Akshita Mittal, BSMS Batch 2019, School of Physics
My internship with Prof. Sanjit Mitra at IUCAA Pune is in the field of gravitational-wave astronomy. In this field, I am working on the estimation of the Hubble parameter using gravitational wave (GW) data from binary black hole mergers (BBHs). This is entirely a theoretical project and hence required a lot of prerequisite reading and coding knowledge. We require the event’s redshift and distance to it to estimate the value of the Hubble parameter. We get information for the distance to the event from the gravitational wave data. Measuring redshift is comparatively easier in the case of binary neutron star mergers (BNSs) because they have an electromagnetic counterpart. On the other hand, BBHs do not. One way of measuring redshift for BBHs is using ‘galaxy catalogs’. However, this method reduces the accuracy of our posterior, i.e. the Hubble parameter. Another hurdle is that BNSs have a comparatively longer signal (40-50s) whereas BBHs’ signal lasts for <0.1s. In this project, I am trying to reduce the dependence of the Hubble Bayesian inference equation on the redshift component, so we can estimate the Hubble parameter without having to worry too much about the redshift of BBHs. Here is an introductory paper to understand how this works.
Contact: akshita19@iisertvm.ac.in
Arjun Kannan, BSMS Batch 2019, School of Physics
After anywhere around 20-25 personalised Emails to professors across reputed research institutes, I got a positive response from Prof. Annapurni Subramaniam for a remote summer internship, the director of the Indian Institute of Astrophysics Bangalore. Before I began working with her on a project, she gave a series of lectures along with a few of her PhD students, which helped me get an insight into certain concepts and, most importantly, to tools and software regularly used in Astronomy (explicitly, VOSA and TOPCAT). I started officially working by the mid of June, the topic of study being a particular class of stars known as B-type subdwarfs. The objective was to reproduce the results of an earlier study on the same type of stars using a different methodology (obviously less rigorous such that it is suitable for an undergrad). In the previous study, the distances to these stars were not available. However, with the advent of better telescopes, new and accurate Astrometry data (parameters like coordinates, distance and colour-magnitude) is released and updated ever so frequently, which enabled me to compute additional parameters (Stellar Luminosity and Radius). Broadly speaking, I utilised the online tool called VOSA to perform curve fitting using the Chi-Square statistic and made various plots of the parameters using Python for visualisation. I also had to make a report of the same in LaTeX, which I did using Overleaf. Overleaf is one of the most convenient online resources for typesetting in LaTeX, as you also get access to various templates. All-in-all, it was an amazing experience to finally delve a bit into the more technical aspect of the subject that I adored for years. If I have to give any advice from personal experience, there is a better chance of getting a reply from Professors when they receive mail in the mornings and on the weekdays. Also, if time permits, I would recommend attempting to type an assignment or two in LaTeX, to get a basic understanding of the same.
Contact: arjunkannan19@iisertvm.ac.in
Parth Anand Ankam, BSMS Batch 19, School of Biology
For the past 10 months I have been helping my mentor Dr. Girish Ratnaparkhi (IISER Pune) figure out the role of serine hydrolases in the innate immunity for Drosophila Melanogaster. In addition to compiling a list of the role of Serine Hydrolases in the Drosophila’s innate immune response from literature, I have also helped write a review paper on the very same topic. For the wetlab work, my mentor had pre-selected targets with designed and constructed plasmids, which I helped express in E.coli and in the three weeks I spent in the lab, I checked the expression of two specific target genes. For my next internship I worked with Dr. Sonal Nagarkar Jaiswal at CCMB Hyderabad. Dr. Sonal works on neural stem cell generation and the project I had taken up was to decipher the role of a particular gene which when mutated would cause a small brain condition in (microcephaly) Drosophila Melanogaster. I was supposed to hypothesize and design experiments to confirm the function of this gene. I am still working on designing the experiments and would likely have a concrete proposal by the end of this month. My final project was with Prof. Jayasri Das Sarma, IISER Kolkata. Prof. Jayasri Das Sarma works with the neurobiological system of mice .She currently works on the neuropathogenesis of mouse hepatitis virus (MHV) infection which mimics certain pathology of Multiple Sclerosis (MS), a human neurological disease. I had a reading project entitled ‘Chemokine receptor knockout mice to study their role in inflammation and neuroinflammation’.
Contact: parthankam19@iisertvm.ac.in
Ira Zibbu, BSMS Batch 19, School of Biology
This summer break I decided to do something far outside my comfort zone— math. Prof. Dond Asha Kisan from the School of Math, IISER TVM was my mentor for the duration of the project and we narrowed down on the field of finite difference methods for partial differential equations. I worked on the Keller-Segel Model of chemotaxis. Chemotaxis is the process by which cells move up or down a chemical gradient. For example bacteria like E.coli move towards amino acids like arginine (which is a source of food) and move away from nickel ions (which is toxic). The Keller-Segel model consists of a pair of coupled differential equations whose solution describes the spatiotemporal distribution of the cells and the chemical. My project started out by reviewing the biochemical pathways involved in chemotaxis in two model organisms— E.coli and Dictyostelium discoideum. Next, I formally described the model and the boundary conditions I would be working with and went over the mathematical justification of the model. There are many finite difference methods that have been used to solve the Keller-Segel model but I wrote programs and performed simulations using an explicit method, which as expected, did not work. I elucidated one of the many implicit schemes and finally interpreted existing results in their relevant biological contexts. As a build up to my project, I also explored many finite difference formulations for solving standard ODEs like the vibration equation and PDEs like the heat equation. This project really deepened my appreciation for applied mathematics, improved my coding skills, and learning to properly typeset in LaTeX was a fun bonus.
You can find there finite difference solvers in MATLAB and my project report here: https://github.com/ira-zibbu/finite-difference-methods
Contact: irazibbu19@iisertvm.ac.in
Ravikiran Hegde, BSMS Batch 19, School of Physics
The gravitational wave observatories around the globe such as LIGO-Virgo have detected more than 50 signals from the coalescence of black holes and neutron stars since the first direct detection of gravitational waves from a pair of colliding black holes on 14th September 2015. Understanding the physical properties of the source from the detected signal buried in the plethora of noise is as demanding as observing a gravitational wave itself. While rigorous analytical and computational techniques are used to estimate the parameters of observed gravitational wave transients, some of the properties of the binary system can be probed from the signals’ time-frequency morphology when the observed signal is loud (high SNR). I applied for an internship under Prof Archana Pai, Dept. of Physics, IIT Bombay, with my long-lived fascination with gravitational-wave science. After some prerequisite reading and tutorials, the primary goal of the initial phase of the project was to calculate the chirp mass and probe parameters such as the luminosity distance, component masses, and orbital radius of the observed compact binary mergers using the time-frequency morphology. The chirp mass is a governing parameter in describing the frequency evolution of the GW signals from a binary system. It is a combination of the total mass (m_1 +m _2) and reduced mass ( m_1 m_2/(m_1 +m_2) ). Using the spectrograms of different GW events, we tried to estimate the chirp mass and further calculate the bounds on other parameters for loud signals. While the internship was entirely online, I learned many new things and got the best out of the semester break. The project has evolved a lot from the beginning phases and is still ongoing. From getting to know about the ongoing research, tools and challenges in the field, to figuring out silly mistakes during the project, I highly appreciate the support from Prof Archana and her students.
For anyone interested in having first-hand experience with gravitational waves, Gravitational Wave Open Science Center (GWOSC) could be a great start. It houses some handy tutorials and a catalogue of all the observed events, amongst other things.
Contact: ravikiran19@iisertvm.ac.in
