The Star Formation History of a Post-Starburst Galaxy Determined From Its Cluster Population

Abstract

The recent star formation histories (SFHs) of post-starburst galaxies have been determined almost exclusively from detailed modeling of their composite star light. This has provided important but limited information on the number, strength, and duration of bursts of star formation. In this work, we present a direct and independent measure of the recent SFH of S12 (plate-mjd-fiber for SDSS 623-52051-207; designated EAS12 in Smercina et al. 2018) from its star cluster population. We detect clusters from high resolution, $UBR$ optical observations from HST, and compare their luminosities and colors with stellar population models to estimate the ages and masses of the clusters. No clusters younger than $\sim$70 Myr are found, indicating star formation shut off at this time. Clusters formed $\sim$120 Myr ago reach masses up to $\sim \mbox{few}\times10^7~M_{\odot}$, several times higher than similar age counterparts formed in actively merging galaxies like the Antennae and NGC 3256. We develop a new calibration based on known properties for 8 nearby galaxies to estimate the star formation rate (SFR) of a galaxy from the mass of the most massive cluster, $M_{\max }$. The cluster population indicates that S12 experienced an extremely intense but short-lived burst $\sim$120 Myr ago, with an estimated peak of $500^{+500}_{-250}~M_{\odot}~\mbox{yr}^{-1}$ and duration of $50\pm 25$ Myr, one of the highest SFRs estimated for any galaxy in the nearby universe. Prior to the recent, intense burst, S12 was forming stars at a moderate rate of $\sim 3{-}5~M_{\odot}~\mbox{yr}^{-1}$, typical of spiral galaxies. However, the system also experienced an earlier burst approximately $1-3$ Gyr ago. While fairly uncertain, we estimate that the SFR during this earlier burst was $\sim20{-}30~M_{\odot}~\mbox{yr}^{-1}$, similar to the current SFR in the Antennae and NGC 3256.

20 pages, 12 figures, 2 tables, accepted to ApJ

References in corpus (15)

• The NumPy array: a structure for efficient numerical computation
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Star formation efficiency in galaxy interactions and mergers: a statistical study
• Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories
• Starbursts triggered by inter-galactic tides and interstellar compressive turbulence
• A parsec-resolution simulation of the Antennae galaxies: Formation of star clusters during the merger
• The evolution of post-starburst galaxies from z=2 to z= 0.5
• High-resolution simulations of galaxy mergers: Resolving globular cluster formation
• The Detailed Evolution of E+A Galaxies into Early Types
• Discovery of Large Molecular Gas Reservoirs in Post-Starburst Galaxies
• PHANGS-HST: Star Cluster Spectral Energy Distribution Fitting with CIGALE
• The Luminosity Function of Star Clusters in 20 Star-Forming Galaxies Based on Hubble Legacy Archive Photometry
• LEGUS and Halpha-LEGUS Observations of Star Clusters in NGC 4449: Improved Ages and the Fraction of Light in Clusters as a Function of Age
• Star Cluster Mass and Age Distributions of Two Fields in M83 Based on HST/WFC3 Observations
• Star Cluster Formation and Destruction in the Merging Galaxy NGC 3256

Cited by in corpus (1)

• After The Fall: Resolving the Molecular Gas in Post-Starburst Galaxies