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Register a new userXMM-Newton long-look observation of the narrow line Seyfert 1 galaxy PKS0558-504; I: Spectral analysis
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We present results from the spectral analysis of a long XMM-Newton observation of the radio-loud NLS1 galaxy PKS0558-504. The source is highly variable, on all sampled time scales. We did not observe any absorption features in either the soft or hard X-ray band. We found weak evidence for the presence of an iron line at ~6.8 keV, which is indicative of emission from highly ionized iron. The 2-10 keV band spectrum is well fitted by a simple power law model, whose slope steepens with increasing flux, similar to what is observed in other Seyferts as well. The soft excess is variable both in flux and shape, and it can be well described by a low-temperature Comptonisation model, whose slope flattens with increasing flux. The soft excess flux variations are moderately correlated with the hard band variations, and we found weak evidence that they are leading them by ~20 ksec. Our results rule out a jet origin for the bulk of the X-ray emission in this object. The observed hard band spectral variations suggest intrinsic continuum slope variations, caused by changes in the heating/cooling ratio of the hot corona. The low-temperature Comptonising medium, responsible for the soft excess emission, could be a hot layer in the inner disc of the source, which appears due to the fact that the source is accreting at a super-Eddington rate. The soft excess flux and spectral variations could be caused by random variations of the accretion rate.
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We present XMM-Newton observations of Mrk 359, the first Narrow Line Seyfert 1 galaxy discovered. Even among NLS1s, Mrk 359 is an extreme case with extraordinarily narrow optical emission lines. The XMM-Newton data show that Mrk 359 has a significant soft X-ray excess which displays only weak absorption and emission features. The (2-10) keV continuum, including reflection, is flatter than the typical NLS1, with Gamma approximately 1.84. A strong emission line of equivalent width approximately 200 eV is also observed, centred near 6.4 keV. We fit this emission with two line components of approximately equal strength: a broad iron-line from an accretion disc and a narrow, unresolved core. The unresolved line core has an equivalent width of approximately 120 eV and is consistent with fluorescence from neutral iron in distant reprocessing gas, possibly in the form of a `molecular torus. Comparison of the narrow-line strengths in Mrk 359 and other low-moderate luminosity Seyfert 1 galaxies with those in QSOs suggests that the solid angle subtended by the distant reprocessing gas decreases with increasing AGN luminosity.
We present the discovery of an outflowing ionized wind in the Seyfert 1 Galaxy Mrk 335. Despite having been extensively observed by most of the largest X-ray observatories in the last decade, this bright source was not known to host warm absorber gas until recent XMM-Newton observations in combination with a long-term Swift monitoring program have shown extreme flux and spectral variability. High resolution spectra obtained by the XMM-Newton RGS detector reveal that the wind consists of three distinct ionization components, all outflowing at a velocity of 5000 km/s. This wind is clearly revealed when the source is observed at an intermediate flux state (2-5e-12 ergs cm^-2 s^-1). The analysis of multi-epoch RGS spectra allowed us to compare the absorber properties at three very different flux states of the source. No correlation between the warm absorber variability and the X-ray flux has been determined. The two higher ionization components of the gas may be consistent with photoionization equilibrium, but we can exclude this for the only ionization component that is consistently present in all flux states (log(xi)~1.8). We have included archival, non-simultaneous UV data from HST (FOS, STIS, COS) with the aim of searching for any signature of absorption in this source that so far was known for being absorption-free in the UV band. In the COS spectra obtained a few months after the X-ray observations we found broad absorption in CIV lines intrinsic to the AGN and blueshifted by a velocity roughly comparable to the X-ray outflow. The global behavior of the gas in both bands can be explained by variation of the covering factor and/or column density, possibly due to transverse motion of absorbing clouds moving out of the line of sight at Broad Line Region scale.
Approximately 10-20% of Active Galactic Nuclei are known to eject powerful jets from the innermost regions. There is very little observational evidence if the jets are powered by spinning black holes and if the accretion disks extend to the innermost regions in radio-loud AGN. Here we study the soft X-ray excess, the hard X-ray spectrum and the optical/UV emission from the radio-loud narrow-line Seyfert 1 galaxy PKS 0558-504 using Suzaku and Swift observations. The broadband X-ray continuum of PKS 0558- 504 consists of a soft X-ray excess emission below 2 keV that is well described by a blackbody (kTe ~ 0.13 keV) and high energy emission that is well described by a thermal Comptonisation (compps) model with kTe ~ 250 keV, optical depth {tau} ~ 0.05 (spherical corona) or kTe ~ 90 keV, {tau} ~ 0.5 (slab corona). The Comptonising corona in PKS 0558-504 is likely hotter than in radio-quiet Seyferts such as IC 4329A and Swift J2127.4+5654. The observed soft X-ray excess can be modelled as blurred reflection from an ionised accretion disk or optically thick thermal Comptonisation in a low temperature plasma. Both the soft X-ray excess emission when interpreted as the blurred reflection and the optical/UV to soft X-ray emission interpreted as intrinsic disk Comptonised emission implies spinning (a > 0.6) black hole. These results suggest that disk truncation at large radii and retrograde black hole spin both are unlikely to be the necessary conditions for launching the jets.
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We present the results of a long-term (1999--2010) spectral optical monitoring campaign of the active galactic nucleus (AGN) Ark 564, which shows a strong Fe II line emission in the optical. This AGN is a narrow line Seyfert 1 (NLS1) galaxies, a group of AGNs with specific spectral characteristics. We analyze the light curves of the permitted Ha, Hb, optical Fe II line fluxes, and the continuum flux in order to search for a time lag between them. Additionally, in order to estimate the contribution of iron lines from different multiplets, we fit the Hb and Fe II lines with a sum of Gaussian components. We found that during the monitoring period the spectral variation (F_max/F_min) of Ark 564 was between 1.5 for Ha to 1.8 for the Fe II lines. The correlation between the Fe II and Hb flux variations is of higher significance than that of Ha and Hb (whose correlation is almost absent). The permitted-line profiles are Lorentzian-like, and did not change shape during the monitoring period. We investigated, in detail, the optical Fe II emission and found different degrees of correlation between the Fe II emission arising from different spectral multiplets and the continuum flux. The relatively weak and different degrees of correlations between permitted lines and continuum fluxes indicate a rather complex source of ionization of the broad line emission region.
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