Investigating the star formation rates of AGNs in three LSST Deep-Drilling Fields relative to the star-forming main sequence

Nathan Cristello

A fundamental question in galaxy and black hole evolution remains how galaxies and their supermassive black holes have evolved together over cosmic time. Specifically, it is still unclear where active galactic nuclei (AGNs) reside with respect to the star-forming main sequence. We use data from three LSST Deep-Drilling Fields (W-CDF-S, ELAIS-S1, and XMM-LSS) to probe this issue in this work. These fields are covered by the largest medium depth X-ray survey and thus contain the largest sample to date for study. To ensure consistency, we locally derive the main sequence from a large reference galaxy sample. In our analysis, we demonstrate that the turnover of the galaxy star-forming main sequence does not allow reliable conclusions to be drawn for high mass AGNs, and we establish a robust safe regime where the results do not depend on the choice of main sequence definition. Under this framework, our results suggest that low mass AGNs (log M★ ~ 9.5 - 10.5 M⊙) generally possess enhanced star formation rates compared to their normal galaxy counterparts while the more common high mass AGNs (log M★ ~ 10.5 - 11.6 M⊙) lie on or below the star-forming main sequence. Further, we propose a model for the evolution of SFRnorm as a function of both M★ and LX.


This poster will be displayed on Monday and Tuesday.


Career Stage: 
Undergrad Student