相关论文: Black hole accretion discs and screened scalar hai…

We present the results of our studies on accretion disks in the proximity of astrophysical black holes. These disks can be of varying degrees of opacity, geometrical shapes, sizes, and volumes. The central compact object is a Schwarzschild…

Inner accretion disc around a black hole provides a rare, natural probe to understand the fundamental physics of the strong gravity regime. A possible tilt of such a disc, with respect to the black hole spin equator, is important. This is…

Scalar fields around compact objects are of interest for scalar-tensor theories of gravity and dark matter models consisting of a massive scalar, e.g. axions. We study the behaviour of a scalar field around a Kerr black hole with non…

We show how to correctly account for scalar accretion onto black holes in scalar field models of dark energy by a consistent expansion in terms of a slow roll parameter. We find an exact solution for the scalar field within our Hubble…

We investigate the orbital structure and observable appearance of rotating Kerr black holes endowed with synchronized scalar hair described by two time-periodic scalar fields with a flat target-space geometry. The presence of scalar hair…

Stellar-mass black holes offer what is perhaps the best scenario to test theories of gravity in the strong-field regime. In particular, f(R) theories, which have been widely discuss in a cosmological context, can be constrained through…

If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong…

Through numerical simulations of a minimally coupled massive Klein-Gordon scalar field, we show that it is possible to grow hair on a Schwarzschild black hole if one assumes an initial periodically time-varying but spatially homogeneous…

In this thesis a computational tool for modelling spectral features of X-ray sources in a strong gravitational field is developed. Six transfer functions, the gravitational and Doppler shift, lensing, emission angle, relative time delay,…

We calculate the iron line profiles from accretion discs with spiral velocity structures around Schwarzschild black holes. We find that quasi-periodic bumps appear in the the profiles, thereby providing a test for spiral wave patterns. This…

Rotating black holes without equatorial reflection symmetry can naturally arise in effective low-energy theories of fundamental quantum gravity, in particular, when parity-violating interactions are introduced. Adopting a theory-agnostic…

Spectral features can arise by reflection of coronal X-rays on a black hole accretion disc. The resulting profile bears various imprints of strong gravitational field acting on the light emitting gas. The observed shape of the reflection…

The spin measurement of black holes has important implications in physics and astrophysics. Regardless of the specific technique to estimate the black hole spin, all the current approaches assume that the space-time geometry around the…

We investigate the possibility to localize scalar field configurations as a model for black hole accretion. We analyze and resolve difficulties encountered when localizing scalar fields in General Relativity. We illustrate this ability with…

We investigate thick accretion structures around Kerr black holes in a swirling background. This stationary and axisymmetric spacetime is composed of a rotating black hole, which is immersed in a rotating background. The swirling background…

We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission…

Horizon-scale images of black holes provide a potential probe of fundamental physics, including tests of gravity and black hole hair. To assess the impact of scalar hair on accretion-flow imaging self-consistently, we construct an…

We investigate stationary slim accretion disks around Kerr black holes. We construct a new numerical method based on the relaxation technique. We systematically cover the whole parameter space relevant to stellar mass X-ray binaries. We…

Using numerical simulations we study the accretion of a phantom scalar field into a black hole and track the black hole horizon shrinking process. We integrate the amount of field left outside the black hole during the process in terms of…

Testing the true nature of black holes - the no-hair hypothesis - will become increasingly more precise in the next few years as new observational data is collected in both the gravitational wave channel and the electromagnetic channel. In…