Related papers: Cloud model of the mean quasar spectrum
Models predict that atomic carbon occurs at the surface and in the process of the formation of molecular clouds, making its fine structure transitions a diagnostic of cloud formation. We study the distribution of atomic carbon in a small…
We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal…
X-ray emissions from cometary atmospheres were modeled from first principles using the charge-exchange interaction with solar wind ions as well as coherent scattering of solar X-rays from dust and ice grains. Scattering cross-sections were…
High resolution X-ray spectroscopy of the warm absorber in the nearby quasar, MR2251-178 (z = 0.06398) is presented. The observations were carried out in 2011 using the Chandra High Energy Transmission Grating and the XMM-Newton Reflection…
We present graphically the results of several thousand photoionization calculations of broad emission line clouds in quasars, spanning seven orders of magnitude in hydrogen ionizing flux and particle density. The equivalent widths of 42…
We demonstrate the importance of near-infrared radiation from hot dust for Compton cooling of electrons/positrons in quasar jets. In our model, we assume that the non-thermal radiation spectra observed in OVV quasars are produced by…
The observed correlation between global low cloud amount and the flux of high energy cosmic rays supports the idea that ionization plays a crucial role in tropospheric cloud formation. We explore this idea quantitatively with a simple model…
Neumayer et al. established the existence of a blue-shifted cloud in the core of Centaurus A, within a few parsecs of the nucleus and close to the radio jet. We propose that the cloud has been impacted by the jet, and that it is in the…
Understanding of clouds is instrumental in interpreting current and future spectroscopic observations of exoplanets. Modelling clouds consistently is complex, since it involves many facets of chemistry, nucleation theory, condensation…
A numerical calculation of properties of finite absorbers and of intergalactic medium based on photoionization equilibrium is performed to confront alternative UV sources in addition to quasars. It is seen that a spectrum including a large…
Recent simulations increasingly resolve the small-scale structure of the circumgalactic medium (CGM), but the dynamical impact of ionising radiation on its cold $10^4$ K component remains poorly understood. We investigate the evolution of…
We study a phenomenological model for the continuum emission of Seyfert galaxies. In this quasi-spherical accretion scenario, the central X-ray source is constituted by a hot spherical plasma region surrounded by spherically distributed…
We have carried out wide-field (0.17 degree^2) and high-angular resolution (21.3 arcsec ~ 0.04 pc) observations in [CI] line toward the Orion-A giant molecular cloud with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope…
The primary radiation generated in the central continuum-forming region of Active Galactic Nuclei can be reprocessed by very dense, small-scale clouds that are optically-thin to Thomson scattering. In spite of the extreme conditions…
We analyze Hubble Space Telescope observations of scattering regions in 20 luminous obscured quasars at $0.24<z<0.65$ (11 new observations and 9 archival ones) observed at rest-frame $\sim 3000$\AA. We find spectacular $5-10$ kpc-scale…
Extreme Scattering Events are sometimes manifest in the light-curves of compact radio-quasars at frequencies of a few GHz. These events are not understood. The model which appears to offer the best explanation requires a new population of…
We present results based on the first 20 Chandra images obtained in a survey of jets in radio selected flat-spectrum quasars (FSRQs), along with new sub-arcsecond radio maps and optical images. We discover jet X-ray flux in 12 sources…
Strong iron fluorescence at 6.4 keV and hard-X-ray emissions from giant molecular clouds in the Galactic center region have been interpreted as reflections of a past outburst of the Sgr A* supermassive black hole. Careful treatment of…
We present a simple, largely empirical but physically motivated model to interpret the mid- and far-infrared spectral energy distributions of galaxies consistently with the emission at ultraviolet, optical and near-infrared wavelengths. Our…
We modeled the spectral energy distribution (SED) of high redshift radio quiet quasars (high-z RQQs). We computed spectra in a patchy corona geometry where an accretion disk extends to the last stable orbit and the Comptonizing active…