Connecting the Cosmic Star Formation Rate with the Local Star Formation

Gribel, Carolina; Miranda, Oswaldo D.; Vilas-Boas, J. W. S.

doi:10.3847/1538-4357/aa921a

Cited by 9 publications

(12 citation statements)

References 87 publications

(126 reference statements)

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“…The analytic models for the SFR rate of Krumholz & McKee (2005), Nordlund (2011), andChabrier (2011), as well as follow-up modifications discussed by Federrath & Klessen (2012), Federrath & Banerjee (2015b), and Gribel et al (2017, are all based on integrals over the lognormal density PDF thereby neglect contributions to the SFR that arise from the PDF power law tail. Numerous studies have now shown that the lognormal form of the PDF of column density or density describes the behavior of diffuse molecular and atomic gas (Berkhuijsen & Fletcher 2008;Hill et al 2008;Burkhart et al 2010;Imara & Burkhart 2016;Bialy et al 2017a).…”

Section: The Piecewise Lognormal + Power Law Density Pdfmentioning

confidence: 99%

“…Analytic calculations for the star formation rate have used the lognormal PDF (Krumholz & McKee 2005;Padoan & Nordlund 2011;Hennebelle & Chabrier 2011;Federrath & Klessen 2012;Renaud et al 2012;Hopkins 2012;Gribel et al 2017), taking the integral starting from a critical density for collapse (ρ crit ), which varies for different authors. In these works, the SFR depends on the exact choice of a number of parameters of order unity as well as on the properties of the lognormal PDF, set by supersonic turbulence.…”

Section: Introductionmentioning

confidence: 99%

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The Star Formation Rate in the Gravoturbulent Interstellar Medium

Burkhart

2018

ApJ

118

135

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Stars form in supersonic turbulent molecular clouds that are self-gravitating. We present an analytic determination of the star formation rate (SFR) in a gravoturbulent medium based on the density probability distribution function of molecular clouds having a piecewise lognormal and power law form. This is in contrast to previous analytic SFR models that are governed primarily by interstellar turbulence which sets purely lognormal density PDFs. In the gravoturbulent SFR model described herein, low density gas resides in the lognormal portion of the PDF. Gas becomes gravitationally unstable past a critical density (ρ crit ), and the PDF begins to forms a power law. As the collapse of the cloud proceeds, the transitional density (ρ t ) between the lognormal and power law portions of the PDF moves towards lower-density while the slope of the power law (α) becomes increasingly shallow. The star formation rate per free-fall time is calculated via an integral over the lognormal from ρ crit to ρ t and an integral over the power law from ρ t to the maximum density. As α becomes shallower the SFR accelerates beyond the expected values calculated from a lognormal density PDF. We show that the star formation efficiency per free fall time in observations of local molecular cloud increases with shallower PDF power law slopes, in agreement with our model. Our model can explain why star formation is spatially and temporally variable within a cloud and why the depletion times observed in local and extragalactic giant molecular clouds vary. Both star-bursting and quiescent star-forming systems can be explained without the need to invoke extreme variations of turbulence in the local interstellar environment.

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Section: The Piecewise Lognormal + Power Law Density Pdfmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Star Formation Rate in the Gravoturbulent Interstellar Medium

Burkhart

2018

ApJ

118

135

View full text Add to dashboard Cite

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“…Most previous analytic calculations for the star formation rate have all hinged on the form of the density PDF being fully lognormal Padoan & Nordlund 2011;Hennebelle & Chabrier 2011;Renaud et al 2012;Hopkins 2012b;Gribel et al 2017). These works calculate the SFR by integrating the lognormal PDF from a critical density for collapse, which varies for different authors.…”

Section: Introductionmentioning

confidence: 99%

The Self-gravitating Gas Fraction and the Critical Density for Star Formation

Burkhart

Mocz

2019

ApJ

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We analytically calculate the star formation efficiency and dense gas fraction in the presence of selfgravitating super-Alfvénic turbulence using the model of Burkhart (2018) which employs a piecewise lognormal and power law density PDF. We show that the PDF transition density between lognormal and power law forms is a mathematically motivated critical density and can be physically related to the density where the Jeans length is comparable to the sonic length, i.e. the post-shock critical density for collapse. When the PDF transition density is taken as the critical density, the star formation efficiency ( ) and depletion time (t depl ) can be calculated from the dense self-gravitating gas faction represented as the fraction of gas in the PDF power law tail. We minimize the number of free parameters in the expressions for and t depl by removing the parameterized critical density criterion for collapse and thus provide a more direct pathway for comparison with observations. We test the analytic predictions for the transition density and dense gas fraction against AREPO moving mesh gravoturbulent simulations and find good agreement. We predict that, when gravity dominates the density distribution in the star forming gas, the star formation efficiency and depletion time should be weakly anti-correlated with the sonic Mach number. The star formation efficiency and depletion time depend primarily on the slope of the power law tail, which directly quantifies the fraction of dense self-gravitating gas and the feedback efficiency. Our model prediction is in agreement with recent observations, such as the M51 PdBI Arcsecond Whirlpool Survey (PAWS).

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“…However, to identify the influence of the IMF exponent on the chemical enrichment of the Universe, we also considered four other values, nominally, 0.85, 1.0, 1.7, and 1.85 allowing the formation of a higher (the first two values) or smaller (the last two values) number of high-mass stars when compared to the reference value 1.35. We also used α = 1 in agreement with Gribel et al (2017), which shows that different properties from the star formation regions in the Galaxy, including the so-called Larson's law, can be well reproduced with α = 1. Therefore, Eq.…”

Section: Cosmic Star Formation Ratementioning

confidence: 78%

Potential contributions of Pop III and intermediate-mass Pop II stars to cosmic chemical enrichment

Corazza

Miranda

Wuensche

2022

A&A

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Context. We propose a semi-analytic model that is developed to understand the cosmological evolution of the mean metallicity in the Universe. In particular, we study the contributions of Population III (Pop III) and Population II (Pop II) stars to the production of Fe, Si, Zn, Ni, P, Mg, Al, S, C, N, and O. Aims. We aim to quantify the roles of two different models in the chemical enrichment of the Universe. The first model (A) considers both stars with Pop III and Pop II yields. For the second model (B), the yields involved are only for Pop II stars. Methods. We start by describing the cosmic star formation rate (CSFR) through an adaptation of a scenario developed within the hierarchical scenario of structure formation with a Press-Schechter-like formalism. We adapt the formalism to implement the CSFR to the standard chemical evolution scenario to investigate the course of chemical evolution on a cosmological basis. Calculations start at redshift z ∼ 20, and we compare the results of our two models with data from damped Lyman-α systems (DLAs), and globular clusters (GCs). Results. Our main results find that metal production in the Universe occurred very early, quickly increasing with the formation of the first stars. When comparing results for [Fe/H] with observations from GCs, yields of Pop II stars are not enough to explain the observed chemical abundances, requiring stars with physical properties similar those expected from Pop III stars. Conclusions. Our semi-analytic model can deliver consistent results for the evolution of cosmic metallicities. Our results show that the chemical enrichment in the early Universe is rapid, and at redshift ∼ 12.5, the metallicity reaches 10 −4 Z for the model that includes Pop III stars. In addition, we explore values for the initial mass function (IMF) within the range [0.85, 1.85].

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Connecting the Cosmic Star Formation Rate with the Local Star Formation

Cited by 9 publications

References 87 publications

The Star Formation Rate in the Gravoturbulent Interstellar Medium

The Star Formation Rate in the Gravoturbulent Interstellar Medium

The Self-gravitating Gas Fraction and the Critical Density for Star Formation

Potential contributions of Pop III and intermediate-mass Pop II stars to cosmic chemical enrichment

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