Related papers: The Emission from Post-Shock Flows in mCVs
The recent Chandra X-ray observations of the nucleus of M31, combined with earlier VLA radio and HST UV spectral measurements, provide the strictest constraints on the nature of accretion onto the supermassive black hole (called M31*…
Context. High resolution X-ray observations of classical T Tauri stars (CTTSs) show a soft X-ray excess due to high density plasma (n_e=10^11-10^13 cm^-3). This emission has been attributed to shock-heated accreting material impacting onto…
We consider the behavior of matter in the accretion column that emerges under accretion in binary systems near the surface of a white dwarf. The plasma heated in a standing shock wave near the white dwarf surface efficiently radiates in the…
We present results of a study of the fast timing variability of the magnetic cataclysmic variable (mCV) EX Hya. It was previously shown that one may expect the rapid flux variability of mCVs to be smeared out at timescales shorter than the…
Compton scattering in the bulk accretion flow of the accretion column in magnetic cataclysmic variables (mCVs) can significantly shift photon energies in the X-ray emission lines resulting from accretion shocks. In particular, Compton…
Steep X-ray spectral slopes, X-ray excesses and preferred spectral energy breaks in the 01-0.3 MeV range are discussed as the possible consequences of the photospheric component of the GRB relativistic outflow, and of pair breakdown in…
The accretion column in magnetic Cataclysmic Variables may have a not negligible Thomson optical depth. A fraction of the thermal radiation from the post-shock region may therefore be scattered - and then polarized - before escaping the…
Using a parameterised function for the mass loss at the base of the post-shock region, we have constructed a formulation for magnetically confined accretion flows which avoids singularities, such as the infinity in density, at the base…
If the diffuse extragalactic gamma ray emission traces the large scale structures of the universe, peculiar anisotropy patterns are expected in the gamma ray sky. In particular, because of the cutoff distance introduced by the absorption of…
High resolution spectroscopy, providing constraints on plasma motions and temperatures, is a powerful means to investigate the structure of accretion streams in CTTS. In particular, the accretion shock region, where the accreting material…
We investigate the feasibility of detecting extensive air showers via their geo-synchrotron X-ray emission from high-altitude platforms. Starting from first principles, we derive a differential expression for the number of emitted photons…
We discuss the evolution of cosmological gamma-ray burst remnants, consisting of the cooling and expanding fireball ejecta together with any swept-up external matter, after the gamma-ray event. We show that significant optical emission is…
The availability of the unprecedented spectral resolution provided by modern X-ray observatories is opening up new areas for study involving the coupled formation of the continuum emission and the cyclotron absorption features in…
Cataclysmic Variables (CVs) are a distinct class of X-ray binaries transferring mass from a donor star to a compact star accretor, a white dwarf. They constitute a laboratory for accretion physics, mechanisms and disk theory together with…
In the standard model, magnetic reconnection at a vertical current sheet above the flare arcade is key to explaining many aspects of solar eruptions. The supra-arcade region is where the vertical current sheet is supposedly located, and…
I describe the modifications to the standard forward-shock model required to account for the X-ray light-curve features discovered by Swift in the early afterglow emission and propose that a delayed, pair-enriched, and highly relativistic…
A personal selection of noteworthy X-ray results on CVs are presented, with emphasis on XMM-Newton and Chandra observations. Progressing roughly from broad-band view to narrow-band, high spectral resolution studies, I summarize: the energy…
It is of great important to study pulsar beam shapes if we are concerned with emission theories and pulsar birth rate. Both observations and/or the inverse Compton scattering model show that different emission components are emitted from…
Context. The accretion process in Classical T Tauri Stars (CTTSs) can be studied through the analysis of some UV and X-ray emission lines which trace hot gas flows and act as diagnostics of the post-shock downfalling plasma. In the UV band,…
AIMS. We investigate the stability and dynamics of accretion shocks in CTTSs, considering the case of beta >= 1 in the post-shock region. In these cases the 1D approximation is not valid and a multi-dimensional MHD approach is necessary.…