학술논문
DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569
Document Type
Working Paper
Author
Hamel-Bravo, Magdalena J.; Fisher, Deanne B.; Berg, Danielle; Björgvinsson, Bjarki; Bolatto, Alberto D.; Cameron, Alex J.; Chisholm, John; Fielding, Drummond B.; Herrera-Camus, Rodrigo; Kacprzak, Glenn G.; Li, Miao; Ciraulo, Barbara Mazzilli; McLeod, Anna F.; McPherson, Daniel K.; Nielsen, Nikole M.; Chu, Bronwyn Reichardt; Vaught, Ryan J. Rickards; Sandstrom, Karin
Source
Subject
Language
Abstract
We present the results of direct-method metallicity measurements in the disk and outflow of the low-metallicity starburst galaxy NGC 1569. We use Keck Cosmic Web Imager observations to map the galaxy across 54$\arcsec$ (800 pc) along the major axis and 48$\arcsec$ (700 pc) along the minor axis with a spatial resolution of 1$\arcsec$ ($\sim$15 pc). We detect common strong emission lines ([\ion{O}{III}] $\lambda$5007, H$\beta$, [\ion{O}{II}] $\lambda$3727) and the fainter [\ion{O}{III}] $\lambda$4363 auroral line, which allows us to measure electron temperature ($T_e$) and metallicity. Theory suggests that outflows drive metals out of the disk driving observed trends between stellar mass and gas-phase metallicity. Our main result is that the metallicity in the outflow is similar to that of the disk, $Z_{\rm out} / Z_{\rm ISM} \approx 1$. This is consistent with previous absorption line studies in higher mass galaxies. Assumption of a mass-loading factor of $\dot{M}_{\rm out}/{\rm SFR}\sim3$ makes the metal-loading of NGC 1569 consistent with expectations derived from the mass-metallicity relationship. Our high spatial resolution metallicity maps reveal a region around a supermassive star cluster (SSC-B) with distinctly higher metallicity and higher electron density, compared to the disk. Given the known properties of SSC-B the higher metallicity and density of this region are likely the result of star formation-driven feedback acting on the local scale. Overall, our results are consistent with the picture in which metal-enriched winds pollute the circumgalactic medium surrounding galaxies, and thus connect the small-scale feedback processes to large-scale properties of galaxy halos.
Comment: 15 pages, 11 figures, accepted by MNRAS
Comment: 15 pages, 11 figures, accepted by MNRAS