X-ray stellar feedback in low-metallicity starbursts. Insights from the template starburst galaxy ESO 338-IG04 and its halo

The X-ray output of low-metallicity starburst galaxies is a key component of stellar feedback, tracing the processes responsible for gas ionization and chemical enrichment. The integrated X-ray luminosity (L_X) from high-mass X-ray binaries in star-forming galaxies scales with the star formation rate (SFR) and the host galaxy metallicity Z. Due to the inverse correlation between L_X/SFR and Z, the contribution of X-ray binaries to the ionizing photon budget is expected to be enhanced in metal-poor systems. Their radiation can potentially ionize in the surrounding interstellar medium, powering nebular ,łambda 4686,Å emission. However, detailed studies of the X-ray emission in individual low-Z starburst galaxies are rare, and their X-ray properties are not well explored. He ii He ii The blue compact dwarf galaxy ESO 338-IG04 (ESO 338-4 hereafter) serves as a nearby template for studying stellar feedback and X-ray emission in low-metallicity starbursts. It combines vigorous recent star formation, a low metallicity (12+łog( / ) X-ray Observatory ( ) and . O H or 12% solar), and a rich population of massive stellar clusters. Extensively observed in optical and UV wavelengths with HST and VLT MUSE, ESO 338-4 is ideally suited for multiwavelength feedback studies. We characterize the X-ray emission of ESO 338-4 and its galactic halo using new deep observations obtained with the Chandra Chandra XMM-Newton We analyzed X-ray spectra, light curves, and images of ESO 338-4 to constrain the nature of its X-ray sources. Additionally, we employed photoionization modeling to assess the significance of X-ray sources to the observed nebular ,łambda 4686,Å emission. He ii We identified five ultraluminous X-ray sources (ULXs) and diffuse hot gas surrounding ESO 338-4. Two of the ULXs are spatially associated with stellar clusters. -1 . The brightest point source, ULX1, is variable on timescales of days and is not associated with a stellar cluster. Last, our modeling demonstrates that X-ray sources significantly affect the ionizing photon budget of the galaxy. Photoionization modeling with ULX1 as the ionizing source predicts a high nebular ,łambda 4686,Å line luminosity of approximately 10^ , , ^ He ii 39 erg s -1 .