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Arxiv: Retrieval of Thermally-Resolved Water Vapor Distributions in Disks Observed with JWST-MIRI Published: 9/5/2024 9:00:05 PM Updated: 9/5/2024 9:00:05 PM

Paper abstract: The mid-infrared water vapor emission spectrum provides a novel way tocharacterize the delivery of icy pebbles towards the innermost (<5 au)regions of planet-forming disks. Recently, JWST MIRI-MRS showed that compactdisks exhibit an excess of low-energy water vapor emission relative to extendedmulti-gapped disks, suggesting that icy pebble drift is more efficient in theformer. We carry out detailed emission line modeling to retrieve the excitationconditions of rotational water vapor emission in a sample of four compact andthree extended disks within the JDISC Survey. We present two-temperature H_2Oslab model retrievals and, for the first time, constrain the spatialdistribution of water vapor by fitting parametric radial temperature and columndensity profiles. Such models statistically outperform the two-temperature slabfits. We find a correlation between the observable hot water vapor mass andstellar mass accretion rate, as well as an anti-correlation between cold watervapor mass and sub-mm dust disk radius, confirming previously reported waterline flux trends. We find that the mid-IR spectrum traces H_2O withtemperatures down to 180-300 K, but the coldest 150-170 K gas remainsundetected. Furthermore the H_2O temperature profiles are generally steeperand cooler than the expected `super-heated' dust temperature in passiveirradiated disks. The column density profiles are used to estimate icy pebblemass fluxes, which suggest that compact and extended disks may produce markedlydistinct inner-disk exoplanet populations if local feeding mechanisms dominatetheir assembly.