相关论文: Investigating the Structure of the Windy Torus in …
Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV absorption features. A convincing argument for…
We present an analysis of the effects of luminosity on the shape of the mid-infrared spectral energy distributions (SEDs) of 234 radio-quiet quasars originally presented by Richards et al. In quasars without evident dust extinction, the…
An integral part of the Unified Model for Active Galactic Nuclei (AGNs) is an axisymmetric obscuring medium, which is commonly depicted as a torus of gas and dust surrounding the central engine. However, a robust, dynamical model of the…
We analyse a sample of 85 luminous (log(nuLnu(3\um)/erg s-1)>45.5) quasars with restframe ~2-11 \um spectroscopy from AKARI and Spitzer. Their high luminosity allows a direct determination of the near-infrared quasar spectrum free from host…
The blue-shifted broad emission lines and/or broad absorption lines seen in many luminous quasars are striking evidence for a broad line region in which radiation driving plays an important role. We consider the case for a similar role for…
The detection of dusty winds dominating the infrared emission of AGN on parsec scales has revealed the limitations of traditional radiative transfer models based on a toroidal distribution of dusty gas. A new, more complex, dynamical…
We use photometric data, from the optical to the mm for a large sample of optically selected radio-quiet quasars, at low and high redshifts, to test emission models from circum-nuclear dusty torii around them. Model parameters, such as dust…
Recent efforts on the modeling of the infrared spectral energy distributions (SEDs) of dwarf galaxies are summarised here. The characterisation of the dust properties in these low metallicity environments is just unfolding, as a result of…
We present preliminary results on fitting of SEDs to 142 z>1 quasars selected in the mid-infrared. Our quasar selection finds objects ranging in extinction from highly obscured, type-2 quasars, through more lightly reddened type-1 quasars…
Using Chandra and HST archival data, we have studied the individual Spectral Energy Distribution (SED) of 11 quasars. All UV spectra show a spectral break around 1100A. 5 X-ray spectra show the presence of a ``soft excess'' and 7 spectra…
We present Spitzer infrared spectra and ultra-violet to mid-infrared spectral energy distributions (SEDs) of 25 luminous type 1 quasars at z \sim 2. In general, the spectra show a bump peaking around 3 {\mu}m, and the 10 {\mu}m silicate…
Evidence indicates that supermassive black holes exist at the centers of most galaxies. Their mass correlates with the galactic bulge mass, suggesting a co-evolution with their host galaxies, most likely through powerful winds. X-ray…
We combine submm photometric data of z>4 quasars, to obtain a mean far-infrared (FIR) (rest-frame) spectral energy distribution (SED) of thermal emission from dust, parameterised by a single temperature (T) and power-law emissivity index…
Ultra-short period planets offer a window into the poorly understood interior composition of exoplanets through material evaporated from their rocky interiors. Among these objects are a class of disintegrating planets, observed when their…
In this first research note of a series of two, we conduct optical/UV investigations of the spectropolarimetric signatures emerging from the structure of quasars (Elvis 2000) applied to a purely theoretical, dusty model. We aim to explore…
According to the unified model of active galactic nuclei (AGNs), a putative dusty torus plays an important role in determining their external appearance. However, very limited information is known about the physical properties of the torus.…
Although dust is widely found in astrophysics, forming dust is surprisingly difficult. The proper combination of low temperature (<2000 K) and high density is mainly found in the winds of late-type giant and supergiant stars which, as a…
We test emission models of circum-nuclear dust torii around quasars, at low and high redshifts, by using a large collection of photometric data for an unbiased sample of 120 optically-selected objects with millimetric and sub-millimetric…
A quasar wind model is proposed to describe the spatial and velocity structure of the broad line region. This model requires detailed photoionization and magnetohydrodynamic simulation, as the broad line region it too small for direct…
We present an analysis of the X-ray properties 10 luminous, dust-reddened quasars from the FIRST-2MASS (F2M) survey based on new and archival Chandra observations. These systems are interpreted to be young, transitional objects predicted by…