Formation of HD molecules in merging dark matter haloes

Shchekinov, Yu. A.; Vasiliev, E. O.

doi:10.1111/j.1365-2966.2006.10117.x

Cited by 49 publications

(58 citation statements)

References 53 publications

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“…An additional effect of the merger could be that the shock-induced electron fraction enhances the cooling. This mechanism was initially proposed by Shchekinov & Vasiliev (2006) and Prieto et al (2014), and recently confirmed by a numerical simulation in the absence of radiative backgrounds (Bovino et al 2014).…”

Section: Cosmological Scenariomentioning

confidence: 66%

Initial mass function of intermediate-mass black hole seeds

Ferrara

Salvadori²,

Yue

et al. 2014

Monthly Notices of the Royal Astronomical Society

160

157

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We study the Initial Mass Function (IMF) and hosting halo properties of Intermediate Mass Black Holes (IMBH, 10 4−6 M ⊙ ) formed inside metal-free, UV illuminated atomic cooling haloes (virial temperature T vir 10 4 K) either via the direct collapse of the gas or via an intermediate Super Massive Star (SMS) stage. These IMBHs have been recently advocated as the seeds of the supermassive black holes observed at z ≈ 6. We achieve this goal in three steps: (a) we derive the gas accretion rate for a proto-SMS to undergo General Relativity instability and produce a direct collapse black hole (DCBH) or to enter the ZAMS and later collapse into a IMBH; (b) we use merger-tree simulations to select atomic cooling halos in which either a DCBH or SMS can form and grow, accounting for metal enrichment and major mergers that halt the growth of the proto-SMS by gas fragmentation. We derive the properties of the hosting haloes and the mass distribution of black holes at this stage, and dub it the "Birth Mass Function"; (c) we follow the further growth of the DCBH by accreting the leftover gas in the parent halo and compute the final IMBH mass. We consider two extreme cases in which minihalos (T vir < 10 4 K) can (fertile) or cannot (sterile) form stars and pollute their gas leading to a different IMBH IMF. In the (fiducial) fertile case the IMF is bimodal extending over a broad range of masses, M ≈ (0.5 − 20) × 10 5 M ⊙ , and the DCBH accretion phase lasts from 10 to 100 Myr. If minihalos are sterile, the IMF spans the narrower mass range M ≈ (1 − 2.8) × 10 6 M ⊙ , and the DCBH accretion phase is more extended (70 − 120 Myr). We conclude that a good seeding prescription is to populate halos (a) of mass 7.5 < log(M h /M ⊙ ) < 8, (b) in the redshift range 8 < z < 17, (c) with IMBH in the mass range 4.75 < (log M • /M ⊙ ) < 6.25.

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Section: Cosmological Scenariomentioning

confidence: 66%

Initial mass function of intermediate-mass black hole seeds

Ferrara

Salvadori²,

Yue

et al. 2014

Monthly Notices of the Royal Astronomical Society

160

157

View full text Add to dashboard Cite

show abstract

“…In this scenario, the merging of multiple dark matter haloes induces the formation of shockwaves in which HD formation is enhanced. Such merging often yields large mass haloes with M halo > 10 7 [(1 + z)/20] −2 M ⊙ (Shchekinov & Vasiliev 2006), whereas our HD-cooling clouds are found in lower mass haloes with ∼ 5 × 10 5 M ⊙ at z ∼ 10 − 16.…”

Section: Jeans Scale: Gravitationally Unstable Cloudsmentioning

confidence: 79%

“…fHD/fH 2 increases sharply in the density range 10 6 cm −3 < nH,cen < 10 7 cm −3 and eventually exceeds 10 −3 . We classify our 1540 samples of primordial clouds as one of three possible cases, depending on fHD/fH 2 during the collapse: H2-cooling cases (1186 cases), HD-cooling cases (151), and the intermediate cases (203), where the numbers 6 Another possible route for HD-cooling primordial starformation is suggested by some studies (Uehara & Inutsuka 2000;Shchekinov & Vasiliev 2006;Prieto et al 2012;Bovino et al 2014;Prieto et al 2014). In this scenario, the merging of multiple dark matter haloes induces the formation of shockwaves in which HD formation is enhanced.…”

Section: Jeans Scale: Gravitationally Unstable Cloudsmentioning

confidence: 99%

Primordial star formation under the influence of far ultraviolet radiation: 1540 cosmological haloes and the stellar mass distribution

Hirano

Hosokawa

Yoshida

et al. 2015

Monthly Notices of the Royal Astronomical Society

321

320

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We perform a large set of cosmological simulations of early structure formation and follow the formation and evolution of 1540 star-forming gas clouds to derive the mass distribution of primordial stars. The star formation in our cosmological simulations is characterized by two distinct populations, the so-called Population III.1 stars and primordial stars formed under the influence of far-ultraviolet (FUV) radiation (Population III.2 D stars). In this work, we determine the stellar masses by using the dependences on the physical properties of star-forming cloud and/or the external photodissociating intensity from nearby primordial stars, which are derived from the results of 2D radiation hydrodynamic simulations of protostellar feedback. The characteristic mass of the Pop III stars is found to be a few hundred solar masses at z ∼ 25, and it gradually shifts to lower masses with decreasing redshift. At high redshifts z > 20, about half of the star-forming gas clouds are exposed to intense FUV radiation and thus give birth to massive Pop III.2 D stars. However, the local FUV radiation by nearby Pop III stars becomes weaker at lower redshifts, when typical Pop III stars have smaller masses and the mean physical separation between the stars becomes large owing to cosmic expansion. Therefore, at z < 20, a large fraction of the primordial gas clouds host Pop III.1 stars. At z 15, the Pop III.1 stars are formed in relatively cool gas clouds due to efficient radiative cooling by H 2 and HD molecules; such stars have masses of a few ×10 M ⊙ . Since the stellar evolution and the final fate are determined by the stellar mass, Pop III stars formed at different epochs play different roles in the early Universe.

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“…HD cooling is also of great importance in situations where an increase in the fractional ionization of the gas has led to an increase in the H 2 fraction. In this situation, the gas often becomes cool enough for HD to dominate (see e.g., Nakamura & Umemura 2002;Nagakura & Omukai 2005;Johnson & Bromm 2006;Shchekinov & Vasiliev 2006). This scenario is discussed in more detail in §3.4 below.…”

Section: Are We Including All Of the Significant Coolants?mentioning

confidence: 99%

Open questions in the study of population III star formation

et al. 2008

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Abstract. The first stars were key drivers of early cosmic evolution. We review the main physical elements of the current consensus view, positing that the first stars were predominantly very massive. We continue with a discussion of important open questions that confront the standard model. Among them are uncertainties in the atomic and molecular physics of the hydrogen and helium gas, the multiplicity of stars that form in minihalos, and the possible existence of two separate modes of metal-free star formation.

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Formation of HD molecules in merging dark matter haloes

Cited by 49 publications

References 53 publications

Initial mass function of intermediate-mass black hole seeds

Initial mass function of intermediate-mass black hole seeds

Primordial star formation under the influence of far ultraviolet radiation: 1540 cosmological haloes and the stellar mass distribution

Open questions in the study of population III star formation

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