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Title: Spatially resolved emission of a high-redshift DLA galaxy with the Keck/OSIRIS IFU

Abstract

We present the first Keck/OSIRIS infrared IFU observations of a high-redshift damped Lyα (DLA) galaxy detected in the line of sight to a background quasar. By utilizing the Laser Guide Star Adaptive Optics to reduce the quasar point-spread function to FWHM ∼ 0.''15, we were able to search for and map the foreground DLA emission free from the quasar contamination. We present maps of the Hα and [O III] λλ5007, 4959 emission of DLA 2222–0946 at a redshift of z ∼ 2.35. From the composite spectrum over the Hα emission region, we measure a star formation rate of 9.5 ± 1.0 M {sub ☉} yr{sup –1} and a dynamical mass of M {sub dyn} = 6.1 × 10{sup 9} M {sub ☉}. The average star formation rate surface density is (Σ{sub SFR}) = 0.55 M {sub ☉} yr{sup –1} kpc{sup –2}, with a central peak of 1.7 M {sub ☉} yr{sup –1} kpc{sup –2}. Using the standard Kennicutt-Schmidt relation, this corresponds to a gas mass surface density of Σ{sub gas} = 243 M {sub ☉} pc{sup –2}. Integrating over the size of the galaxy, we find a total gas mass of M {sub gas} = 4.2 × 10{sup 9} Mmore » {sub ☉}. We estimate the gas fraction of DLA 2222–0946 to be f {sub gas} ∼ 40%. We detect [N II] λ6583 emission at 3σ significance with a flux corresponding to a metallicity of 75% solar. Comparing this metallicity with that derived from the low-ion absorption gas ∼6 kpc away, ∼30% solar, indicates possible evidence for a metallicity gradient or enriched in/outflow of gas. Kinematically, both Hα and [O III] emission show relatively constant velocity fields over the central galactic region. While we detect some red and blueshifted clumps of emission, they do not correspond with rotational signatures that support an edge-on disk interpretation.« less

Authors:
 [1]
  1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI, 96822 (United States)
Publication Date:
OSTI Identifier:
22357185
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 785; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; COMPARATIVE EVALUATIONS; COSMOLOGY; DENSITY; EMISSION; GALAXIES; INFRARED RADIATION; LYMAN LINES; MASS; METALLICITY; QUASARS; RED SHIFT; SPECTRA; STARS; SURFACES; VELOCITY

Citation Formats

Jorgenson, Regina A., and Wolfe, Arthur M., E-mail: raj@ifa.hawaii.edu. Spatially resolved emission of a high-redshift DLA galaxy with the Keck/OSIRIS IFU. United States: N. p., 2014. Web. doi:10.1088/0004-637X/785/1/16.
Jorgenson, Regina A., & Wolfe, Arthur M., E-mail: raj@ifa.hawaii.edu. Spatially resolved emission of a high-redshift DLA galaxy with the Keck/OSIRIS IFU. United States. https://doi.org/10.1088/0004-637X/785/1/16
Jorgenson, Regina A., and Wolfe, Arthur M., E-mail: raj@ifa.hawaii.edu. 2014. "Spatially resolved emission of a high-redshift DLA galaxy with the Keck/OSIRIS IFU". United States. https://doi.org/10.1088/0004-637X/785/1/16.
@article{osti_22357185,
title = {Spatially resolved emission of a high-redshift DLA galaxy with the Keck/OSIRIS IFU},
author = {Jorgenson, Regina A. and Wolfe, Arthur M., E-mail: raj@ifa.hawaii.edu},
abstractNote = {We present the first Keck/OSIRIS infrared IFU observations of a high-redshift damped Lyα (DLA) galaxy detected in the line of sight to a background quasar. By utilizing the Laser Guide Star Adaptive Optics to reduce the quasar point-spread function to FWHM ∼ 0.''15, we were able to search for and map the foreground DLA emission free from the quasar contamination. We present maps of the Hα and [O III] λλ5007, 4959 emission of DLA 2222–0946 at a redshift of z ∼ 2.35. From the composite spectrum over the Hα emission region, we measure a star formation rate of 9.5 ± 1.0 M {sub ☉} yr{sup –1} and a dynamical mass of M {sub dyn} = 6.1 × 10{sup 9} M {sub ☉}. The average star formation rate surface density is (Σ{sub SFR}) = 0.55 M {sub ☉} yr{sup –1} kpc{sup –2}, with a central peak of 1.7 M {sub ☉} yr{sup –1} kpc{sup –2}. Using the standard Kennicutt-Schmidt relation, this corresponds to a gas mass surface density of Σ{sub gas} = 243 M {sub ☉} pc{sup –2}. Integrating over the size of the galaxy, we find a total gas mass of M {sub gas} = 4.2 × 10{sup 9} M {sub ☉}. We estimate the gas fraction of DLA 2222–0946 to be f {sub gas} ∼ 40%. We detect [N II] λ6583 emission at 3σ significance with a flux corresponding to a metallicity of 75% solar. Comparing this metallicity with that derived from the low-ion absorption gas ∼6 kpc away, ∼30% solar, indicates possible evidence for a metallicity gradient or enriched in/outflow of gas. Kinematically, both Hα and [O III] emission show relatively constant velocity fields over the central galactic region. While we detect some red and blueshifted clumps of emission, they do not correspond with rotational signatures that support an edge-on disk interpretation.},
doi = {10.1088/0004-637X/785/1/16},
url = {https://www.osti.gov/biblio/22357185}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 785,
place = {United States},
year = {Thu Apr 10 00:00:00 EDT 2014},
month = {Thu Apr 10 00:00:00 EDT 2014}
}