true for more massive clusters. We also find that binary stars blur some of the observational differences that occur when a cluster-mass-dependent stellar upper mass limit is imposed when filling the IMF. The effect is greatest when modelling the observed Hα-to-FUV star formation rate ratios in galaxies. This is because mass transfer and merging of stars owing to binary evolution create more massive stars and stars that have greater mass than the initial maximum imposed on the stellar population.

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Modeling the ionizing spectra of H II regions: individual stars versus stellar ensembles

Cited by 11 publications

References 46 publications

The Evolution and Properties of Rotating Massive Star Populations

The Evolution and Properties of Rotating Massive Star Populations

Another thread in the tapestry of stellar feedback: X-ray binaries

Stochasticity, a variable stellar upper mass limit, binaries and star formation rate indicators

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