  The dense molecular clump P1 in the infrared dark cloud (IRDC) complex
G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our
previous Submillimeter Array (SMA) observations revealed several jet-like CO
outflows emanating from the protostars, indicative of intense accretion and
potential interaction with ambient natal materials. Here we present the
Expanded Very Large Array (EVLA) spectral line observations toward P1 in the
NH3 (J,K) = (1,1), (2,2), (3,3) lines, as well as H2O and class I CH3OH masers.
Multiple NH3 transitions reveal the heated gas widely spread in the 1 pc clump.
The temperature distribution is highly structured; the heated gas is offset
from the protostars, and morphologically matches the outflows very well. Hot
spots of spatially compact, spectrally broad NH3 (3,3) emission are also found
coincident with the outflows. A weak NH3 (3,3) maser is discovered at the
interface between an outflow jet and the ambient gas. These findings suggest
that protostellar heating may not be effective in suppressing fragmentation
during the formation of massive cores.
