Details

Autor(en) / Beteiligte

• Li 李, Jialu 佳璐
• Harris, Andrew I.
• Rosolowsky, Erik
• Kepley, Amanda A.
• Frayer, David
• Bolatto, Alberto D.
• Leroy, Adam K.
• Donovan Meyer, Jennifer
• Church, Sarah
• Gundersen, Joshua Ott
• Cleary, Kieran

Titel

GBT/Argus Observations of Molecular Gas in the Inner Regions of IC 342

Ist Teil von

• The Astrophysical journal, 2024-03, Vol.963 (2), p.117

Ort / Verlag

Philadelphia: IOP Publishing

Erscheinungsjahr

2024

Link zum Volltext

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• Abstract We report observations of the ground state transitions of 12 CO, 13 CO, C 18 O, HCN, and HCO + at 88–115 GHz in the inner region of the nearby galaxy IC 342. These data were obtained with the 16 pixel spectroscopic focal plane array Argus on the 100 m Robert C. Byrd Green Bank Telescope (GBT) at 6″–9″ resolution. In the nuclear bar region, the intensity distributions of 12 CO(1–0) and 13 CO(1–0) emission trace moderate densities, and differ from the dense gas distributions sampled in C 18 O(1–0), HCN(1–0), and HCO + (1–0). We observe a constant HCN(1–0)-to-HCO + (1–0) ratio of 1.2 ± 0.1 across the whole ∼1 kpc bar. This indicates that the HCN(1–0) and HCO + (1–0) lines have intermediate optical depth, and that the corresponding n H 2 of the gas producing the emission is of order 10 4.5−6 cm −3 . We show that HCO + (1–0) is thermalized and HCN(1–0) is close to thermalization. The very tight correlation between the HCN(1–0) and HCO + (1–0) intensities across the 1 kpc bar suggests that this ratio is more sensitive to the relative abundance of the two species than to the gas density. We confirm an angular offset (∼10″) between the spatial distribution of molecular gas and the star formation sites. Finally, we find a breakdown of the L IR – L HCN correlation at high spatial resolution due to the effect of incomplete sampling of star-forming regions by HCN emission in IC 342. The scatter of the L IR – L HCN relation decreases as the spatial scale increases from 10″ to 30″ (170–510 pc), and is comparable to the scatter of the global relation at a scale of 340 pc.