On the Kennicutt-Schmidt scaling law of submillimetre galaxies

Miettinen, Oscari and Delvecchio, I. and Smolčić, Vernesa and Aravena, M. and Brisbin, D. and Karim, A. (2017) On the Kennicutt-Schmidt scaling law of submillimetre galaxies. Astronomy and Astrophysics, 602. L9-7. ISSN 0004-6361

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Abstract

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 ΣSFR ∝Σgas0.81±0.01 and ΣSFR ∝Σgas0.84±0.39, respectively. Conclusions. The slightly sub-linear K-S slopes we derived suggest that the SF efficiency (SFE) is nearly constant across the Σgas range probed. Under the assumption of a Galactic CO-to-H2 conversion factor (αCO) 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 Σgas ≳ 103.9 M⊙ pc-2, which suggests that they are Eddington-limited. 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 αCO values of SMGs are needed to further constrain their Σgas values.

Item Type: Article
Keywords: galaxies, evolution – galaxies, formation – galaxies, starburst – galaxies, star formation – submillimeter, galaxies
Date: 15 June 2017
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © ESO 2017. This research was funded by the European Union’s Seventh Framework programme under grant agreement 337595 (ERC Starting Grant, “CoSMass”). M.A. acknowledges partial support from FONDE-CYT through grant 1140099. A.K. acknowledges support by the Collaborative Research Council 956, sub-project A1, funded by the Deutsche Forschungsgemeinschaft (DFG). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00478.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 08 Nov 2017 10:28
Last Modified: 08 Nov 2017 10:28
URI: http://digre.pmf.unizg.hr/id/eprint/5681

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