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HST Grism-derived Forecasts for Future Galaxy Redshift Surveys

Bagley, Micaela B. and Scarlata, Claudia and Mehta, Vihang and Teplitz, Harry and Baronchelli, Ivano and Eisenstein, Daniel J. and Pozzetti, Lucia and Cimatti, Andrea and Rutkowski, Michael and Wang, Yun and Merson, Alexander (2020) HST Grism-derived Forecasts for Future Galaxy Redshift Surveys. Astrophysical Journal, 897 (1). Art. No. 98. ISSN 1538-4357. doi:10.3847/1538-4357/ab9828.

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The mutually complementary Euclid and Roman galaxy redshift surveys will use Hα- and [O III]-selected emission-line galaxies (ELGs) as tracers of the large-scale structure at 0.9 ≾ z ≾ 1.9 (Hα) and 1.5 ≾ z ≾ 2.7 ([O III]). It is essential to have a reliable and sufficiently precise knowledge of the expected numbers of Hα-emitting galaxies in the survey volume in order to optimize these redshift surveys for the study of dark energy. Additionally, these future samples of ELGs will, like all slitless spectroscopy surveys, be affected by a complex selection function that depends on galaxy size and luminosity, line equivalent width (EW), and redshift errors arising from the misidentification of single ELGs. Focusing on the specifics of the Euclid survey, we combine two slitless spectroscopic WFC3-IR data sets—3D-HST+AGHAST and the WFC3 Infrared Spectroscopic Parallel survey—to construct a Euclid-like sample that covers an area of 0.56 deg² and includes 1277 ELGs. We detect 1091 (~3270 deg⁻²) Hα+[N II]-emitting galaxies in the range 0.9 ≤ z ≤ 1.6 and 162 (~440 deg⁻²) [O III] λ5007 emitters over 1.5 ≤ z ≤ 2.3 with line fluxes ≥2 × 10⁻¹⁶ erg s⁻¹ cm⁻². The median of the Hα+[N II] EW distribution is ~250 Å, and the effective radii of the continuum and Hα+[N II] emission are correlated with a median of ~0.”38 and significant scatter (σ ~ 0.”2–0.”35). Finally, we explore the prevalence of redshift misidentification in future Euclid samples, finding potential contamination rates of ~14%–20% and ~6% down to 2 × 10⁻¹⁶ erg s⁻¹ cm−2 and 6 × 10⁻¹⁷ erg s⁻¹ cm⁻², respectively, although with increased wavelength coverage these percentages drop to nearly zero.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bagley, Micaela B.0000-0002-9921-9218
Scarlata, Claudia0000-0002-9136-8876
Mehta, Vihang0000-0001-7166-6035
Teplitz, Harry0000-0002-7064-5424
Baronchelli, Ivano0000-0003-0556-2929
Cimatti, Andrea0000-0002-4409-5633
Rutkowski, Michael0000-0003-3527-1428
Additional Information:© 2020 The American Astronomical Society. Received 2019 June 14; revised 2020 May 29; accepted 2020 May 30; published 2020 July 7. We thank the anonymous referee for a careful review and for helpful comments that improved this paper. We would also like to thank Karlen Shahinyan, Ben Sunnquist, Marc Rafelski, Y. Sofia Dai, and Melanie Beck for help with the visual inspection and identification of emission lines. We would also like to thank Ginevra Favole for her contributions to the WISP catalog completeness analysis and Hervé Aussel for helpful discussions regarding the Euclid Science Performance Verification efforts. M.B.B. would like to thank Francesco Valentino for his generosity in providing number counts and discussing his analysis. This research was partially supported by NASA ROSES grant 12-EUCLID12-0004. Y.W. was supported in part by NASA grant 15-WFIRST15-0008 Cosmology with the High Latitude Survey WFIRST Science Investigation Team. A.C. and L.P. acknowledge the support from the grants PRIN-MIUR 2015 and ASI n.2018-23-HH.0. Support for WISP (HST programs GO-11696, 12283, 12568, 12902, 13517, 13352, and 14178) was provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This work is partially based on observations taken by the 3D-HST Treasury Program (GO 12177 and 12328) with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Facility: HST (WFC3). - Software: Astropy (Astropy Collaboration et al. 2013), aXe (Kümmel et al. 2009), aXeSIM (Kümmel et al. 2007), NumPy (Oliphant et al. 2006; van der Walt et al. 2011), SciPy (Virtanen et al. 2020), Source Extractor (Bertin & Arnouts 1996), Galfit(Peng et al. 2010).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Ministero dell'Istruzione, dell'Université della Ricerca (MIUR)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)2018-23-HH.0
Space Telescope Science InstituteUNSPECIFIED
Subject Keywords:Emission line galaxies ; Redshift surveys ; Spectroscopy
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Emission line galaxies (459); Redshift surveys (1378); Spectroscopy (1558)
Record Number:CaltechAUTHORS:20200707-132402495
Persistent URL:
Official Citation:Micaela B. Bagley et al 2020 ApJ 897 98
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104258
Deposited By: Tony Diaz
Deposited On:07 Jul 2020 20:41
Last Modified:16 Nov 2021 18:30

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