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 »
- Authors:
-
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)
- 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}
}