binary systems, disk accretion; black holes, neutron stars, AGN; General Relativity
De FalcoVittorio, BattistaEmmanuele, FalangaMaurizio (2018), Lagrangian formulation of the general relativistic Poynting-Robertson effect, in Physical Review D
, 97(8), 1-11.
De Falco V., Kuiper L., Bozzo E., Ferrigno C., Poutanen J., Stella L., Falanga M. (2017), The transitional millisecond pulsar IGR J18245-2452 during its 2013 outburst at X-rays and soft gamma-rays, in Astronomy & Astrophysics
, 603, A16-A16.
De Falco V., Kuiper L., Bozzo E., Galloway D. K., Poutanen J., Ferrigno C., Stella L., Falanga M. (2017), The 2015 outburst of the accretion-powered pulsar IGR J00291+5934: INTEGRAL and Swift observations, in Astronomy & Astrophysics
, 599, A88-A88.
De Falco Vittorio, Falanga Maurizio, Stella Luigi (2016), Approximate analytical calculations of photon geodesics in the Schwarzschild metric, in Astronomy & Astrophysics
, 595, A38-A38.
The physics of accretion onto compact objects has been experiencing a golden age in terms of discoveries for many decades. Space satellites like XMM-Newton, INTEGRAL (ESA missions), RXTE and Chandra (NASA missions) have collected over the years a wealth of information, which have in turn provided astronomers with new insights into the physics of X-ray sources. The project considers X-ray binary systems where matter is accreted onto a neutron star (NS) or a stellar-mass black hole (BH). We are also interested in Active Galactic Nuclei (AGN), i.e., galaxies very likely hosting a supermassive black hole at their center, which is thought to accrete mass at a huge rate, allowing such sources to be very bright at different wavelengths.For all of these objects, the X-ray part of the emitted spectrum gives us clues about the processes occurring in the innermost regions of the accretion disk. In the case of black holes, the motion of matter in the vicinity of the event horizon lets us to investigate the space-time distortion generated by the central object, allowing us to infer important characteristics such as its mass and spin. This is also a unique opportunity to study gravity in the strong-field regime and represents a very powerful diagnostic to validate the predictions of General Relativity under extreme conditions.After decades of observations, there are still many points to be addressed and to be given an adequate explanation. Among these, are: is the profile and variability of the very broad Fe K-line that is observed in many AGNs due to matter orbiting the disk very close to the innermost stable circular orbit? What is the origin of the observed Quasi-Periodic-Oscillations (QPOs) in the power spectrum of neutron stars and black holes binaries light-curves? Do current models include all the relevant physical processes and are they adequate to fit and interpret the data?In the research project we propose a program to address this issues through different complementary techniques, which involve both theoretical modeling and observational data analysis. We put forward a new approach which includes unprecedentedly-explored theoretical models comprising the effects of radiation on the motion of particles in the accretion disks; we also make use of advanced spectral and timing analysis with which to compare the model with real data available from past, current and future space satellites. In particular:•The effects of the presence of a radiation field on the dynamics of the accretion flow will be included in the proposed model. This model lays its foundations on the the so-called Poynting-Robertson effect, a phenomenon which has been first taken into account in the context of planetology and in the study of the motion of comets and dust in the solar system. We will develop a numerical code for simulating the motion of the plasma in accretion disks an thus the observed Fe K-line and light-curves variability including the Poynting-Robertson effect in a fully-relativistic picture.•We will use time resolved X-ray data and spectral analysis techniques to compare the code results with observations in the aim of adjusting the code parameters and try to give new and innovative explanations to some observed features of accretion-powered sources.It will be necessary to hire a PhD student in order to develop numerical codes for these astrophysical applications of the GR Poynting-Robertson effect.