Discovery of a Molecular Collision Front in Interacting Galaxies NGC 4567/4568 with ALMA

Abstract

We present results of ${}^{12}$CO(J = 1-0) imaging observations of NGC 4567/4568, a galaxy pair in a close encounter, with Atacama Large Millimetre/submillimetre Array. For the first time, we find clear evidence of a molecular collision front whose velocity dispersion is 16.8$\pm$1.4 km s${}^{-1}$ at the overlapping region owing to high spatial and velocity resolution. By integrating over the velocity width that corresponds to the molecular collision front, we find a long filamentary structure with a size of 1800 pc $\times$ 350 pc at the collision front. This filamentary molecular structure spatially coincides with a dark-lane seen in R-band image. We find four molecular clouds in the filament, each with a radius of 30 pc and mass of 10${}^6{M}_{\odot }$; the radii matching a typical value for giant molecular clouds and the masses corresponding to those between giant molecular clouds and giant molecular associations. All four clouds are gravitationally bound. The molecular filamentary structure and its physical conditions are similar to the structure expected via numerical simulation. The filament could be a progenitor of super star clusters.

6 pages, 4 figures, 1 table; accepted for publication in ApJL

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Cited by in corpus (8)

• VERTICO: The Virgo Environment Traced In CO Survey
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• CO Multi-line Imaging of Nearby Galaxies (COMING). XII. CO-to-H${}_2$ Conversion Factor and Dust-to-Gas Ratio
• ALMA Observations of Giant Molecular Clouds in M33 III: Spatially Resolved Features of the Star-Formation Inactive Million-solar-mass Cloud
• Property of Young Massive Clusters in a Galaxy-Galaxy Merger Remnant
• Properties of Molecular Gas in Galaxies in Early and Mid Stages of Interaction. III. Resolved Kennicutt-Schmidt Law
• Multi-wavelength and Multi-CO View of The Minor Merger Driven Star Formation in the Nearby LIRG NGC 3110
• Investigating physical states of molecular gas in the overlapping region of interacting galaxies NGC4567/4568 using ALMA