Using principal component analysis to understand the variability of PDS 456

Abstract

We present a spectral-variability analysis of the low-redshift quasar PDS 456 using principal component analysis. In the XMM-Newton data, we find a strong peak in the first principal component at the energy of the Fe absorption line from the highly blueshifted outflow. This indicates that the absorption feature is more variable than the continuum, and that it is responding to the continuum. We find qualitatively different behaviour in the Suzaku data, which is dominated by changes in the column density of neutral absorption. In this case, we find no evidence of the absorption produced by the highly ionized gas being correlated with this variability. Additionally, we perform simulations of the source variability, and demonstrate that PCA can trivially distinguish between outflow variability correlated, anti-correlated, and un-correlated with the continuum flux. Here, the observed anti-correlation between the absorption line equivalent width and the continuum flux may be due to the ionization of the wind responding to the continuum. Finally, we compare our results with those found in the narrow-line Seyfert 1 IRAS 13224-3809. We find that the Fe K UFO feature is sharper and more prominent in PDS 456, but that it lacks the lower energy features from lighter elements found in IRAS 13224-3809, presumably due to differences in ionization.

arXiv comment7 pages, 8 figures, accepted to MNRAS (updated to correct Gallo & Fabian references)

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Cited by in corpus (28)

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• Searching for Ultra-fast Outflows in AGN using Variability Spectra
• Resolving the soft X-ray ultra fast outflow in PDS 456
• The variable, fast soft X-ray wind in PG 1211+143
• Variable Nature of Magnetically-Driven Ultra-Fast Outflows
• A momentum conserving accretion disk wind in the narrow line Seyfert 1, I Zwicky 1
• Extreme ultra-soft X-ray variability in an eROSITA observation of the Narrow-Line Seyfert 1 Galaxy 1H 0707-495
• Tracking the Iron K$\alpha$ line and the Ultra Fast Outflow in NGC 2992 at different accretion states
• The nature of the extreme X-ray variability in the NLS1 1H 0707-495
• 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
• Tell-Tale Spectral Signatures of MHD-driven Ultra-Fast Outflows in AGNs
• The flaring X-ray corona in the quasar PDS 456
• Modelling X-ray RMS spectra I: intrinsically variable AGN
• A high velocity component to the complex absorption in IRAS 13349+2438
• The X-ray Disk/Wind Degeneracy in AGN
• Supermassive Black Hole Winds in X-rays -- SUBWAYS. III. A population study on ultra-fast outflows
• A Rapid and Large-Amplitude X-ray Dimming Event in a z ~ 2.6 Radio-Quiet Quasar
• Resolving the X-ray obscuration in a low flux observation of the quasar PDS 456
• Detection of a possible multiphase ultra-fast outflow in IRAS 13349+2438 with NuSTAR and XMM-Newton
• X-ray Variability in the Symbiotic Binary RT Cru: Principal Component Analysis
• Modelling X-ray RMS spectra II: the ultra-fast outflow of PDS 456
• Stellar wind variability in Cygnus X-1 from high-resolution excess variance spectroscopy with Chandra
• Disentangling the X-ray variability in the Lyman continuum emitter Haro 11
• Effects of ultra-fast outflows on X-ray time lags in AGN
• Relativistic spectroscopy of the extreme NLS1 IRAS13224-3809
• Probing extreme black-hole outflows on short timescales via high spectral-resolution X-ray imagers
• IGR J12580+0134: The Nearest Tidal Disruption Event and its Faint Resurrection