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Abstract:

High-z starbursts provide a unique laboratory to study ISM properties under extreme, gas-rich conditions compared to their low-z analogs. I will present observations and analysis of three distinct starbursts at z～1.5 using high-resolution (0.04 - 0.3") ALMA and JWST NIRCam/MIRI data. The molecular line CO J = 5-4 traces spatially resolved star formation and kinematics while the FIR continuum assesses the dust/gas content on scales of ~0.3-3 kpc. All systems exhibit dusty, gas-rich, centrally concentrated rotating disks with enhanced SF activity in their cores, likely growing bulges rapidly. In one merging pair, ALMA detects clear molecular outflows, potentially linked to strong SF feedback or interactions. The NIRCam data in multiple filters reveals diverse structures including highly obscured starbursting cores, unobscured tidal tails, clumps, and normal spiral features at redder wavelengths in two of the three starbursts. The latter indicates a minor merger or gas-rich disk instability may be as effective to trigger a starburst. Furthermore, within one dust-obscured starbursting core, the spatial profiles of the IR luminosity (L_IR) inferred by CO5-4 and the luminosity at 8μm (L_8) inferred by MIRI/F1800W are dissimilar thus leading to a significant deficit of mid-IR emission in the core. This may result from PAH destruction by intense ionizing radiation or a decrease of emissions from photodissociation regions, similar to SF regions in nearby galaxies and AGN host galaxies, aligning with the global properties of distant starbursts. These observations demonstrate the importance of spatially resolved studies on the physics of gas and stars and the evolution of compact distant starbursts.