FUGIN hot core survey. I. Survey method and initial results for $l = 10^\circ-20^\circ$

TL;DR

This study introduces a spectral-line-based survey method for hot cores, applying it to the FUGIN data to identify and characterize high-mass star formation regions in the Galactic plane.

Contribution

The paper presents a new method combining line stacking and follow-up observations to efficiently identify hot cores in large survey data.

Findings

Identified 22 hot cores and 14 dense clumps in the $l=10^\u00b0-20^\u00b0$ Galactic region.

Hot cores are associated with high-mass star formation signposts like WISE HII regions and methanol masers.

Bolometric luminosity to clump mass ratios are consistent with hot core star formation stages.

Abstract

We have developed a method to make a spectral-line-based survey of hot cores, which represent an important stage of high-mass star formation, and applied the method to the data of the FUGIN (FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope) survey. First, we select hot core candidates by searching the FUGIN data for the weak hot core tracer lines (HNCO and CH$_3$CN) by stacking, and then we conduct follow-up pointed observations on these candidates in C$^{34}$S, SO, OCS, HC$_3$N, HNCO, CH$_3$CN, and CH$_3$OH $J=2-1$ and $J=8-7$ lines to confirm and characterize them. We applied this method to the $l = 10^\circ-20^\circ$ portion of the FUGIN data and identified 22 "Hot Cores" (compact sources with more than two significant detection of the hot core tracer lines, i.e., SO, OCS, HC$_3$N, HNCO, CH$_3$CN, or CH$_3$OH $J=8-7$ lines) and 14 "Dense Clumps" (sources with more than two significant detection of C$^{34}$S, CH$_3$OH $J=2-1$, or the hot core tracer lines). The identified Hot Cores are found associated with signposts of high-mass star formation such as ATLASGAL clumps, WISE HII regions, and Class II methanol masers. For those associated with ATLASGAL clumps, their bolometric luminosity to clump mass ratios are consistent with the star formation stages centered at the hot core phase. The catalog of FUGIN Hot Cores provides a useful starting point for further statistical studies and detailed observations of high-mass star forming regions.