Mopra line survey mapping of NGC 6334I and I(N) at 3mm

Abstract

A 5 × 5arcmin^2 region encompassing NGC 6334I and I(N) has been mapped at a wavelength of 3mm (from 83.5 to 115.5GHz) with the Mopra telescope at an angular resolution between 33 and 36arcsec. This investigation has made use of the recently installed 3mm Monolithic Microwave Integrated Circuit (MMIC) receiver and the Mopra Spectrometer with broad-band capabilities permitting total coverage of the entire frequency range with just five different observations. In total, the spatial distributions of 19 different molecules, ions and radicals, along with additional selected isotopologues, have been studied. Whilst most species trace the sites of star formation, CH3CN appears to be most closely associated with NGC 6334I and I(N). Both CN and C2H appear to be widespread, tracing gas that is not associated with active star formation. Both N2H+ and HC3N closely resemble dust continuum emission, showing that they are reliable tracers of dense material as well as the youngest stages of high-mass star formation. Hot (Eu/k > 100K) thermal CH3OH emission is preferentially found towards NGC 6334I, contrasting with I(N), where only cold (Eu/k < 22K) thermal CH3OH emission is found.