ISM MASSES AND THE STAR FORMATION LAW AT Z = 1 TO 6: ALMA OBSERVATIONS OF DUST CONTINUUM IN 145 GALAXIES IN THE COSMOS SURVEY FIELD

By N. Scoville, K. Sheth, H. Aussel, P. V. Vanden Bout, P. Capak, A. Bongiorno, C. Casey, L. Murchikova, J. Koda, J. Álvarez-Márquez and 10 more. 2015

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ALMA Cycle 2 observations of long-wavelength dust emission in 145 star-forming galaxies are used to probe the evolution of the star-forming interstellar medium (ISM). We also develop a physical basis and empirical calibration (with 72 low-z and z ∼ 2 galaxies) for using the dust continuum as a quantitative probe of ISM masses. The galaxies with the highest star formation rates (SFRs) at ⟨ z ⟩ ?> = 2.2 and 4.4 have gas masses up to 100 times that of the Milky Way and gas mass fractions reaching 50%–80%, i.e., gas masses 1-4× their stellar masses. We find a single high-z star formation law: SFR = 35 M mol 0.89 × ( 1 + z ) z = 2 0.95 × ( sSFR ) MS 0.23 ?> M ⊙ ?> yr−1—an approximately linear dependence on the ISM mass and an increased star formation efficiency per unit gas mass at higher redshift. Galaxies above the main sequence (MS) have larger gas masses but are converting their ISM into stars on a timescale only slightly shorter than those on the MS; thus, these “starbursts” are largely the result of having greatly increased gas masses rather than an increased efficiency of converting gas to stars. At z > 1, the entire population of star-forming galaxies has ∼2–5 times shorter gas depletion times than low-z galaxies. These shorter depletion times indicate a different mode of star formation in the early universe—most likely dynamically driven by compressive, high-dispersion gas motions—a natural consequence of the high gas accretion rates.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/f283b4c336eba29cd425e19808f75c77ea3741f7

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Citations in the corpus

The SINS/zC-SINF Survey of z ∼ 2 Galaxy Kinematics: SINFONI Adaptive Optics–assisted Data and Kiloparsec-scale Emission-line Properties (2018, background): “This object has by far the largest nuclear Fbroad/Fnarrow ratio (∼ 3), such that narrower line emission that would trace star formation around the center is comparatively very weak (Förster Schreiber et al. 2014; Genzel et al. 2014a).”
An Extreme Protocluster of Luminous Dusty Starbursts in the Early Universe (2017, methodology): “…conversion from 12CO(6–5) to 12CO(1–0) luminosity and the conversion from 12CO(1–0) luminosity to molecular gas mass. Alternatively, we could use the rest-frame m870 m luminosity as a proxy for the molecular gas mass, following Scoville et al. (2016), Hughes et al. (2017), and Oteo et al. (2017c).”
A deep ALMA image of the Hubble Ultra Deep Field (2016, background): “…Hodge et al. 2013; Karim et al. 2013; Ouchi et al. 2013; Bussmann et al. 2015; Capak et al. 2015; Maiolino et al. 2015; Simpson et al. 2015a, 2015b; Scoville et al. 2016), including gravitationally lensed sources (e.g. Weiss et al. 2013; Watson et al. 2015; Béthermin et al. 2016; Knudsen et al.…”
Evolution of Interstellar Medium, Star Formation, and Accretion at High Redshift (2017, methodology): “(See the appendix in (Scoville et al. 2016) for a more extensive discussion.)”
The ALPINE-ALMA [CII] survey (2020, methodology): “Gas fractions at z > 4: Comparing Mdyn to reliable emissionline-corrected stellar masses from deep Spitzer imaging (Laigle et al. 2016; Faisst et al. 2019) and gas mass estimates from FIR measurements (e.g., Scoville et al. 2016) puts the first direct constraints on the gas fractions fgas at z > 4.”
PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions (2017, methodology): “In comparison, the other large survey of the molecular gas properties in high-z SFGs from 1mm ALMA dust photometry (Scoville et al. 2016, 2017) has <logδMS>=0.5-1 between z=1-3 and thus is even more strongly biased to above MS galaxies.”
The dust content of galaxies from z = 0 to z = 9 (2016, background): “…the decrease in dust mass can be explained by the observed and inferred decrease in the gas fraction of galaxies (e.g., Tacconi et al. 2010; Narayanan et al. 2012; Tacconi et al. 2013; Saintonge et al. 2013; Santini et al. 2014; Béthermin et al. 2015; Popping et al. 2015; Scoville et al. 2016).”
ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: THE INFRARED EXCESS OF UV-SELECTED z = 2–10 GALAXIES AS A FUNCTION OF UV-CONTINUUM SLOPE AND STELLAR MASS (2016, result): “For example, the typical flux measured by Scoville et al. (2016) for detected z ∼ 4.4 galaxies in their very high-mass (& 2 × 1010 M⊙) sample is ∼200µJy, which contrasts with the ∼35µJy seen in the 3 faintest z ∼ 2-3 galaxies tentatively detected here.”