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arXiv · 2307.02788

Resolving cosmic star formation histories of present-day bulges, disks, and spheroids with ProFuse

Sabine Bellstedt·Aaron S. G. Robotham·Simon P. Driver·Claudia del P. Lagos·Luke J. M. Davies·Robin H. W. Cook
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Abstract

We present the first look at star formation histories of galaxy components using ProFuse, a new technique to model the 2D distribution of light across multiple wavelengths using simultaneous spectral and spatial fitting of purely imaging data. We present a number of methods to classify galaxies structurally/morphologically, showing the similarities and discrepancies between these schemes. We show the variation in component-wise mass functions that can occur simply due to the use of a different classification method, which is most dramatic in separating bulges and spheroids. Rather than identifying the best-performing scheme, we use the spread of classifications to quantify uncertainty in our results. We study the cosmic star formation history (CSFH), forensically derived using ProFuse with a sample of ~7,000 galaxies from the Galaxy And Mass Assembly (GAMA) survey. Remarkably, the forensic CSFH recovered via both our method (ProFuse) and traditional SED fitting (ProSpect) are not only exactly consistent with each other over the past 8 Gyr, but also with the in-situ CSFH measured using ProSpect. Furthermore, we separate the CSFH by contributions from spheroids, bulges and disks. While the vast majority (70%) of present-day star formation takes place in the disk population, we show that 50% of the stars that formed at cosmic noon (8-12 Gyr ago) now reside in spheroids, and present-day bulges are composed of stars that were primarily formed in the very early Universe, with half their stars already formed ~12 Gyr ago.

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Sabine Bellstedt, Aaron S. G. Robotham, Simon P. Driver, Claudia del P. Lagos, Luke J. M. Davies, Robin H. W. Cook. 2023-07-06. Resolving cosmic star formation histories of present-day bulges, disks, and spheroids with ProFuse. https://arxiv.org/abs/2307.02788

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