SDSS-IV MaNGA: Modeling the spectral line-spread function to subpercent accuracy

David R. Law; Kyle B. Westfall; Matthew A. Bershady; Michele Cappellari; Renbin Yan; Francesco Belfiore; Dmitry Bizyaev; Joel R. Brownstein; Yanping Chen; Brian Cherinka; Niv Drory; Daniel Lazarz; Shravan Shetty

doi:10.3847/1538-3881/abcaa2

SDSS-IV MaNGA: Modeling the spectral line-spread function to subpercent accuracy

David R. Law
, Kyle B. Westfall
, Matthew A. Bershady
, Michele Cappellari
, Renbin Yan
, Francesco Belfiore
, Dmitry Bizyaev
, Joel R. Brownstein
, Yanping Chen
, Brian Cherinka
, Niv Drory
, Daniel Lazarz
, Shravan Shetty

Physics And Astronomy

Research output: Contribution to journal › Article › peer-review

85 Scopus citations

Abstract

The Sloan Digital Sky Survey IV Mapping Nearby Galaxies at APO (MaNGA) program has been operating from 2014 to 2020, and has now observed a sample of 9269 galaxies in the low redshift universe (z ∼ 0.05) with integral-field spectroscopy. With rest-optical (λλ0.36-1.0 μm) spectral resolution R ∼ 2000 the instrumental spectral line-spread function (LSF) typically has 1σ width of about 70 km s⁻¹, which poses a challenge for the study of the typically 20-30 km s⁻¹ velocity dispersion of the ionized gas in present-day disk galaxies. In this contribution, we present a major revision of the MaNGA data pipeline architecture, focusing particularly on a variety of factors impacting the effective LSF (e.g., under-sampling, spectral rectification, and data cube construction). Through comparison with external assessments of the MaNGA data provided by substantially higher-resolution R ∼ 10,000 instruments, we demonstrate that the revised MPL-10 pipeline measures the instrumental LSF sufficiently accurately (≤0.6% systematic, 2% random around the wavelength of Hα) that it enables reliable measurements of astrophysical velocity dispersions σ_Hα ∼ 20 km s⁻¹ for spaxels with emission lines detected at signal-to-noise ratio > 50. Velocity dispersions derived from [O II], Hβ, [O III], [N II], and [S II] are consistent with those derived from Hα to within about 2% at σ_Hα > 30 km s⁻¹. Although the impact of these changes to the estimated LSF will be minimal at velocity dispersions greater than about 100 km s⁻¹, scientific results from previous data releases that are based on dispersions far below the instrumental resolution should be reevaluated.

Original language	English
Article number	52
Journal	Astronomical Journal
Volume	161
Issue number	2
DOIs	https://doi.org/10.3847/1538-3881/abcaa2
State	Published - Jan 6 2021

Bibliographical note

Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.

Funding

Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. D.R.L. appreciates productive discussions with Jeb Bailey, and constructive suggestions by the anonymous referee. R.Y. and D.L. acknowledge support by NSF AST-1715898. M.A.B. acknowledges NSF Awards AST-1517006 and AST-1814682. We therefore conclude that the MaNGA data products provided with internal release MPL-10 are sufficiently well calibrated to allow scientific analysis of the ionized-gas velocity dispersions down to about 20 km s−1 with sufficient care and attention to detail. Previous public MaNGA data releases (DR13, DR14, DR15) exhibit few-percent systematic biases in the instrumental LSF however (see Figure 13) that will complicate efforts to perform such analyses. Updated MaNGA products will be released publicly in DR17. D.R.L. appreciates productive discussions with Jeb Bailey, and constructive suggestions by the anonymous referee. R.Y. and D.L. acknowledge support by NSF AST-1715898. M.A.B. acknowledges NSF Awards AST-1517006 and AST-1814682. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS website is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatário Nacional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.

Funders	Funder number
IPMU
Kavli Institute for the Physics and Mathematics of the Universe
MPIA Heidelberg
Max-Planck-Institut für extraterrestrische Physik (MPE)
New Mexico State University, New York University
Observatário Nacional
Universidad Nacional Autónoma de México, University of Arizona
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China	AST-1715898, AST-1517006, AST-1814682
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China
Alfred P Sloan Foundation
Yale University
American Institute of Physics
National Science Foundation Office of International Science and Engineering
Vanderbilt Digestive Diseases Research Center, Vanderbilt University Medical Center
Ohio Water Resources Center, Ohio State University
University of Wisconsin-Madison
University of Colorado Boulder
University of Utah Health
The George Washington University
The Johns Hopkins University
Mellon College of Science, Carnegie Mellon University
Notre Dame Integrated Imaging Facility, University of Notre Dame
The Pennsylvania State University
Virginia Agricultural Experiment Station, Virginia Polytechnic Institute and State University
University of Portsmouth
Oxford Martin School, University of Oxford
Maritime and Port Authority of Singapore
Ministério da Ciência, Tecnologia e Inovação
University of Tokyo
Leibniz-Institut für Astrophysik Potsdam
National Astronomical Observatories, Chinese Academy of Sciences
Max-Planck-Institut für Astrophysik
Max-Planck-Institut für Astronomie
Instituto de Astrofísica de Canarias

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-3881/abcaa2

Cite this

@article{8293b18848f9483eb3484724e95a2d2e,

title = "SDSS-IV MaNGA: Modeling the spectral line-spread function to subpercent accuracy",

abstract = "The Sloan Digital Sky Survey IV Mapping Nearby Galaxies at APO (MaNGA) program has been operating from 2014 to 2020, and has now observed a sample of 9269 galaxies in the low redshift universe (z ∼ 0.05) with integral-field spectroscopy. With rest-optical (λλ0.36-1.0 μm) spectral resolution R ∼ 2000 the instrumental spectral line-spread function (LSF) typically has 1σ width of about 70 km s−1, which poses a challenge for the study of the typically 20-30 km s−1 velocity dispersion of the ionized gas in present-day disk galaxies. In this contribution, we present a major revision of the MaNGA data pipeline architecture, focusing particularly on a variety of factors impacting the effective LSF (e.g., under-sampling, spectral rectification, and data cube construction). Through comparison with external assessments of the MaNGA data provided by substantially higher-resolution R ∼ 10,000 instruments, we demonstrate that the revised MPL-10 pipeline measures the instrumental LSF sufficiently accurately (≤0.6\% systematic, 2\% random around the wavelength of Hα) that it enables reliable measurements of astrophysical velocity dispersions σHα ∼ 20 km s−1 for spaxels with emission lines detected at signal-to-noise ratio > 50. Velocity dispersions derived from [O II], Hβ, [O III], [N II], and [S II] are consistent with those derived from Hα to within about 2\% at σHα > 30 km s−1. Although the impact of these changes to the estimated LSF will be minimal at velocity dispersions greater than about 100 km s−1, scientific results from previous data releases that are based on dispersions far below the instrumental resolution should be reevaluated.",

author = "Law, \{David R.\} and Westfall, \{Kyle B.\} and Bershady, \{Matthew A.\} and Michele Cappellari and Renbin Yan and Francesco Belfiore and Dmitry Bizyaev and Brownstein, \{Joel R.\} and Yanping Chen and Brian Cherinka and Niv Drory and Daniel Lazarz and Shravan Shetty",

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AU - Law, David R.

AU - Westfall, Kyle B.

AU - Bershady, Matthew A.

AU - Cappellari, Michele

AU - Yan, Renbin

AU - Belfiore, Francesco

AU - Bizyaev, Dmitry

AU - Brownstein, Joel R.

AU - Chen, Yanping

AU - Cherinka, Brian

AU - Drory, Niv

AU - Lazarz, Daniel

AU - Shetty, Shravan

PY - 2021/1/6

Y1 - 2021/1/6

N2 - The Sloan Digital Sky Survey IV Mapping Nearby Galaxies at APO (MaNGA) program has been operating from 2014 to 2020, and has now observed a sample of 9269 galaxies in the low redshift universe (z ∼ 0.05) with integral-field spectroscopy. With rest-optical (λλ0.36-1.0 μm) spectral resolution R ∼ 2000 the instrumental spectral line-spread function (LSF) typically has 1σ width of about 70 km s−1, which poses a challenge for the study of the typically 20-30 km s−1 velocity dispersion of the ionized gas in present-day disk galaxies. In this contribution, we present a major revision of the MaNGA data pipeline architecture, focusing particularly on a variety of factors impacting the effective LSF (e.g., under-sampling, spectral rectification, and data cube construction). Through comparison with external assessments of the MaNGA data provided by substantially higher-resolution R ∼ 10,000 instruments, we demonstrate that the revised MPL-10 pipeline measures the instrumental LSF sufficiently accurately (≤0.6% systematic, 2% random around the wavelength of Hα) that it enables reliable measurements of astrophysical velocity dispersions σHα ∼ 20 km s−1 for spaxels with emission lines detected at signal-to-noise ratio > 50. Velocity dispersions derived from [O II], Hβ, [O III], [N II], and [S II] are consistent with those derived from Hα to within about 2% at σHα > 30 km s−1. Although the impact of these changes to the estimated LSF will be minimal at velocity dispersions greater than about 100 km s−1, scientific results from previous data releases that are based on dispersions far below the instrumental resolution should be reevaluated.

AB - The Sloan Digital Sky Survey IV Mapping Nearby Galaxies at APO (MaNGA) program has been operating from 2014 to 2020, and has now observed a sample of 9269 galaxies in the low redshift universe (z ∼ 0.05) with integral-field spectroscopy. With rest-optical (λλ0.36-1.0 μm) spectral resolution R ∼ 2000 the instrumental spectral line-spread function (LSF) typically has 1σ width of about 70 km s−1, which poses a challenge for the study of the typically 20-30 km s−1 velocity dispersion of the ionized gas in present-day disk galaxies. In this contribution, we present a major revision of the MaNGA data pipeline architecture, focusing particularly on a variety of factors impacting the effective LSF (e.g., under-sampling, spectral rectification, and data cube construction). Through comparison with external assessments of the MaNGA data provided by substantially higher-resolution R ∼ 10,000 instruments, we demonstrate that the revised MPL-10 pipeline measures the instrumental LSF sufficiently accurately (≤0.6% systematic, 2% random around the wavelength of Hα) that it enables reliable measurements of astrophysical velocity dispersions σHα ∼ 20 km s−1 for spaxels with emission lines detected at signal-to-noise ratio > 50. Velocity dispersions derived from [O II], Hβ, [O III], [N II], and [S II] are consistent with those derived from Hα to within about 2% at σHα > 30 km s−1. Although the impact of these changes to the estimated LSF will be minimal at velocity dispersions greater than about 100 km s−1, scientific results from previous data releases that are based on dispersions far below the instrumental resolution should be reevaluated.

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JO - Astronomical Journal

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ER -

SDSS-IV MaNGA: Modeling the spectral line-spread function to subpercent accuracy

Abstract

Bibliographical note

Funding

ASJC Scopus subject areas

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