TY - JOUR
T1 - Absorption-line probes of the prevalence and properties of outflows in present-day star-forming galaxies
AU - Chen, Yan Mei
AU - Tremonti, Christy A.
AU - Heckman, Timothy M.
AU - Guinevere, Kauffmann
AU - Weiner, Benjamin J.
AU - Jarle, Brinchmann
AU - Jing, Wang
N1 - Funding Information:
The authors are grateful to Professor E. S. R. Gopal, Director, National Physical Laboratory, New Delhi for his keen interest in this work. Financial assistance from the Department of Biotechnology, Government of India, New Delhi under Grant No. BT/02/038/93-PID is gratefully acknowledged.
PY - 2010/8
Y1 - 2010/8
N2 - We analyze star-forming galaxies drawn from SDSS DR7 to show how the interstellar medium (ISM) Na I λλ5890, 5896 (Na D) absorption lines depend on galaxy physical properties, and to look for evidence of galactic winds. We combine the spectra of galaxies with similar geometry/physical parameters to create composite spectra with signalto-noise ∼300. The stellar continuum is modeled using stellar population synthesis models, and the continuumnormalized spectrum is fit with two Na I absorption components. We find that (1) ISM Na D absorption lines with equivalent widths EW > 0.8 Å are only prevalent in disk galaxies with specific properties - large extinction (Av), high star formation rates (SFR), high SFR per unit area (ΣSFR), or high stellar mass (M*); (2) the ISM Na D absorption lines can be separated into two components: a quiescent disk-like component at the galaxy systemic velocity and an outflow component; (3) the disk-like component is much stronger in the edge-on systems, and the outflow component covers a wide angle but is stronger within 60° of the disk rotation axis; (4) the EW and covering factor of the disk component correlate strongly with dust attenuation, highlighting the importance that dust shielding may play in the survival of Na I; (5) the EW of the outflow component depends primarily on ΣSFR and secondarily on AV; and (6) the outflow velocity varies from ∼120 to 160 km s-1 but shows little hint of a correlation with galaxy physical properties over the modest dynamic range that our sample probes (1.2 dex in log ΣSFR and 1 dex in log M*).
AB - We analyze star-forming galaxies drawn from SDSS DR7 to show how the interstellar medium (ISM) Na I λλ5890, 5896 (Na D) absorption lines depend on galaxy physical properties, and to look for evidence of galactic winds. We combine the spectra of galaxies with similar geometry/physical parameters to create composite spectra with signalto-noise ∼300. The stellar continuum is modeled using stellar population synthesis models, and the continuumnormalized spectrum is fit with two Na I absorption components. We find that (1) ISM Na D absorption lines with equivalent widths EW > 0.8 Å are only prevalent in disk galaxies with specific properties - large extinction (Av), high star formation rates (SFR), high SFR per unit area (ΣSFR), or high stellar mass (M*); (2) the ISM Na D absorption lines can be separated into two components: a quiescent disk-like component at the galaxy systemic velocity and an outflow component; (3) the disk-like component is much stronger in the edge-on systems, and the outflow component covers a wide angle but is stronger within 60° of the disk rotation axis; (4) the EW and covering factor of the disk component correlate strongly with dust attenuation, highlighting the importance that dust shielding may play in the survival of Na I; (5) the EW of the outflow component depends primarily on ΣSFR and secondarily on AV; and (6) the outflow velocity varies from ∼120 to 160 km s-1 but shows little hint of a correlation with galaxy physical properties over the modest dynamic range that our sample probes (1.2 dex in log ΣSFR and 1 dex in log M*).
KW - Evolution - Galaxies
KW - Galaxies
KW - Star formation
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U2 - 10.1088/0004-6256/140/2/445
DO - 10.1088/0004-6256/140/2/445
M3 - Article
AN - SCOPUS:78049334418
SN - 0004-6256
VL - 140
SP - 445
EP - 461
JO - Astronomical Journal
JF - Astronomical Journal
IS - 2
ER -