The accretion of phantom fields by black holes within a thermodynamic context is addressed. For a fluid violating the dominant energy condition, case of a phantom fluid, the Euler and Gibbs relations permit two different possibilities for the entropy and temperature: a situation in which the entropy is negative and the temperature is positive or vice-versa. In the former case, if the generalize...

Deep optical imaging and spectroscopy of stellar objects in the radio lobes of Cygnus A have been carried out. Brighter optical objects close to the radio hotspots are either confirmed or suspected Galactic stars. Very faint optical emission is found coinciding with hotspot D (R∼ 23.1) and hotspot B (V ∼ 25.4). The implications of these observations are discussed in the context of a double twin...

We calculate the jet power of the classical Blandford-Znajek (BZ) model and hybrid model developed by Meier (2001) based on the global solutions of advection dominated accretion flows (ADAFs) surrounding Kerr black holes. We find that the jet power of the hybrid model is larger than that of the pure BZ model. The jet power will dominate over the accretion power and the objects will enter into “...

Black holes of stellar mass and neutron stars in binary systems are first detected as hard X-ray sources using high-energy space telescopes. Relativistic jets in some of these compact sources are found by means of multiwavelength observations with ground-based telescopes. The X-ray emission probes the inner accretion disk and immediate surroundings of the compact object, whereas the synchrotron...

Black holes can be inserted in very rich astrophysical environments, such as accretion disks. Although isolated black are simple objects general relativity, their disks may significantly enrich the field configurations of surroundings. Alternative theories gravity lead to novel hole solutions, which represented by small deviations metric due an effective stress-energy tensor. Among key aspects ...

We find a new two-temperature hot branch of equilibrium solutions for stationary accretion disks around black holes. In units of Eddington accretion rate defined as 10LEdd/c , the accretion rates to which these solutions correspond are within the range ṁ1 <∼ ṁ <∼ 1, here ṁ1 is the critical rate of advection-dominated accretion flow (ADAF). In these solutions, the energy loss rate of the ions by...