A Global Star Forming Episode in M31 2-4 Gyr Ago

Abstract

We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2-4 Gyr ago, producing $\sim$60% of the stellar mass formed in the past 5 Gyr. The presence of this episode in the inner disk was discovered by modeling the optical resolved star color-magnitude diagrams of low extinction regions in the main disk of M31 (3$<$R$<$20 kpc) as part of the Panchromatic Hubble Andromeda Treasury. This measurement confirms and extends recent measurements of a widespread star formation enhancement of similar age in the outer disk, suggesting that this burst was both massive and global. Following the galaxy-wide burst, the star formation rate of M31 has significantly declined. We briefly discuss possible causes for these features of the M31 evolutionary history, including interactions with M32, M33 and/or a merger.

12 pages, 2 tables, 6 figures, accepted for publication in ApJ

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Cited by in corpus (13)

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• Elemental Abundances in M31: Gradients in the Giant Stellar Stream
• The M31/M33 tidal interaction: A hydrodynamic simulation of the extended gas distribution
• The Panchromatic Hubble Andromeda Treasury XX: The Disk of M31 is Thick
• Unravelling stellar populations in the Andromeda Galaxy
• Measuring Star-Formation Histories, Distances, and Metallicities with Pixel Color-Magnitude Diagrams I: Model Definition and Mock Tests
• Large-scale Hydrodynamical Shocks as the Smoking Gun Evidence for a Bar in M31
• Measuring Star Formation Histories, Distances, and Metallicities with Pixel Color-Magnitude Diagrams II: Applications to Nearby Elliptical Galaxies
• Resolved SPLASH Chemodynamics in Andromeda's PHAT Stellar Halo and Disk: On the Nature of the Inner Halo Along the Major Axis
• Testing the Momentum-driven Supernova Feedback Paradigm in M31
• The role of mass loss in constraining quenching time in dwarf galaxies from AGB and RGB star counts
• The Panchromatic Hubble Andromeda Southern Treasury (PHAST). II. The Spatially Resolved Recent Star Formation History in M31