High Energy Variability Of Synchrotron-Self Compton Emitting Sources: Why One Zone Models Do Not Work And How We Can Fix It

With the anticipated launch of GLAST, the existing X-ray telescopes, and the enhanced capabilities of the new generation of TeV telescopes, developing tools for modeling the variability of high energy sources such as blazars is becoming a high priority. We point out the serious, innate problems one zone synchrotron-self Compton models have in simulating high energy variability. We then present the first steps toward a multi zone model where non-local, time delayed Synchrotron-self Compton electron energy losses are taken into account. By introducing only one additional parameter, the length of the system, our code can simulate variability properly at Compton dominated stages, a situation typical of flaring systems. As a first application, we were able to reproduce variability similar to that observed in the case of the puzzling `orphan' TeV flares that are not accompanied by a corresponding X-ray flare.Comment: to appear in the 1st GLAST symposium proceeding

Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of their Matter Content

We propose a method for estimating the composition, i.e. the relative amounts of leptons and protons, of extragalactic jets which exhibit X-ray bright knots in their kpc scale jets. The method relies on measuring, or setting upper limits on, the component of the Cosmic Microwave Background (CMB) radiation that is bulk-Comptonized by cold electrons in the relativistically flowing jet. These measurements, along with modeling of the broadband knot emission that constrain the bulk Lorentz factor of the jets, can yield estimates of the jet power carried by protons and leptons. We provide an explicit calculation of the spectrum of the bulk-Comptonized (BC) CMB component and apply these results to PKS 0637--752 and 3C 273, two superluminal quasars with Chandra-detected large scale jets. What makes these sources particularly suited for such a procedure is the absence of significant non-thermal jet emission in the `bridge', the region between the core and the first bright jet knot, which guarantees that most of the electrons are cold there, leaving the BC scattered CMB radiation as the only significant source of photons in this region. At lambda=3.6-8.0 microns the most likely band to observe the BC scattered CMB emission, the Spitzer angular resolution (~ 1''-3) is considerably smaller than the `bridges' of these jets (~10''), making it possible to both measure and resolve this emission.Comment: to appear in the Ap

The JetCurry Code. I. Reconstructing Three-Dimensional Jet Geometry from Two-Dimensional images

We present a reconstruction of jet geometry models using numerical methods based on a Markov ChainMonte Carlo (MCMC) and limited memory Broyden-Fletcher-Goldfarb-Shanno (BFGS) optimized algorithm. Our aim is to model the three-dimensional geometry of an AGN jet using observations, which are inherently two-dimensional. Many AGN jets display complex hotspots and bends over the kiloparsec scales. The structure of these bends in the jets frame may be quite different than what we see in the sky frame, transformed by our particular viewing geometry. The knowledge of the intrinsic structure will be helpful in understanding the appearance of the magnetic field and hence emission and particle acceleration processes over the length of the jet. We present the method used, as well as a case study based on a region of the M87 jet.Comment: Submitted to ApJ on Feb 01, 201