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http://hdl.handle.net/20.500.12386/30297
Title: | On the Kennicutt-Schmidt scaling law of submillimetre galaxies | Authors: | Oskari Miettinen DELVECCHIO, IVAN Vernesa Smolčić Manuel Aravena Drew Brisbin Alexander Karim |
Issue Date: | 2017 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 602 | First Page: | L9 | Abstract: | The star formation rate per unit area correlates well with the gas surface density for different types of galaxies. However, this Kennicutt-Schmidt law has not yet been examined for a large, homogeneously selected sample of SMGs, which could provide useful SF implementation information for models of massive galaxy formation and evolution. We aim at determining the K-S law parameters for the first time for a well-selected, statistical sample of SMGs. We used ALMA to conduct a 0.2" resolution, 870 $\mu$m imaging survey of 40 SMGs in COSMOS, which were initially selected at 1.1 mm. We analysed a sample of 32/40 target SMGs, for which our new ALMA 870 $\mu$m 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. We divided our sample into equally large subsamples of main-sequence objects and starbursts, and found their K-S relations to be of the form $\Sigma_{\rm SFR} \propto \Sigma_{\rm gas}^{0.81\pm0.01}$ and $\Sigma_{\rm SFR} \propto \Sigma_{\rm gas}^{0.84\pm0.39}$, respectively. The slightly sub-linear K-S slopes we derived suggest that the SF efficiency is nearly constant across the $\Sigma_{\rm gas}$ range probed. Under the assumption of a Galactic CO-to-H$_2$ conversion factor 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%. The corresponding gas depletion times are $\sim480$ Myr and 370 Myr. On average, our SMGs have $\Sigma_{\rm gas}\gtrsim10^{3.9}$ M$_{\odot}$ 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 $\alpha_{\rm CO}$ values of SMGs are needed to further constrain their $\Sigma_{\rm gas}$ values. | URI: | http://hdl.handle.net/20.500.12386/30297 | URL: | https://www.aanda.org/articles/aa/full_html/2017/06/aa31157-17/aa31157-17.html http://arxiv.org/abs/1706.00589v1 |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201731157 | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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Miettinen_KS2017.pdf | pdf editoriale | 1.03 MB | Adobe PDF | View/Open |
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