26-30 June 2023
Centro Congressi Federico II
Europe/Rome timezone

Evidence for short-term column density variability in the nearby changing-look Compton thick AGN NGC 1358: results from a multi-year NuSTAR-XMM-Newton monitoring to characterize the obscuring medium nearby accreting supermassive black holes

Not scheduled
Aula Magna (Centro Congressi Federico II)

Aula Magna

Centro Congressi Federico II

Via Partenope, 36, Napoli, Italy
Poster Poster


Stefano Marchesi (Università di Bologna)


In this talk, I will present the results of a multi-epoch monitoring with NuSTAR and XMM-Newton of NGC 1358, a heavily obscured AGN whose properties made it an ideal changing look candidate.

The source was indeed found to be highly variable in line-of-sight column density (NHlos) over time-scales from weeks to years, even transitioning from a Compton thick state (NHlos>1E24 cm-2) to a Compton thin one. By measuring both luminosity and column density variability over such a wide range of time-scales, we found a a tentative anti-correlation between the two parameters: the more luminous the AGN, the smaller the amount of NHlos. Such a result can be understood in the framework of Chaotic Cold Accretion clouds driving recursive AGN feedback.

Besides this important result, our monitoring campaign proved how a multi epoch X-ray monitoring is key to simultaneously constraining the three otherwise highly degenerate parameters that define the obscuring medium geometry: the torus average column density and covering factor, and the inclination angle between the torus axis and the observer.

In the final part of the talk, I will briefly discuss how we plan to soon extend this multi-epoch approach to a larger sample of heavily obscured, nearby AGN, to better characterize the properties of the obscuring material surrounding accreting supermassive black holes, as well as constrain AGN feeding models.

Primary author

Stefano Marchesi (Università di Bologna)

Presentation Materials

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