A toolbox for modeling the multiwavelength emission of quasar jets

Quasars are a category of active galaxies; these are believed to host a super-massive black hole at their centers that accretes matter from its surrounding. As matter falls toward the black hole, it heats up, radiating enormous amounts of energy, up to 10,000 time the star light produced by all the stars in the galaxy hosting the black hole. In one out of ten of these quasars, for reasons that are not yet totally understood, some of the matter instead of falling into the black hole, forms two jets that stream outward with velocities very close to the speed of light.

Chandra, more than beautiful pictures

Chandra is currently the X-ray orbiting observatory with the highest angular resolution and it is responsible for many fabulous recent discoveries. One of the fields that is being revolutionized by Chandra is that of the study of quasar jets, and this is where this project focuses. Up until recently, jets had been mostly seen in the radio, but with Chandra we have seen several of them in X-rays. You can see one of them in the following picture of quasar PKS 1127-145 by a publication from Siemiginowska et al. 2002, ApJ, 570, 543 .

radio+X-ray map of

The color represents the X-ray emission and the contours the radio. This is more than a beautiful picture. Note the small, but significant displacement between the radio and the X-rays, with the radio peaking further out than the X-rays. One of the things you will learn in this project is that the radio emission (which by the way is synchrotron emission, the type of emission resulting when relativistic electrons spiral in a magnetic field) should in fact peak further in instead of further out from the X-rays (which we believe to be due to inverse Compton scattering a process is which an energetic electron kicks a low energy photon to high energies).

Theorists come to rescue

Such puzzling morphological characteristics can result from the gradual deceleration of a relativistic flow (Georganopoulos & Kazanas, ApJ 604, L81) . Not only that, but the offsets between radio and X-ray emission carry the imprint of the deceleration, and this gives us the possibility to derive the deceleration of the jets from the observed offsets. This is a figure from our paper that shows the radio and the X-ray emission at two different jet orientation angles (don't worry about the two bottom graphs for now).

simulated jet emission maps

What will you do?

Under guidance, you will work toward building a computer code that in its final form will calculate the synchrotron and inverse Compton emission from a decelerating relativistic jet. The code will be eventually become publicly available for researchers to use, so it has to be extremely well documented and clear. Our goal is to start by building the framework, essentially a structure of black boxes that will perform different taskc (e.g. calculate thet synchrotron emissivity at a given location in the jet). These black boxes will be empty in the beginning, and we will fill them in gradually as we understand the physics. If a publication results from this work, expect to be one of the co-authors.

What do you need to know?

You will need to know a computer language such as C or Fortran, as well as know or be prepared to learn IDL (if you don't even know what IDL is don't worry). You don't have to know any astrophysics, but you will learn quite a bit during this project. You will also learn the relevant physics. This will be done through both discussions and self-study.

Where and with whom will you do it?

Most of it will be done here at UMBC with Markos Georganopoulos . A fraction of it may be done in NASA/Goddard with Demosthenes Kazanas.

Questions? E-mail me at: georgano@umbc.edu