Astronomy Tea Talk

Speaker 1: Dr. Ross Silver

Title: The NuSTAR and XMM-Newton Survey of the North Ecliptic Pole Time Domain Field

Abstract:

The North Ecliptic Pole (NEP) Time Domain Field (TDF) is a unique portion of the sky well equipped for time-domain studies because it resides in the JWST northern continuous viewing zone (CVZ) and it has a superb combination of low foreground extinction and an absence of AB<= 16 mag stars. This region has now been observed by NuSTAR for 2.64 Ms in three different cycles thus far, making it the deepest NuSTAR extragalactic survey to date, with an additional 900ks being taken during Cycle 9. Moreover, the NuSTAR survey's main goal was to observe simultaneously with JWST. Concurrent XMM-Newton observations are also available to perform a broadband X-ray analysis. In this talk, I present the results of this multiwavelength variability campaign, including the deepest measurement of the LogN-LogS in the hard X-rays and CT fraction.

Speaker 2: Dr. Xiurui Zhao

Title: A systematic study of AGN torus with NuSTAR

Abstract:

The dusty torus is an important component of the active galactic nuclei (AGN) surrounding the center supermassive black hole (SMBH). It is believed that AGN are observed in different types due to the dusty torus: type 2 AGN are those AGN whose broad line region is obscured by the dusty torus. However, the physical and geometrical properties are still unclear to date, due to its tiny size (~1 pc). In this talk, I will present our recent effort to study the torus using hard X-ray spectroscopy with NuSTAR using a sample of heavily obscured AGN. We found that the AGN tori are optically and geometrically thick with its average column density of 10^24 cm-2 and average covering factor of 67%.