skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: DIRECT EVIDENCE OF COLD GAS IN DLA 0812+32B

Abstract

We present the first direct evidence for cold gas in a high redshift DLA galaxy. We measured several multiplets of weak neutral carbon (C I) transitions in order to perform a curve of growth analysis. A DELTA chi{sup 2} test constrains the best-fit Doppler parameter, b = 0.33{sup +0.05}{sub -0.04} km s{sup -1} and log N(C I) = 13.30 +- 0.2 cm{sup -2}. This Doppler parameter constrains the kinetic temperature of the gas to T <= 78 K (T <= 115 K, 2sigma). We used the associated C I fine structure lines to constrain the volume density of the gas, n(H I) approx40-200 cm{sup -3} (2sigma), resulting in a lower limit on the cloud size of approximately 0.1-1 parsec. While it is difficult to determine the metallicity of the cold component, the absence of Cr II indicates that the cold cloud suffers a high level of dust depletion. Additionally, the large amount of Lyman and Werner-band molecular hydrogen absorption (log N(H{sub 2}){sub total} = 19.88 cm{sup -2}, f{sub H{sub 2}} >= 0.06) with an excitation temperature of T{sub ex} = 46 K as determined by the rotational J = 0 and J = 1 states, is consistent with the presencemore » of cold gas. We propose that this cloud may be gravitationally confined and may represent a transition gas phase from primarily neutral atomic gas, to a colder, denser molecular phase that will eventually host star formation.« less

Authors:
;  [1];  [2]
  1. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)
  2. Department of Physics and Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0424 (United States)
Publication Date:
OSTI Identifier:
21367446
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 704; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/704/1/247; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; CARBON; DUSTS; EXCITATION; FINE STRUCTURE; GALACTIC EVOLUTION; GALAXIES; HYDROGEN; MULTIPLETS; QUASARS; RED SHIFT; STARS; COSMIC RADIO SOURCES; ELEMENTS; ENERGY-LEVEL TRANSITIONS; EVOLUTION; NONMETALS; SORPTION

Citation Formats

Jorgenson, Regina A, Carswell, Robert F, Wolfe, Arthur M, and Xavier Prochaska, J., E-mail: raj@ast.cam.ac.u. DIRECT EVIDENCE OF COLD GAS IN DLA 0812+32B. United States: N. p., 2009. Web. doi:10.1088/0004-637X/704/1/247.
Jorgenson, Regina A, Carswell, Robert F, Wolfe, Arthur M, & Xavier Prochaska, J., E-mail: raj@ast.cam.ac.u. DIRECT EVIDENCE OF COLD GAS IN DLA 0812+32B. United States. https://doi.org/10.1088/0004-637X/704/1/247
Jorgenson, Regina A, Carswell, Robert F, Wolfe, Arthur M, and Xavier Prochaska, J., E-mail: raj@ast.cam.ac.u. 2009. "DIRECT EVIDENCE OF COLD GAS IN DLA 0812+32B". United States. https://doi.org/10.1088/0004-637X/704/1/247.
@article{osti_21367446,
title = {DIRECT EVIDENCE OF COLD GAS IN DLA 0812+32B},
author = {Jorgenson, Regina A and Carswell, Robert F and Wolfe, Arthur M and Xavier Prochaska, J., E-mail: raj@ast.cam.ac.u},
abstractNote = {We present the first direct evidence for cold gas in a high redshift DLA galaxy. We measured several multiplets of weak neutral carbon (C I) transitions in order to perform a curve of growth analysis. A DELTA chi{sup 2} test constrains the best-fit Doppler parameter, b = 0.33{sup +0.05}{sub -0.04} km s{sup -1} and log N(C I) = 13.30 +- 0.2 cm{sup -2}. This Doppler parameter constrains the kinetic temperature of the gas to T <= 78 K (T <= 115 K, 2sigma). We used the associated C I fine structure lines to constrain the volume density of the gas, n(H I) approx40-200 cm{sup -3} (2sigma), resulting in a lower limit on the cloud size of approximately 0.1-1 parsec. While it is difficult to determine the metallicity of the cold component, the absence of Cr II indicates that the cold cloud suffers a high level of dust depletion. Additionally, the large amount of Lyman and Werner-band molecular hydrogen absorption (log N(H{sub 2}){sub total} = 19.88 cm{sup -2}, f{sub H{sub 2}} >= 0.06) with an excitation temperature of T{sub ex} = 46 K as determined by the rotational J = 0 and J = 1 states, is consistent with the presence of cold gas. We propose that this cloud may be gravitationally confined and may represent a transition gas phase from primarily neutral atomic gas, to a colder, denser molecular phase that will eventually host star formation.},
doi = {10.1088/0004-637X/704/1/247},
url = {https://www.osti.gov/biblio/21367446}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 704,
place = {United States},
year = {Sat Oct 10 00:00:00 EDT 2009},
month = {Sat Oct 10 00:00:00 EDT 2009}
}