Testing star formation laws on spatially resolved regions in a z ≈ 4.3 starburst galaxy

Sharda, Piyush; Cunha, Elisabete da; Federrath, Christoph; Wisnioski, Emily; Teodoro, Enrico M. Di; Tadaki, Ken-ichi; Yun, Min S.; Aretxaga, I.; Kawabe, Ryohei

doi:10.1093/mnras/stz1543

Cited by 25 publications

(16 citation statements)

References 65 publications

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“…For example, Sharda et al [324] used the high-resolution ALMA data on SDP.81, along with one of the individual resolved star-forming regions identified by Swinbank et al [309], to test various star formation models, arguing that a multi-freefall (turbulence) model [326] best fits the data. They found similar results in the more recent analysis of two star-forming clumps in the bright (unlensed) AzTEC-1 SMG at z ≃ 4.3 [323], suggesting that the high SFR in high-redshift starbursts is sustained by an interplay between gravity and turbulence. Meanwhile, Dessauges-Zavadsky et al [321] used 30 pc ALMA mapping of the CO(4-3) emission in the z = 1.036 'Cosmic Snake' to identify 17 molecular clouds in this Milky Way progenitor.…”

Section: Kpc-and Pc-scale Studiessupporting

confidence: 77%

“…A handful of such studies have been done in very bright and/or lensed galaxies using other radio/(sub-)millimetre facilities [49,51,283,[315][316][317][318][319], and ALMA observations of lensed sources have pushed these studies further (e.g. [320][321][322][323][324][325]), in some cases to individual star-forming 'clumps'. For example, Sharda et al [324] used the high-resolution ALMA data on SDP.81, along with one of the individual resolved star-forming regions identified by Swinbank et al [309], to test various star formation models, arguing that a multi-freefall (turbulence) model [326] best fits the data.…”

Section: Kpc-and Pc-scale Studiesmentioning

confidence: 99%

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High-redshift star formation in the Atacama large millimetre/submillimetre array era

2020

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The Atacama Large Millimetre/submillimetre Array (ALMA) is currently in the process of transforming our view of star-forming galaxies in the distant ( z ≳ 1 ) universe. Before ALMA, most of what we knew about dust-obscured star formation in distant galaxies was limited to the brightest submillimetre sources—the so-called submillimetre galaxies (SMGs)—and even the information on those sources was sparse, with resolved (i.e. sub-galactic) observations of the obscured star formation and gas reservoirs typically restricted to the most extreme and/or strongly lensed sources. Starting with the beginning of early science operations in 2011, the last 9 years of ALMA observations have ushered in a new era for studies of high-redshift star formation. With its long baselines, ALMA has allowed observations of distant dust-obscured star formation with angular resolutions comparable to—or even far surpassing—the best current optical telescopes. With its bandwidth and frequency coverage, it has provided an unprecedented look at the associated molecular and atomic gas in these distant galaxies through targeted follow-up and serendipitous detections/blind line scans. Finally, with its leap in sensitivity compared to previous (sub-)millimetre arrays, it has enabled the detection of these powerful dust/gas tracers much further down the luminosity function through both statistical studies of colour/mass-selected galaxy populations and dedicated deep fields. We review the main advances ALMA has helped bring about in our understanding of the dust and gas properties of high-redshift ( z ≳ 1 ) star-forming galaxies during these first 9 years of its science operations, and we highlight the interesting questions that may be answered by ALMA in the years to come.

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Section: Kpc-and Pc-scale Studiessupporting

confidence: 77%

Section: Kpc-and Pc-scale Studiesmentioning

confidence: 99%

High-redshift star formation in the Atacama large millimetre/submillimetre array era

2020

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“…For the rest of this paper, we also include, if not otherwise stated, three non-lensed and one lensed DSFGs in our sample (see Table 7). These sources have 4 𝑧 5 and have accurate beam-smearing corrected [CII] kinematic measurements (Sharda et al 2019;Fraternali et al 2020;Rizzo et al 2020).…”

Section: Discussionmentioning

confidence: 99%

Dynamical properties of z $\sim 4.5$ dusty star-forming galaxies and their connection with local early type galaxies

Rizzo,

Vegetti,

Fraternali

et al. 2021

Preprint

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There is a large consensus that gas in high-𝑧 galaxies is highly turbulent, because of a combination of stellar feedback processes and gravitational instabilities driven by mergers and gas accretion. In this paper, we present the analysis of a sample of five Dusty Star Forming Galaxies (DSFGs) at 4 𝑧 5. Taking advantage of the magnifying power of strong gravitational lensing, we quantified their kinematic and dynamical properties from ALMA observations of their [CII] emission line. We combined the dynamical measurements obtained for these galaxies with those obtained from previous studies to build the largest sample of 𝑧 ∼ 4.5 galaxies with high-quality data and sub-kpc spatial resolutions, so far. We found that all galaxies in the sample are dynamically cold, with rotation-to-random motion ratios, 𝑉/𝜎, between 7 to 15. The relation between their velocity dispersions and their star-formation rates indicates that stellar feedback is sufficient to sustain the turbulence within these galaxies and no further mechanisms are needed. In addition, we performed a rotation curve decomposition to infer the relative contribution of the baryonic (gas, stars) and dark matter components to the total gravitational potentials. This analysis allowed us to compare the structural properties of the studied DSFGs with those of their descendants, the local early type galaxies. In particular, we found that five out of six galaxies of the sample show the dynamical signature of a bulge, indicating that the spheroidal component is already in place at 𝑧 ∼ 4.5.

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“…Systematic motions such as large-scale rotation and shear can often be seen in the velocity (1st-moment) maps of molecular clouds (Federrath et al 2016;Sharda et al 2018Sharda et al , 2019Menon et al 2021). However, such large-scale motions should not be considered turbulent motions, at least not on the integral scale (diameter) of the cloud itself.…”

Section: First-moment Mapsmentioning

confidence: 99%

“…Rotational and shearing motions appear in the 1st-moment map of a cloud as a gradient, unless the LOS is along the rotation axis (Myers & Benson 1983;Goldsmith & Arquilla 1985). This gradient can be fit to, and subtracted from, the velocity map of the cloud to isolate the turbulent motions (Federrath et al 2016;Sharda et al 2018Sharda et al , 2019Menon et al 2021). The standard deviation of the resulting velocity map can then be used as a measurement of turbulence.…”

Section: Introductionmentioning

confidence: 99%

A new method for measuring the 3D turbulent velocity dispersion of molecular clouds

Stewart,

Federrath

2021

Preprint

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The structure and star formation activity of a molecular cloud are fundamentally linked to its internal turbulence. However, accurately measuring the turbulent velocity dispersion is challenging due to projection effects and observational limitations, such as telescope resolution, particularly for clouds that include non-turbulent motions, such as large-scale rotation. Here we develop a new method to recover the three-dimensional (3D) turbulent velocity dispersion (𝜎 𝑣,3D ) from position-positionvelocity (PPV) data. We simulate a rotating, turbulent, collapsing molecular cloud and compare its intrinsic 𝜎 𝑣,3D with three different measures of the velocity dispersion accessible in PPV space: 1) the spatial mean of the 2nd-moment map, 𝜎 i , 2) the standard deviation of the gradient/rotation-corrected 1st-moment map, 𝜎 (c−grad) , and 3) a combination of 1) and 2), called the 'gradient-corrected parent velocity dispersion', 𝜎 (p−grad) = (𝜎 2 i + 𝜎 2 (c−grad) ) 1/2 . We show that the gradient correction is crucial in order to recover purely turbulent motions of the cloud, independent of the orientation of the cloud with respect to the line of sight (LOS). We find that with a suitable correction factor and appropriate filters applied to the moment maps, all three statistics can be used to recover 𝜎 𝑣,3D , with method 3 being the most robust and reliable. We determine the correction factor as a function of the telescope beam size for different levels of cloud rotation, and find that for a beam FWHM 𝑓 and cloud radius 𝑅, the 3D turbulent velocity dispersion can best be recovered from the gradient-corrected parent velocity dispersion via 𝜎 𝑣 ,3D = [(−0.29 ± 0.26) 𝑓 /𝑅 + 1.93 ± 0.15] 𝜎 (p−grad) for 𝑓 /𝑅 < 1, independent of the level of cloud rotation or LOS orientation.

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Testing star formation laws on spatially resolved regions in a z ≈ 4.3 starburst galaxy

Cited by 25 publications

References 65 publications

High-redshift star formation in the Atacama large millimetre/submillimetre array era

High-redshift star formation in the Atacama large millimetre/submillimetre array era

Dynamical properties of z $\sim 4.5$ dusty star-forming galaxies and their connection with local early type galaxies

A new method for measuring the 3D turbulent velocity dispersion of molecular clouds

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