Star Cluster Formation and Destruction in the Merging Galaxy NGC 3256

Abstract

We use the Advanced Camera for Surveys on the Hubble Space Telescope to study the rich population of young massive star clusters in the main body of NGC 3256, a merging pair of galaxies with a high star formation rate (SFR) and SFR per unit area (${\Sigma }_{\mathrm{SFR}}$). These clusters have luminosity and mass functions that follow power laws, $dN/dL\propto L^{\alpha }$ with $\alpha =-2.23\pm 0.07$, and $dN/dM\propto M^{\beta }$ with $\beta =-1.86\pm 0.34$ for $\tau <10$ Myr clusters, similar to those found in more quiescent galaxies. The age distribution can be described by $dN/d\tau \propto {\tau }^{\gamma }$, with $\gamma \approx -0.67\pm 0.08$ for clusters younger than about a few hundred million years, with no obvious dependence on cluster mass. This is consistent with a picture where $\sim 80\%$ of the clusters are disrupted each decade in time. We investigate the claim that galaxies with high ${\Sigma }_{\mathrm{SFR}}$ form clusters more efficiently than quiescent systems by determining the fraction of stars in bound clusters ($\Gamma$) and the CMF/SFR statistic (CMF is the cluster mass function) for NGC 3256 and comparing the results with those for other galaxies. We find that the CMF/SFR statistic for NGC 3256 agrees well with that found for galaxies with ${\Sigma }_{\mathrm{SFR}}$ and SFRs that are lower by $1-3$ orders of magnitude, but that estimates for $\Gamma$ are only robust when the same sets of assumptions are applied. Currently, $\Gamma$ values available in the literature have used different sets of assumptions, making it more difficult to compare the results between galaxies.

18 pages, 15 figures, accepted for publication in ApJ. Image quality on some figures has been degraded to comply with arxiv file limitations

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• Great Balls of FIRE I: The formation of star clusters across cosmic time in a Milky Way-mass galaxy
• Mass Functions of Giant Molecular Clouds and Young Star Clusters in Six Nearby Galaxies
• The formation of clusters and OB associations in different density spiral arm environments
• Gems of the Galaxy Zoos -- a Wide-Ranging Hubble Space Telescope Gap-Filler Program
• The SUNBIRD survey: the K-band luminosity functions of young massive clusters in intensely star-forming galaxies
• A Massive Dense Gas Cloud close to the Nucleus of the Seyfert galaxy NGC 1068
• The Star Formation History of a Post-Starburst Galaxy Determined From Its Cluster Population