First Results from JACKS: A VLA Ammonia View of Gas Heating and Star-forming Cores in the Central Molecular Zone

Abstract

The Central Molecular Zone (CMZ) combines warm molecular gas, strong turbulence, and a star-formation rate below that expected from its dense-gas reservoir. The JVLA Ammonia C-configuration K-band Survey (JACKS) is designed to connect these environmental conditions to the thermal and kinematic structure of compact, potentially star-forming gas. JACKS follows the footprint of the ALMA Central Molecular Zone Exploration Survey (ACES) with 31 Very Large Array mosaic fields. Its K-band setup covers the metastable NH${}_3$ $(1,1)$--$(5,5)$ inversion transitions, five non-metastable NH${}_3$ lines, the 22-GHz H${}_2$O maser transition, H64$\alpha$ and H66$\alpha$, and broad continuum windows. The nominal resolutions are approximately $1.5^{\prime \prime }$ ($0.06$ pc at the Galactic Centre) and $0.4$ km s${}^{-1}$ for the NH${}_3$ lines. We present preliminary imaging products that demonstrate water-maser self-calibration, compact and extended continuum emission, filamentary NH${}_3$ structure, and complex compact sources with multiple velocity components. Tests that combine JACKS with the SWAG and HOPS ammonia surveys recover progressively larger angular scales. These early products establish the survey's ability to connect core-scale gas heating and kinematics to the cloud-scale CMZ environment; quantitative temperature, opacity, and core-population measurements will follow from the uniformly reduced data set.

arXiv comment11 pages, 9 figures. Included in International Astronomical Union Proceedings Series: Traversing the Galactic Center in Space and Time, Proceedings IAU Symposium No. 405