10.1007/s11443-008-3003-4

doi:10.1007/s11443-008-3003-4

Cited by 4 publications

(2 citation statements)

References 19 publications

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“…The interstellar pressure of gas (Elmegreen & Parravano 1994;Blitz & Rosolowsky 2006) may also be a factor. However, we see higher interstellar pressure in M33 than in the MW (Kasparova & Zasov 2008), so given this hypothesis we would expect more massive clouds. We can therefore rule out the interstellar pres- sure as the main driver of this inefficient cloud formation.…”

Section: Power-law Fittingmentioning

confidence: 67%

A high-resolution, dust-selected molecular cloud catalogue of M33, the Triangulum Galaxy

Williams

Gear

Smith

2018

Monthly Notices of the Royal Astronomical Society

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We present a catalogue of Giant Molecular Clouds (GMCs) in M33, extracted from cold dust continuum emission. Our GMCs are identified by computing dendrograms. We measure the spatial distribution of these clouds, and characterise their dust properties. Combining these measured properties with CO(J =2-1) and 21cm Hi data, we calculate the gas-to-dust ratio (GDR) of these clouds, and from this compute a total cloud mass. In total, we find 165 GMCs with cloud masses in the range of 10 4 -10 7 M . We find that radially, log 10 (GDR) = −0.043(±0.038) R[kpc] + 1.88(±0.15), a much lower GDR than found in the Milky Way, and a correspondingly higher α CO factor. The mass function of these clouds follows a slope proportional to M −2.84 , steeper than many previous studies of GMCs in local galaxies, implying that M33 is poorer at forming massive clouds than other nearby spirals. Whilst we can rule out interstellar pressure as the major contributing factor, we are unable to disentangle the relative effects of metallicity and Hi velocity dispersion. We find a reasonably featureless number density profile with galactocentric radius, and weak correlations between galactocentric radius and dust temperature/mass. These clouds are reasonably consistent with Larson's scaling relationships, and many of our sources are co-spatial with earlier CO studies. Massive clouds are identified at large galactocentric radius, unlike in these earlier studies, perhaps indicating a population of CO-dark gas dominated clouds at these larger distances.

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Section: Power-law Fittingmentioning

confidence: 67%

A high-resolution, dust-selected molecular cloud catalogue of M33, the Triangulum Galaxy

Williams

Gear

Smith

2018

Monthly Notices of the Royal Astronomical Society

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“…The vertical distribution of diffuse, atomic gas in massive disc galaxies is commonly assumed to result from a state of hydrostatic equilibrium, in which the gravitational force due to the combined potential of dark matter, stars and gas balances the effective pressure of the gas, due to its combined turbulent and thermal velocity dispersion. Hydrostatic equilibrium is assumed in calculations of a wide range of galaxy properties, including the shape of the Milky Way's dark matter halo (Olling & Merrifield 2000), the mid-plane pressure in nearby galaxies (Elmegreen 1989(Elmegreen , 1993 and its connection to the ratio of molecular to atomic gas (Blitz & Rosolowsky 2004, 2006Kasparova & Zasov 2008;Yim et al 2011Yim et al , 2014, as well as the relationship between giant molecular cloud properties and the ambient pressure of gas at the galactic mid-plane (e.g. Field et al 2011;Hughes et al 2013;Schruba et al 2019;Sun et al 2020a;Jeffreson et al 2020).…”

Section: Introductionmentioning

confidence: 99%

On the scale height of the molecular gas disc in Milky Way-like galaxies

Jeffreson

Sun

Wilson

2022

Monthly Notices of the Royal Astronomical Society

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We study the relationship between the scale-height of the molecular gas disc and the turbulent velocity dispersion of the molecular interstellar medium within a simulation of a Milky Way-like galaxy in the moving-mesh code Arepo. We find that the vertical distribution of molecular gas can be described by a Gaussian function with a uniform scale-height of ∼50 pc. We investigate whether this scale-height is consistent with a state of hydrostatic balance between gravity and turbulent pressure. We find that the hydrostatic prediction using the total turbulent velocity dispersion (as one would measure from kpc-scale observations) gives an over-estimate of the true molecular disc scale-height. The hydrostatic prediction using the velocity dispersion between the centroids of discrete giant molecular clouds (cloud-cloud velocity dispersion) leads to more-accurate estimates. The velocity dispersion internal to molecular clouds is elevated by the locally-enhanced gravitational field. Our results suggest that observations of molecular gas need to reach the scale of individual molecular clouds in order to accurately determine the molecular disc scale-height.

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Vertical Equilibrium, Energetics, and Star Formation Rates in Magnetized Galactic Disks Regulated by Momentum Feedback From Supernovae

Kim¹,

Ostriker

2015

ApJ

120

127

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Recent hydrodynamic (HD) simulations have shown that galactic disks evolve to reach well-defined statistical equilibrium states. The star formation rate (SFR) selfregulates until energy injection by star formation feedback balances dissipation and cooling in the interstellar medium (ISM), and provides vertical pressure support to balance gravity. In this paper, we extend our previous models to allow for a range of initial magnetic field strengths and configurations, utilizing three-dimensional, magnetohydrodynamic (MHD) simulations. We show that a quasi-steady equilibrium state is established as rapidly for MHD as for HD models unless the initial magnetic field is very strong or very weak, which requires more time to reach saturation. Remarkably, models with initial magnetic energy varying by two orders of magnitude approach the same asymptotic state. In the fully saturated state of the fiducial model, the integrated energy proportions E turb : E th : δE mag : E mag are 0.35 : 0.39 : 0.15 : 0.11, while the proportions of midplane support P turb : P th : δΠ mag : Π mag are 0.49 : 0.18 : 0.18 : 0.15. Vertical profiles of total effective pressure satisfy vertical dynamical equilibrium with the total gas weight at all heights. We measure the "feedback yields" η c ≡ P c /Σ SFR (in suitable units) for each pressure component, finding that η turb ∼ 4 and η th ∼ 1 are the same for MHD as in previous HD simulations, and δη mag ∼ 1. These yields can be used to predict the equilibrium SFR for a local region in a galaxy based on its observed gas and stellar surface densities and velocity dispersions. As the ISM weight (or dynamical equilibrium pressure) is fixed, an increase in η from turbulent magnetic fields reduces the predicted Σ SFR by ∼ 25% relative to the HD case.

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10.1007/s11443-008-3003-4

Cited by 4 publications

References 19 publications

A high-resolution, dust-selected molecular cloud catalogue of M33, the Triangulum Galaxy

A high-resolution, dust-selected molecular cloud catalogue of M33, the Triangulum Galaxy

On the scale height of the molecular gas disc in Milky Way-like galaxies

Vertical Equilibrium, Energetics, and Star Formation Rates in Magnetized Galactic Disks Regulated by Momentum Feedback From Supernovae

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