DUVET: Resolved direct metallicity measurements in the outflow of starburst galaxy NGC 1569
Magdalena J. Hamel-Bravo, Deanne B. Fisher, Danielle Berg, Bjarki Bj"orgvinsson, Alberto D. Bolatto, Alex J. Cameron, John Chisholm, Drummond B. Fielding, Rodrigo Herrera-Camus, Glenn G. Kacprzak, Miao Li, Barbara Mazzilli Ciraulo, Anna F. McLeod, Daniel K. McPherson, Nikole M. Nielsen, Bronwyn Reichardt Chu, Ryan J. Rickards Vaught, Karin Sandstrom
arXiv:2404.04600v1 Announce Type: new
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.arXiv:2404.04600v1 Announce Type: new
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.