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Register a new userOn the relativistic iron line and soft excess in the Seyfert 1 galaxy Markarian 335
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Paul M. ONeill
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We report on a 133 ks XMM-Newton observation of the Seyfert 1 galaxy Markarian 335. The 0.4-12 keV spectrum contains an underlying power law continuum, a soft excess below 2 keV, and a double-peaked iron emission feature in the 6-7 keV range. We investigate the possibility that the double-peaked emission might represent the characteristic signature of the accretion disc. Detailed investigations show that a moderately broad, accretion disc line is most likely present, but that the peaks may be owing to narrower components from more distant material. The peaks at 6.4 and 7 keV can be identified, respectively, with the molecular torus in active galactic nucleus unification schemes, and very highly ionized, optically thin gas filling the torus. The X-ray variability spectra on both long (~100 ks) and short (~1 ks) timescales disfavour the recent suggestion that the soft excess is an artifact of variable, moderately ionized absorption.
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We present for the first time the timing and spectral analyses for a narrow-line Seyfert 1 galaxy, SBS 1353+564, using it{XMM-Newton} and it{Swift} multi-band observations from 2007 to 2019. Our main results are as follows: 1) The temporal variability of SBS 1353+564 is random, while the hardness ratio is relatively constant over a time span of 13 years; 2) We find a prominent soft X-ray excess feature below 2 keV, which cannot be well described by a simple blackbody component; 3) After comparing the two most prevailing models for interpreting the origin of the soft X-ray excess, we find that the relativistically smeared reflection model is unable to fit the data above 5 keV well and the X-ray spectra do not show any reflection features, such as the Fe Kalpha emission line. However, the warm corona model can obtain a good fitting result. For the warm corona model, we try to use three different sets of spin values to fit the data and derive different best-fitting parameter sets; 4) We compare the UV/optical spectral data with the extrapolated values of the warm corona model to determine which spin value is more appropriate for this source, and we find that the warm corona model with non-spin can sufficiently account for the soft X-ray excess in SBS 1353+564.
We have carried out a systematic analysis of the nearby (z=0.0279) active galaxy Zw 229.015 using multi-epoch, multi-instrument and deep pointed observations with XMM-Newton, Suzaku, Swift and NuSTAR. Spectral and temporal variability are examined in detail on both the long (weeks-to-years) and short (hours) timescales. A deep Suzaku observation of the source shows two distinct spectral states; a bright-soft state and a dim-hard state in which changes in the power law component account for the differences. Partial covering, blurred reflection and soft Comptonisation models describe the X-ray spectra comparably well, but the smooth, rather featureless, spectrum may be favouring the soft Comptonisation scenario. Moreover, independent of the spectral model, the observed spectral variability is ascribed to the changes in the power law continuum only and do not require changes in the properties of the absorber or blurred reflector incorporated in the other scenarios. The multi-epoch observations between 2009 and 2018 can be described in similar fashion. This could be understood if the primary emission is originating at a large distance from a standard accretion disc or if the disc is optically thin and geometrically thick as recently proposed for Zw 229.015. Our investigation shows that Zw 229.015 behaves similar to sources like Akn 120 and Mrk 530, that exhibit a strong soft-excess, but weak Compton hump and Fe K${alpha}$ emission.
I report the discovery of a prominent broad and asymmetrical feature near 6.4 keV in the Seyfert 1 MCG-02-14-009 (z=0.028) with XMM-Newton/EPIC. The present short X-ray observation (PN net exposure time ~5 ks) is the first one above 2 keV for MCG-02-14-009. The feature can be explained by either a relativistic iron line around either a Schwarzschild (non-rotating) or a Kerr (rotating) black hole. If the feature is a relativistic iron line around a Schwarzschild black hole, the line energy is 6.51 (+0.21,-0.12) keV with an equivalent width of 631 (+259,-243) eV and that the inclination angle of the accretion disc should be less than 43 degrees. A relativistically blurred photoionized disc model gives a very good spectral fit over the broad band 0.2-12keV energy range. The spectrum is reflection dominated and this would indicate that the primary source in MCG-02-14-009 is located very close to the black hole, where gravitational light bending effect is important (about 3-4 Rg), and that the black hole may rapidly rotate.
The origin of soft X-ray excess emission from type 1 active galactic nuclei has remained a major problem for the last two decades. It has not been possible to distinguish alternative models for the soft excess emission despite the excellent data quality provided by XMM-Newton and Chandra. Here we present observations of time lags between the soft and hard band X-ray emission and discuss the implications to the models for the soft excess. We also device a method to distinguish the models for the soft excess using Suzakus broadband capability.
We present the results of an extensive analysis of the ``ASCA AO2 observation of the Seyfert 1 galaxy NGC4051. The target exhibits broadband [0.5--10 keV] variability by a factor $sim 8$ on time scales $sim 10^4 s$, with a typical doubling time $sim 500 s$. The spectrum is characterized by a strong emission excess over the extrapolated power law at energies $E le 1 keV$. Absorption edges due to ionized oxygen species OVII and OVIII are detected together with an emission-like feature at $E sim 0.93 keV$. The OVII edge undergoes significant variability on a timescale as low as $sim 10^4 s$, whilst no contemporary variability of the OVIII feature is detected. Typical variability time scales place constraints on the location and the density of the absorbing matter. In the self-consistent hypothesis of a high energy ($E ge 2.3 keV$) power law reflected by an infinite plane-parallel cold slab, a photon index change ($Delta Gamma = 0.4$) has also been observed; a natural explanation can be found in the framework of non-thermal Comptonization models. The iron line is redshifted (centroid energy $E sim 6.1 keV$) and broad ($sigma > 0.2 keV$); multicomponent structure is suggestive of emission from a relativistic accretion disk; however if the disk is not ionized a contribution by a molecular torus or an iron overabundance by a factor $sim 1.5$ are required.
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