Related papers: Recurrent microblazar activity in Cygnus X-1?

The duty-cycle of powerful radio galaxies and quasars such as the prototype Cygnus A is poorly understood. X-ray observations of inverse-Compton scattered Cosmic Microwave Background (ICCMB) photons probe lower Lorentz-factor particles than…

We summarize recent observations of Cyg X-1 during its 1996 state transition. The results favor an emission geometry with a central optically thin corona surrounded by an optically thick, geometrically thin accretion disk. As the soft state…

We present H-alpha and [O III] (5007 Angstroms) images of the nebula powered by the jet of the black hole candidate and microquasar Cygnus X-1, observed with the 2.5m Isaac Newton Telescope (INT). The ring-like structure is luminous in [O…

We study long-term radio/X-ray correlations in Cyg X-1. We find the persistent existence of a compact radio jet in its soft state. This represents a new phenomenon in black-hole binaries, in addition to compact jets in the hard state and…

Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor to the emitted spectral energy distribution for sub-Eddington black holes. For example, recent observations of radio-to-X-ray correlations and…

The X-ray luminosity of black holes is produced through the accretion of material from their companion stars. Depending on the mass of the donor star, accretion of the material falling onto the black hole through the inner Lagrange point of…

Standard shot-noise models, which seek to explain the broadband noise variability that characterises the X-ray lightcurves of X-ray binaries and active galaxies, predict that the power spectrum of the X-ray lightcurve is stationary (i.e.…

We show that waves propagating in a transition disk can explain the short term temporal behavior of Cygnus X-1. In the transition disk model the spectrum is produced by saturated Comptonization within the inner region of the accretion disk…

We discuss implications of a strong flare event observed in the Seyfert galaxy MCG-6-30-15 assuming that the emission is due to localized magnetic reconnection. We conduct detailed radiative transfer modeling of the reprocessed radiation…

The Galactic black hole transient GRS1915+105 is famous for its markedly variable X-ray and radio behaviour, and for being the archetypal galactic source of relativistic jets. It entered an X-ray outburst in 1992 and has been active ever…

The rapid and seemingly random fluctuations in X-ray luminosity of Seyfert galaxies provided early support for the standard model in which Seyferts are powered by a supermassive black hole fed from an accretion disc. However, since EXOSAT…

We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state based on four observations with NuSTAR. Despite the basic similarity of the observed spectra, there is clear spectral variability between epochs. To investigate…

Context. Blazar AO 0235+164, located at redshift z = 0.94, has undergone several sharp multi-spectral-range flaring episodes during the last decades. In particular, the episodes peaking in 2008 and 2015, that received extensive…

Here we study a 1-200 keV energy spectrum of the black hole binary Cygnus X-1 taken with NuSTAR and Suzaku. This is the first report of a NuSTAR observation of Cyg X-1 in the intermediate state, and the observation was taken during the part…

A possibility to detect X-rays from star-formation burst activities in proto-elliptical galaxies is considered. The X-ray flux of an emission due to inverse Compton scattering of the cosmic microwave background (CMB) by high energy…

The cm-wavelength radio flares on Cygnus X-3 have been studied for many years. Our recent paper (Spencer et al., 2022) looked again at the minor flares (flux density S of a few 100 mJy) and compared their properties with those of a sample…

We consider implications of high-energy neutrino emission from blazar flares, including the recent event IceCube-170922A and the 2014-2015 neutrino flare that could originate from TXS 0506+056. First, we discuss their contribution to the…

The radiation observed by blazars is believed to originate from the transformation of bulk kinetic energy of relativistic jets into random energy. A simple way to achieve this is to have an intermittent central power source, producing…

The ultra-luminous X-ray source (ULX) M82 X-1 is one of the most promising intermediate mass black hole candidates in the local universe based on its high X-ray luminosities ($10^{40}-10^{41} {\rm erg s^{-1}}$) and quasi-periodic…

Aims. We investigate observations of the X-ray binary Cygnus X-1 with unusually high hardness and low flux. In particular, we study the characteristic frequencies seen in the PDS and the hardness-flux correlation within and between these…