相关论文: An Explanation for the soft X-ray excess in AGN

We present a large sample of type 1 AGN spectra taken with XMM-Newton. We fit them with the relativistically blurred photoionized disc model of Ross & Fabian (2005). This model is based on an illuminated accretion disc of fluorescing and…

(abridged) The soft excess seen in the X-ray spectra of many high mass accretion rate AGN can be well modelled by reflection from a partially ionised accretion disc. However, the derived parameters are often extreme, both in terms of the…

We have observed with XMM-Newton four radiatively efficient active type 1 galaxies with black hole masses < 10^6 Msun, selected optically from the SDSS. We show here that their soft X-ray spectrum exhibits a soft excess with the same…

Over the last few years several models have been proposed to interpret the widespread soft excess observed in the X-ray spectra of type 1 active galactic nuclei (AGN). In particular, reflection from the photoionized accretion disc blurred…

The soft excess seen in many AGN is most probably due to partially ionized material moving at relativistic speeds close to the black hole. There are currently two potential geometries for this material, one where it is out of the line of…

The 2-10 keV continuum of AGN is well represented by a single power law, generally attributed to a hot comptonizing medium, such as a corona above the accretion disk. At smaller energies the continuum displays an excess with respect to the…

We investigate the nature of the soft excess below 1 keV observed in AGN. We use the XMM-Newton data of the low redshift, optically bright quasar, PG 1211+143, and we compare it with the Narrow Line Seyfert 1 galaxy, 1H 0707-495, which has…

The standard alpha-disc model predicts an anti-correlation between the density of the inner accretion disc and the black hole mass times square of the accretion rate, as seen in higher mass ($M_{\rm BH}>10^{6} M_{\odot}$) active galactic…

X-ray reflection generates much of the spectral complexity in the X-ray spectra of AGN. It is argued that strong relativistic blurring of the reflection spectrum should commonly be expected from objects accreting at a high Eddington rate.…

'Bare' active galactic nuclei (AGN) are a subclass of Type 1 AGN that show little or no intrinsic absorption. They offer an unobscured view of the central regions of the AGN and therefore serve as ideal targets to study the relativistic…

We present a high density disc reflection spectral analysis of a sample of 17 Seyfert 1 galaxies to study the inner disc densities at different black hole mass scales and accretion rates. All the available XMM-Newton observations in the…

The 2-10 keV continuum of AGN is generally well represented by a single power law. However, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ''soft X-ray excess''. Until…

The nature and origin of the soft X-ray excess in radio quiet AGN is still an open issue. The interpretation in terms of thermal disc emission has been challanged by the discovery of the constancy of the effective temperature despite the…

Understanding the nature of the accretion disk, its interplay with the X-ray corona, and assessing black hole spin demographics are some open challenges in astrophysics. In this work, we examine the predictions of the standard $\alpha$-disk…

The X-ray spectra of many active galactic nuclei (AGN) exhibit a `soft excess' below 1keV, whose physical origin remains unclear. Diverse models have been suggested to account for it, including ionised reflection of X-rays from the inner…

We apply a reflection-based model to the best available XMM-Newton spectra of X-ray bright UltraLuminous X-ray (ULX) sources (NGC 1313 X-1, NGC 1313 X-2, M 81 X-6, Holmberg IX X-1, NGC 5408 X-1 and Holmberg II X-1). A spectral drop is…

The soft excess in active galactic nuclei (AGNs) may arise through a combination of relativistic reflection and the effects of a warm corona at the surface of the accretion disc. Detailed examination of the soft excess can therefore…

Above $\sim$3 keV, the X-ray spectrum of the active galactic nuclei (AGN) is characterized by the intrinsic continuum and compton reflection features. For type-1 AGN, several regions could contribute to the reflection. In order to…

We discuss the origin of the soft X-ray excess seen in AGN. There are clear advantages to models where this arises from atomic processes in partially ionised material rather than where it is a true continuum component. However, current data…

(Abridged) Narrow Line Seyfert 1 (NLS1) galaxies have low mass black holes and mass accretion rates close to (or exceeding) Eddington, so a standard blackbody accretion disc should peak in the EUV. However, the lack of true absorption…