The DUVET Survey: Direct $T_e$-based metallicity mapping of metal-enriched outflows and metal-poor inflows in Mrk 1486

TL;DR

This study uses direct electron temperature measurements to map metallicity in Mrk 1486, revealing inflows and outflows with distinct metallicities, providing new insights into galaxy baryon cycle processes.

Contribution

First to simultaneously measure metallicity of inflows, outflows, and disk gas using a consistent $T_e$-based method in Mrk 1486.

Findings

Outflow metallicity is 0.20 dex higher than ISM metallicity.

Metal-poor inflows are below 5% of solar metallicity.

Negative $T_e$ gradient along the minor axis indicates outflows are metal-enriched.

Abstract

We present electron temperature ($T_e$) maps for the edge-on system Mrk 1486, affording "direct-method" gas-phase metallicity measurements across $5.\!\!^{\prime\prime}8$ (4.1 kpc) along the minor axis and $9.\!\!^{\prime\prime}9$ (6.9 kpc) along the major axis. These maps, enabled by strong detections of the [OIII]$\lambda$4363 auroral emission line across a large spatial extent of Mrk 1486, reveal a clear negative minor axis $T_e$ gradient in which temperature decreases with increasing distance from the disk plane. We find that the lowest metallicity spaxels lie near the extremes of the major axis, while the highest metallicity spaxels lie at large spatial offsets along the minor axis. This is consistent with a picture in which low metallicity inflows dilute the metallicity at the edges of the major axis of the disk, while star formation drives metal-enriched outflows along the minor axis. We find that the outflow metallicity in Mrk 1486 is 0.20 dex (1.6 times) higher than the average ISM metallicity, and more than 0.80 dex (6.3 times) higher than metal-poor inflowing gas, which we observe to be below 5 % $Z_\odot$. This is the first example of metallicity measurements made simultaneously for inflowing, outflowing, and inner disk ISM gas using consistent $T_e$-based methodology. These measurements provide unique insight into how baryon cycle processes contribute to the assembly of a galaxy like Mrk 1486.