The MOSDEF Survey: The First Direct Measurements of the Nebular Dust Attenuation Curve at High Redshift
Abstract
We use a sample of 532 star-forming galaxies at redshifts z ≃ 1.4–2.6 with deep rest-frame optical spectra from the MOSFIRE Deep Evolution Field (MOSDEF) survey to place the first constraints on the nebular attenuation curve at high redshift. Based on the first five low-order Balmer emission lines detected in the composite spectra of these galaxies (Hα through Hε), we derive a nebular attenuation curve that is similar in shape to that of the Galactic extinction curve, suggesting that the dust covering fraction and absorption/scattering properties along the lines of sight to massive stars at high redshift are similar to those of the average Milky Way sight line. The curve derived here implies nebular reddening values that are, on average, systematically larger than those derived for the stellar continuum. In the context of stellar population synthesis models that include the effects of stellar multiplicity, the difference in reddening of the nebular lines and stellar continuum may imply molecular cloud crossing timescales that are a factor of ≳ 3x longer than those inferred for local molecular clouds, star formation rates that are constant or increasing with time such that newly formed and dustier OB associations always dominate the ionizing flux, and/or that the dust responsible for reddening the nebular emission may be associated with nonmolecular (i.e., ionized and neutral) phases of the interstellar medium. Our analysis points to a variety of investigations of the nebular attenuation curve that will be enabled with the next generation of ground- and space-based facilities.
Additional Information
© 2020. The American Astronomical Society. Received 2020 July 4; revised 2020 August 27; accepted 2020 September 7; published 2020 October 20. Based on data 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 NASA and was made possible by the generous financial support of the W.M. Keck Foundation. We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171; archival grant AR-13907, provided by NASA through the Space Telescope Science Institute; and grant NNX16AF54G from the NASA ADAP program. We are grateful to the MOSFIRE instrument team for building this powerful instrument and to Marc Kassis at the Keck Observatory for his many valuable contributions to the execution of the MOSDEF survey. We also acknowledge the 3D-HST collaboration, who provided us with spectroscopic and photometric catalogs used to select MOSDEF targets and derive stellar population parameters. We also thank I. McLean, K. Kulas, and G. Mace for taking observations for the MOSDEF survey in 2013 May and June. We wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the observations presented herein would not have been possible.Attached Files
Published - Reddy_2020_ApJ_902_123.pdf
Accepted Version - 2009.10085.pdf
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Additional details
- Eprint ID
- 106196
- Resolver ID
- CaltechAUTHORS:20201021-160146951
- AST-1312780
- NSF
- AST-1312547
- NSF
- AST-1312764
- NSF
- AST-1313171
- NSF
- AR-13907
- NASA
- NNX16AF54G
- NASA
- NASA Hubble Fellowship
- W. M. Keck Foundation
- Created
-
2020-10-22Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department