Dr. Denise Gabuzda
I have been involved with VLBI polarization studies of AGN since the birth of this field in the 1980's. One of my special areas of interest is searching for observational evidence for the presence of helical jet magnetic fields, which are expected to be produced theoretically when the jets are "launched", due to the combination of the rotation of the central black hole and accretion disc and the jet outflow. I am also very interested in the possibilities offered by space VLBI, due to its ability to provide high resolution observations of the phenomena that are strongest at relatively long wavelengths, such as Faraday rotation.
Sebastian Knuettel, Ph.D student
I am a radio astronomy Ph.D. student with funding from the IRC. In my PhD project, I will carry out studies of the magnetic fields of energetic outflows from the centers of active galaxies using an approach based on multi-wavelength observations. Some AGNs eject radio-emitting jet outflows, which extend for thousands of light years from the galactic center. It is believed that the jets remain extremely narrow due to collimation by their B fields, which are predicted by theoretical models to be helical. I will probe the B fields in the immediate vicinity of the jet outflows using observations of Faraday Rotation. A monotonic change in the Faraday Rotation across a jet indicates the presence of a helical or toroidal B field wrapped around the jet. I will map out the intensity, polarization, and Faraday Rotation distributions for AGN jet outflows on large scales using observations obtained with the Very Large Array and on small to intermediate scales using the Very Long Baseline Array. I will also investigate the jet B field structure over multiple epochs when possible.
Juliana Motter, Visiting Ph.D student
I'm Juliana Motter, a PhD student at the University of São Paulo (Brazil). Here at UCC, I'm a Visiting PhD Student sponsored by the Brazilian Government. Back in Brazil I was working on the analysis of the kinematics of parsec scales jets of AGN using a method called Cross-entropy. In the radio group at UCC my research project focuses in analyzing high resolution VLBI radio data for AGNs with extended jets at wavelengths in the range 18 - 22cm to study the magnetic fields in theses structures and to look for helical perturbations or precession of the jets.
Colm Coughlan, Ph.D. student
My PhD project was funded by the IRC. My main project was developing a Maximum Entropy Method (MEM) based deconvolution technique for polarised VLBI data. This technique is less subjective, more mathematically rigorous and offers better resolution than the CLEAN algorithm. I have implemented the algorithm in C++ and I am using it on existing data from the VLBA to probe the polarisation and Faraday rotation measure structure of relativistic jets from AGN at small scales. My project also included running Monte Carlo simulations of observations with MEM to characterise the behaviour of the algorithm and understand its systematic errors. As a secondary project I began the development of an analytical error model for the CLEAN algorithm, which will allow statistical analysis of highly correlated neighbouring pixels in CLEAN maps. I'm now working as a postdoctoral researcher at the Dublin Institute for Advanced Studies.
Eoin Murphy, Ph.D. student
My PhD project was funded by the IRC. My area of research involved computational studies of the transverse structures of AGN jets. I also investigated the transverse polarization of AGN jets in order to determine the fundamental magnetic field parameters implied in a model in which a helical magnetic field threads the AGN jets. Another part of my project involved computational studies of the resolution requirements for observing differernt types of tranverse structure (primarily transverse Rotation Measure gradients) in jets observed using Very Long Baseline Interferometry. I'm now working for the Bank of Ireland as a Data Analyst.
Fiona Healy, Master's Degree student
In my Master's project, I studied 5 BL-Lac objects observed at wavelengths from 18 to 22 cm at two epochs separated by several years. I analyzed their polarization structure in order to learn more about the behaviour and time evolution of their magnetic field structures. I am now working on a PhD on radio emission from young stellar objects at the University of Manchester.