WP 3 – Adulthood

Galaxy properties and AGN

What galaxy and environment properties facilitate accretion onto the black holes?

The focus of this comprehensive WP is on AGN host galaxies and their environment. We will exploit all the latest panchromatic surveys of AGN in the optical (SDSSIV, BOSS, and JPAS), X-rays (XXL, Stripe82X, XMM-Slew, ROSAT), IR (All WISE) and multiwavelength (LeMMINGs, for which SOTON has preferential access) – which are dominated by AGN in the adulthood peak/post-peak prolonged phase, most appropriate to maximize AGN occurrence in galaxies. Advanced Bayesian inference/Monte Carlo routines will efficiently account for multiple selection effects providing new and de-biased AGN luminosity functions, accretion rate densities, and spatial clustering. Cutting-edge deep-learning methods will be applied to AGN host galaxies’ morphologies.

Artist's impression of a dust-enshrouded black hole
An Artist’s impression of a dust-enshrouded black hole
Task 3A: Host galaxies and small-scale environment

Accurate determinations of AGN host galaxy morphologies can distinguish between secular (e.g., bars/clumps) and externally-induced (e.g., mergers) triggering events that led to the current phase of AGN activity (which is believed to be shorter than the timescale of disappearance of galaxy merger features). Additionally, we will study in detail the current star formation histories of AGN host galaxies. With its high spatial resolution (0.22 arcsec/pixel), J-PAS will allow for spatially-resolved AGN-galaxy SED fitting. The complete, panchromatic LeMMINGs sample will also be used to probe AGN accretion distributions down to the smallest galaxies/luminosities.

Task 3B: The large scale environments of AGN

We will provide accurate measures of the accretion and space density distributions of AGN as a function of redshift, luminosity and environment. In particular, recent X-ray surveys (e.g., XXL, Stripe82X) combine sufficient area and sensitivity that promise a leap forward in constraining AGN statistics in often neglected low luminosity regimes. AGN “clustering” (environmental/spatial distribution) as a function of luminosity and obscuration, can shed light on the role of interactions in triggering AGN, determining the host dark matter halo masses thus allowing comparisons to cosmological models (WP4). Intriguing preliminary results by BID4BEST members using this technique suggest that many AGN appear not to be caused by merger events.