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The CASSOWARY spectroscopy survey: a new sample of gravitationally lensed galaxies in SDSS

Stark, Daniel P. and Auger, Matthew and Belokurov, Vasily and Jones, Tucker and Robertson, Brant and Ellis, Richard S. and Sand, David J. and Moiseev, Alexei and Eagle, Will and Myers, Thomas (2013) The CASSOWARY spectroscopy survey: a new sample of gravitationally lensed galaxies in SDSS. Monthly Notices of the Royal Astronomical Society, 436 (2). pp. 1040-1056. ISSN 0035-8711. doi:10.1093/mnras/stt1624.

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Bright gravitationally lensed galaxies provide our most detailed view of galaxies at high redshift. The very brightest (r < 21) systems enable high spatial and spectral resolution measurements, offering unique constraints on the outflow energetics, metallicity gradients and stellar populations in high-redshift galaxies. Yet as a result of the small number of ultrabright z ≃ 2 lensed systems with confirmed redshifts, most detailed spectroscopic studies have been limited in their scope. With the goal of increasing the number of bright lensed galaxies available for detailed follow-up, we have undertaken a spectroscopic campaign targeting wide separation (≳3 arcsec) galaxy–galaxy lens candidates within the Sloan Digital Sky Survey (SDSS). Building on the earlier efforts of our Cambridge and Sloan Survey Of Wide Arcs in Thesky survey, we target a large sample of candidate galaxy–galaxy lens systems in SDSS using a well-established search algorithm which identifies blue arc-like structures situated around luminous red galaxies. In this paper, we present a new redshift catalogue containing 29 lensed sources in SDSS confirmed through spectroscopic follow-up of candidate galaxy–galaxy lens systems. Included in this new sample are two of the brightest galaxies (r = 19.6 and 19.7) known at z ≃ 2, a low metallicity (12 + log (O/H) ≃ 8.0) extreme nebular line emitting galaxy at z = 1.43, and numerous systems for which detailed follow-up will be possible. The source redshifts span 0.9 < z < 2.5 (median redshift of 1.9), and their optical magnitudes are in the range 19.6 ≲ r ≲ 22.3. We present a brief source-by-source discussion of the spectroscopic properties extracted from our confirmatory spectra and discuss some initial science results. Preliminary lens modelling reveals average source magnifications of 5–10 times. With more than 50 gravitationally lensed z ≳ 1 galaxies now confirmed within SDSS, it will soon be possible for the first time to develop generalized conclusions from detailed spectroscopic studies of the brightest lensed systems at high redshift.

Item Type:Article
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URLURL TypeDescription Paper
Belokurov, Vasily0000-0002-0038-9584
Jones, Tucker0000-0001-5860-3419
Ellis, Richard S.0000-0001-7782-7071
Sand, David J.0000-0003-4102-380X
Additional Information:© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 August 23. Received 2013 August 23; in original form 2013 March 16. First published online: October 7, 2013. We thank the referee for a useful report which strengthened the paper. We thank Fuyan Bian, Zheng Cai, Linhua Jiang, Ian McGreer and Evan Schneider for conducting some of the MMT observations used in this paper. We thank Sirio Belli and Matthew Schenker for assistance with the Palomar observations and analysis. DPS acknowledges support from NASA through Hubble Fellowship grant no. HST-HF-51299.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS5-265555. BR is supported by Steward Observatory and the University of Arizona College of Science. AM is grateful for the financial support of the Dynasty’ Foundation. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. This paper also includes data gathered with the 6.5m Magellan Telescopes located at Las Campanas Observatory, Chile and is partly based on observations obtained with the 6m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The BTA observations were carried out with the financial support of the Ministry of Education and Science of Russian Federation (contracts no. 16.518.11.7073 and 14.518.11.7070).
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF-51299.01
Steward ObservatoryUNSPECIFIED
University of ArizonaUNSPECIFIED
Dynasty FoundationUNSPECIFIED
Ministry of Education and Science of Russian Federation16.518.11.7073
Ministry of Education and Science of Russian Federation14.518.11.7070
Subject Keywords: galaxies: evolution galaxies: formation galaxies: high-redshift cosmology: observations
Issue or Number:2
Record Number:CaltechAUTHORS:20140204-101604729
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Official Citation: Daniel P. Stark, Matthew Auger, Vasily Belokurov, Tucker Jones, Brant Robertson, Richard S. Ellis, David J. Sand, Alexei Moiseev, Will Eagle, and Thomas Myers The CASSOWARY spectroscopy survey: a new sample of gravitationally lensed galaxies in SDSS MNRAS (December 01, 2013) Vol. 436 1040-1056 first published online October 7, 2013 doi:10.1093/mnras/stt1624
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43641
Deposited By: Ruth Sustaita
Deposited On:04 Feb 2014 18:43
Last Modified:10 Nov 2021 16:40

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