# A 3 mm Spectral Line Survey toward the Barred Spiral Galaxy NGC 3627

## TL;DR

This study presents a spectral line survey of NGC 3627, revealing that molecular chemical compositions are remarkably consistent across different galactic regions despite varying star-formation activities, serving as a standard template for nearby galaxies.

## Contribution

It provides the first comprehensive spectral line survey of NGC 3627 across multiple regions, highlighting the chemical uniformity and establishing a standard molecular composition template.

## Key findings

- Chemical compositions are similar across different regions despite physical differences.
- The molecular abundances resemble those in our Galaxy and M51, indicating universal chemical characteristics.
- Local physical conditions have limited impact on the overall chemical makeup at kiloparsec scales.

## Abstract

We conduct spectral line survey observations in the 3 mm band toward a spiral arm, a bar-end, and a nuclear region of the nearby barred spiral galaxy NGC 3627 with the IRAM 30 m telescope and the Nobeyama 45 m telescope. Additional observations are performed toward the spiral arm and the bar-end in the 2 mm band. We detect 8, 11, and 9 molecular species in the spiral arm, the bar-end, and the nuclear region, respectively. Star-formation activities are different among the three regions, and in particular, the nucleus of NGC 3627 is known as a LINER/Seyfert 2 type nucleus. In spite of these physical differences, the chemical composition shows impressive similarities among the three regions. This result means that the characteristic chemical composition associated with these regions is insensitive to the local physical conditions such as star formation rate, because such local effects are smeared out by extended quiescent molecular gas on scales of 1 kpc. Moreover, the observed chemical compositions are also found to be similar to those of molecular clouds in our Galaxy and the spiral arm of M51, whose elemental abundances are close to those in NGC 3627. Therefore, this study provides us with a standard template of the chemical composition of extended molecular clouds with the solar metalicity in nearby galaxies.