THE DISRUPTION OF GIANT MOLECULAR CLOUDS BY RADIATION PRESSURE & THE EFFICIENCY OF STAR FORMATION IN GALAXIES

By N. Murray, E. Quataert, T. Thompson. 2009

341 citations recorded by the source corpus.

Star formation is slow in the sense that the gas consumption time is much longer than the dynamical time. It is also inefficient; star formation in local galaxies takes place in giant molecular clouds (GMCs), but the fraction of a GMC converted to stars is very small, ϵGMC ∼ 5%. In luminous starbursts, the GMC lifetime is shorter than the main-sequence lifetime of even the most massive stars, so that supernovae can play no role in GMC disruption. We investigate the disruption of GMCs across a wide range of galaxies from normal spirals to the densest starbursts; we take into account the effects of H ii gas pressure, shocked stellar winds, protostellar jets, and radiation pressure produced by the absorption and scattering of starlight on dust grains. In the Milky Way, a combination of three mechanisms—jets, H ii gas pressure, and radiation pressure—disrupts the clouds. In more rapidly star-forming galaxies such as “clump” galaxies at high-redshift, ultra-luminous infrared galaxies (ULIRGs), and submillimeter galaxies, radiation pressure dominates natal cloud disruption. We predict the presence of ∼10–20 clusters with masses ∼107 M☉ in local ULIRGs such as Arp 220 and a similar number of clusters with M* ∼ 108 M☉ in high redshift clump galaxies; submillimeter galaxies will have even more massive clusters. We find that ϵGMC = πGΣGMCc/(2(L/M*)) for GMCs that are optically thin to far-infrared radiation, where ΣGMC is the GMC gas surface density. The efficiency in optically thick systems continues to increase with ΣGMC, but more slowly, reaching ∼35% in the most luminous starbursts. The disruption of bubbles by radiation pressure stirs the interstellar medium (ISM) to velocities of ∼10 km  s−1 in normal galaxies and to ∼100 km  s−1 in ULIRGs like Arp 220, consistent with observations. Thus, radiation pressure may play a dominant dynamical role in the ISM of star-forming galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/ae91e824ea2988e130d1e58e09de36e051587f54

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. A. Dekel
4. R. Dav'e
5. E. Quataert
6. T. Naab
7. R. Somerville
8. Volker Springel

Citations in the corpus

• WHAT DRIVES THE EXPANSION OF GIANT H ii REGIONS?: A STUDY OF STELLAR FEEDBACK IN 30 DORADUS (2010, background): “Indeed, if NGC 2070 was more massive, the radiation pressure could even expel gas at high enough velocities to launch a galactic wind (Murray et al. 2010a).”
• THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES THE REST-FRAME FAR-INFRARED EMISSION OF SUB-MILLIMETER GALAXIES (2014, background): “Andrews & Thompson (2011) show via the balance of radiation pressure from star formation with self-gravitation, that the maximum star formation rate surface density, assuming optically thick dust emission (τ > 1) 18, and in the absence of nuclear heating via an active galactic nucleus (AGN), is SFRm”
• An origin for multiphase gas in galactic winds and haloes (2015, background): “…cold cloud acceleration have also been suggested, including momentum deposition by supernovae, the radiation pressure of starlight on dust grains (Murray et al. 2005, 2010, 2011; Hopkins et al. 2012; Zhang & Thompson 2012; Krumholz & Thompson 2013; Davis et al. 2014; Thompson & Krumholz 2014;…”
• A DIVERSITY OF PROGENITORS AND HISTORIES FOR ISOLATED SPIRAL GALAXIES (2012, background): “…dynamical friction (although it is debated if they survive the intense star formation they host and the associated feedback – Krumholz & Dekel 2010; Murray et al. 2010), where they participate in building the bulge, thus providing another channel for bulge formation at high redshift (Noguchi…”
• STAR FORMATION EFFICIENCIES AND LIFETIMES OF GIANT MOLECULAR CLOUDS IN THE MILKY WAY (2010, background): “We note that in almost all our sources,Frad> Fgas, as expected for such massive clusters (Murray et al. 2010).”
• Cool outflows in galaxies and their implications (2020, background): “This is determined by the opacity per unit gas mass, κ, which is proportional to the dust-to-gas ratio, and the luminosity-to-mass ratio of the stellar population (Murray et al. 2010; Skinner and Ostriker 2015).”
• Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, background): “Other works assume more significant trapping (Murray et al. 2010; Krumholz & Dekel 2010; Hopkins et al. 2012), which makes the assumed strength of the radiative stellar feedback lower than in other simulations.”
• Before the first supernova: combined effects of H II regions and winds on molecular clouds (2014, positive): “Murray et al. (2010) argue in a similar fashion and present models of W49 and G298.”
• EVIDENCE FOR UBIQUITOUS COLLIMATED GALACTIC-SCALE OUTFLOWS ALONG THE STAR-FORMING SEQUENCE AT z ∼ 0.5 (2013, background): “This pressure disrupts the gas and dust in the surrounding giant molecular clouds (GMCs) when the stellar mass in a given cluster approaches a critical fraction of the total associated GMC mass (Murray et al. 2010).”
• Radiative feedback and the low efficiency of galaxy formation in low-mass haloes at high redshift (2013, methodology): “The radiation from massive stars is an important source of pressure in dense, star-forming regions before supernova explosions (Murray et al. 2010; Hopkins et al. 2011; Agertz et al. 2013).”
• MAXIMALLY STAR-FORMING GALACTIC DISKS. I. STARBURST REGULATION VIA FEEDBACK-DRIVEN TURBULENCE (2011, background): “As pointed out by Murray et al. (2010), this implies that there is a minimum value of εGMC for the pressure associated with reprocessed radiation to disrupt the cloud; the shell can only become unbound if εGMC > ψ −1 ≡ εmin.”
• SHORT-LIVED STAR-FORMING GIANT CLUMPS IN COSMOLOGICAL SIMULATIONS OF z ≈ 2 DISKS (2010, background): “Conflicting theoretical claims have been made (Murray et al. 2010; Krumholz & Dekel 2010), while probing that question directly with observations is a difficult task.”
• Modeling UV Radiation Feedback from Massive Stars. II. Dispersal of Star-forming Giant Molecular Clouds by Photoionization and Radiation Pressure (2018, background): “…SFE and relative role of photoionization to radiation pressure are in qualitative agreement with the predictions of Kim et al. (2016), which adopted the idealizations of instantaneous star formation and spherical shell expansion (see also Fall et al. 2010; Murray et al. 2010; Rahner et al. 2017).”
• The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, background): “Other works assume more significant trapping (Murray et al. 2010; Krumholz & Dekel 2010; Hopkins et al. 2012), which makes the assumed strength of the radiative stellar feedback here lower than in other simulations.”