Astral Odyssey: Thesis Journeys Part 7

In a cosmic conversation, Sanatan Jaminy illuminated his journey from theoretical cosmology to the wonders of gravitational waves and beyond. His thesis on cosmological redshift drift, guided by Dr. Kinjalk Lochan, delved into the evolution of universe-spanning phenomena

 1. What was your thesis topic ?

My thesis exposed me to the field of theoretical astrophysics. Black holes have always been a subject of fascination for me and I got the opportunity to explore the field. Although it was a review thesis, i.e. I did a review on the works already published in the field and nothing original, I learned about the research in the field of theoretical physics. During the summer of 2022, I came across a phenomenon, the ”Penrose Process” and it blew my mind. It talks about the possibility of extracting energy from a rotating black hole. In my thesis, I extended upon this and studied a better phenomenon, Super-radiance. Better as in it is more easily observable than the penrose process. We can find frequencies of the fields surrounding a black hole that may undergo super-radiance and thus extracting mass and spin from the black hole. These fields can form a cloud around a black hole that may radiate gravitational waves, whose detection will provide us with the information about these fields. To work on the models of the gravitational waves from the system of the black hole and the (scalar) cloud, I needed to understand the concept of detection of gravitational waves, so in the second half of my project, I worked on the quasinormal modes of black holes. Detection of gravitational waves is dominated by these modes. 

2. Who was your guide ? 

Dr. Kinjalk Lochan

 3. Why did you choose ? 

It was suggested to me by my supervisor. I sticked with it because it was easy enough to understand for somebody like me who still had a very basic understanding of GR.

I worked on Cosmological Redshift Drift. My thesis was focused on the theoretical understanding of the cosmological redshift and how it changes (redshift drift) with the evolution of the universe. I also tried to understand the feasibility of redshift drift measurements, and how it works in the context of modified theories of gravity.

4. What did you like about it? 

I liked how delving into the theoretical underpinnings of the topic helped me clear up a lot of doubts and misunderstandings I had accumulated over the years. It was enlightening at many points, to understand and work out the math yourself and see how certain fascinating concepts about cosmology, that we have all are familiar with, arise out of the calculations. 

5. Was Astro always the plan? 

Yes. Although my thesis was theoretical and was about cosmology. I tried doing a few things in the data part of astronomy in my earlier internships. Did not like it much. Was very late when I realised that I was more interested in theory.

I had been fascinated by the night sky ever since I was about 12 or 13 years old. By the time I was 15 I had firmly decided that I was going to be an astronomer. It was the reason that I came to IISER to study physics.

6. Internship done in this field ? 

I worked under Dr. Smriti Mahajan on modelling the star formation histories for galaxies. I was also selected for the summer school done by Kritika (The astronomy club of IITB) where I learnt a fair bit about photometry and supernovae. This was the summer after my 2nd year.

The next year I worked under Dr. Harvinder Kaur Jassal on Cosmology again. This year I realised I had a lot of ground to cover in the theory part. Most of the summer was spent learning very basic theory.

The summer after 4th year was spent working on the thesis itself. I did have the opportunity to attend a workshop on Black Holes conducted by the IIA around this time. It was held at the Vainu Bappu Observatory in Kavalur. Was a wonderful experience staying at the observatory and the night sky was just spectacular. 

7. Any prerequisites that you would recommend?

As such there are no prerequisites for anything. You learn as you go along.

Although it does help to build up your knowledge and understanding in the earlier years. Especially if you think you might want to do theory later, it is extremely important to be grounded in mathematics in general from the very beginning. It becomes increasingly difficult to make that switch from computational to theoretical as time goes on.

8. Any mistakes that you have done, and would recommend the juniors to avoid? 

As I already mentioned, decide in your first 2 years if you would like to do theory. If yes, then start building up on it at least from your major years. I would also mention that it is extremely important that you choose your supervisor carefully. It is best to work with somebody who you already have experience with and are comfortable with their working style. It also helps to talk to your seniors who have worked under the professor that you are considering asking.

9. What are your future plans?

Not a PhD in science is all I am sure of currently :). I have been told that I am really good at teaching, so might just take up teaching XD. My time at IISER allowed me to realise that there are a lot of other things that I am interested in. I am still considering my options. It is a big world and there is a lot of stuff that one could be doing. Not sure where I will end up but I am excited for the future.

PS - Even though I don't wish to remain in academia, I still am in love with astronomy, and will continue to be all my life. Maybe I will start a sky-watching club back here at home. One thing on the top of my to-do list would be getting a lot of fancy equipment that we all craved for, for The Astronomy Club as soon as I get a job and start earning.

--Avni (MS22)