Shining light on the census of supermassive black hole accretion with NuLANDS
Abstract
Most mass is accreted onto supermassive black holes behind thick columns of gas and dust in the nuclei of large galaxies. An accurate assessment of the material feeding and obscuring the central engine in Active Galactic Nuclei (AGN) provides important insights into the co-evolution of supermassive black holes and galaxies across cosmic time. However, current estimates of the heavily obscured AGN fraction vary drastically between $\sim 10-60\%$ of the entire population, and it remains unclear what drives this broad range. A striking handicap of previous works has been the inability to effectively select heavily obscured AGN with approximately equal probability relative to the (often brighter) less-obscured AGN population. To investigate such issues, I present NuLANDS - one of the largest NuSTAR legacy surveys ever performed based on joint far-IR/X-ray constraints, aimed at constructing an obscuration-unbiased census of AGN in the local Universe. In this talk, I highlight the importance of multi-wavelength selection in bypassing obscuration biases and describe the computational challenges faced when uniformly exploring complex multi-dimensional parameter spaces for many sources. I will then present the first results from NuLANDS, finding the fraction of heavily obscured AGN to be consistent with the most recent predictions from Cosmic X-ray Background modelling. NuLANDS thus marks a major step in completing the census of supermassive black hole activity in the nearby Universe and will provide vital insights into the densest regions of the AGN obscurer.
- Publication:
-
Black-hole activity feedback from Bondi-radius to galaxy-cluster scales
- Pub Date:
- June 2022
- Bibcode:
- 2022bhaf.confE..37B
- Keywords:
-
- supermassive black hole;
- AGN;
- galactic nuclei