A Physical Model for the X-ray Time Lags of Narrow Line Seyfert Type 1 Active Galactic Nuclei

Abstract

We study the origin of the soft X-ray excess seen in the 'simple' Narrow Line Seyfert 1 galaxy PG1244+026 using all available spectral-timing information. This object shows the standard switch between soft leading the hard band on long timescales, to the opposite behaviour on short timescales. This is interpreted as a combination of intrinsic fluctuations propagating down through the accretion flow giving the soft lead, together with reflection of the hard X-rays giving the soft lag. We build a full model of the spectral and time variability including both propagation and reflection, and compare our model with the observed power spectra, coherence, covariance, lag-frequency and lag-energy spectra. We compare models based on a separate soft excess component with those based on reflection dominated soft emission. Reflection dominated spectra have difficulty reproducing the soft lead at low frequency since reflection will always lag. They also suffer from high coherence and nearly identical hard and soft band power spectra in disagreement with the observations. This is a direct result of the power law and reflection components both contributing to the hard and soft energy bands, and the small radii over which the relativistically smeared reflection is produced transmitting too much high frequency power into the soft band. Conversely, we find the separate soft excess models (where the inner disc radius is $>6R_g$) have difficulty reproducing the soft lag at high frequency, as reflected flux does not contribute enough signal to overwhelm the soft lead. However, reflection should also be accompanied by reprocessing and this should add to the soft excess at low energies. This model can quantitatively reproduce the switch from soft lead to soft lag seen in the data and reproduces well the observed power spectra and other timing features which reflection dominated models cannot.

arXiv comment19 pages, 15 figures; accepted for publication in MNRAS

References in corpus (29)

• Intrinsic disc emission and the Soft X-ray Excess in AGN
• RXTE Observation of Cygnus X-1: II. Timing Analysis
• An Explanation for the soft X-ray excess in AGN
• Is the soft excess in AGN real?
• Investigating a Fluctuating-accretion Model for the Spectral-timing Properties of Accreting Black Hole Systems
• On the X-ray time lags in the black hole candidates
• Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton
• Discovery of a relation between black hole mass and soft X-ray time lags in active galactic nuclei
• X-Ray Variability Coherence: How to Compute it, What it Means, and How it Constrains Models of Cyg X-1 and GX 339-4
• XMM-Newton EPIC observations of 21 low-redshift PG quasars
• A physical model for the continuum variability and QPO in accreting black holes
• The causal connection between disc and power-law variability in hard state black hole X-ray binaries
• Spectral evolution of magnetic flares and time lags in accreting black hole sources
• X-ray continuum variability of MCG-6-30-15
• X-ray reflection in the NLS1 1H 0707-495
• Accretion disc variability in the hard state of black hole X-ray binaries
• Multiwavelength campaign on Mrk 509. IV. Optical-UV-X-ray variability and the nature of the soft X-ray excess
• Universal spectral shape of high accretion rate AGN
• Modelling variability in black hole binaries: linking simulations to observations
• Investigating the nature of narrow-line Seyfert 1 galaxies with high-energy spectral complexity
• Frequency-dependent time lags in the X-ray emission of the Seyfert galaxy NGC 7469
• Negative X-ray reverberation time delays from MCG-6-30-15 and Mrk 766
• The Closest Look at 1H0707-495: X-ray Reverberation Lags with 1.3 Ms of Data
• The soft X-ray emission of Ark 120. XMM-Newton, NuSTAR, and the importance of taking the broad view
• Understanding Reverberation Lags in 1H0707-495
• A new way to measure supermassive black hole spin in accretion disc dominated Active Galaxies
• A soft X-ray reverberation lag in the AGN ESO 113-G010
• The curious time lags of PG 1244+026: Discovery of the iron K reverberation lag
• Can the soft excess in AGN originate from disc reflection?

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• A Consistent Picture Emerges: A Compact X-ray Continuum Emission Region in the Gravitationally Lensed Quasar SDSS J0924+0219
• EUCLIA - Exploring the UV/optical continuum lag in active galactic nuclei. I. a model without light echoing
• Super-Eddington QSO RX J0439.6-5311. I. Origin of the Soft X-ray Excess and Structure of the Inner Accretion Flow
• Super-Eddington QSO RX J0439.6-5311. II. Multi-wavelength Constraints on the Global Structure of the Accretion Flow
• A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070
• A Physical Model for the Spectral-Timing Properties of Accreting Black Holes
• Re-observing the NLS1 Galaxy RE J1034+396. II. New Insights on the Soft X-ray Excess, QPO and the Analogy with GRS 1915+105
• The thermal-radiative wind in low mass X-ray binary H 1743-322; Radiation hydrodynamic simulations
• Returning radiation in strong gravity around black holes: Reverberation from the accretion disc
• X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei
• X-ray reverberation lags of the Fe-K line due to AGN disc winds
• Direct probe of the inner accretion flow around the supermassive black hole in NGC 2617
• Reaching the Peak of the quasar spectral energy distribution - II. Exploring the accretion disc, dusty torus and host galaxy
• Reaching the Peak of the Quasar Spectral Energy Distribution I: Observations and Models
• Accretion disk/corona emission from a radio-loud narrow line Seyfert 1 galaxy PKS 0558-504
• Complex Narrow Line Seyfert 1s: High spin or high inclination?
• Evolution of the truncated disc and inner hot-flow of GX 339-4
• X-ray variability analysis of a large series of XMM-Newton + NuSTAR observations of NGC 3227
• Discovery of soft and hard X-ray time lags in low-mass AGNs
• X-ray time lags in PG 1211+143
• X-ray Lags in PDS 456 Revealed by Suzaku Observations
• Observations of X-ray reverberation around black holes
• X-ray spectral and temporal analysis of Narrow Line Seyfert 1 galaxy Was 61
• Spectral Energy Distribution Variations of Nearby Seyfert Galaxies During AGN Watch Monitoring Programs
• A Systematic Study of the Short-Term X-ray Variability of Seyfert Galaxies I. Diversity of the X-ray Rms Spectra
• An Analytical Fourier-Transformation Model for the Production of Hard and Soft X-Ray Time Lags in AGNs: Application to 1H 0707-495
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