Simona Vegetti visited ASTRON for 2 months from the beginning December 2011 till the end of January 2012. She is currently a postdoctoral Pappalardo Fellow at the Massachusetts Institute of Technology. Her main research interest is testing cosmological models at the small scales using strong gravitational lensing. She came to ASTRON to work with John McKean on the Strong Lensing at High Angular Resolution Program (SHARP). SHARP was founded by S. Vegetti, J. Mckean, D. Lagattuta, M. Auger, C. Fassnacht and L. Koopmans with the goals of searching for low mass substructure in cosmological distant galaxies, built up information on the substructure mass function and compare with prediction from numerical simulations. During Simona’s visit a SHARP workshop was held at ASTRON and the first results by the collaboration on the detection of a dwarf galaxy at redshift 1 were published in Nature. Simona really enjoyed her stay and would like to thank ASTRON and the Helena Kluyver program.
Lakshmi Saripalli visited ASTRON for three months from September to November 2011. Her research centers on radio galaxy populations and addresses questions relating to their origin, morphologies and growth. She would like to thank the Helena Kluyver women visitor program for the opportunity to visit ASTRON at the exciting time when science with LOFAR has begun to take its sure steps towards solid results. In her visit she plans to collaborate with Dr Raffaella Morganti on a few projects with the common theme of radio galaxies. One of the projects involves HI absorption studies of a sample of radio galaxies where the interest is to determine the detection rate of absorbing neutral hydrogen gas towards the core regions. Combining this sample with previous samples will enable a wider study that will allow exploration of several interesting questions. Her stay is also aimed at wider interactions on the general theme of radio galaxy science. A sensitive radio survey that she recently carried out forms the backdrop to their discussions where they use the imaging data on faint radio galaxy populations to identify future lines of study particularly in the area of their origin and lifecycles. Lakshmi is a staff member at the Raman Research Institute, Bangalore (India).
Prof Renée Kraan-Korteweg - Head of the Department of Astronomy at the University of Capetown (2011)
As part of her sabbatical leave, Renee Kraan-Korteweg spent about one third of the period March to August 2011 at ASTRON - the remainder at the Kapteyn Institute. Renee holds the Chair of Astronomy and is Head of the Astronomy Department at the University of Cape Town (UCT), and one of the (founding) directors of the Research Centre of Astrophysics, Cosmology and Gravity there. Her research interests encompass extragalactic large-scale structures, dynamics in the local Universe, cosmic flow fields and systematic HI-surveys. In this she is particular passionate about identifying galaxies (like Dwingeloo 1) and unveiling the large-scale structures of galaxies hidden by the Zone of Avoidance. During her visits, she interacted mostly with the astronomers involved in the preparation of the future Apertif HI-surveys. Given the complementarity of the large HI-projects planned with the SKA Pathfinders Apertif, MeerKAT and ASKAP, their discussions focused on future research collaborations between UCT and ASTRON, as well as joint student supervision options. She gave a lunch talk on Astronomy Development in South Africa, a colloquium on the Great Attractor, and a talk at the bi-monthly HI meetings on the importance of the WNSHS in resolving bulk flow controversies due to the Zone of Avoidance. She furthermore assisted at the Girlsday organized by ASTRON, JIVE & NOVA on April 14 (see photo).
While at ASTRON, she was named second runner-up by the Minister of Science and Technology of South Africa for the "Distinguished Women in Science Awards". The awards in 2011 were in honour of "Promoting Women's Access and Excellence in Reseach and Innovation Careers", hence much in line with the aims of the Helena Kluyver programme.
Katarzyna Otmianowska-Mazur visited ASTRON for two weeks (8-19) in November 2010. She started a scientific collaboration with Marijke Haverkorn (ASTRON) on the subject of modeling of the evolution of the magnetic field structure, cosmic ray distribution and gas density topology in the Milky Way. The project involves making MHD simulations of the cosmic-ray driven dynamo model for the Milky Way as a barred galaxy in order to get results similar to the observed polarized intensity, magnetic vectors, gas velocity and HI distribution. The scientific field: she specializes in magnetohydrodynamical (MHD) models of galaxies of all astrophysical scales. Her research is focused on issues like reconnections in galactic interstellar medium, cosmic ray-driven dynamo in galaxies, magnetic field evolution in spiral, barred and irregular galaxies and in Virgo cluster galaxies. Since 2005, Katarzyna holds the post of the Director of the Astronomical Observatory at Jagiellonian University in Krakow. She is also the PI of the LOFAR project in Poland.
Luisa Ostorero visited ASTRON for two weeks in August 2010. She is currently a postdoc fellow at the University of Torino, and she was one of the 2009 Italian fellows of the L'Oreal-UNESCO programme "For Women in Science". Her main research topic is the study of active galactic nuclei with a multiwavelength perspective. The project which brought her to ASTRON focuses on the class of compact radio galaxies, likely representing the early phase of the evolution of active galaxies. In collaboration with Raffaella Morganti, Luisa carried out a program of observations of the HI absorption in a sample of X-ray emitting compact radio galaxies. The observations were performed with the WSRT during 2008-2009, and analysed during Luisa's stay. The data acquired with the WSRT will be relevant for the investigation of the connection between the absorptions of the radio and X-ray radiation in these galaxies: this connection is expected to shed light both on the origin of their X-ray emission and on the properties of the absorbing circumnuclear matter.
Anya Bilous visited ASTRON in June-August 2010. Currently, she is a PhD student at the University of Virginia, working within the NRAO pulsar group under the supervision of Dr. Scott Ransom. Her research interests concentrate mainly on pulsars, especially on multiwavelength single-pulse studies. During her stay at ASTRON she used the data from the just-opened LOFAR telescope to look for Abnormally Intensive Pulses, which have been recently discovered at frequencies below 30 MHz. The huge bandwidth of LOFAR allowed her to do a thorough single-pulse study of pulsars with Abnormally Intensive Pulses at frequencies from 30 to 170 MHz, revealing the differences in single-pulse properties in this frequency range. Miss Bilous would like to thank ASTRON and the Helena Kluyver Female Visitor Programme for a wonderful experience of working in ASTRON.
Patricia (Trish) Henning visited ASTRON in June 2010. She is an associate professor of physics and astronomy at the University of New Mexico in Albuquerque, and also is the director of its Institute for Astrophysics. She is currently serving as the vice chair of the US SKA Consortium. Her research efforts include large surveys for HI galaxies for mapping large-scale structure, and studying the HI properties of the galaxies themselves. She leads a low-Galactic-latitude HI survey with the Arecibo L-band Feed Array, and collaborates on other high-latitude projects. During her visit, she discussed with ASTRON staff and other visiting astronomers the opportunities for future extragalactic HI emission surveys with WSRT and Apertif. While at ASTRON, she gave a colloquium looking at the state of large HI surveys, and their future into the SKA era.
Snežana Stanimirović visited ASTRON in mid June-July 2010. She is currently an assistant professor of astronomy at the University of Wisconsin, Madison. Her research interests involve studies of the interstellar and intergalactic medium through various radio surveys (e.g. GALFA-HI, GASKAP). With ASTRON colleagues, she explored possibilities for future very sensitive observations of HI in absorption with the WSRT and large-scale HI emission surveys with Apertif. Snežana also gave a lecture for the summer students focusing on HI studies of the interstellar medium. For about ten days she was accompanied by a graduate student Min-Young Lee (UW) to work on the analysis of the interface region between atomic and molecular gas across the Perseus molecular cloud.
Mousumi Roy visited ASTRON for 5 weeks in Nov-Dec 2009. Currently, she is pursuing a PhD under Dr. Danielle George at the University of Manchester, within the Microwave and Communication Systems Research group. Her research interests involve design of MMIC-based front-end transceiver components, with special emphasis on LNAs. During her stay in ASTRON, in collaboration with Roel Witvers and Laurens Bakker, she helped set-up an on-wafer probing system, to be used in conjunction with an automated tuner used for noise parameter measurements and the state-of-the-art PNAX. Using this set-up, she performed noise and S-parameter measurements and characterization of wafer pHEMT and mHEMT transistors of various technologies (GaAs, InP) and gate lengths, from four different foundries, across a wide range of biases. The aim of this noise modelling and characterization work was to analyze the suitability of these transistors in front-end LNA designs for the SKA project. Miss Roy and Dr. George would like to thank ASTRON and the Helena Kluyver Female Visitor Programme for giving Miss Roy an opportunity to work in ASTRON.
Paola Di Matteo visited ASTRON in November 2009. Currently, she is a postdoc fellow at the Paris Observatory. Her main research interests include the physical processes related to galaxy interactions and mergers and how they affect the observedproperties of galaxies. During her stay at ASTRON, in collaboration with Paolo Serra, she beganthe analysis of N-body simulations of gas-rich major mergers in order to study the properties of stellar populations in the early-type merger remnants and how they compare with the gas distribution. The results of this study will be compared to observational data of stellar populations and age gradients in early-type galaxies and to their HI distribution obtained with the Westerbork radio telescope.
Rym Feliachi visited ASTRON in the period January-March 2009. Her research interest is mitigation of radio frequency interference by using cyclostationary signal processing techniques. Currently she is pursuing a PhD at the Prism Institute of the University of Orleans. She investigates the effectiveness of cyclostationary spatial filters to suppress interference, by theoretical analysis, simulation, and by experimental verification. During her stay at ASTRON, she applied her algorithms on LOFAR data. She demonstrated experimentally that cyclostationary spatial filters have certain advantages over “classic” spatial filters. As cyclostationary techniques offer a better separation between transmitter signals and noise signals, cyclostationary filters are less sensitive to calibration errors. When applied to a strong pager signal in the LOFAR band at 169 MHz, the cyclostationary filter showed a 10 dB better suppression than the classic spatial filter approach.
Isabella Prandoni visited ASTRON for three weeks in August 2008. At ASTRON, she has worked on the First Look Survey, using WSRT/VLA and GMRT data, and exploiting the available multiwavelength information (optical, FIR, etc.). This work is mainly aimed at studying the radio spectral properties of the faint AGN population, in order to disentangle different accretion regimes. This also represents preparatory work for what we will be able to do in more detail with Lofar. Isabella is a staff astronomer at the Institute of Radioastronomy in Bologna and an expert on radio and optical deep surveys. Her main scientific interest is the understanding of the faint radio population, a mix of star-forming galaxies and active galactic nuclei (AGN). She is particularly interested in the physical and evolutionary properties of the low-luminosity AGN component.
Elena Redkina visited ASTRON for a period of 3 weeks during summer 2007. She performed the assembling and measurements of the 16 Vivaldi element array, which was initially designed by her in collaboration with antenna designers of ASTRON. This array was used for verification of the combined EM-MW model of the connected Vivaldi elements with microstrip feed excitations. The positive measurement results of this array complement the initial modeling study and are currently being prepared for submission to AP Trans. journal.
Elena is currently a lecturer at the Sevastopol National Technical University, Crimea, Ukraine.