2025/10/06 by Hamel-Bravo, M. J., Fisher, D. B., Berg, D. A. +5
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2510.05332
We present VLT/X-shooter spectroscopy of the extremely metal-poor starburst galaxy SBS 0335-052E, a nearby (D ∼54 Mpc) analog of high-redshift systems, probing its outflow up to a distance of ∼2.6 kpc. Using direct-method oxygen abundances, we find a complex metallicity profile that generally declines with distance, decreasing by 0.37 dex from the galaxy center out to 2.4 kpc into the outflow. This implies a metal-loading factor roughly an order of magnitude lower than predictions based on the mass-metallicity relation for low-mass galaxies. We also detect extended HeII emission, including a broad, redshifted component beyond 2 kpc, distinct from narrow emission associated with star clusters. No Hβ emission is detected associated with the broad redshifted component, implying extremely high HeII/Hβ ratios (0.7--4.8). Such extreme values, combined with the decreasing metallicity, challenge current models for stellar feedback. The contribution of an intermediate-mass black hole could simultaneously account for the declining metallicity and the unusually extended HeII emission.