Positive feedback, quenching and sequential super star cluster (SSC) formation in NGC 4945

Abstract

We have used ALMA imaging (resolutions 0.1\arcsec-0.4\arcsec) of ground and vibrationally excited lines of HCN and HC${}_3$N toward the nucleus of NGC 4945 to trace the protostellar phase in Super Star Clusters (proto-SSC). Out of the 14 identified SSCs, we find that 8 are in the proto-SSC phase showing vibrational HCN emission with 5 of them also showing vibrational HC${}_3$N emission. We estimate proto-SSC ages of 5-9.7$\times$10${}^4$ yr. The more evolved ones, with only HCN emission, are close to reach the Zero Age Main Sequence (ZAMS; ages $\gtrsim$10${}^5$ yr). The excitation of the parental cloud seems to be related to the SSC evolutionary stage, with high ($\sim$65 K) and low ($\sim$25 K) rotational temperatures for the youngest proto and ZAMS SSCs, respectively. Heating by the HII regions in the SSC ZAMS phase seems to be rather local. The youngest proto-SSCs are located at the edges of the molecular outflow, indicating SSC formation by positive feedback in the shocked regions. The proto-SSCs in NGC 4945 seem to be more evolved than in the starburst galaxy NGC 253. We propose that sequential SSC formation can explain the spatial distribution and different ages of the SSCs in both galaxies.

arXiv comment5 pages, 4 figures, 3 tables. Accepted for publication in MNRAS Letters

References in corpus (20)

• The Starburst-Driven Molecular Wind in NGC 253 and the Suppression of Star Formation
• Chandra observations of NGC 253. II: On the origin of diffuse X-ray emission in the halos of starburst galaxies
• The MAGNUM survey: different gas properties in the outflowing and disk components in nearby active galaxies with MUSE
• Spectral Line Identification and Modelling (SLIM) in the MAdrid Data CUBe Analysis (MADCUBA) package: An interactive software for data cube analysis
• Forming Super Star Clusters in the Central Starburst of NGC 253
• Spatially resolved optical IFU spectroscopy of the inner superwind of NGC 253
• HNCO abundances in galaxies: Tracing the evolutionary state of starbursts
• High-resolution X-ray imaging and spectroscopy of the core of NGC 4945 with XMM-Newton and Chandra
• The molecular outflow in NGC253 at a resolution of two parsecs
• Modelling of the Effects of Stellar Feedback during Star Cluster Formation Using a Hybrid Gas and N-Body Method
• Super Hot Cores in NGC 253: Witnessing the formation and early evolution of Super Star Clusters
• The Circumnuclear Molecular Gas in the Seyfert Galaxy NGC4945
• Super Star Clusters in the Central Starburst of NGC 4945
• Molecular line emission in NGC 4945, imaged with ALMA
• The Greenhouse Effect in Buried Galactic Nuclei and the Resonant HCN Vibrational Emission
• The Morpho-Kinematic Architecture of Super Star Clusters in the Center of NGC253
• From large scale gas compression to cluster formation in the Antennae overlap region
• Vibrationally excited HC3N emission in NGC1068: Tracing the recent star formation in the starburst ring
• On the thermal structure of the proto-Super Star Cluster 13 in NGC 253
• The multi-phase ISM in the nearby composite AGN-SB galaxy NGC 4945: large (parsecs) scale mechanical heating

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