The Star Formation Laws of Eddington-Limited Star-Forming Disks

Ballantyne, D. R.; Armour, J. N.; Indergaard, John

doi:10.1088/0004-637x/765/2/138

Cited by 7 publications

(5 citation statements)

References 65 publications

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“…Such high densities make the gaseous interstellar medium (ISM) highly optically thick even in the re-radiated IR, and the radiation pressure on dust grains makes the system become Eddington-limited (e.g. Ballantyne et al 2013;Thompson & Krumholz 2016, and references therein). Interestingly, the K-S slope for the radiation-pressure-supported, Eddington-limited disk is expected to be unity (the stellar radiative flux F ⋆ ∝ Σ SFR , and the Eddington flux F Edd ∝ Σ gas ; Thompson et al 2005;Ostriker & Shetty 2011), which is broadly consistent with our results, particularly for starburst SMGs for which the K-S slope is consistent with unity within ∼ 0.4σ.…”

Section: Data Analysis Results and Discussionmentioning

confidence: 99%

On the Kennicutt-Schmidt scaling law of submillimetre galaxies

Miettinen

Delvecchio

Smolčić

et al. 2017

A&A

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Context. The star formation rate (SFR) per unit area correlates well with the gas surface density for different types of galaxies. However, this Kennicutt-Schmidt (K-S) law has not yet been examined for a large, homogeneously selected sample of submillimetre galaxies (SMGs), which could provide useful SF implementation information for models of massive galaxy formation and evolution. Aims. We aim at determining the K-S law parameters for the first time for a well-selected, statistical sample of SMGs. Methods. We used the Atacama Large Millimetre/submillimetre Array (ALMA) to conduct a high resolution (0 . 2), 870 µm continuum imaging survey of 40 SMGs, which were initially selected at 1.1 mm in the COSMOS field. We analysed a sample of 32 out of the 40 target SMGs, for which our new ALMA 870 µm data provide information about the spatial extent of dust emission, and all of which have dust-obscured SFR and dust-based gas mass estimates available from our previous study. Results. We divided our sample into equally large subsamples of main-sequence (MS) objects and starbursts (factor of >3 above the MS), and found their K-S relations to be of the form Σ SFR ∝ Σ 0.81±0.01 gas and Σ SFR ∝ Σ 0.84±0.39 gas , respectively. Conclusions. The slightly sub-linear K-S slopes we derived suggest that the SF efficiency (SFE) is nearly constant across the Σ gas range probed. Under the assumption of a Galactic CO-to-H 2 conversion factor (α CO ) for the whole sample, the MS SMGs obey a constant global SFE of about 21% per 100 Myr, while that of starburst SMGs is about 27% per 100 Myr. The corresponding gas depletion times are ∼480 Myr and 370 Myr. On average, our SMGs have Σ gas 10 3.9 M pc −2 , which suggests that they are Eddingtonlimited. This is consistent with the theoretical expectation of a linear K-S relation for such systems. However, size measurements of the CO-emitting regions of SMGs, and the α CO values of SMGs are needed to further constrain their Σ gas values.

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Section: Data Analysis Results and Discussionmentioning

confidence: 99%

On the Kennicutt-Schmidt scaling law of submillimetre galaxies

Miettinen

Delvecchio

Smolčić

et al. 2017

A&A

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“…Equation 21 predicts a smooth variation in X CO based on the physical conditions within a galaxy, rather than a bimodality. Obreschkow & Rawlings (2009) applied a Bayesian analysis to literature observational data, and recovered a similar relation between the conversion factor and CO surface brightness, while Ballantyne et al (2013) evolved analytic models for Eddington-limited starbursts to also find an inverse relationship between X CO and W CO . Similarly, Lagos et al (2012) utilize a semi-analytic model coupled with a photo-dissociation region (PDR) code to investigate the relationship between X CO , metallicity, UV intensity, and gas surface density.…”

Section: Deriving H 2 Gas Masses From High-redshift Galaxiesmentioning

confidence: 89%

Dusty star-forming galaxies at high redshift

2014

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Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10 13 L with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrared instrumentation in recent years, both spacebased and ground-based, has led to the detection of nearly a million DSFGs, yet our understanding of the underlying astrophysics that govern the start and end of the dusty starburst phase is still in nascent stage. This review is aimed at summarizing the current status of DSFG studies, focusing especially on the detailed characterization of the bestunderstood subset (submillimeter galaxies, who were summarized in the last review of this field over a decade ago, Blain et al. 2002), but also the selection and characterization of more recently discovered DSFG populations. We review DSFG population statistics, their physical properties including dust, gas and stellar contents, their environments, and current theoretical models related to the formation and evolution of these galaxies.

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“…Therefore, it would be interesting to study how the vertical distribution of SF affects the scale-height h and N H distribution of NSDs. The Kennicutt-Schmidt law (which is also called the star-formation law) relates starformation rate density Σ * to the surface gas density Σ gas by Σ gas ∝ Σ α * (Schmidt 1959;Kennicutt 1998;Kennicutt & Evans 2012), where α is expected to be ≈ 1 for radiation pressure dominated regions (Ballantyne et al 2013). Hence, we model the linear vertical distribution of Σ * on Σ using the prescription presented by Hubeny & Hubeny (1998).…”

Section: Vertical Distribution Of σ *mentioning

confidence: 99%

Modelling the vertical structure of nuclear starburst discs: a possible source of AGN obscuration at z ∼ 1

Gohil¹,

Ballantyne²

2017

Monthly Notices of the Royal Astronomical Society

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Nuclear starburst discs (NSDs) are star-forming discs that may be residing in the nuclear regions of active galaxies at intermediate redshifts. One dimensional (1D) analytical models developed by Thompson et al. (2005) show that these discs can possess an inflationary atmosphere when dust is sublimated on parsec scales. This make NSDs a viable source for AGN obscuration. We model the two dimensional (2D) structure of NSDs using an iterative method in order to compute the explicit vertical solutions for a given annulus. These solutions satisfy energy and hydrostatic balance, as well as the radiative transfer equation. In comparison to the 1D model, the 2D calculation predicts a less extensive expansion of the atmosphere by orders of magnitude at the parsec/sub-parsec scale, but the new scale-height h may still exceed the radial distance R for various physical conditions. A total of 192 NSD models are computed across the input parameter space in order to predict distributions of a line of sight column density N H . Assuming a random distribution of input parameters, the statistics yield 56% of Type 1, 23% of Compton-thin Type 2s (CN), and 21% of Compton-thick (CK) AGNs. Depending on a viewing angle (θ) of a particular NSD (fixed physical conditions), any central AGN can appear to be Type 1, CN, or CK which is consistent with the basic unification theory of AGNs. Our results show that log[N H (cm -2 )] ∈ [23,25.5] can be oriented at any θ from 0°to ≈80°due to the degeneracy in the input parameters.

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The Star Formation Laws of Eddington-Limited Star-Forming Disks

Cited by 7 publications

References 65 publications

On the Kennicutt-Schmidt scaling law of submillimetre galaxies

On the Kennicutt-Schmidt scaling law of submillimetre galaxies

Dusty star-forming galaxies at high redshift

Modelling the vertical structure of nuclear starburst discs: a possible source of AGN obscuration at z ∼ 1

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