The cooling of shock-compressed primordial gas

By Jarrett L. Johnson, Volker Bromm. 2005

139 citations recorded by the source corpus.

We find that at redshifts z? 10, HD line cooling allows strongly shocked primordial gas to cool to the temperature of the cosmic microwave background (CMB). This temperature is the minimum value attainable via radiative cooling. Provided that the abundance of HD, normalized to the total number density, exceeds a critical level of ∼10 -8 , the CMB temperature floor is reached in a time which is short in comparison to the Hubble time. We estimate the characteristic masses of stars formed out of shocked primordial gas in the wake of the first supernovae, and resulting from the virialization of dark matter haloes during hierarchical structure formation to be ∼ 10 M ⊙ . In addition, we show that cooling by HD enables the primordial gas in relic H II regions to cool to temperatures considerably lower than those reached via H 2 cooling alone. We confirm that HD cooling is unimportant in cases where the primordial gas does not go through an ionized phase, as in the formation process of the very first stars in z? 20 minihaloes of mass ∼10 6 M ⊙ .

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/31f975661eb12b092d87ad44ce72b3aa535c3cfd

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

Population III stars: hidden or disappeared? (2007, background): “…Machacek, Bryan, Abel 2003; Omukai & Yoshii 2003; Yoshida et al. 2003; Susa & Umemura 2006), HD chemistry (Nagakura & Omukai 2005; Greif & Bromm 2006; Johnson & Bromm 2006; Yoshida et al. 2007) and radiative transfer (Ciardi, Ferrara & Abel 2000; Ricotti, Gnedin & Shull 2001; Kitayama et al. 2001).”
The first stars: formation of binaries and small multiple systems (2009, methodology): “We use the same chemical network as used in Johnson & Bromm (2006) and include the same cooling terms.”
The first galaxies : assembly, cooling and the onset of turbulence (2008, methodology): “This latter mode had previously been termed Pop II.5 (Mackey et al. 2003; Greif & Bromm 2006; Johnson & Bromm 2006).”
Two populations of metal-free stars in the early Universe (2006, background): “By reaching the CMB limit, these haloes produce stars with typical masses & 10 M⊙, about an order of magnitude less than is the case for Pop III (Johnson & Bromm 2006a).”
Uncertainties in H2 and HD chemistry and cooling and their role in early structure formation (2008, methodology): “…an initially ionized state, enough HD forms to cool the gas down to temperatures close to the temperature of the cosmic microwave background (CMB) (Nakamura & Umemura 2002; Nagakura & Omukai 2005; Johnson & Bromm 2006; Shchekinov & Vasiliev 2006; Johnson, Greif & Bromm 2007; Yoshida et al. 2007).”
Two Regimes of Turbulent Fragmentation and the Stellar Initial Mass Function from Primordial to Present-Day Star Formation (2007, background): “…earliest turbulent conditions are found within halos of approximately 108 M , cooled to the background temperature by nonequilibrium formation of HD (Johnson & Bromm 2006), approximate values of mean density, temperature, and column density are n0 ¼ 1 cm 3, T0 ¼ 43 K, and N0 ¼ 1021 cm 2, giving…”
Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “In particular, whereas cooling in the first phase of star formation was provided by H2, in this second phase cooling would be driven by HD leading to lower gas temperatures and smaller stellar masses (e.g., Johnson & Bromm 2006 and Greif & Bromm 2006).”
The birth of a galaxy – III. Propelling reionization with the faintest galaxies (2014, background): “In addition, some are directly affected by radiative and SN feedback from Pop III stars (Johnson & Bromm 2006; Wise & Abel 2008b; Greif et al. 2010; Maio et al. 2010; Wise et al. 2012b; Muratov et al. 2013; Pawlik, Milosavljević & Bromm 2013).”
Formation and evolution of primordial protostellar systems (2012, background): “A second, less important coolant is hydrogen deuteride (HD), which may become relevant at low temperatures due to its permanent dipole moment (Flower et al. 2000; Nakamura & Umemura 2002; Greif & Bromm 2006; Johnson & Bromm 2006; Ripamonti 2007; McGreer & Bryan 2008).”
Possible indirect confirmation of the existence of Pop III massive stars by gravitational wave (2014, background): “In the early Universe, the metal pollution is mainly driven by the Pop III SNe (e.g. Madau, Ferrara & Rees 2001).”
Fragmentation of star-forming clouds enriched with the first dust (2006, background): “…cooling triggered in relic H II regions around very massive stars after the death of the exciting star (Uehara & Inutsuka 2000; Nagakura & Omukai 2005; Johnson & Bromm 2006), shock compression induced by the first SN explosions (MacKey, Bromm & Hernquist 2003; Salvaterra, Ferrara & Schneider 2004).”
The First Stars (2012, background): “This allows the gas to cool further, in some cases reaching a temperature as low as the CMB temperature, TCMB (e.g. Nakamura & Umemura, 2002; Nagakura & Omukai, 2005; Johnson & Bromm, 2006; Yoshida et al., 2007; McGreer & Bryan, 2008; Kreckel et al., 2010).”
Probing the formation of the first low‐mass stars with stellar archaeology (2007, background): “…has been suggested that the temperature floor set by the cosmic microwave background, TCMB = 2.7K (1+z), may imply a redshift dependent characteristic mass of stars formed in the early Universe (e.g. Uehara& Inutsuka 2000; Clarke & Bromm 2003; Johnson & Bromm 2006; but see also Omukai et al. 2005).”
The aftermath of the first stars: massive black holes (2006, methodology): “…hydride (HD) molecules inside relic H II regions may provide an avenue for the formation of Population II.5 (Pop II.5) stars, with masses of the order of 10 M⊙ and formed from strongly ionized primordial gas (Mackey, Bromm & Hernquist 2003; Johnson & Bromm 2006; see also Nagakura & Omukai 2005).”
Early Cosmological H II/He III Regions and Their Impact on Second-Generation Star Formation (2006, background): “…a (suggested) possibility of the formation of low-mass metal-free stars in relic H ii regions (Nagakura & Omukai 2005; Vasiliev & Shchekinov 2005; Johnson & Bromm 2006), where enhanced molecular hydrogen production enables the gas temperature to be significantly lower than in a neutral…”