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Narrow absorption lines seen in the 2-10 keV spectra of active galaxies and Galactic black holes are normally attributed to iron in high velocity outflows or inflows. We consider the possibility that such features could arise naturally in the accretion disc. Resonant absorption by highly ionised iron (e.g. Fe XXVI and Fe XXV) in an optically-thin plasma that is located above the disc and rotating with it could reproduce narrow features in the reflection component of the spectrum as it emerges from the disc. Depending on the inclination of the disc and the exact geometry of the hot plasma (e.g. does it blanket the disc or a ring) apparently narrow absorption features could be detected between 4-10 keV. Such an explanation requires no high velocity outflow/inflow and is consistent with a reflection-based interpretation for accreting black holes systems.
We extract all the XMM-Newton EPIC pn burst mode spectra of GX 339-4, together with simultaneous/contemporaneous RXTE data. These include three disc dominated and two soft intermediate spectra, and the combination of broad bandpass/moderate spectral
The current paradigm for the AGN phenomenon is a central engine that consists of an inflow of material accreting in the form of a disk onto a supermassive black hole. Observations in the UV and optical find high velocity ionized material outflowing f
It has been argued that the recently detected ring-down gravity waveforms could be indicative only of the presence of light rings in a horizonless object, such as a surgical Schwarzschild wormhole, with the frequencies differing drastically from thos
We discuss the effects of a comptonizing corona on the appearance of the reflection components, and in particular of the reflection hump, in the X-rays spectra of accreting black holes. Indeed, in the framework of a thermal corona model, we expect th
Recent trend of research indicates that not only massive but also massless (asymptotic Newtonian mass zero) wormholes can reproduce post-merger initial ring-down gravitational waves characteristic of black hole horizon. In the massless case, it is th