The nature of the extreme X-ray variability in the NLS1 1H 0707-495

Abstract

We examine archival XMM-Newton data on the extremely variable narrow-line Seyfert 1 (NLS1) active galactic nucleus (AGN) 1H 0707-495. We construct fractional excess variance (Fvar) spectra for each epoch, including the recent 2019 observation taken simultaneously with eROSITA. We explore both intrinsic and environmental absorption origins for the variability in different epochs, and examine the effect of the photoionised emission lines from outflowing gas. In particular, we show that the unusual soft variability first detected by eROSITA in 2019 is due to a combination of an obscuration event and strong suppression of the variance at 1 keV by photoionised emission, which makes the variance below 1 keV appear more extreme. We also examine the variability on long timescales, between observations, and find that it is well described by a combination of intrinsic variability and absorption variability. We suggest that the typical extreme high frequency variability which 1H 0707-495 is known for is intrinsic to the source, but the large amplitude, low frequency variability that causes prolonged low-flux intervals is likely dominated by variable low-ionisation, low velocity absorption.

Ejection–accretion connection in NLS1 AGN 1H 1934-063

“…As we are mainly interested in the search for resolved spectral lines and evidence for outflows in 1H 1934, we start with a modelindependent spectral-variability analysis. According to Parker et al ( 2015Parker et al ( , 2017aParker et al ( , 2021, the principal component analysis (PCA) and the fractional root-mean-square (RMS) variability amplitude ( F var ) spectra could identify a series of variability peaks in both the first PCA component and F var spectrum corresponding to the strongest absorption lines from the UFO, because the UFO can be highly variable on timescale of hours or less and exhibit a rapid response to changes in the continuum. The PCA method performs a singular value decomposition (SVD) to decompose a matrix of spectra, and split it according to the given time bin, into a set of orthogonal PCs which account for the majority of the coherent variability of the source.…”

Effects of the refractive index of the X-ray corona on the emission lines in AGN

“…We remark that the imaginary part of n responsible for the absorption will determine the flux contribution in each energy band, hence affect the amount of dilution on reverberation features commonly seen in the lag spectra (Emmanoulopoulos et al 2014;Wilkins et al 2016;Ingram et al 2019;Caballero-García et al 2020) as well as in the PSD profiles (Emmanoulopoulos et al 2016;Papadakis et al 2016;Chainakun et al 2021,b). The imaginary part of n that dilutes the flux and produces wavelength-dependent absorption may be important for modelling other timing profiles such as the excess variance which is recently used to probe the intrinsic and absorption variability in AGN (Parker et al 2020(Parker et al , 2021. By treating n as a complex number, it would be possible to model the mean and timing spectra, and simultaneously fit them to the AGN data by, e.g., fine-tuning the real and imaginary parts of n.…”

Predicting the black hole mass and correlations in X-ray reverberating AGN using neural networks

“…For example, the Fvar can be affected by the constant or less-variable emission component, e.g. from outflowing gas, that is varied among different AGN (Parker et al 2021). The constant emission component raises the mean but does not affect the standard deviation of the data, so the Fvar decreases.…”

“…Vaughan, Fabian, & Nandra 2003). Recently, the Fvar spectra have been used to probe the intrinsic and environmental absorption origins for the X-ray variability in AGN (Parker et al 2021).…”