X-ray flaring in PDS 456 observed in a high-flux state

Abstract

We present an analysis of a $190$\,ks (net exposure) \textit{Suzaku} observation, carried out in 2007, of the nearby ($z=0.184$) luminous (L${}_{\mathrm{bol}}\sim 10^{47}$\,erg\,s${}^{-1}$) quasar PDS\,456. In this observation, the intrinsically steep bare continuum is revealed compared to subsequent observations, carried out in 2011 and 2013, where the source is fainter, harder and more absorbed. We detected two pairs of prominent hard and soft flares, restricted to the first and second half of the observation respectively. The flares occur on timescales of the order of $\sim 50$\,ks, which is equivalent to a light-crossing distance of $\sim 10R_{\mathrm{g}}$ in PDS\,456. From the spectral variability observed during the flares, we find that the continuum changes appear to be dominated by two components: (i) a variable soft component ($<2$\,keV), which may be related to the Comptonized tail of the disc emission, and (ii) a variable hard power-law component ($>2$\,keV). The photon index of the latter power-law component appears to respond to changes in the soft band flux, increasing during the soft X-ray flares. Here the softening of the spectra, observed during the flares, may be due to Compton cooling of the disc corona induced by the increased soft X-ray photon seed flux. In contrast, we rule out partial covering absorption as the physical mechanism behind the observed short timescale spectral variability, as the timescales are likely too short to be accounted for by absorption variability.

arXiv comment34 pages, 13 figures, accepted for publication in MNRAS

References in corpus (41)

• On the Absorption of X-rays in the Interstellar Medium
• On characterising the variability properties of X-ray light curves from active galaxies
• Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter
• Hard X-ray Detector (HXD) on Board Suzaku
• Intrinsic disc emission and the Soft X-ray Excess in AGN
• An Explanation for the soft X-ray excess in AGN
• Ubiquitous variability of X-ray absorbing column densities in Seyfert 2 Galaxies
• A Massive X-Ray Outflow from the Quasar PDS 456
• Black hole feedback in the luminous quasar PDS 456
• Occultation measurement of the size of the X-ray emitting region in the Active Galactic Nucleus of NGC 1365
• Broad iron L-line and X-ray reverberation in 1H0707-495
• A Compton-thick Wind in the High Luminosity Quasar, PDS 456
• A long, hard look at MCG-6-30-15 with XMM-Newton II: detailed EPIC analysis and modelling
• An absorption origin for the X-ray spectral variability of MCG-6-30-15
• Magnetic reconnection: flares and coronal heating in Active Galactic Nuclei
• Discovery of high-frequency iron K lags in Ark 564 and Mrk 335
• The Fragmentation of Pre-enriched Primordial Objects
• The variable X-ray spectrum of Markarian 766 - I. Principal components analysis
• Simultaneous NuSTAR and XMM-Newton 0.5-80 keV spectroscopy of the Narrow Line Seyfert 1 galaxy SWIFT J2127.4+5654
• X-ray reverberation in 1H0707-495 revisited
• A reflection origin for the soft and hard X-ray excess of Ark 120
• A blurred reflection interpretation for the intermediate flux state in Mrk 335
• Short term X-ray spectral variability of the quasar PDS 456 observed in a low flux state
• Broadband study of hard X-ray selected absorbed AGN
• Revealing the X-ray Variability of AGN with Principal Component Analysis
• The Connection between Ultraviolet and X-ray Outflows in AGN: the case of PDS 456
• Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456
• Discovery of a Luminous Quasar in the Nearby Universe
• PDS 456: an Extreme Accretion Rate Quasar?
• Evidence for Nonlinear X-ray Variability from the Broad-line Radio Galaxy 3C 390.3
• Optical and infrared observations of the luminous quasar PDS 456: a radio-quiet analogue of 3C 273?
• X-ray Characteristics of NGC 3516: A View through the Complex Absorber
• Extreme X-ray variability in the luminous quasar PDS 456
• ASTE Observations of Warm Gas in Low-mass Protostellar Envelopes: Different Kinematics between Submillimeter and Millimeter Lines
• The effects of X-ray absorption variability in NGC 4395
• Variability of the High Velocity Outflow in the Quasar PDS 456
• Revealing the location and structure of the accretion disk-wind in PDS456
• A Variable Partial Covering Model for the Seyfert 1 Galaxy MCG-6-30-15
• Direct Measurement of the X-ray Time-Delay Transfer Function in Active Galactic Nuclei
• The Global Implications of the Hard X-ray Excess in Type 1 AGN
• Remarkable Spectral Variability of PDS 456

Cited by in corpus (17)

• A physical model of the broadband continuum of AGN and its implications for the UV/X relation and optical variability
• Evidence for a radiatively driven disc-wind in PDS 456?
• Resolving the soft X-ray ultra fast outflow in PDS 456
• Tracking the Iron K$\alpha$ line and the Ultra Fast Outflow in NGC 2992 at different accretion states
• The soft excess of the NLS1 galaxy Mrk 359 studied with an XMM-Newton-NuSTAR monitoring campaign
• Using principal component analysis to understand the variability of PDS 456
• Relativistic components of the Ultra-Fast Outflow in the Quasar PDS 456 from Chandra/HETGS, NuSTAR and XMM-Newton observations
• The first broadband X-ray view of the narrow line Seyfert 1 Ton S180
• NuSTAR view of the black hole wind in the galaxy merger IRAS F11119$+$3257
• The flaring X-ray corona in the quasar PDS 456
• Magnetohydrodynamic Winds Driven by the Line Force from the Standard Thin Disk around Supermassive Black Holes. I. The Case of Weak Magnetic Field
• Detection of a possible multiphase ultra-fast outflow in IRAS 13349+2438 with NuSTAR and XMM-Newton
• The lively accretion disk in NGC 2992. II. The 2019/2021 X-ray monitoring campaigns
• X-ray Lags in PDS 456 Revealed by Suzaku Observations
• XMM-Newton --NuSTAR monitoring campaign of the Seyfert 1 galaxy IC 4329A
• Relativistic Reflection Modeling in AGN and Related Variability from PCA: A Brief Review
• Accretion-disk reflection in the Seyfert 1 galaxy NGC 3783 as viewed by Chandra grating spectroscopy