Simple interpolation functions for the galaxy-wide stellar initial mass function and its effects in early-type galaxies

Dabringhausen, J.

doi:10.1093/mnras/stz2562

Cited by 12 publications

(10 citation statements)

References 174 publications

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“…Thus, BiPoS1 follows essentially the theory of the IGIMF for the stellar population (e.g. Kroupa & Weidner 2003;Weidner & Kroupa 2005;Kroupa et al 2013;Jeřábková et al 2018;Dabringhausen 2019) when it calculates its binary content. BiPoS1 assumes here that gas expulsion sets in after 3 Myr.…”

Section: Discussionmentioning

confidence: 99%

“…What is not covered by BiPoS1 are IMFs that are flatter than α2 = 2.3 in the high-mass range. Such IMFs may occur in the most massive star clusters (Dabringhausen et al 2012;Jeřábková et al 2017), and conseqently also in galaxies with the highest star formation rates (Fontanot et al 2017;Jeřábková et al 2018;Dabringhausen 2019).…”

Section: The Binary Population At Its Birthmentioning

confidence: 99%

“…This can be translated into maximum stellar masses that were formed with those SFRs with the theory of integrated galactic stellar initial mass functions (IGIMFs) (Kroupa & Weidner 2003). According to equation ( 14) in Dabringhausen (2019), the result is mmax = 9.9 M⊙ for the most massive star in OB1a and mmax = 10.6 M⊙ for the most massive star in OB1b. Thus, in retrospective, the choice of Mscp = 1400 M⊙ for OB1a and Mscp = 800 M⊙ for OB1b proves to be appropriate, because only about 0.5 per cent of the stars which formed with the full canonical IMF are more massive than 10 M⊙, and they account for about 20 per cent of the total mass of the full canonical IMF.…”

Section: Two Small Star-forming Regions In Orionmentioning

confidence: 99%

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BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population

Dabringhausen,

Marks,

Kroupa

2021

Preprint

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The first version of the Binary Population Synthesizer (BiPoS1) is made publicly available. It allows to efficiently calculate binary distribution functions after the dynamical processing of a realistic population of binary stars during the first few Myr in the hosting embedded star cluster. Instead of time-consuming N-body simulations, BiPoS1 uses the stellar dynamical operator Ω ρ ecl dyn (log 10 (E b ), t), which determines the fraction of surviving binaries depending on the binding energy of the binaries, E b . The Ω-operator depends on the initial star cluster density, ρ ecl , as well as the time, t, until the residual gas of the star cluster is expelled. BiPoS1 has also a galactic-field mode, in order to synthesize the stellar population of a whole galaxy. At the time of gas expulsion, the dynamical processing of the binary population is assumed to effiently end due to the subsequent expansion of the star cluster. While BiPoS1 has been used previously unpublished, here we demonstrate its use in the modelling of the binary populations in the Orion Nebula Cluster, in OB associations and as an input for simulations of globular clusters.

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Section: Discussionmentioning

confidence: 99%

Section: The Binary Population At Its Birthmentioning

confidence: 99%

Section: Two Small Star-forming Regions In Orionmentioning

confidence: 99%

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BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population

Dabringhausen,

Marks,

Kroupa

2021

Preprint

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“…Note that 1 < ζ < 1.3 for a galaxy with a constant SFR and a canonical gwIMF, but ζ also depends on the gwIMF and can reach values as large as 2-3 for extreme star-bursting, low-metallicity galaxies (according to the IGIMF theory, see e.g. Yan et al 2017;Dabringhausen 2019;Yan et al 2019).…”

Section: The Local Volumementioning

confidence: 99%

Constraints on the star formation histories of galaxies in the Local Cosmological Volume

Kroupa,

Haslbauer,

Banik

et al. 2020

Preprint

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The majority of galaxies with current star-formation rates (SFRs), SF R o 10 −3 M /yr, in the Local Cosmological Volume where observations should be reliable, have the property that their observed SF R o is larger than their average star formation rate. This is in tension with the evolution of galaxies described by delayed-τ models, according to which the opposite would be expected. The tension is apparent in that local galaxies imply the star formation timescale τ ≈ 6.7 Gyr, much longer than the 3.5 − 4.5 Gyr obtained using an empirically determined main sequence at several redshifts. Using models where the SFR is a power law in time of the form ∝ (t − t 1 ) η for t 1 = 1.8 Gyr (with no stars forming prior to t 1 ) implies that η = 0.18 ± 0.03. This suggested near-constancy of a galaxy's SFR over time raises non-trivial problems for the evolution and formation time of galaxies, but is broadly consistent with the observed decreasing main sequence with increasing age of the Universe.

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“…The stellar α element to iron peak element ratio, for example [Mg/Fe], is a classic indicator of the star formation timescale (SFT) for galaxies (applied in, e.g. Thomas et al 2005, Segers et al 2016, Liu et al 2016b, Kriek et al 2019, and Dabringhausen 2019. It is known that possibly more than half of the iron in the Universe is produced by Type Ia supernovae (SNIa) which explode on average about a billion years after the formation of their parental stellar population (e.g., Maoz & Mannucci 2012).…”

Section: Introductionmentioning

confidence: 99%

The star formation timescale of elliptical galaxies -- Fitting [Mg/Fe] and total metallicity simultaneously

Yan,

Jerabkova,

Kroupa

2019

Preprint

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The alpha element to iron peak element ratio, for example [Mg/Fe], is a commonly applied indicator of the galaxy star formation timescale (SFT) since the two groups of elements are mainly produced by different types of supernovae that explode over different timescales. However, it is insufficient to consider only [Mg/Fe] when estimating the SFT. The [Mg/Fe] yield of a stellar population depends on its metallicity. Therefore, it is possible for galaxies with different SFTs and at the same time different total metallicity to have the same [Mg/Fe]. This effect has not been properly taken into consideration in previous studies. In this study, we assume the galaxy-wide stellar initial mass function (gwIMF) to be canonical and invariant. We demonstrate that our computation code reproduces the SFT estimations of previous studies where only the [Mg/Fe] observational constraint is applied. We then demonstrate that once both metallicity and [Mg/Fe] observations are considered, a more severe "downsizing relation" is required. This means that either lowmass ellipticals have longer SFTs (> 4 Gyr for galaxies with mass below 10 10 M ) or massive ellipticals have shorter SFTs (≈ 200 Myr for galaxies more massive than 10 11 M ) than previously thought. This modification increases the difficulty in reconciling such SFTs with other observational constraints. We show that applying different stellar yield modifications does not relieve this formation timescale problem. The quite unrealistically short SFT required by [Mg/Fe] and total metallicity would be prolonged if a variable stellar gwIMF were assumed. Since a systematically varying gwIMF has been suggested by various observations this could present a natural solution to this problem.1 Not to be confused with the downsizing of the galaxy age or star formation rate (SFR), which is the original meaning of downsizing (Cowie et al. 1996). See Fontanot et al. (2009 for a summary of the many manifestations of downsizing.

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Simple interpolation functions for the galaxy-wide stellar initial mass function and its effects in early-type galaxies

Cited by 12 publications

References 174 publications

BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population

BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population

Constraints on the star formation histories of galaxies in the Local Cosmological Volume

The star formation timescale of elliptical galaxies -- Fitting [Mg/Fe] and total metallicity simultaneously

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