My research is focussed on the study of accreting supermassive black holes, also called Active Galactic Nuclei (AGN). In the last decades it has become evident that probably most galaxies have gone through an AGN phase, which might have played a crucial role in their formation and evolution.

My work is aimed at constraining the structure and evolution of the material surrounding supermassive black holes. To do so I mostly use X-ray and multi-wavelength observations (optical and IR in particular). X-rays are a great tool to study the inner regions of supermassive black holes, since they are produced very close to the central engine. Studying the emission absorbed and reprocessed by the circumnuclear material it is possible to shed light on the structure and evolution of the environment of supermassive black holes.

  Artistic representation of the circumnuclear material around an AGN
(Credits: NASA)

 

In the past years I have been working very actively on the BAT AGN Spectroscopical Survey (BASS). This multi-wavelength all-sky survey is based on the AGN detected by the NASA hard X-ray satellite Swift/BAT. The energy range probed by Swift/BAT (14-195 keV) guarantees that the sample is unbiased by obscuration up to Compton-thick column densities, making it the most complete sample of local AGN available. Within the BASS collaboration I am in charge of the broad-band X-ray analysis of all BAT-detected AGN, and of the studies of the obscuration properties.

Since 2015 I have also been intensively working with the NuSTAR science team. NuSTAR is a NASA-led astronomical satellite with the first focussing hard X-ray telescope in-orbit. One of my main achievements with NuSTAR was the recent discovery that most AGN located in U/LIRGs undergoing mergers are obscured. In particular, we found that the obscuring material around AGN in the last stages of mergers almost fully covers the supermassive black hole. We also found an enhancement in the fraction of Compto-thick AGN in mergers with respect to those in isolated galaxies. You can read the NASA press release about this article here.

  AGN detected by the Swift/BAT survey (Ricci et al. 2017c)