ASTRON/JIVE Summer Student Programme 2014

Tarraneh Eftekhari
My name is Tarraneh Eftekhari, and I am an undergraduate wrapping up my final year at the University of New Mexico. This summer, I worked with Richard Fallows on heliospheric faraday rotation from the Crab pulsar. Our aim was to deduce the solar wind contribution to the magnetic field. As linearly polarized radiation travels through interplanetary space, we expect to observe some level of faraday rotation due to the magnetic field of the solar wind. The Crab nebula is particularly interesting since it both scintillates as a result of the solar wind and contains a polarized radio source for measuring faraday rotation. Measurements of the scintillation constrain the velocity and turbulence of the solar wind while faraday rotation reveals the strength of the magnetic field parallel to our line of sight. In order to measure faraday rotation accurately, however, it is necessary to take into account Ionospheric contributions which vary over the course of a day. Using total electron content (TEC) maps derived via GPS satellite measurements, we were able to remove these contributions from our observed values in order to obtain subtle variations in the observed rotation measures. By utilizing rotation measure synthesis, we are able to extract faraday depths and ultimately deduce the magnetic field along the line of sight. Observing the Crab at varying distances from the sun allowed us to place initial constraints on changes in the rotation measure, and consequently, magnetic field at varying distances from the sun.
My summer at ASTRON was truly an unforgettable experience. I learned so much during my time there and look forward to applying all these newly found skills to my future endeavors.
In what felt like such a short time, I met so many great individuals from all over the world and made some lasting friendships. I will always remember Wednesday night bridge and weekly trips to the Bos Pub, but more importantly, I will remember the wonderful people who I shared in these experiences with and all the conversations we had. I am incredibly thankful for the opportunity, and I look forward to hopefully seeing some familiar faces in the future.

Luke Pratley
My name is Luke Pratley, I am from Wellington, New Zealand. I recently finished my Masters degree in Physics at the Victoria University of Wellington. The title of my summer research project was "An Initial Multifrequency Snapshot Sky Survey Cluster Sample". This project was supervised by George Heald and Michael Wise. My work with George Heald was to help with the Multifrequency Snapshot Sky (MSSS), and I was working with Michael Wise to use MSSS to investigate diffuse radio emission in galaxy clusters. I feel my research experience was valuable, I was encouraged to be creative and work independently where possible.
MSSS is a radio survey that was observed using LOFAR. MSSS consists of snapshot observations using LOFAR's LBA (60 MHz) and HBA (150 MHz), and it is the first survey performed using LOFAR that covers the entire northern sky. While the observations for MSSS are finished, the sources need to be catalogued and the images need to be reprocessed before a first release. I helped George Heald with creating source catalogues from the MSSS-HBA images, which would allow one to start reprocessing the images. I also worked on quality control of the source catalogue and images.
A radio survey such as MSSS provides a good opportunity to investigate the environment of galaxy clusters (~100 to 1000 galaxies). Sometimes merging galaxy clusters have diffuse radio emission throughout the cluster, in what's known as a radio halo. Since not many radio halos have been discovered, they are not well understood. However, radio halos are believed to be generated by turbulence within the thermal gas of the cluster (intra-cluster medium), this turbulence is driven by mergers of the clusters with each other or with smaller groups of galaxies. To test this hypothesis and understand the properties of radio halos, we need to discover more radio halos. I worked with Michael Wise to investigate galaxy clusters with known or suspected radio halos using MSSS. Investigating known radio halos could be valuable experience for finding new radio halos in MSSS from a large cluster sample .
Spending my summer at ASTRON was a phenomenal experience, the community was very welcoming and we were provided with lots of opportunities to do new and fun things. Playing bridge and the (almost) weekly BBQ at the guesthouse will be something I will miss. I tried many new things, such as wadlopen, rock climbing, and kayaking. It was also nice to see the Dutch countryside, and learn about the Dutch culture. The part of the experience I valued the most was getting to know the community and the other summer students.
Kamlesh Rajpurohit
Hi ...I come from Mount Abu, India and I am a first year Ph.D. student at Thüringer Landessternwarte Tautenburg (TLS), Germany.
At JIVE this summer I worked on Scintillation of radio emissions from planetary spacecraft with Giuseppe Cimò , Guifré Molera and Space Science group (SpaSIA). During my summer internship I've got familiar with Scintillation data analysis software , Matlab and I was introduced to the world of VLBI. I am very thankful to JIVE /ASTRON and I truly appreciate their involvement in variety of research activities to which I was exposed at this stage of my research carrier.
In total , the whole program is an enriching experience for all the students who wish to work in the field of Astronomy. The staff at the Institute is very welcoming, kind and caring. Other summer students from all over the world was very friendly and was awesome. Summer student lectures, Colloquium, Astro-lunch and JIVE coffee meetings allowed us to learn more about radio astronomy and scientific happenings. Visit to WSRT and LOFAR station was a great experience.
I would like to thank my supervisors, fellow summer students and all of the JIVE /ASTRON members for making this experience incredible & unforgettable.
Naomi Robertson
My name is Naomi Robertson and I am an undergraduate Astrophysics student at the University of Edinburgh.  At Astron this summer I worked with John Mckean using Herschel Space Telescope data to produce far-infrared spectral energy distributions of 104 strongly lensed quasars.  Strong gravitational lensing occurs when a galaxy or galaxy cluster acts as a magnifying glass by bending and amplifying the light of more distant objects that are behind it.  Thus the lensing increases the flux of the background object – in our case the quasar- meaning that we see fainter objects that would be below the detection limit if they had not been lensed.  The aim of this project was to constrain star formation properties of gravitationally lensed quasars via measurements of their far infrared spectra.  It is widely believed that AGN activity is related to the evolution of the host galaxy with some suggesting that quasar activity and star formation are dependent on the same influx of cold gas from mergers for example. Ongoing star formation must be occurring if O and B type stars are present.  These stars emit ultra-violet light which heats up the inter-stellar dust and is re-emitted in the infrared.  This emission is then redshifted into the far infrared regime.  To investigate whether star formation is linked to AGN activity we need to consider the light from the quasar and the host galaxy separately.  The dust bump associated with star formation is an unbiased way of investigating this and is described by a modified blackbody.  This ‘greybody’ can be fitted to our data to get an estimate of the dust temperature which can be used to find the infra-red luminosity and thus deduce the star formation rate.  73% of the sample have a detection in at least one of the Herschel bands, with no noticble deifference between radio loud and radio quiet AGN.  Majority of these detections are associated with ongoing star formation which is occuring at the same time as quasar activity. 
My time at Astron was fantastic.  I learnt so much over the 10 weeks I was there from my project, the summer student lectures (these were a real eye opener to the different areas of radio astronomy) , astro-lunchs and my fellow students. The outings to ESTEC, WRST and LOFAR were awesome too.All the social events that were organised for us – whether it was a guesthouse BBQ, wadlopen, kayaking, rock climbing, bridge or having dinner at Bospub – were a great opportunity to speak to staff and get to know my fellow summer students.  My Astron experience will certainly have a lasting impact on me, be it the skills I have learned or friends I have gained.
Susan Schmitz 
My name is Susan Schmitz and I just finished a Bachelor of Science in Physics and Astronomy and the University of Iowa.  I am now working on a Phd in Physics at the University of Pennsylvania.  This summer I worked with Dr. Ciriaco Goddi, Dr. Gabriele Surcis, and Dr. Huib Jan van Langevelde using 6.7 GHz methanol masers to investigate high mass star formation.  Due to observational limitations our understanding of high mass star formation has been limited and there are several competing models which can be constrained by measurements of gas dynamics and magnetic fields very close to the protostars to characterize mass accretion.  My work was focused on the calibration of 6.7 GHz methanol maser EVN (European VLBI Network) observations of the W51 complex, focusing on one particular promising ultracompact HII region.  These observations are the first part in a larger three epoch study of the region to determine precise 3-D kinematics of the gas surrounding the protostars.  I used AIPS and ParselTongue (python scripting for AIPS) to calibrate the data set and also worked to expand the ParselTongue script for polarization calibration.  The project gave me the opportunity to learn about high mass star formation, which I was completely unfamiliar with, and to improve my skills with both AIPS and Python.
Outside of my project, the summer programme offered a number of great opportunities.  Astrolunch was a great way to hear about all the other exciting research going on at ASTRON and JIVE and the twice a week lectures for the summer students helped to provide a solid foundation into the different aspects of radio astronomy.  Also, the trips to Westerbork and the ESA center in Leiden were great opportunities to learn more about the history and current work being done both in radio astronomy, and in astronomy more generally in the Netherlands.  But even beyond research, there's a real feeling of community with people spending time together outside of work at weekly bridge nights and frequent barbecues.  Wadlopen (walking through the mud and water out to the island Ameland during low tide) was a particularly great experience!  I'd like to thank my supervisors and everyone else at ASTRON and JIVE for their support and for making the summer such a wonderful experience.
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