Lunch talk on Jun. 18, 2025

Seyfert 1 NGC 3783 from soft to hard X-ray: Absorption, Reflection and spectral-timing technique

Speaker: Chen Li (Leiden University)

Venue: SWIFAR Building 2111

Time: 12:45 PM, Wednesday, Jun. 18, 2025

Abstract: 

Active galactic nuclei (AGN) of active galaxy are powerful sources of multiple-band radiation. As gas funnels in toward the supermassive black hole (SMBH) at the center of a galaxy, collisions and angular momentum conservation cause the formation of an optically thick, geometrically thin accretion disk around the black hole. Outward from accretion disk, dusty torus of infrared emission resides and contributing the infrared emission, which transitions into the broad-line region (BLR). Closer in, the X-ray emitting region, popularly known as the corona, is geometrically and radiatively compact with a size typically ≲ 10Rg  which was thought dynamic structure as its rapid and extreme variability. The Fe fluorescence emission line as a tracer was able to revel the different scale reflection component of disk illuminated by X-ray corona. In other hands, outflows from AGN are one of the fundamental mechanisms by which the central SMBH interacts with its host galaxy. Detected in ≥50% of nearby AGNs, these outflows have been found to carry kinetic energy that is a large fraction of the AGN power, and thereby give feedback to their host galaxies. Outflow detected in X-ray band usually was illuminated by X-ray source corona, which make outflow photoionization (non-) equilibrium and imprint information in absorption spectroscopy. Hence, the dynamics, kinematics, and ionization structure of ionized outflows—ranging from the vicinity of the accretion disk to the outer regions of the host galaxy—determine how these outflows transfer momentum and energy into the galaxy and influence their surroundings. Especially, determining the precise distance at which the outflow is launched is essential for investigating the launching mechanism and the impact of outflow on the surrounding medium. In my PhD period, I have worked on these two topics (with absorption and emission spectrum) in NGC 3783, including time-dependent photoionization modelling and spectral-timing method to determine sub-pc distance of X-ray outflow, and Fe K-alpha emission lines complex modelling to diagnose the accretion disk from innermost to outmost.  In my talk, I will mainly focus on to talk about my X-ray outflow projects in NGC 3783 which to calculate and/or determine the distance of outflow with time-dependent photoionization model and spectral-timing technique. In addition to, I also will briefly update you the preliminary revolutionary result of Fe K-alpha emission modelling of NGC 3783 with the unprecedented power of X-ray micro-calorimeter spectroscopy onboard XRISM. It’s extraordinary high energy resolution of 4.5 eV @6.4 keV enable us to resolve the Fe K alpha emission extremely well, which can be compared with other wavelength observation, such as VLTI/gravity and optical reverberation mapping.

Report PPT:  SWIFA_Chen Li.pptx