Long Wang (KIAA Kavli Institute for Astronomy and Astrophysics, Peking University)
Introducing the DRAGON simulation project, we present direct N-body simulations of four massive globular clusters (GCs) with 10^6 stars and 5% primordial binaries at a high level of accuracy and realism. The GC evolution is computed with NBODY6++GPU and follows the dynamical and stellar evolution of individual stars and binaries, kicks of neutron stars and black holes, and the effect of a tidal field. Our model show a large fraction of black holes (BHs) are retained in the GCs. This BHs form a dense system can significantly change the GC evolution. Since recently the gravitational waves (GW) emitted by a BH-BH binary is discovered by advanced-LIGO. We also investigate the BH properties in our models and check whether the BH-BH binaries can reach the merging cases via GW radiations. The detailed comparison with Monte-Carlo methods (MOCCA and CMC) for BH properties are also provided.
Giorgio Matt (University of Rome)
X-ray astronomy is now a mature and consolidated field, as far as imaging, spectroscopy and timing are concerned. On the other hand, X-ray polarimetry is very much lagging behind, the only positive measurement dating back to the 70s. This is due to the combination of instrinsic difficulties (polarimetry is a photon hungry technique) and to technical limitations. The advent of a new type of detectors, based on the photoelectric effect, make it now possible to meaningfully search for polarization on hundreds of X-ray sources. I will review the main open astrophysical questions that will benefit from X-ray polarimetry (including the use of cosmic sources as laboratory for fundamental physics), and present XIPE, a mission selected by ESA for a phase A study (with the final selection expected in summer 2017).
Barbara De Marco (Max-Planck-Institut für extraterrestrische Physik)
Accreting black hole (BH) systems are characterized by strong, aperiodic variability on a wide range of time scales. The variable primary X-ray radiation interacts with any surrounding matter, including the accretion disc. Short light travel time delays are expected between the primary and the reprocessed emission in the disc. These, so-called “X-ray reverberation lags” can be used to map the geometry of the very inner regions of the accretion flow. I will review recent studies of X-ray reverberation lags in accreting BH systems, discussing the analogies between X-ray reverberation lags in active galactic nuclei (AGN) and in BH X-ray binaries (BHXRB), and showing how the latter give indirect evidence of evolving disc geometry during the outburst.
Fu-Guo Xie (谢富国) (Shanghai Astronomical Observatory)
The central engine in X-ray binaries (XRBs) and AGNs is under active debate in recent years. One leading theoretical scenario is the accretion-jet model. This model has achieved great success, as it can explain a large body of observed phenomena in these systems, including the broadband spectrum, the timing properties, and the radio/X-ray luminosity correlation (the so-called fundamental plane in AGNs, where black hole mass is taken into account). In this talk, I will discuss several new progresses, e.g. the numerical simulation realization of the two-phase accretion stage during the outburst evolution in XRBs, the three branch relationship between the index and X-ray flux in XRBs and AGNs, and the unified paradigm on the two radio/X-ray correlations observed in XRBs
