Astral Odyssey: Thesis Journey Part 4

In this captivating interview, Niranjan Ashok shares his deep dive into the enigmatic world of neutron star accretion. Highlighting his thesis on accretion processes onto magnetized neutron stars with misaligned axes, he traced his fascination back to a pivotal summer internship under the SRFP program.

 Q. What was your thesis topic?

Accretion onto strongly-magnetized neutron stars which have a misalignment between their magnetic and rotation axes. 

Q. Why did you choose? 

I got an opportunity to work on this topic in the summer of 2022 as part of the joint SRFP program of the three national science academies. I was more inclined towards theoretical works rather than observational works and this summer internship gave a good introduction to the topic. I decided to work with the same supervisor for the thesis as I liked both the research field and the work environment.

 Q. What did you like about it?

 The initial factor which attracted me to this topic was the realization that accretion processes onto compact objects could be modeled using fluid dynamics, a domain of Physics which I didn’t think had many applications in Astrophysics. Fluid dynamics is in reality used in other domains as well, like planet formation, galaxy evolution, in modeling jets etc. Even though we have detected a lot of pulsars, which are neutron stars with strong magnetic fields having a misalignment between their magnetic and rotation axes, we do not yet have a good enough understanding to explain all of these observations. The predictive capacity of theoretical studies and a possibility of explaining the physics behind the observations made the topic interesting to me. 

Q. Who was your guide?

 Dr. Indranil Chattopadhyay of Aryabhatta Research Institute of Observational Sciences(ARIES) Nainital. He is the PI heading the Relativistic Astrophysics group at ARIES which studies jets and accretion processes near compact objects. My local guide was Dr. 

Q. Was Astro always the plan?

 Kind of yes. I came to IISER thinking I will major in Physics and will do my thesis in Astrophysics as I was interested in it from school days. However, I was confused between Physics and Biology while choosing the major as I had liked the BIO2xx courses on evolution and ecology a lot.The internships I did in Astro and the IDC201 course made the decision-making a bit easier. After a lot of thought I chose Physics majors but I still find time to attend talks and lectures in Ecology. 

Q. Internships done in the field? 

1. My first summer project involved simulating meteor showers using the basics of celestial mechanics, under the guidance of Dr. Jasjeet Singh Bagla. 

2. In the second summer I worked with Dr. Anand Narayanan of IIST Thiruvananthapuram on exoplanet detection using radial velocity method.

 3. I also did a reading project in the second summer on basics of General Relativity and the applications of Special relativity in Astronomy with the guidance of Dr. Harvinder Kaur Jassal. 

4. The third and fourth summer and thesis were in studying accretion around neutron stars. 

Q. What are the prerequisites for this field? 

A good understanding of fluid dynamics is necessary for theoretical studies on neutron star accretion. The book by Arnab Rai Choudhuri titled ‘The Physics of Fluids and Plasmas’ is a good starting point. There are NPTEL courses on Astrophysical fluid dynamics as well. For a more detailed insight into applications of fluid dynamics in studying accretion processes, you can refer to the book ‘Magnetohydrodynamics in Binary Stars’ by Campbell.

 Q. Any mistakes that you have made, which you would like to share with the juniors? 

I would recommend everyone to actively seek help and suggestions from friends and seniors. For a large part of my college life, I was reluctant to seek help from others when it came to academic matters. Interacting with others who might have faced similar issues or may have done similar courses/projects as you will increase your productivity. The same applies to discussing your ideas and problems with PhDs while doing the thesis project.

--Avni (MS22)