Constant Pressure Model for Warm Absorber in Mrk 509 Reveals Outflow Structures from 900 Ks XMM-Newton Data

Understanding the powerful outflows from active galaxies is crucial to understanding their influence on surrounding environments, and a team led by Krzysztof Hryniewicz from the National Centre for Nuclear Research, Agata Różańska from the Nicolaus Copernicus Astronomical Centre, and Tek Prasad Adhikari from the University of Science and Technology of China now presents a new approach to modelling these phenomena. The researchers analysed high-resolution X-ray observations of the nearby galaxy Mrk 509, developing a self-consistent model that treats the warm absorber, a gas cloud absorbing X-rays, as a stratified medium held at constant total pressure. This method allows the team to simultaneously fit the overall energy distribution and the detailed absorption lines, providing stronger constraints on the gas structure than previous analyses. The resulting model successfully explains the observed spectrum of Mrk 509, pinpointing the warm absorber cloud’s location at just 0. 02 parsecs from the galaxy’s centre, consistent with its proximity to the accretion disk and broad line region.

Warm Absorber and Foreground Absorption Analysis

The team meticulously analysed X-ray spectra from Mrk 509, obtained with the Reflection Grating Spectrometer on the XMM-Newton satellite. They focused on identifying and modelling both the intrinsic absorption from gas surrounding the galaxy and absorption from gas within our own galaxy along the line of sight. The analysis carefully accounts for all absorption, as well as instrumental effects, to accurately model the underlying X-ray emission and identify spectral features, ultimately determining the temperature, density, and ionization state of the absorbing material. The research involved detailed modelling of the observed X-ray spectrum, starting with a broad continuum representing the galaxy’s overall emission. Absorption components were then added to account for gas in our galaxy and the warm absorber surrounding Mrk 509, alongside emission lines originating from the galaxy’s central engine. By carefully accounting for these components, they accurately determined the physical properties of the absorbing gas.

Constant Pressure Warm Absorber in Mrk 509

Scientists demonstrate that a model of gas under constant total pressure accurately explains the observed X-ray spectrum of Mrk 509. The team modelled the warm absorber as a stratified medium where the total pressure remains constant, generating a grid of synthetic spectra using the Titan photoionization code and comparing them to the observed data. The models incorporate multiwavelength observations to define the illuminating energy distribution and account for absorption from intervening gas. The best-fit model is relatively thin, with a hydrogen column density consistent with previous analyses, and the observed absorption lines are not saturated, indicating an accurate capture of the gas’s properties. The.

Warm Absorber Located Near Accretion Disk

This research presents a detailed analysis of warm absorber gas in Mrk 509, utilizing high-resolution X-ray observations and a physically motivated model of gas under constant total pressure. By modelling the warm absorber as a stratified medium, the team successfully fitted the observed X-ray spectra and constrained the physical properties of the absorbing gas, including its density and location, indicating the warm absorber cloud resides near the inner regions of the accretion disk and broad line region. The study builds upon previous work and demonstrates that a constant total pressure model effectively explains the observed data, providing a more comprehensive understanding of the gas structure. The team acknowledges the challenges associated with computational complexity and spectral fitting, but their findings represent a significant step forward in understanding the properties and dynamics of outflows in active galactic nuclei, and future research may focus on refining these models and exploring thermal instabilities within the photoionized gas.