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A kpc-scale-resolved study of unobscured and obscured star formation activity in normal galaxies at z = 1.5 and 2.2 from ALMA and HiZELS

Cheng, Cheng; Ibar, Edo; Smail, Ian; Molina, Juan; Sobral, David; Escala, Andrés; Best, Philip; Cochrane, Rachel; Gillman, Steven; Swinbank, Mark; Ivison, R.J.; Huang, Jia-Sheng; Hughes, Thomas M.; Villard, Eric; Cirasuolo, Michele

A kpc-scale-resolved study of unobscured and obscured star formation activity in normal galaxies at z = 1.5 and 2.2 from ALMA and HiZELS Thumbnail


Authors

Cheng Cheng

Edo Ibar

Juan Molina

David Sobral

Andrés Escala

Philip Best

Rachel Cochrane

Steven Gillman

R.J. Ivison

Jia-Sheng Huang

Thomas M. Hughes

Eric Villard

Michele Cirasuolo



Abstract

We present Atacama Large Millimeter/Submillimeter Array (ALMA) continuum observations of a sample of nine star-forming galaxies at redshifts 1.47 and 2.23 selected from the High-z Emission Line Survey (HiZELS). Four galaxies in our sample are detected at high significance by ALMA at a resolution of 0′′.25 at rest-frame 355 μm. Together with the previously observed H α emission, from adaptive optics-assisted integral-field-unit spectroscopy (∼0′′.15 resolution), and F606W and F140W imaging from the Hubble Space Telescope (∼0′′.2 resolution), we study the star formation activity, stellar and dust mass in these high-redshift galaxies at ∼kpc-scale resolution. We find that ALMA detection rates are higher for more massive galaxies (M* > 1010.5 M⊙) and higher [N II]/H α ratios (>0.25, a proxy for gas-phase metallicity). The dust extends out to a radius of 8 kpc, with a smooth structure, even for those galaxies presenting clumpy H α morphologies. The half-light radii (Rdust) derived for the detected galaxies are of the order ∼4.5 kpc, more than twice the size of submillimetre-selected galaxies at a similar redshift. Our global star formation rate estimates – from far-infrared and extinction-corrected H α luminosities – are in good agreement. However, the different morphologies of the different phases of the interstellar medium suggest complex extinction properties of the high-redshift normal galaxies.

Citation

Cheng, C., Ibar, E., Smail, I., Molina, J., Sobral, D., Escala, A., …Cirasuolo, M. (2020). A kpc-scale-resolved study of unobscured and obscured star formation activity in normal galaxies at z = 1.5 and 2.2 from ALMA and HiZELS. Monthly Notices of the Royal Astronomical Society, 499(4), 5241-5256. https://doi.org/10.1093/mnras/staa3036

Journal Article Type Article
Acceptance Date Sep 28, 2020
Online Publication Date Oct 2, 2020
Publication Date 2020-12
Deposit Date May 5, 2021
Publicly Available Date Jun 29, 2021
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 499
Issue 4
Pages 5241-5256
DOI https://doi.org/10.1093/mnras/staa3036
Publisher URL https://ui.adsabs.harvard.edu/abs/2020MNRAS.499.5241C

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2020, The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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