Spatially Resolved Chemistry in Nearby Galaxies. I. The Center of IC 342
164 citations recorded by the source corpus.
We have imaged emission from the millimeter lines of eight molecules—C2H, C34S, N2H+, CH3OH, HNCO, HNC, HC3N, and SO—in the central half-kiloparsec of the nearby spiral galaxy IC 342. The 5'' (~50 pc) resolution images were made with the Owens Valley Millimeter Array. Using these and previously published CO and HCN images, we obtain a picture of the chemistry within the nuclear region on the size scales of individual giant molecular clouds. Bright emission is detected from all but SO. There are marked differences in morphology for the different molecules. A principal-component analysis is performed to quantify similarities and differences among the images. This analysis reveals that while all molecules are to zeroth order correlated, that is, that they are all found in dense molecular clouds, there are three distinct groups of molecules distinguished by the location of their emission within the nuclear region. N2H+, C18O, HNC, and HCN are widespread and bright, good overall tracers of dense molecular gas. C2H and C34S, tracers of photodissociation region chemistry, originate exclusively from the central 50-100 pc region, where radiation fields are high. The third group of molecules, CH3OH and HNCO, correlates well with the expected locations of bar-induced orbital shocks. The good correlation of HNCO with the established shock tracer molecule CH3OH is evidence that this molecule, whose chemistry has been uncertain, is indeed produced by the processing of grain mantles. HC3N is observed to correlate tightly with 3 mm continuum emission, demonstrating that the young starbursts are the sites of the warmest and densest molecular gas. We compare our HNC images with the HCN images of Downes and coworkers to produce the first high-resolution, extragalactic HCN/HNC map: the HNC/HCN ratio is near unity across the nucleus, and the correlation of both of these gas tracers with star formation is excellent. The ratio exhibits no obvious correlation with gas temperature or star formation strength.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/2bf6ad946d679c2226146e1b633c56c3fcd41de3
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Astronomy and Astrophysics
Citations in the corpus
- Molecular gas kinematics within the central 250 pc of the Milky Way (2016, background): “6 HNCO is also extended towards the nuclei of other galaxies e.g. IC 342 (Meier & Turner 2005).”
- A 2 Millimeter Spectral Line Survey of the Starburst Galaxy NGC 253 (2006, background): “The abundance of C2H given in Table 7 has been taken from Meier & Turner (2005) toward the D position.”
- THE PdBI ARCSECOND WHIRLPOOL SURVEY (PAWS). I. A CLOUD-SCALE/MULTI-WAVELENGTH VIEW OF THE INTERSTELLAR MEDIUM IN A GRAND-DESIGN SPIRAL GALAXY (2013, background): “Therefore it is observationally very challenging on the size scales considered here to discriminate between GMCs that are full PDRs (like in the center of Maffei 2; Meier & Turner 2012) or only have PDR surface layers (as in the center of IC 342; Meier & Turner 2005).”