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Published May 10, 2018 | Published + Submitted
Journal Article Open

The DEIMOS 10K Spectroscopic Survey Catalog of the COSMOS Field


We present a catalog of 10,718 objects in the COSMOS field, observed through multi-slit spectroscopy with the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope in the wavelength range ~5500–9800 Å. The catalog contains 6617 objects with high-quality spectra (two or more spectral features), and 1798 objects with a single spectroscopic feature confirmed by the photometric redshift. For 2024 typically faint objects, we could not obtain reliable redshifts. The objects have been selected from a variety of input catalogs based on multi-wavelength observations in the field, and thus have a diverse selection function, which enables the study of the diversity in the galaxy population. The magnitude distribution of our objects is peaked at I_(AB) ~ 23 and K_(AB) ~ 21, with a secondary peak at K_(AB) ~ 24. We sample a broad redshift distribution in the range 0 < z < 6, with one peak at z ~ 1, and another one around z ~ 4. We have identified 13 redshift spikes at z > 0.65 with chance probabilities < 4 × 10^(−4), some of which are clearly related to protocluster structures of sizes >10 Mpc. An object-to-object comparison with a multitude of other spectroscopic samples in the same field shows that our DEIMOS sample is among the best in terms of fraction of spectroscopic failures and relative redshift accuracy. We have determined the fraction of spectroscopic blends to about 0.8% in our sample. This is likely a lower limit and at any rate well below the most pessimistic expectations. Interestingly, we find evidence for strong lensing of Lyα background emitters within the slits of 12 of our target galaxies, increasing their apparent density by about a factor of 4.

Additional Information

© 2018 The American Astronomical Society. Received 2017 December 27; revised 2018 March 12; accepted 2018 March 13; published 2018 May 9. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We would like to thank the anonymous referee for very useful feedback, which helped to improve the presentation significantly. Support for this work was provided in part by NASA through ADAP grant NNX16AF29G. A.J.B. acknowledges support from NASA ADAP grant NNX14AJ66G and NSF grant AST-1715145. We would also like to recognize the contributions from all of the members of the COSMOS Team who helped in obtaining and reducing the large amount of multi-wavelength data that are now publicly available through the NASA Infrared Science Archive (IRSA) at http://irsa.ipac.caltech.edu/Missions/cosmos.html. In particular, we would like to acknowledge the contribution of several colleagues who have provided interesting targets for the multislit masks throughout the years: H. Aussel, M. Brusa, M. Civano, E. Daddi, J. Donley, E. Le Floch, K. Jahnke, T. Nagao, C. Scarlata, J. Silverman, and V. Smolcic. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We thank the IfA graduate students Jason Chu and Travis Berger for observing some of our multi-slit masks with DEIMOS. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are extremely grateful to have the opportunity to conduct observations from this mountain. Facilities: Keck:2 - . Software: Dsimulator (http://www2.keck.hawaii.edu/inst/deimos/dsim.html), spec2d (Cooper et al. 2012a; Newman et al. 2013), SpecPro (Masters & Capak 2011).

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Published - Hasinger_2018_ApJ_858_77.pdf

Submitted - 1803.09251.pdf


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