Evolution of starless cores in massive clumps seen by the ALMA ASHES and QUARKS surveys

Abstract

We present a systematic comparative analysis of 324 starless cores in early-phase infrared-dark clouds (IRDCs; ASHES survey) and evolved-phase infrared-bright clouds (IRBCs; QUARKS survey) using 1.3 mm continuum and line data by the Atacama Large Millimeter/submillimeter Array (ALMA). Despite having comparable sizes ($\sim$2500 au),starless cores in IRBCs exhibit systematically higher median mass ($1.5M_{\odot }$ vs. $0.6M_{\odot }$), number density, and surface density--enhancements of approximately a factor of two relative to starless cores in IRDCs. Starless cores in IRBCs also display relatively stronger non-thermal motions ($\sigma \sim 0.5\mathrm{km}{\mathrm{s}}^{-1}$ vs. $0.3\mathrm{km}{\mathrm{s}}^{-1}$), higher total virial parameters (median ${\alpha }_{\mathrm{vir},\mathrm{tot}}\sim$ 2.3 vs. 1.0), and steeper density profiles, indicating more centrally concentrated structures in feedback-driven, turbulence-enhanced environments. These findings support a dual evolutionary origin: (i) new core formation in evolved IRBCs under altered initial conditions, and (ii) subsequent dynamical mass growth via accretion from extended reservoirs. The prevalence of low-mass starless cores--even in late-stage IRBC environments--challenges models requiring massive prestellar cores and instead favors competitive-like dynamical mass accretion scenarios for high-mass star formation.

22 pages, 12 figures, accepted by ApJ