Systematic comparison of photoionised plasma codes with application to spectroscopic studies of AGN in X-rays

Abstract

Atomic data and plasma models play a crucial role in the diagnosis and interpretation of astrophysical spectra, thus influencing our understanding of the universe. In this investigation we present a systematic comparison of the leading photoionisation codes to determine how much their intrinsic differences impact X-ray spectroscopic studies of hot plasmas in photoionisation equilibrium. We carry out our computations using the Cloudy, SPEX, and XSTAR photoionisation codes, and compare their derived thermal and ionisation states for various ionising spectral energy distributions. We examine the resulting absorption-line spectra from these codes for the case of ionised outflows in active galactic nuclei. By comparing the ionic abundances as a function of ionisation parameter $\xi$, we find that on average there is about 30% deviation between the codes in $\xi$ where ionic abundances peak. For H-like to B-like sequence ions alone, this deviation in $\xi$ is smaller at about 10% on average. The comparison of the absorption-line spectra in the X-ray band shows that there is on average about 30% deviation between the codes in the optical depth of the lines produced at log $\xi$ ~ 1 to 2, reducing to about 20% deviation at log $\xi$ ~ 3. We also simulate spectra of the ionised outflows with the current and upcoming high-resolution X-ray spectrometers, on board XMM-Newton, Chandra, Hitomi, and Athena. From these simulations we obtain the deviation on the best-fit model parameters, arising from the use of different photoionisation codes, which is about 10 to 40%. We compare the modelling uncertainties with the observational uncertainties from the simulations. The results highlight the importance of continuous development and enhancement of photoionisation codes for the upcoming era of X-ray astronomy with Athena.

Accepted for publication in Astronomy & Astrophysics (A&A), 15 pages, 9 figures

References in corpus (3)

• Atomic Data for X-ray Astrophysics
• Collisional Ionization Equilibrium for Optically Thin Plasmas. I. Updated Recombination Rate Coefficients for Bare though Sodium-like Ions
• Dielectronic recombination of Fe^{13+}: benchmarking the M-shell

Cited by in corpus (29)

• Chasing obscuration in type-I AGN: discovery of an eclipsing clumpy wind at the outer broad-line region of NGC 3783
• Density diagnostics of ionized outflows in active galactic nuclei: X-ray and UV absorption lines from metastable levels in Be-like to C-like ions
• Relation between winds and jets in radio-loud AGN
• Magnesium and silicon in interstellar dust: an X-ray overview
• Changing-look event in NGC 3516: continuum or obscuration variability?
• The nature of the extreme X-ray variability in the NLS1 1H 0707-495
• Transient obscuration event captured in NGC 3227. I. Continuum model for the broadband spectral energy distribution
• High-resolution X-ray spectroscopy of the stellar wind in Vela X-1 during a flare
• An ionised accretion disc wind in Hercules X-1
• Eppur si muove: Evidence of disc precession or a sub-milliparsec SMBH binary in the QPE-emitting galaxy GSN 069
• Multi-wavelength observations of the obscuring wind in the radio-quiet quasar MR 2251-178
• Vertical wind structure in an X-ray binary revealed by a precessing accretion disk
• Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-ray Excess
• A deep, multi-epoch Chandra HETG study of the ionized outflow from NGC 4051
• The lively accretion disk in NGC 2992. II. The 2019/2021 X-ray monitoring campaigns
• The multi-epoch X-ray tale of I Zwicky 1 outflows
• Stratified wind from a super-Eddington X-ray binary is slower than expected
• Science with hot astrophysical plasmas
• Observations of Her X-1 in low states during SRG/eROSITA all-sky survey
• The hot interstellar medium towards 4U 1820-30: a Bayesian analysis
• Chandra imaging of the $\sim$kpc extended outflow in 1H 0419-577
• A systematic study of photoionized emission and warm absorption signatures of the NLS1 Mrk 335
• Time-dependent photoionization spectroscopy of the Seyfert galaxy NGC 3783
• The long stare at Hercules X-1 -- I. Emission lines from the outer disk, the magnetosphere boundary and the accretion curtain
• New radiative loss curve from updates to collisional excitation in the low-density, optically thin plasmas in SPEX
• Transient obscuration event captured in NGC 3227 IV. Origin of the obscuring cloud variability
• Galaxy cluster photons alter the ionisation state of the nearby warm-hot intergalactic medium
• On the impact of an intermediate duration X-ray burst on the accretion environment in IGR J17062-6143
• Power of simultaneous X-ray and UV high-resolution spectroscopy for probing AGN outflows