Radiative cooling functions for primordial molecules

Coppola, Carla Maria; Lodi, Lorenzo; Tennyson, Jonathan

doi:10.1111/j.1365-2966.2011.18723.x

Cited by 59 publications

(73 citation statements)

References 41 publications

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“…The largest discrepancy for G ν between our calculations and the experiment is 2.47 cm −1 , which occurs for v = 22, while the largest difference for ΔG ν +1/2 is smaller at 1.85 cm −1 for v = 22. Some select transition energies are listed in Table 3 along with the corresponding experimental results of Dulick et al (1998) and the calculations of Coppola et al (2011). It can be seen that the current results are in excellent agreement with experiments, the largest discrepancy being 0.027 cm −1 .…”

Section: Resultssupporting

confidence: 68%

“…comm. ) and Coppola et al (2011), along with the low-density limit cooling function (n H ≤ 100 cm −3 ) due to H collisions (Galli & Palla 1998) (see the Appendix for a further discussion). All three LTE cooling functions are seen to be in excellent agreement over the considered temperature range.…”

Section: Resultsmentioning

confidence: 99%

“…In a variety of applications, it is useful to obtain the radiative cooling function in the high-density or local thermodynamic equilibrium (LTE) limit (see for example Coppola et al 2011). In LTE, the radiative cooling function only depends on the rovibrational energies, degeneracies, and transition probabilities.…”

Section: Rovibrational Eigenvalues Transition Probabilities and Relmentioning

confidence: 99%

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On the X¹Σ⁺rovibrational spectrum of lithium hydride

Shi

Stancil

Wang

2013

A&A

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The complete line list of rovibrational transitions of the X 1 Σ + state of LiH is computed. The line list includes all possible dipoleallowed transition energies and oscillator strengths that cover the transition energy range 3.27−19476 cm −1 . The line list was obtained using an accurate potential and dipole moment function constructed from available experimental and theoretical data. This paper discusses the agreement of the current calculations with previous theoretical and experimental results. We also provide the radiative cooling function in the high-density limit over a wide temperature range and compare them with previous results. A simulated collisionally-broadened LiH opacity relevant to cool dwarf stars is also presented.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Section: Rovibrational Eigenvalues Transition Probabilities and Relmentioning

confidence: 99%

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On the X¹Σ⁺rovibrational spectrum of lithium hydride

Shi

Stancil

Wang

2013

A&A

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“…Our chemical network includes collisional ionization, radiative recombination, photo-ionization and photodissociation processes, the formation of molecules and a multilevel model of atomic hydrogen. We found that the presence of a background flux photo-ionizes the gas and raises the gas temperature to ≥10 4 K. We found that for weak radiation fields (J 21 < 100), cooling due to H 2 decreases the temperature to at least 1000 K. For J 21 < 0.1, cooling by HD is important as well, leading to gas temperatures of ∼100 K. We note that the HD cooling function was recently revisited by Coppola et al (2011). However, they only find differences at high temperatures, where H 2 dominates the cooling.…”

Section: Discussionmentioning

confidence: 81%

Lyman alpha emission from the first galaxies: implications of UV backgrounds and the formation of molecules

Latif

Schleicher

Spaans

et al. 2011

A&A

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The Lyman alpha line is a robust tracer of high redshift galaxies. We present estimates of Lyman alpha emission from a protogalactic halo illuminated by UV background radiation fields with various intensities. For this purpose, we performed cosmological hydrodynamics simulations with the adaptive mesh refinement code FLASH, including a detailed network for primordial chemistry, comprising the formation of primordial molecules, a multi-level model for the hydrogen atom as well as the photo-ionization and photo-dissociation processes in a UV background. We find that the presence of a background radiation field J 21 excites the emission of Lyman alpha photons, increasing the Lyman α luminosity up to two orders of magnitude. For a halo of ∼10 10 M , we find that a maximum flux of 5 × 10 −15 erg cm −2 s −1 is obtained for J 21 × f esc = 0.1, where f esc is the escape fraction of the ionizing radiation. Depending on the environmental conditions, the flux may vary by three orders of magnitude. For J 21 × f esc > 0.1 the Lyman alpha luminosity decreases as the atomic hydrogen abundance becomes rather small. The fluxes derived here can be probed using Subaru and the upcoming James Webb Space Telescope. The emission of Lyman alpha photons is extended and comes from the envelope of the halo rather than its core. In the center of the halo, line trapping becomes effective above columns of 10 22 cm −2 and suppresses the emission of Lyman alpha. In addition, cooling by primordial molecules may decrease the gas temperature in the central region, which further reduces Lyman α emission. In the central core, H 2 is photo-dissociated for a background flux of J 21 ≥ 1000. For weaker radiation fields, i.e. J 21 < 0.1, H 2 and HD cooling are particularly strong in the center of the halo, leading to gas temperatures as low as ∼100 K. We also performed a parameter study with different escape fractions of ionizing photons and explored the relative role of ionizing and dissociating radiation. We find that Lyman alpha emission depends more on the strength of the ionizing background. For a constant ionizing background, the Lyman α flux increases at least by an order of magnitude for stronger photodissociation.

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“…Within the rate equations for the HD + isotope we have specifically included the spontaneous downward relaxation rates computed by Coppola et al [24]. Figure 7a compares the temporal evolutions of the first three levels of p-H into its j = 0 state, while the o-D + 2 system needs more than 6 s to reach the same dominant population of its ground rotational state.…”

Section: Computing the Relaxation Times From The Master Equationsmentioning

confidence: 99%

Rotationally inelastic cross sections, rates and cooling times for para-H2 +, ortho-D2 + and HD+ in cold helium gas

et al. 2017

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Abstract. In the present work we discuss the dynamical processes guiding the relaxation of the internal rotational energy of three diatomic ions, the para-H + 2 , the ortho-D + 2 and the HD + in collision with He atoms. The state-changing cross sections and rates for these Molecular Hydrogen Ions (MHIs) are obtained from Close Coupling quantum dynamics calculations and the decay times into their respective ground states are computed by further solving the relevant time-evolution equations. The comparison of the results from the three molecules allows us to obtain a detailed understanding, and a deep insight, on the relative efficiencies of the relaxation processes considered.

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Radiative cooling functions for primordial molecules

Cited by 59 publications

References 41 publications

On the X¹Σ⁺rovibrational spectrum of lithium hydride

On the X¹Σ⁺rovibrational spectrum of lithium hydride

Lyman alpha emission from the first galaxies: implications of UV backgrounds and the formation of molecules

Rotationally inelastic cross sections, rates and cooling times for para-H2 +, ortho-D2 + and HD+ in cold helium gas

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Radiative cooling functions for primordial molecules

Cited by 59 publications

References 41 publications

On the X1Σ+rovibrational spectrum of lithium hydride

On the X1Σ+rovibrational spectrum of lithium hydride

Lyman alpha emission from the first galaxies: implications of UV backgrounds and the formation of molecules

Rotationally inelastic cross sections, rates and cooling times for para-H2 +, ortho-D2 + and HD+ in cold helium gas

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On the X¹Σ⁺rovibrational spectrum of lithium hydride

On the X¹Σ⁺rovibrational spectrum of lithium hydride