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Using the Expanded Very Large Array, we have mapped the vicinity of the OrionBN/KL Hot Core with sub-arcsecond angular resolution in seven metastableinversion transitions of ammonia: (J,K)=(6,6) to (12,12). This emission comesfrom levels up to 1500 K above the ground state, enabling identification ofsource(s) responsible for heating the region. We used this multi-transitiondataset to produce images of the rotational/kinetic temperature and the columndensity of ammonia for ortho and para species separately and on aposition-by-position basis. We find rotational temperature and column densityin the range 160-490 K and (1-4)x10^17 cm^-2, respectively. Ourspatially-resolved images show that the highest (column) density and hottestgas is found in a northeast-southwest elongated ridge to the southeast ofSource I. We have also measured the ortho-para ratio of ammonia, estimated tovary in the range 0.9-1.6. Enhancement of ortho with respect to para and theoffset of hot ammonia emission peaks from known (proto)stellar sources provideevidence that the ammonia molecules have been released from dust grains intothe gas-phase through the passage of shocks and not by stellar radiation. Wepropose that the combined effect of Source I's proper motion and itslow-velocity outflow impinging on a pre-existing dense medium is responsiblefor the excitation of ammonia and the Orion Hot Core. Finally, we found for thefirst time evidence of a slow (5 km/s) and compact (1000 AU) outflow towardsIRc7.

Unveiling Sources of Heating in the Vicinity of the Orion BN/KL Hot Core as Traced by Highly Excited Inversion Transitions of Ammonia