1. DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569
- Author
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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, 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, and Sandstrom, Karin
- 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
- Published
- 2024