Spectral Analysis of 1H0707-495 with XMM-Newton

We present the results of a 500 ksec long XMM-Newton observation and a 120 ksec long quasi-simultaneous Chandra observation of the Narrow Line Seyfert 1 galaxy 1H0707-495 performed in 2010 September. Consistent with earlier results by Fabian et al. (2009) and Zoghbi et al. (2010), the spectrum is found to be dominated by relativistically broadened reflection features from an ionised accretion disc around a maximally rotating black hole. Even though the spectra changed between this observation and earlier XMM-Newton observations, the physical parameters of the black hole and accretion disc (i.e., spin and inclination) are consistent between both observations. We show that this reflection spectrum is slightly modified by absorption in a mildly relativistic, highly ionised outflow which changed velocity from around 0.11c to 0.18c between 2008 January and 2010 September. Alternative models, in which the spectral shape is dominated by absorption, lead to spectral fits of similar quality, however, the parameters inferred for the putative absorber are unphysical.

The quasar PG 0844+349 in an X-ray weak state

In March 2009 the well-studied quasar, PG 0844+349, was discovered with Swift to be in an X-ray weak state. A follow-up XMM-Newton observation several weeks later generated a good quality spectrum of the source, showing substantial curvature and spectral hardening. In combination with archival data at two previous epochs when the source was in a bright state, we examine the long-term spectral and timing properties of PG 0844+349 spanning nearly ten years and a factor of ten in brightness. Partial covering and blurred reflection models are compared to the data at each flux state while attempting to maintain consistency between the various epochs. In terms of the blurred reflection model, PG 0844+349 is in a reflection dominated state during the 2009 X-ray weak observations, which can be understood in terms of light bending. Moreover, the light bending scenario can also account for the short-term (i.e. ~1000s) spectral variability in the source. Other models cannot be decisively ruled out, but we note distinguishing features of the models that can be explored for in higher signal-to-noise data from current and future observatories.

A long hard look at the minimum state of PG 2112+059 with XMM-Newton

XMM-Newton successfully detected the minimum state of PG 2112+059 during a short snapshot observation and performed a long follow-up observation. The high signal-to-noise spectra are modelled assuming different emission scenarios and compared with archival spectra taken by XMM-Newton and Chandra. The PG 2112+059 X-ray spectra acquired in May 2007 allowed the detection of a weak iron fluorescent line, which is interpreted as being caused by reflection from neutral material at some distance from the primary X-ray emitting source. The X-ray spectra of PG 2112+059 taken at five different epochs during different flux states can be interpreted within two different scenarios. The first consists of two layers of ionised material with column densities of N_H ~5 x 10^22 cm^-2 and N_H ~3.5 x 10^23 cm^-2, respectively. The first layer is moderately ionised and its ionisation levels follow the flux changes, while the other layer is highly ionised and does not show any correlation with the flux of the source. The spectra can also be interpreted assuming reflection by an ionised accretion disk seen behind a warm absorber. The warm absorber ionisation is consistent with being correlated with the flux of the source, which provides an additional degree of self-consistency with the overall reflection-based model. We explain the spectral variability with light bending according to the models of Miniutti and Fabian and constrain the black hole spin to be a/M > 0.86. Both scenarios also assume that a distant cold reflector is responsible for the Fe K alpha emission line. Light bending provides an attractive explanation of the different states of PG 2112+059 and may also describe the physical cause of the observed properties of other X-ray weak quasars.

XMM-Newton reveals the intrinsically X-ray weak nature of the quasar PG 0043+039

This paper was withdrawn due to a misidentification of the source.

XMM-Newton observation of the deep minimum state of PG 2112+059: A spectrum dominated by reflection from the accretion disk?

We analyse a 75ks XMM-Newton observation of PG 2112+059 performed in November 2005 and compare it with a 15ks XMM-Newton observation taken in May 2003. PG 2112+059 was found in a deep minimum state as its 0.2-12 keV flux decreased by a factor of 10 in comparison to the May 2003 observation. During the deep minimum state the spectra show strong emission in excess of the continuum in the 3-6 keV region. The excess emission corresponds to an EW = 26.1 keV whereas its shape resembles that of heavily absorbed objects. The spectra of both observations of PG 2112+059 can be explained statistically by a combination of two absorbers where one shows a high column density, $N_{H} sim 4.5 times 10^{23} cm^{-2}$, and the other high ionisation parameters. As the ionisation parameter of the high flux state, $xi sim 34 erg cm s^{-1}$, is lower than the value found for the deep minimum state, $xi sim 110 erg cm s^{-1}$, either the absorbers are physically different or the absorbing material is moving with respect to the X-ray source. The spectra can also be explained by a continuum plus X-ray ionised reflection on the accretion disk, seen behind a warm absorber. The ionisation parameter of the high state ($xi sim 5.6 erg cm s^{-1}$) is higher than the ionisation parameter of the deep minimum state ($xi sim 0.2 erg cm s^{-1}$), as expected for a stationary absorber. The values found for the ionisation parameters are in the range typical for AGNs. The spectra observed during the deep minimum state are reflection dominated and show no continuum emission. These can be understood in the context of light bending near the supermassive black hole as predicted by Minutti and Fabian.