Stacked star formation rate profiles of bursty galaxies exhibit 'coherent' star formation

Abstract

In a recent work based on 3200 stacked H$\alpha$ maps of galaxies at $z\sim 1$, Nelson et al.~find evidence for `coherent star formation': the stacked SFR profiles of galaxies above (below) the 'star formation main sequence' (MS) are above (below) that of galaxies on the MS at all radii. One might interpret this result as inconsistent with highly bursty star formation and evidence that galaxies evolve smoothly along the MS rather than crossing it many times. We analyze six simulated galaxies at $z\sim 1$ from the Feedback in Realistic Environments (FIRE) project in a manner analogous to the observations to test whether the above interpretations are correct. The trends in stacked SFR profiles are qualitatively consistent with those observed. However, SFR profiles of individual galaxies are much more complex than the stacked profiles: the former can be flat or even peak at large radii because of the highly clustered nature of star formation in the simulations. Moreover, the SFR profiles of individual galaxies above (below) the MS are not systematically above (below) those of MS galaxies at all radii. We conclude that the time-averaged coherent star formation evident stacks of observed galaxies is consistent with highly bursty, clumpy star formation of individual galaxies and is not evidence that galaxies evolve smoothly along the MS.

7 pages, 4 figures, accepted for publication in ApJL

References in corpus (8)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization
• Star formation in AEGIS field galaxies since z=1.1 . Staged galaxy formation, and a model of mass-dependent gas exhaustion
• The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation

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