Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 2017 | Published + Submitted
Journal Article Open

(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. III. Environments

Abstract

We investigate the environment of 23 submillimetre galaxies (SMGs) drawn from a signal-to-noise (S/N)-limited sample of SMGs originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey of a Cosmic Evolution Survey (COSMOS) subfield and then followed up with the Submillimetre Array and Plateau de Bure Interferometer at 890 μm and 1.3 mm, respectively. These SMGs already have well-defined multiwavelength counterparts and redshifts. We also analyse the environments of four COSMOS SMGs spectroscopically confirmed to lie at redshifts z_(spec) > 4.5, and one at z_(spec) = 2.49 resulting in a total SMG sample size of 28. We search for overdensities using the COSMOS photometric redshifts based on over 30 UV-NIR photometric measurements including the new UltraVISTA data release 2 and Spitzer/SPLASH data, and reaching an accuracy of σ_(Δz/ (1 + z)) = 0.0067 (0.0155) at z < 3.5 (>3.5). To identify overdensities we apply the Voronoi tessellation analysis, and estimate the redshift-space overdensity estimator δ_g as a function of distance from the SMG and/or overdensity centre. We test and validate our approach via simulations, X-ray detected groups or clusters, and spectroscopic verifications using VUDS and zCOSMOS catalogues which show that even with photometric redshifts in the COSMOS field we can efficiently retrieve overdensities out to z ≈ 5. Our results yield that 11 out of 23 (48%) JCMT/AzTEC 1.1 mm SMGs occupy overdense environments. Considering the entire JCMT/AzTEC 1.1 mm S/N ≥ 4 sample and taking the expected fraction of spurious detections into account, this means that 35–61% of the SMGs in the S/N-limited sample occupy overdense environments. We perform an X-ray stacking analysis in the 0.5–2 keV band using a 32″ aperture and our SMG positions, and find statistically significant detections. For our z < 2 subsample we find an average flux of (4.0 ± 0.8) × 10^(-16) erg s^(-1) cm^(-2) and a corresponding total mass of M_(200) = 2.8 × 10^(13)M⊙. The z > 2 subsample yields an average flux of (1.3 ± 0.5) × 10^(-16) erg s^(-1) cm^(-2) and a corresponding total massof M_(200) = 2 × 10^(13)M⊙. Our results suggest a higher occurrence of SMGs occupying overdense environments at z ≥ 3 than at z < 3. This may be understood if highly star-forming galaxies can only be formed in the highest peaks of the density field tracing the most massive dark matter haloes at early cosmic epochs, while at later times cosmic structure may have matured sufficiently that more modest overdensities correspond to sufficiently massive haloes to form SMGs.

Additional Information

© 2016 ESO. Received: 17 July 2015; Accepted: 4 April 2016; Published online 19 December 2016. This research was funded by the European Union's Seventh Framework programme under grant agreement 337595 (ERC Starting Grant, "CoSMass"). A.F. wishes to acknowledge Finnish Academy award, decision 266918. This work was supported in part by the National Science Foundation under Grant No. PHYS-1066293 and the hospitality of the Aspen Center for Physics. This work is partly based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and and 185.A-0791 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. This research has made use of NASA's Astrophysics Data System, and the NASA/IPAC Infrared Science Archive, which is operated by the JPL, California Institute of Technology, under contract with the NASA. We greatfully acknowledge the contributions of the entire COSMOS collaboration consisting of more than 100 scientists. More information on the COSMOS survey is available at http://www.astro.caltech.edu/~cosmos. We thank the VUDS team for making the data in the COSMOS field available prior to public release.

Attached Files

Published - aa26989-15.pdf

Submitted - 1604.01775.pdf

Files

1604.01775.pdf
Files (20.0 MB)
Name Size Download all
md5:c92cad872f6a9d30c3d201a261d28883
10.0 MB Preview Download
md5:2e3d9d71e6010a2907664872eca75b61
10.0 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023