Shaping the structure of a GMC with radiation and winds

Abstract

We study the effect of stellar feedback (photodissociation/ionization, radiation pressure and winds) on the evolution of a Giant Molecular Cloud (GMC), by means of a 3D radiative transfer, hydro-simulation implementing a complex chemical network featuring H2 formation and destruction. We track the formation of individual stars with mass M > 1 M⊙ with a stochastic recipe. Each star emits radiation according to its spectrum, sampled with 10 photon bins from near-infrared to extreme ultra-violet bands; winds are implemented by energy injection in the neighbouring cells. We run a simulation of a GMC with mass M = 105 M⊙, following the evolution of different gas phases. Thanks to the simultaneous inclusion of different stellar feedback mechanisms, we identify two stages in the cloud evolution: (1) radiation and winds carve ionized, low-density bubbles around massive stars, while FUV radiation dissociates most H2 in the cloud, apart from dense, self-shielded clumps; (2) rapid star formation (SFR≃ 0.1 M⊙ − 1) consumes molecular gas in the dense clumps, so that UV radiation escapes and ionizes the remaining HI gas in the GMC. H2 is exhausted in 1.6 Myr, yielding a final star formation efficiency of 36 per cent. The average intensity of FUV and ionizing fields increases almost steadily with time; by the end of the simulation (t = 2.5 Myr) we find 〈G0〉 ≃ 103 (in Habing units), and a ionization parameter 〈Uion〉 ≃ 102, respectively. The ionization field has also a more patchy distribution than the FUV one within the GMC. Throughout the evolution, the escape fraction of ionizing photons from the cloud is fion, esc ≲ 0.03.

A survey of high-$z$ galaxies: SERRA simulations

“…Finally, simulations of individual MCs shows that -depending on the metallicity, turbulence and the observed band -15% to 70% of the photons can escape from the cloud before it is disrupted (Decataldo et al 2020;Kimm et al 2021). If true, molecular clouds would contribute significantly to UV emission, at the same time reducing the FIR emission from our galaxies.…”

Radiation hydrodynamics simulations of massive star cluster formation in giant molecular clouds

“…In particular, turbulence motion in GMCs induces the high-density contrast and the star formation in a stochastic manner (Larson 1981). Recently, radiation hydrodynamics simulations have been performed to study star cluster formation and destruction of clouds (e.g., Vázquez-Semadeni et al 2010;Dale et al 2012Dale et al , 2013Howard et al 2017;Geen et al 2017;Gavagnin et al 2017;He et al 2019;Decataldo et al 2020;Grudić et al 2018Grudić et al , 2020Ali 2021;Fujii et al 2021). Kim et al (2018) showed that the photoionization feedback played a dominant role in the suppression of star formation.…”

Far and extreme UV radiation feedback in molecular clouds and its influence on the mass and size of star clusters

“…In these clouds, SNe occurs and evacuates the gas from the clouds (e.g., Geen et al 2016). Stellar wind pushes out surrounding gas (e.g., Dale et al 2014;Decataldo et al 2020;Geen et al 2021;Rosen et al 2021), and heats up the gas to ( 10 5 K) via the shock (e.g., Lancaster et al 2021a,b). Indeed, X-ray emission is observed from the region inside the expanding shell (Luisi et al 2021), which is likely to be induced by the stellar wind.…”

“…The EUV feedback finally disrupt a host cloud and quenches the star formation, resulting in the low star formation efficiencies (SFEs) (e.g., Matzner 2002;Krumholz & Matzner 2009;Fall et al 2010;Kim et al 2016;Inoguchi et al 2020). Recently, these processes have been investigated in detail by performing radiation hydrodynamics simulations (RHD) (e.g., Vázquez-Semadeni et al 2010;Dale et al 2012Dale et al , 2013Howard et al 2017;Geen et al 2017;Gavagnin et al 2017;Kim et al 2018;He et al 2019;Decataldo et al 2020;Grudić et al 2018Grudić et al , 2021González-Samaniego & Vazquez-Semadeni 2020;Bending et al 2020;Ali 2021;Fujii et al 2021). In cases with the clouds where the EUV feedback is dominant, the SFEs increase with initial surface densities of clouds (Σ) (e.g., Fall et al 2010;Kim et al 2018).…”