Related papers: Gamma rays from Fast Black-Hole Winds
The $\gamma$-ray emission observed in several classes of Galactic and extragalactic astrophysical sources appears to be linked to accreting black holes and rotational powered neutron stars. These systems are prodigious cosmic accelerators,…
A majority of the $\gamma$-ray emission from star-forming galaxies is generated by the interaction of high-energy cosmic rays with the interstellar gas and radiation fields. Star-forming galaxies are expected to contribute to both the…
A new scenario for the emission of high-energy gamma-rays from dark matter annihilation around massive black holes is presented. A black hole can leave its parent halo, by means of gravitational radiation recoil, in a merger event or in the…
Gamma-ray bursts and ultra-high-energy cosmic rays provide an important testing ground for fundamental physics. A simple-minded analysis of some gamma-ray bursts would lead to a huge estimate of the overall energy emitted, and this…
Understanding the astrophysics of feedback in active galactic nuclei (AGN) is key to understanding the growth and co-evolution of supermassive black holes and galaxies. AGN-driven winds/outflows are potentially the most effective way of…
Force balance considerations put a limit on the rate of AGN radiation momentum output, $L/c$, capable of driving galactic superwinds and reproducing the observed $\mbh -\sigma $ relation between black hole mass and spheroid velocity…
We describe the physical mechanisms of launching and acceleration of wind from an active galactic nucleus (AGN) accretion disk. We focus on the radiation line force driven and magnetic driven wind models, which operate on the accretion disk…
Dense populations of stars surround the nuclear regions of galaxies. In active galactic nuclei, these stars can interact with the relativistic jets launched by the supermasive black hole. In this work, we study the interaction of early-type…
It is proposed that gamma-ray bursts are created in the mergers of double neutron star binaries and black hole neutron star binaries at cosmological distances. Bursts with complex profiles and relatively long durations are the result of…
Ultra-fast outflows (UFOs) with mildly relativistic velocities are measured using the X-ray spectra of radio-quiet and -loud active galactic nuclei (AGNs). In general, UFOs are believed to be generated from the accretion disk around a black…
Gamma-ray bursts (GRB) are short and intense bursts of $\sim$100 keV$-$1MeV photons, usually followed by long-lasting decaying afterglow emission in a wide range of electromagnetic wavelengths from radio to X-ray and, sometimes, even to GeV…
Recent radio observations support a picture for star formation where there is accretion of matter onto a central protostar with the ejection of molecular outflows that can affect the surrounding medium. The impact of a supersonic outflow on…
I show that Eddington accretion episodes in AGN are likely to produce winds with velocities $v \sim 0.1c$ and ionization parameters up to $\xi \sim 10^4$ (cgs), implying the presence of resonance lines of helium-- and hydrogenlike iron.…
The little we do know of the physical conditions in gamma-ray bursters makes them conducive to the acceleration of high-energy cosmic rays, especially if they are at cosmological distances. We find that, with the observed statistics and…
As an inaugural investigation under the X-ray Winds In Nearby-to-distant Galaxies (X-WING) program, we assembled a dataset comprising 132 active galactic nuclei (AGNs) spanning redshifts $z \sim 0$-$4$ characterized by blueshifted…
The time lag between soft and hard X-ray photons has been observed in many active galactic nuclei (AGN) and can reveal the accretion process and geometry around supermassive black holes (SMBHs). High-frequency Fe K and soft lags are…
In this contribution I summarize our current knowledge of the nature and significance of starburst-driven galactic superwinds. These flows are driven primarily by the kinetic energy supplied by supernovae. Superwinds are complex, multiphase…
Several active galaxies show strong evidence for fast ($v_{\rm out} \sim 1000~{\rm km\,s}^{-1}$) massive ($\dot{M} =$ several $\times 1000~\msun\,{\rm yr}^{-1}$) gas outflows. Such outflows are expected on theoretical grounds once the…
Galactic winds are associated with intense star formation and AGNs. Depending on their formation mechanism and velocity they may remove a significant fraction of gas from their host galaxies, thus suppressing star formation, enriching the…
Tidal forces close to massive black holes can violently disrupt stars that make a close approach. These extreme events are discovered via bright X-ray and optical/UV flares in galactic centers. Prior studies based on modeling decaying flux…