Together with Henrik Junklewitz and Torsten Enßlin, I've just submitted a new paper to A&A introducing Faraday caustics to the world. Never heard of them? I don't blame you, we just coined the phrase. So what are they? They are singularities that appear in the Faraday spectrum, i.e. the distribution of polarized intensity as a function of Faraday depth (analogous to rotation measure). These singularities are caused by reversals of the magnetic field direction along the line of sight.
Sounds a pretty obscure, I know, but there are two reasons why they are important to understand. First, the RM Synthesis technique (used to measure Faraday spectra) is becoming very popular. Anyone looking at the polarized emission from diffuse polarized sources, e.g. the synchrotron emission from the interstellar medium in the Milky Way, is bound to find these Faraday caustics in their data. It's important to understand what these features are and where they come from in order to properly understand the results. Furthermore we show how Faraday caustics can be used as a powerful tool for studying the structural and statistical properties of magnetic fields. In this way, observations of Faraday caustics could be used to greatly improve our understanding of both the large and small-scale properties of the magnetic field in the Milky Way, for example.
If you are interested in learning more, our paper entitled "Faraday caustics: Singularities in the Faraday spectrum and their utility as probes of magnetic field properties" is available in pre-print now.
Saturday, May 28, 2011
SS 433 jet evolution paper accepted!
This week I received word that a paper that I've written along with David Roberts and John Wardle, entitled "Structure and Magnetic Fields in the Precessing Jet System SS433 III. Evolution of the Intrinsic Brightness of the Jets from a Deep Multi-Epoch VLA Campaign" (whew... that's a mouthful), has been accepted for publication in the Astrophysical Journal. It is tentatively scheduled to appear in the July 10, 2011, v735 - 2 issue so keep an eye out. Of course, if you can't wait that long there is a pre-print version available.
As you might have gathered from the title, this is one in a series of papers on SS 433. I am working on a follow up to this now where we will look at the images of linear polarization from the same data analyzed in paper III. We hope to have it submitted by the Fall. For reference, here are links to the first two papers in the series: Paper I, Paper II.
As you might have gathered from the title, this is one in a series of papers on SS 433. I am working on a follow up to this now where we will look at the images of linear polarization from the same data analyzed in paper III. We hope to have it submitted by the Fall. For reference, here are links to the first two papers in the series: Paper I, Paper II.
Tuesday, November 10, 2009
Movies of SS433
SS 433 is a microquasar that continuously emits a pair of powerful jets visible with optical, x-ray, and of course radio telescopes. One of the unique things about SS 433 is that its jets appear to have a corkscrew-esque shape on the sky. This is because the "nozzles" of the jets precess wildly. You can think of it like water shooting out of a garden hose that is being twirled around in your hand.
Using a series of five 5 GHz (C-Band) VLA images of SS 433, I have made a couple of movies that nicely illustrate the jet motion. They span roughly 3 months in the summer of 2007. The first movie is of total radio power and in it you can see the spiral jet pattern propagate outward radially from the bright central source. The second movie shows the evolution of the linear polarization in the jets (contours are of polarized intensity and the tick marks indicate the polarization angle).
Using a series of five 5 GHz (C-Band) VLA images of SS 433, I have made a couple of movies that nicely illustrate the jet motion. They span roughly 3 months in the summer of 2007. The first movie is of total radio power and in it you can see the spiral jet pattern propagate outward radially from the bright central source. The second movie shows the evolution of the linear polarization in the jets (contours are of polarized intensity and the tick marks indicate the polarization angle).
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