2025/10/17 by Shi, Yanlong, Dai, Liang, Murray, Norman +3 · 2 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2510.15823
The lensed Sunburst Arc (z = 2.369) hosts a young (∼2--4 \rm Myr), massive (M_⋆ ∼ 107 M_\odot), compact (R\rm eff ∼ 8 \rm pc) Lyman-continuum (LyC) leaking super star cluster, which powers a compact (< 10 \rm pc), high-pressure nebula at sub-solar metallicity ∼0.2 Z_\odot and with an anomalously elevated nitrogen-to-oxygen ratio log(\rm N/O) ∼ -0.2. We present semi-analytic models and 3D magnetohydrodynamic simulations with radiative feedback in an attempt to reproduce this system. The results indicate that the progenitor giant molecular cloud (GMC) may have M\rm cloud \gtrsim 3 × 107 M_\odot and R\rm cloud ∼ 70 \rm pc, corresponding to a surface density ∼103--104 M_\odot \rm pc-2. Incorporating feedback from individual Very Massive Stars (VMSs; ≥ 100 M_\odot) sampled from the Kroupa initial mass function, we find that their winds rapidly enrich ∼ 104 M_\odot of nearby gas with nitrogen (∼ 1 dex) and helium (∼ 0.1--0.2 dex). In the first 1--3 Myr, some cold gas falls to the system center where a central cluster builds up from sub-cluster mergers. There, the gas is photoionized, pressurized, and chemically enriched by the newly formed VMSs, before being radiatively expelled in the next ∼1 \rm Myr. We find that both VMS feedback and a high-surface-density progenitor GMC are necessary to reproduce the observed nebular properties, such as high N/O, high pressure, and stellar proximity. Low metallicity (Z ≤ 0.004) may be essential to avoid overproduction of carbon from WC stars. Such enrichment processes localized to compact starburst events may have caused strong nitrogen emission from dense ionized gas as observed in high-redshift galaxies such as GN-z11 and GS3073.