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Beyond Models: A Direct Empirical Measurement of Galaxy Formation at z < 6

Presentation #310.05 in the session Evolution of Galaxies V.

Published onJun 29, 2022
Beyond Models: A Direct Empirical Measurement of Galaxy Formation at z < 6

We present a new observational approach to uncover empirically how galaxy formation occurred at z < 6 using a combination of measured minor and major mergers and the star formation history. We use data from the deepest ground-based and Hubble Space Telescope surveys of distant galaxies to measure the major and minor merger histories for galaxies at z < 3, and major mergers at z < 6, the highest redshifts where this type of study can be performed until JWST. We demonstrate through machine learning, structure, and pair analyses how the merger history evolves and determine the role of minor mergers for the first time within this process. We measure the star formation history for galaxies within the same stellar mass and redshift limits. This allows us to quantify the role of star formation as well as mergers within the galaxy formation process. We find that the role of star formation and mergers varies over cosmic time pointing towards different physical mechanisms driving galaxy formation at different epochs. We conclude with a discussion about the implications for these results in the broader context of galaxy formation models and theories.

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