Seminars take place in the lecture room of the Spořilov building (see contacts) unless noted otherwise.

Scheduled seminars

Constructing a Census of Growing Supermassive Black Holes - First Results from the NuLANDS Survey

Peter Boorman

Sensitive X-ray observations have revealed that most growing supermassive black holes (aka Active Galactic Nuclei - AGN) are obscured by large columns of gas, with their broadband spectra peaking in the X-ray and IR regimes. As such, these regimes carry complementary information about the AGN intrinsic and reprocessing structures. In this talk, I will discuss multiple techniques of selection and characterisation of obscured AGN, including new results based upon an X-ray 'Baldwin Effect' in heavily obscured sources. This study indicates that simplistic modelling of reprocessed X-ray spectra in highly obscured AGN underpredicts their growth rates, and thus a ‘representative' census of the entire AGN population is essential. To tackle this issue, we have begun the NuSTAR Local AGN N(H) Distribution Survey (NuLANDS) — a > 4 Ms legacy survey of AGN currently underway with NuSTAR, XMM-Newton and the Neil Gehrels Swift Observatory. The novel IR selection and optical classification of the sample ensures we are unbiased by X-ray obscuration up to the highest columns of material. I will present the preliminary results from the survey, most notably the indication that > 30% of all AGN in the local Universe are heavily obscured, and that hard X-ray selection alone preferentially selects less-obscured AGN. These preliminary NuLANDS results thus mark a major step towards completing the local census of accretion activity amongst AGN, as well as understanding the role obscuration plays in their evolution.

Location: Sporilov, mistnost 101

Radio-Active CoWS: Probing the Role of Environment on Radio-AGN at z~1 with MaDCoWS

Emily Moravec

AGN properties and dense environments are connected in a myriad of ways. For galaxies, the hot gas found in dense environments can impact AGN fueling and confine AGN outflows. Meanwhile, feedback from AGN jets can have a significant mechanical and thermal impact upon the surrounding gas. To better understand the interplay between AGN and the hot intracluster medium in galaxy clusters, we have been investigating the distribution of AGN and properties of the AGN population associated with z~1 galaxy clusters from the Massive and Distant Clusters of WISE Survey (MaDCoWS). I will first give an overview of MaDCoWS, which is the first cluster survey capable of discovering massive clusters at these redshifts over the full extragalactic sky, and will discuss key results from this program. I will then focus upon our studies of the AGN population. I will first discuss the distribution of AGN relative to the clusters. Then, I will present the results from a study with the JVLA to determine the radio morphologies of extended radio sources and the properties of their host-galaxies in a sub-sample of ~50 MaDCoWS clusters. Using optical, infrared, and radio data, we investigate correlations between the size and luminosity of the radio-AGN with stellar mass, cluster-centric radius, and cluster richness. We find a remarkable diversity of radio galaxy and host galaxy properties across a range of cluster properties.

Location: mistnost 101 Sporilov

If you would like to give a seminar, please contact Georgios Loukes-Gerakopoulos or Vladimír Karas.