Variable Nature of Accretion Disk Outflows around Supermassive Black Holes in Active Galaxies

Authors

• Mary Ogborn, James Madison UniversityFollow

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Date of Graduation

5-2021

Semester of Graduation

Spring

Publish

yes

Degree Name

Bachelor of Science (BS)

Department

Department of Physics and Astronomy

First Advisor

Keigo Fukumura

Second Advisor

Sean Scully

Third Advisor

Sean Scully

Abstract

Seyfert galaxies are a sub-class of active galactic nuclei (AGNs) in which outflows are ubiquitously observed and thought to be produced from accretion disks surrounding supermassive black holes (SMBHs). These outflows manifest themselves as blueshifted absorption features in their X-Ray spectra (aka. warm absorbers (WAs)), allowing for spectroscopic analysis to examine the physical conditions of the constituent plasma as well as the AGN itself. In the context of magnetohydrodynamics (MHD), we utilize a magnetically-driven disk-wind model that describes the behavior within the disk and to study 3 exemplary Seyfert 1 AGNs in an effort to constrain the strength of the observed winds using multi-epoch space-borne Chandra X-Ray Observatory’s High Energy Transmission Grating Spectrometer (HETGS) data. By spectral modeling, we find that the observed multi-ion X-Ray absorbers are well accounted for by the MHD wind model in the timeaveraged spectra suggesting the density of 20 × 1012-40 × 1012 cm−3 at the base of the outflows. Using the time-resolved spectra, it is implied that the wind conditions in general appear to remain almost unchanged over multi-epoch observations. On the other hand, we also find a few epochs in which the wind density seems to vary (e.g. ∼ 20 × 1012 cm−3 to ∼ 90 × 1012 cm−3 over the time-scale of ∼ 4 months) at a statistically significant level, which could be attributed to the intrinsic change in the wind property. We also demonstrate the feasibility of detecting these winds expected from future micro-calorimeter X-Ray missions (i.e. XRISM and Athena) by calculating simulated spectra