Related papers: Partial alignment between jets and megamasers: Coh…
In a recent paper arXiv:0709.0299, we introduced a spin expansion that provides a simple yet powerful way to understand aspects of binary black hole (BBH) merger. This approach relies on the symmetry properties of initial and final…
In the Galactic microquasars with double peak kHz quasi-periodic oscillations (QPOs), the ratio of the two frequencies is 3:2. This supports the suggestion that double peak kHz QPOs are due to a non-linear resonance between two modes of…
The observation of gravitational-wave signals from merging black-hole binaries enables direct measurement of the properties of the black holes. An individual observation allows measurement of the black-hole masses, but only limited…
In this book chapter, we will briefly review the current empirical understanding of the relation between accretion state and and outflows in accreting stellar mass black holes. The focus will be on the empirical connections between X-ray…
Black hole-neutron star (BHNS) mergers are thought to be sources of gravitational waves (GWs) with coincident electromagnetic (EM) counterparts. To further probe whether these systems are viable progenitors of short gamma-ray bursts (sGRBs)…
Models of jet production in black hole systems suggest that the properties of the accretion disk - such as its mass accretion rate, inner radius, and emergent magnetic field - should drive and modulate the production of relativistic jets.…
While supermassive binary black holes inspiral toward merger they may also experience significant accretion of matter from a surrounding disk. We study the dynamics of this system, simultaneously describing the evolving spacetime and…
The spins of stellar-mass black holes (BHs) and the power outputs of their jets are measurable quantities. Unfortunately, the currently employed methods do not agree and the results are controversial. Two major issues concern the…
In this Letter we revisit arguments suggesting that the Bardeen-Petterson effect can coalign the spins of a central supermassive black hole binary accreting from a circumbinary (or circumnuclear) gas disc. We improve on previous estimates…
We investigate whether models based on the assumption that jets in quasars are powered by rotating black holes can explain the observed radio dichotomy of quasars. We show that in terms of the ``spin paradigm'' models, radio-loud quasars…
In this work we study the co-evolution of central black holes (BHs) and host galaxies by utilizing an advanced iteration of the DELPHI semi-analytical model of galaxy formation and evolution. Based on dark matter halo merger trees spanning…
We derive the mass function of supermassive black holes (SMBHs) over the redshift range 0<z<2, using the latest deep luminosity and mass functions of field galaxies. Applying this mass function, combined with the bolometric luminosity…
We investigate evolution of an accretion disc in binary black hole (BBH) systems and possible electromagnetic counterparts of the gravitational waves from mergers of BBHs. Perna et al. (2016) proposed a novel evolutionary scenario of an…
The component black holes (BHs) observed in gravitational-wave (GW) binary black hole (BBH) events tend to be more massive and slower spinning than those observed in black hole X-ray binaries (BH-XRBs). Without modeling their evolutionary…
Angular momentum transport in high-mass stars is commonly modeled by extrapolating the behavior of better-observed low-mass stars. According to the conventional picture, the cores of most black hole progenitors lose almost all of their…
Proto-stellar clusters, likely progenitors of globular clusters, are compact with typical mass $\sim 10^6\,{\rm M}_\odot$ and size $\sim 1\,{\rm pc}$, as revealed recently by JWST observations at $z\sim 10$. Sufficiently high compactness…
The astrophysical origins of the binary black hole systems seen with gravitational waves are still not well understood. However, features in the distribution of black-hole masses, spins, redshifts, and eccentricities provide clues into how…
The spin-orbit tilt angles $\theta_{1(2)}$ of merging stellar-mass black holes provide key insights into their astrophysical origin. Non-parametric population modelling of The LIGO, Virgo, and KAGRA Collaborations (2025a, arXiv:2508.18083)…
Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However, the physics of tilted discs (e.g., angular momentum…
Millisecond pulsars (MSPs) are spun up during their accretion phase in a binary system. The exchange of angular momentum between the accretion disk and the star tends to align the spin and orbital angular momenta on a very short time scale…