Related papers: Revisiting the EC/CMB model for extragalactic larg…
I present here a short personal view of our understanding of the Chandra detected knots and hot spots of powerful Fanaroff Rilley (FR) II radio galaxies and quasars in the context of leptonic models. Observations of the knots and hot spots…
We propose a method for estimating the matter content of quasar jets which exhibit Chandra - detected knots in their kpc scale jets. The method relies on measuring the component of the Cosmic Microwave Background (CMB) radiation that is…
The aim of this short paper is to motivate and encourage research in the field of Active Galactic Nuclei (AGN). Here we summarize the main open questions concerning the central engine. Is the central black hole rapidly spinning and can we…
In recent work, we have identified two sub-populations of radio-loud AGN which appear to be distinguished by jet structure, where low-efficiency accreting systems produce `weak' jets which decelerate more rapidly than the `strong' jets of…
The spectra of blazars form a sequence which can be parametrized in term of their observed bolometric luminosity. At the most powerful extreme of the sequence we find objects whose jet power can rival the power extracted by accretion, while…
We report the Chandra detection of an X-ray jet in 3C 15. The peak of the X-ray emission in the jet is 4.1'' (a projected distance of 5.1 kpc) from the nucleus, and coincident with a component previously identified in the radio and optical…
Different works have recently found an increase of the average X-ray-to-radio luminosity ratio with redshift in the blazar population. We evaluate here whether the inverse Compton interaction between the relativistic electrons within the…
We are conducting an X-ray survey of flat spectrum radio quasars (FSRQs) with extended radio structures. We summarize our results from the first stage of our survey, then we present findings from its continuation. We have discovered jet…
We explore the emissions by accelerated electrons in shocked shells driven by jets in active galactic nuclei (AGNs). Focusing on powerful sources which host luminous quasars, the synchrotron radiation and inverse Compton (IC) scattering of…
Context. Supermassive black holes in the centres of radio-loud active galactic nuclei (AGN) can produce collimated relativistic outflows (jets). Magnetic fields are thought to play a key role in the formation and collimation of these jets,…
We explore the evolution of the emissions by accelerated electrons in shocked shells driven by jets in active galactic nuclei (AGNs). Focusing on powerful sources which host luminous quasars, we evaluated the broadband emission spectra by…
We present an XMM observation of the radio jet and diffuse halo of the nearby radio galaxy NGC6251. The EPIC spectrum of the galaxy's halo is best-fitted by a thermal model with temperature kT~1.6 keV and subsolar abundances. Interestingly,…
Accurate estimation of the Cosmic Microwave Background (CMB) angular power spectrum is enticing due to the prospect for precision cosmology it presents. Galactic foreground emissions, however, contaminate the CMB signal and need to be…
We present some early results on AGN from the Chandra X-ray Observatory, highlighting high resolution spectroscopy using the High Energy Transmission Grating Spectrometer (HETGS). The quasar PKS 0637-752 was found to have a very bright…
High resolution cosmic microwave background (CMB) experiments have allowed us to precisely measure the CMB temperature power spectrum down to very small scales (multipole $\ell \sim 3000$). Such measurements at multiple frequencies enable…
Most modeling attempts of blazars use a small emission zone located close to the central black hole in order to explain the broad-band spectral energy distribution. Here we present a case where additionally to the small region a…
The jet of the quasar 3C273 is observed at different spectral bands. This jet has a knot structure. Jet radiation in radio and optical bands are connected with synchrotron mechanism, while the emission mechanism producing the X-rays is…
We study the contribution of thermal and non-thermal processes to the inverse Compton emission of the radio galaxy M 87 by modelling its broad-band emission. Through this we aim to derive insight into where within the AGN the X-ray,…
There is good evidence for X-ray emission associated with AGN jets which are relativistically boosted towards the observer. But to what jet radius does such X-ray emission persist? To attempt to answer this question one can look at radio…
Context: Few Active Galactic Nuclei (AGN) reveal a double sided jet system. However, these are crucial to understand basic physical properties of extragalactic jets. Aims: We address the questions whether jets in AGN are symmetric in…