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Summer student programme 2017

Emma Alexander

EmmaHi, I’m Emma, and I’m from the UK. I attended the ASTRON/JIVE summer programme after finishing my undergraduate masters in Physics with Astrophysics at the University of Manchester. This summer, I worked with Jess Broderick on spectral data acquired by the Engineering Development Array (EDA), a test facility for the low-frequency component of the Square Kilometre Array (SKA1-Low). The EDA consists of 256 dipole antennas forming a single station in Western Australia, and is an essential on-site verification of SKA1-Low precursor technology. The main goal of my project was to see if the EDA was capable of detecting radio recombination lines (RRLs) from a 3-hour observation of the galactic center. Low-frequency RRLs originate from electron transitions between high energy atomic levels and trace the low-density, cold interstellar medium (ISM), probing properties of these regions such as electron density and temperature. We found both carbon and hydrogen RRLs, with the results being promising as a proof of concept for this technology.

During this project I’ve learnt a lot about fields I’ve not worked in before, and developed my research skills along the way. I’ve spent a lot of time coding in Python, so hopefully I’ve improved there! The wide range of topics covered by the summer lectures gave us an interesting insight into current work in radio astronomy.

I’m due to start my PhD in astrophysics (also radio astronomy) when I get back to Manchester, and this summer programme has been the perfect bridge towards it in my career. Along the way I’ve made great friends, visited amazing places, and explored the beautiful nearby Dutch countryside. Massive thank you to Jess, to Raymond Oonk for the invaluable advice, to everyone involved in the organisation of the programme, and to everyone else at ASTRON and JIVE who made us feel so welcome!

Yennifer Angarita Arenas

YenniferMy name is Yennifer Angarita and I’m an undergraduate student at The University of Antioquia of Medellín-Colombia. This summer I worked with Dr. Robert Schulz and Dr. Jay Blanchard on a radio-loud and gamma-ray emitting young Active Galactic Nuclei (AGN) called PKS 2004-447 . This source has been included in the multi-wavelength AGN monitoring program, Tracking Active galactic Nuclei with Austral Milliarcsecond Interferometry (TANAMI). Consequently, the source has been observed several times at 8.4GHz with the Australian Long Baseline Array (LBA), plus other stations at Chile, Antarctic and South Africa. The main goal of my project was to study the evolution in time and the variability of this source, and for that I processed four TANAMI (VLBI) observations which I used to learn imaging and modelfitting VLBI data in Difmap (a software for imaging of visibility data from interferometer arrays of radio telescopes world-wide) and analyzed the results in particular with respect to temporal changes in the core and jet. I also used Python for the analysis of the results, from which I gained important insight into the physics of powerful AGN.

While I was having fun doing science I also had time to share great moments and experiences with ASTRON/JIVE people and summer colleges. I will never forget the trips we made to different telescopes (my favorite was the Effelsberg Radio Telescope) and to other places in the Netherlands, as well as to nearby countries. This experience has left a great mark in my life and so I am grateful with all who made this possible. Finally, I want to thank my supervisors, Robert and Jay, who were always attentive, patient and taught me many awesome things.

Ann Njeri

Ann NjeriI am from Nairobi, Kenya and finalizing my master’s thesis at the University of Nairobi. My summer project at JIVE was “Maser Bowshocks in a Water Fountain Outflow: IRAS 18043-2116” under the supervision of Ross Burns and Gabor Orosz.

When less massive stars die, in the Asymptotic Giant Branch (AGB) phase, they are accompanied by powerful outflows. IRAS 18043-2116 is a young post-AGB star that exhibits highly collimated high velocity H20 maser (Microwave Amplification by Stimulated Emission of Radiation) jets and is classified as a Water Fountain (WF). WFs are considered to be an intermediate stage between AGB and Planetary Nebulae (PNe). They show highly collimated, high-velocity (>100 km/s) outflows traced by 22 GHz H2Omasers. The spatial distributions and kinematics of the jets of WFs offer important clues in morphological changes from a very symmetrical AGB to a largely asymmetrical PN. Therefore, the main objective of my summer project was to study the 3-D kinematics of H2O masers in these WF using Very Long Baseline Interferometry (VLBI). Using Very Long Baseline Array (VLBA) data, the results proved that the outflow in our source is jet driven rather than wind driven. This is the first evidence so far of a jet driven outflow with symmetric bowshocks in a water fountain obtained using VLBI observations.

Besides working and learning, I did enjoy my stay at Astron/JIVE. The environment is lovely and serene for walking and cycling through the woods. I loved the flexible working environment. I have never eaten so many pancakes in my entire life, Dutch pancakes are the best! I got to travel around Europe and spoke my English version of the Dutch, German and French languages at some point. Wadlopen – where you walk from the mainland to an island across mudflats – was the icing of my summer, thanks to Bob Campbell! Fellow summer students, the Indian girls killed my taste buds with their very spicy Indian food, everyone at Astron/JIVE was friendly and welcoming. And thanks to my two “super cool” (in Ross’s voice) supervisors, Ross and Gabor, from whom I have learnt so much in this area of spectral data analysis of VLBI data. #summer@jive/astron #nosummerlikethedutchsummer

Chen Xie

Chen XieMy name is Chen Xie, and I’m from China. Thanks to the ASTRON/JIVE summer program, I got the best summer of my life. I worked at ASTRON with Dr. Emanuela Orru, Dr. Marco Iacobelli, and Dr. Aleksandar Shulevski on diffuse radio emission in galaxy clusters. Currently, only a few tens of clusters with diffuse radio emission were found, and most of them were low redshift and X-ray luminous clusters. A larger and more complete cluster sample is needed in order to better understand this phenomenon and the evolution of it. In our summer project, we doubled the number of galaxy clusters with diffuse radio emission at low frequency and we also have some new discoveries. Based on our flux measurements at low frequency, we were able to examine the correlations found in the literature at high frequency.

Besides the exciting results we got, the life living here was absolutely amazing. When I look the photos we took, I see the magnificent radio telescopes we climbed, the fun trips we had, and the nice people we met. Even the chocolate espresso provided by ASTON is so perfect. I am really grateful for having this unique opportunity to do some research in radio astronomy. It helps me sharpen my python skill, and shows me the promising future of radio astronomy that I want to follow. I want to thank my supervisors for the guidance and patience, my fellow summer students, and all the people who made this summer program successful.

Nivedita Mahesh

NiveditaMy name is Nivedita Mahesh and I just completed my first year in graduate school at Arizona State University, USA. This summer program was a total blessing – both in terms of work and fun. I worked with Dr. Andre Offringa on LOFAR data of a patch of sky called the 3c196 flanking field. We had to test the suitability of the field for Epoch of Reionization (EoR) studies. EoR marks the era of the birth of the first stars in the universe. LOFAR with its good sensitivity due to its dense core of antennas makes EoR one of its key science projects. Signals from the EoR are nearly 13Gyears old, are very faint and are obscured by all the foreground galaxies and instrumental noise. This makes foreground removal a major challenge. In this project we used a new technique for foreground removal, which reduced the foreground contribution significantly. We carried out analyses to show that this field with further improvements in processing could be viable for EoR science.

To mention a few of my favourite moments at work – the feeling of elation when I made my first radio image (considering I have an engineering background), humbling moments of realization with Dr. Offringa that we are actually looking for the very first structures in the cosmos, climbing the Effelsberg secondary mirror, the mind stirring conversations even at social gatherings (consequence of having so many physicists together) and my first astronomy research talk. Each day at the guesthouse was an enjoyable experience with my fellow summer students. The surrounding forest and corn fields, spectacular night skies, quaint little town of Dwingeloo – all have left memories for a lifetime. I am definitely going to miss all the spontaneous trips we undertook as a group. Listening to ASTRON’s in-house rock band and dancing with professors, post docs and fellow students at the Midzommer Barbecue made me realize that ASTRON folks are as talented at fun as at work – all in all the most wholesome people I have ever worked with! I am back at ASU and I just can’t stop talking about my summer at ASTRON!

Mel Rose

MelMy name is Mel Rose, and I have just graduated from Harvard University with an undergraduate degree in Astrophysics/Engineering Sciences. During my time at ASTRON, I learned how to process radio data of gigahertz-peaked spectrum (GPS) radio sources under the supervision of Joe Callingham. GPS radio sources are a type of active galactic nuclei (AGN) that can morphologically resemble tiny versions of powerful, lobed radio galaxies. Due to their small scale morphologies, GPS sources have been hypothesized to be the young precursors to large radio galaxies. However, population studies have revealed an overabundance of detected GPS when compared to large radio galaxies. An alternative “frustration” model suggests that GPS sources are not small in size due to youth but instead due to stifling, dense nuclear plasma surroundings that “frustrate” their attempts to grow larger. Identifying the absorption mechanism responsible for the spectral turnover is vital in differentiating between the “youth” and “frustration” models since the physics in each scenario is different. Until now the spectra of these sources have been too sparsely sampled to identify the dominant absorption mechanism in the population. Because these spectra had not really been seen before, it was exciting to be the first to investigate that piece of the universe. Another element of the summer program that I really appreciated was all the field trips – from looking at telescope arrays to swimming in the North Sea.

Avni Paresh Parmar

AvniHello! I am Avni Paresh Parmar from India. I completed my Masters in Physics at Pune University, with Astronomy and Astrophysics as my specialisation subject. My experience this summer at ASTRON/JIVE was awesome! The work environment at JIVE is super cool! I worked with Ilse van Bemmel, Jay Blanchard and Megan Argo at JIVE on ‘Jet Kinematics of NGC 660’. NGC 660 is a polar ring galaxy, and had a massive radio outburst in the core of the galaxy sometime between 2008 and 2010. A monitoring project was started with the European VLBI Network (EVN) in 2013 to study this new Active Galactic Nucleus activity in the core of NGC 660. We thus had a collection of EVN datasets for each year from 2013 until 2016, which we then reduced in AIPS. AIPS (Astronomical Image Processing System) is a software package for editing, calibration, imaging, etc. of radio interferometric data. I learnt many new skills in this process like fringe fitting technique (a process used to combine the data recorded at different telescopes), scripting AIPS in ParselTongue, imaging and model fitting in Difmap (Difmap or difference mapping is an imaging program in which iterative cleaning process is used to converge to the real source structure) and plotting in python. We got some unexpected and equally exciting results and awe have concluded that the activity in the core of NGC 660 has slowed down over these epochs after the first few years of the outburst event.

Apart from the work experience I enjoyed all the regular social events, like JIVE coffee, Astro lunch talks, Wednesday Bospub visits and Wednesday board games. All the official trips to WSRT, LOFAR core and ESTEC were amazing. Climbing up to the apex of the 100 m Effelsberg telescope during our visit to Germany for the Bonn-Dwingeloo meeting was a memorable lifetime experience. Following the annual tradition for summer students, we went ‘wadlopen’ at Ameland – where you walk across the mud flats from the mainland to an island, and the day was one of my unforgettable days in life. It was so nice of Bob Campbell (JIVE) to take us to the seal rehabilitation centre in Pieterburen.

Living in the guest house of ASTRON with other summer students was fun, whether it be cooking different dishes in the kitchen, watching horror movies, BBQs in the backyard, or setting the optical telescope to see planets. Watching the Perseid meteor shower beside the Dwingeloo telescope along with the stretch of milky way overhead, the Andromeda galaxy, and later on the Moon was incredible!

Finally, I would like to thank my supervisors, other people at ASTRON/JIVE and all summer students that made my stay wonderful!


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