Formation of Carbon-Enhanced Metal-Poor Stars in the Presence of Far-Ultraviolet Radiation

Bovino, S.; Schleicher, Dominik R. G.; Latif, Muhammad

doi:10.1088/2041-8205/790/2/l35

Cited by 28 publications

(27 citation statements)

References 52 publications

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“…Along with cosmic structure formation, not only the metallicity but other important factors evolve with time. The evolution of the abundance pattern of metals or the composition of dust grains (Schneider et al 2012;Chiaki et al 2016;Chiaki & Yoshida 2020), heating by the warmer cosmic microwave background (CMB) at high redshift (Smith & Sigurdsson 2007;Jappsen et al 2009;Schneider & Omukai 2010;Meece et al 2014;Bovino et al 2014;Safranek-Shrader et al 2014;Riaz et al 2020), the strength of the turbulent motion induced by the expansion of H ii regions or by SN explosions (Smith et al 2015;Chiaki et al 2018), and the effects of the magnetic fields generated at some cosmic evolutionary stages (Machida et al 2009;Machida & Nakamura 2015;Higuchi et al 2018). While these points are important to fully understand the star formation process during the evolution of cosmic structures, they are tangled up making it difficult to capture the metallicity effect on the stellar mass distribution.…”

Section: Introductionmentioning

confidence: 99%

Transition of the initial mass function in the metal-poor environments

Chon,

Omukai,

Schneider

2021

Preprint

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We study star cluster formation in a low-metallicity environment using three dimensional hydrodynamic simulations. Starting from a turbulent cloud core, we follow the formation and growth of protostellar systems with different metallicities ranging from 10 −6 to 0.1 Z . The cooling induced by dust grains promotes fragmentation at small scales and the formation of low-mass stars with M * ∼ 0.01-0.1 M when Z/Z 10 −5 . While the number of low-mass stars increases with metallicity, the stellar mass distribution is still top-heavy for Z/Z 10 −2 compared to the Chabrier initial mass function (IMF). In these cases, star formation begins after the turbulent motion decays and a single massive cloud core monolithically collapses to form a central massive stellar system. The circumstellar disk preferentially feeds the mass to the central massive stars, making the mass distribution top-heavy. When Z/Z = 0.1, collisions of the turbulent flows promote the onset of the star formation and a highly filamentary structure develops owing to efficient fine-structure line cooling. In this case, the mass supply to the massive stars is limited by the local gas reservoir and the mass is shared among the stars, leading to a Chabrier-like IMF. We conclude that cooling at the scales of the turbulent motion promotes the development of the filamentary structure and works as an important factor leading to the present-day IMF.

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Section: Introductionmentioning

confidence: 99%

Transition of the initial mass function in the metal-poor environments

Chon,

Omukai,

Schneider

2021

Preprint

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“…Another scenario predicts the formation of seed black holes from very compact nuclear star clusters, which may form at redshifts of ∼10−15, after some metal enrichment has occurred so that metal line-cooling becomes effective, and in the presence of A&A 572, A22 (2014) trace amounts of dust (Schneider et al 2003;Portegies Zwart et al 2004;Schneider et al 2012a,b;Omukai et al 2005;Omukai 2012;Clark et al 2008;Klessen et al 2012;Dopcke et al 2011Dopcke et al , 2013Safranek-Shrader et al 2014;Bovino et al 2014a). In such a cluster, stellar collisions can occur in a runaway fashion and lead to the formation of a very massive star, finally resulting in a seed black hole with a mass up to ∼3000 M (Begelman & Rees 1978;Devecchi & Volonteri 2009;Devecchi et al 2010Devecchi et al , 2012Lupi et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Effects of turbulence and rotation on protostar formation as a precursor of massive black holes

Borm

Bovino

Latif

et al. 2014

A&A

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Context. The seeds of the first supermassive black holes may have resulted from the direct collapse of hot primordial gas in 10 4 K haloes, forming a supermassive or quasi-star as an intermediate stage.Aims. We explore the formation of a protostar resulting from the collapse of primordial gas in the presence of a strong Lyman-Werner radiation background. Particularly, we investigate the impact of turbulence and rotation on the fragmentation behaviour of the gas cloud. We accomplish this goal by varying the initial turbulent and rotational velocities. Methods. We performed 3D adaptive mesh refinement simulations with a resolution of 64 cells per Jeans length using the ENZO code, simulating the formation of a protostar up to unprecedentedly high central densities of 10 21 cm −3 and spatial scales of a few solar radii. To achieve this goal, we employed the KROME package to improve modelling of the chemical and thermal processes. Results. We find that the physical properties of the simulated gas clouds become similar on small scales, irrespective of the initial amount of turbulence and rotation. After the highest level of refinement was reached, the simulations have been evolved for an additional ∼5 freefall times. A single bound clump with a radius of 2 × 10 −2 AU and a mass of ∼7 × 10 −2 M is formed at the end of each simulation, marking the onset of protostar formation. No strong fragmentation is observed by the end of the simulations, regardless of the initial amount of turbulence or rotation, and high accretion rates of a few solar masses per year are found. Conclusions. Given such high accretion rates, a quasi-star of 10 5 M is expected to form within 10 5 years.

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“…Frebel et al 2010) suggest that at the metallicity (𝑍 crit ) at which the metal cooling function dominates over the molecular one, the modalities of SF transition from Population III SF regime to the standard Population II-I regime. Different studies suggest 𝑍 crit varies from ∼10 −6 𝑍 (Schneider et al 2006) to ∼10 −3 𝑍 (Bromm & Loeb 2003;Bovino et al 2014). For this analysis we adopt the latter as our metallicity threshold.…”

Section: Star Formation Schemementioning

confidence: 99%

Modelling H$_2$ and its effects on star formation using a joint implementation of GADGET-3 and KROME

Sillero,

Tissera,

Lambas

et al. 2021

Preprint

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We present P-GADGET3-K, an updated version of GADGET3, that incorporates the chemistry package KROME. P-GADGET3-K follows the hydrodynamical and chemical evolution of cosmic structures, incorporating the chemistry and cooling of H 2 and metal cooling in non-equilibrium. We performed different runs of the same ICs to assess the impact of various physical parameters and prescriptions, namely gas metallicity, molecular hydrogen formation on dust, star formation recipes including or not H 2 dependence, and the effects of numerical resolution. We find that the characteristics of the simulated systems, both globally and at kpc-scales, are in good agreement with several observable properties of molecular gas in star-forming galaxies. The surface density profiles of SFR and H 2 are found to vary with the clumping factor and resolution. In agreement with previous results, the chemical enrichment of the gas component is found to be a key ingredient to model the formation and distribution of H 2 as a function of gas density and temperature. A SF algorithm that takes into account the H 2 fraction together with a treatment for the local stellar radiation field improves the agreement with observed H 2 abundances over a wide range of gas densities and with the molecular Kennicutt-Schmidt law, implying a more realistic modelling of the star formation process.

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Formation of Carbon-Enhanced Metal-Poor Stars in the Presence of Far-Ultraviolet Radiation

Cited by 28 publications

References 52 publications

Transition of the initial mass function in the metal-poor environments

Transition of the initial mass function in the metal-poor environments

Effects of turbulence and rotation on protostar formation as a precursor of massive black holes

Modelling H$_2$ and its effects on star formation using a joint implementation of GADGET-3 and KROME

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