University of Leicester
Cooke_2018_ApJ_861_100.pdf (3.23 MB)

An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: Identifying Candidate z similar to 4.5 [C II] Emitters

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posted on 2019-07-25, 15:04 authored by EA Cooke, I Smail, AM Swinbank, SM Stach, FX An, B Gullberg, O Almaini, CJ Simpson, JL Wardlow, AW Blain, SC Chapman, C-C Chen, CJ Conselice, KEK Coppin, D Farrah, DT Maltby, MJ Michalowski, D Scott, JM Simpson, AP Thomson, P van der Werf
We report the results of a search for serendipitous [C ii] 157.74 μm emitters at z sime 4.4–4.7 using the Atacama Large Millimeter/submillimeter Array (ALMA). The search exploits the AS2UDS continuum survey, which covers ~50 arcmin2 of the sky toward 695 luminous (S 870 gsim 1 mJy) submillimeter galaxies (SMGs), selected from the SCUBA-2 Cosmology Legacy Survey 0.96 deg2 Ultra Deep Survey (UDS) field. We detect 10 candidate line emitters, with an expected false detection rate of 10%. All of these line emitters correspond to 870 μm continuum-detected sources in AS2UDS. The emission lines in two emitters appear to be high-J CO, but the remainder have multi-wavelength properties consistent with [C ii] from z sime 4.5 galaxies. Using our sample, we place a lower limit of $\gt 5\times {10}^{-6}\,{\mathrm{Mpc}}^{-3}$ on the space density of luminous (L IR sime 1013 ${L}_{\odot }$) SMGs at z = 4.40–4.66, suggesting $\geqslant 7$% of SMGs with ${S}_{870\mu {\rm{m}}}\gtrsim 1$ mJy lie at 4 < z < 5. From stacking the high-resolution (~0farcs15 full-width half maximum) ALMA 870 μm imaging, we show that the [C ii] line emission is more extended than the continuum dust emission, with an average effective radius for the [C ii] of ${r}_{{\rm{e}}}={1.7}_{-0.2}^{+0.1}$ kpc, compared to r e = 1.0 ± 0.1 kpc for the continuum (rest-frame 160 μm). By fitting the far-infrared photometry for these galaxies from 100 to 870 μm, we show that SMGs at z ~ 4.5 have a median dust temperature of T d = 55 ± 4 K. This is systematically warmer than 870 μm selected SMGs at z sime 2, which typically have temperatures around 35 K. These z sime 4.5 SMGs display a steeper trend in the luminosity-temperature plane than z ≤ 2 SMGs. We discuss the implications of this result in terms of the selection biases of high-redshift starbursts in far-infrared/submillimeter surveys.


E.A.C., B.G., and I.R.S. acknowledge support from the ERC Advanced Investigator Grant DUSTYGAL (321334) and STFC (ST/P000541/1). I.R.S. also acknowledges support from a Royal Society/Wolfson Merit Award. J.L.W. acknowledges an STFC Ernest Rutherford Fellowship. M.J.M. acknowledges the support of the National Science Centre, Poland through the POLONEZ grant 2015/19/P/ST9/04010; this project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 665778. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.01528.S, ADS/JAO.ALMA#2016.1.00434.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST 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.



Astrophysical Journal, 2018, 861:100

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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