Caroline Bertemes

About 90% of the stellar build-up in galaxies is thought to occur gradually on the Main Sequence (MS), with the tightness of this relation commonly interpreted as a consequence of the self-regulative nature of galaxies. Importantly, the scatter of the relation (at the level of ~0.2-0.3 dex across observed redshifts) encodes key information about the nature of the driver(s) of star formation. In particular, it is currently still unclear whether there are multiple pathways of stellar mass growth. In other words, does the observed scatter in the MS relation stem from systematic long-term differences in the star formation histories of galaxies residing above/below the Main Sequence today (set by e.g. variations in halo assembly)? Or can the spread simply be attributed to short-term stochastic fluctuations in the growth rates of galaxies (e.g. variations in gas inflow, minor mergers, "breathing" cycles of star-bursting episodes followed by a suppression due to feedback)?
The above questions are also indirectly related to the end of the lifecycle of galaxies. By discriminating between a predominantly smooth or bursty evolution of galaxies, quenching may be interpreted as a natural progression of a continuous decline in star formation (slow quenching) or a disruptive process (fast quenching).
Within this framework, I will present new insights into the the star formation histories of massive star-forming SDSS-IV MaNGA galaxies, as reconstructed via full spectro-photometric fitting with the novel stellar population synthesis code Bagpipes (Carnall et al., 2018).