| Type |
Journal Article |
| Names |
Yan-Mei Chen, Christy A. Tremonti, Timothy M. Heckman, Guinevere Kauffmann, Benjamin J. Weiner, Jarle Brinchmann, Jing Wang |
| Publication |
The Astronomical Journal |
| Volume |
140 |
| Issue |
2 |
| Pages |
445-461 |
| Date |
August 1, 2010 |
| URL |
http://adsabs.harvard.edu/abs/2010AJ....140..445C |
| Library Catalog |
NASA ADS |
| Abstract |
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
signal-to-noise ~300. The stellar continuum is modeled using stellar
population synthesis models, and the continuum-normalized 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 *). |
| Tags |
GALAXIES: EVOLUTION, galaxies: star formation |