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ISM Masses and Star Formation at z = 1 to 6 ALMA Observations of Dust Continuum in 180 Galaxies in COSMOS

Scoville, N. and Sheth, K. and Aussel, H. and Vanden Bout, P. and Capak, P. and Bongiorno, A. and Casey, C. M. and Murchikova, L. and Koda, J. and Pope, A. and Toft, S. and Ivison, R. and Sanders, D. and Manohar, S. and Lee, N. (2015) ISM Masses and Star Formation at z = 1 to 6 ALMA Observations of Dust Continuum in 180 Galaxies in COSMOS. . (Submitted)

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ALMA Cycle 2 observations of the long wavelength dust emission in 180 star-forming (SF) galaxies are used to investigate the evolution of ISM masses at z = 1 to 6.4. The ISM masses exhibit strong increases from z = 0 to < z > = 1.15 and further to < z > = 2.2 and 4.8, particularly amongst galaxies above the SF galaxy main sequence (MS). The galaxies with highest SFRs at < z > = 2.2 and 4.8 have gas masses 100 times that of the Milky Way and gas mass fractions reaching 50 to 80%, i.e. gas masses 1 – 4x their stellar masses. For the full sample of galaxies, we find a single, very simple SF law: SFR ∝ M^(0.9)_(ISM), i.e. a 'linear' dependence on the ISM mass { on and above the MS. Thus, the galaxies above the MS are converting their larger ISM masses into stars on a timescale similar to those on the MS. At z > 1, the entire population of star-forming galaxies has ~5 – 10x shorter gas depletion times (~ 0.2 Gyr) than galaxies at low redshift. These shorter depletion times are due to a different, dominant mode of SF in the early universe - dynamically driven by compressive, high dispersion gas motions and/or galaxy interactions. The dispersive gas motions are a natural consequence of the extraordinarily high gas accretion rates which must occur to maintain the prodigious SF.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Scoville, N.0000-0002-0438-3323
Sheth, K.0000-0002-5496-4118
Casey, C. M.0000-0002-0930-6466
Koda, J.0000-0002-8762-7863
Sanders, D.0000-0002-1233-9998
Lee, N.0000-0001-5500-1324
Additional Information:We thank Zara Scoville for proof reading the manuscript. This paper makes use of the following ALMA data: ADS/JAO.ALMA# 2013.1.00034.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Subject Keywords:cosmology: observations; galaxies: evolution; galaxies: ISM
Record Number:CaltechAUTHORS:20150715-154118222
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58899
Deposited By: Tony Diaz
Deposited On:16 Jul 2015 22:46
Last Modified:01 Nov 2017 18:53

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