Multi-epoch X-ray spectral analysis of Centaurus A: revealing new constraints on iron emission line origins

Abstract

We conduct X-ray reverberation mapping and spectral analysis of the radio galaxy Centaurus A to uncover its central structure. We compare the light curve of the hard X-ray continuum from Swift Burst Alert Telescope observations with that of the Fe K$\alpha$ fluorescence line, derived from the Nuclear Spectroscopic Telescope Array (NuSTAR), Suzaku, XMM-Newton, and Swift X-ray Telescope observations. The analysis of the light curves suggests that a top-hat transfer function, commonly employed in reverberation mapping studies, is improbable. Instead, the relation between these light curves can be described by a transfer function featuring two components: one with a lag of $0.19_{-0.02}^{+0.10}\mathrm{pc}/c$, and another originating at $r>1.7\mathrm{pc}$ that produces an almost constant light curve. Further, we analyze the four-epoch NuSTAR and six-epoch Suzaku spectra, considering the time lag of the reflection component relative to the primary continuum. This spectral analysis supports that the reflecting material is Compton-thin, with $N_{\mathrm{H}}=3.14_{-0.74}^{+0.44}\times 10^{23}{\mathrm{cm}}^{-2}$. These results suggest that the Fe K$\alpha$ emission may originate from Compton-thin circumnuclear material located at sub-parsec scale, likely a dust torus, and materials at a greater distance.

19 pages, 13 figures, 7 tables, accepted for publication in PASJ

References in corpus (17)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• X-ray reverberation around accreting black holes
• Is Quasar Optical Variability a Damped Random Walk?
• The central parsecs of Centaurus A: High Excitation Gas, a Molecular Disk, and the Mass of the Black Hole
• The NuSTAR spectrum of Mrk 335: Extreme relativistic effects within 2 gravitational radii of the event horizon?
• IACHEC Cross-Calibration of Chandra, NuSTAR, Swift, Suzaku, and XMM-Newton with 3C 273 and PKS 2155-304
• Chandra and XMM-Newton Observations of the Nucleus of Centaurus A
• The broad band spectral variability of MCG-6-30-15 observed by NuSTAR and XMM-Newton
• On the difference of torus geometry between hidden and non-hidden broad line active galactic nuclei
• TANAMI monitoring of Centaurus A: The complex dynamics in the inner parsec of an extragalactic jet
• The Suzaku Observation of the Nucleus of the Radio-Loud Active Galaxy Centaurus A: Constraints on Abundances of the Accreting Material
• Systematic Study of AGN Clumpy Tori with Broadband X-ray Spectroscopy: Updated Unified Picture of AGN Structure
• Application of X-Ray Clumpy Torus Model (XCLUMPY) to 10 Obscured Active Galactic Nuclei Observed with Suzaku and NuSTAR
• NuSTAR hard X-ray spectra of radio galaxies
• Localizing narrow Fe K$\alpha$ emission within bright AGN
• The hard X-ray continuum of Cen A observed with INTEGRAL SPI
• Dust Reverberation Mapping of Type 2 AGN NGC 2110 Realized with X-ray and 3-5 $\mu$m IR monitoring