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I am a PhD candidate working with the Accretion physics group at Curtin university that focusses on studying all aspects of accreting stellar mass black holes. I am particularly interested in understanding how these extreme objects are born.

Local Time 09:00:00 – 17:00:00

The goal of my PhD is to understand the phenomenon of natal kicks and black hole birth mechanisms better. The two leading theories for creating a stellar mass black hole are

  • Direct collapse – wherein a massive star directly collapses onto itself with little or no mass ejection.
  • Delayed formation in a supernova – wherein there is fallback of matter onto a proto-neutron star and that gives rise to a black hole.

There are conflicting arguments on the relation between how massive a black hole is and which way it was born. There are limited observational constraints on black hole formation because of the rare chance that we might actually observe one in the process of forming.

So we need another tell that helps us observe the black hole in its current state and estimate how it might have formed. I use black hole X-ray binaries as a probe to understand black hole birth. I am interested in measuring the natal kick a black hole binary system gets when a black hole is born, as it can be related to how the black hole was born. A strong natal kick implies the black hole was born with a supernova explosion and suffered a recoil kick and even additional velocity due to asymmetries in the explosion. On the contrary a weak natal kick will imply that the black hole was born with a direct collapse!

I am achieving this by measuring the proper motion of black hole X-ray binaries in our Galaxy using radio Very Long Baseline Interferometry, which enables me to measure proper motion of the order of a few mas/yr.  Combining the proper motion with the systemic radial velocity and distance to the source, I have been tracking the Galactocentric orbits of 16 such systems.

The orbit of a black hole X-ray binary system, Swift J1753.5-0127, in our Galaxy. The high kick velocity and extremely eccentric orbit of this system has been attributed to a kick imparted to the system when the black hole was born with a supernova explosion.

I am leading proper motion and parallax measurement campaigns with the VLBA, the EVN and the LBA that gives us access to the entire sky and lets us observe any black hole X-ray binary system that gets bright enough to observe in the radio wavelengths. This will enable us to get a statistically significant sample sets of systems with estimated natal kicks and in turn help us conduct population studies of black hole X-ray binaries.

Measuring natal kicks have other important implications. It affects the accretion and jet mechanisms as it can lead spin-orbit misalignment of the binary system. Natal kick that a black hole system receives is a huge controlling factor in the number of black holes that are retained in globular clusters. I am interested in studying how the natal kick strength affects the rate of black hole mergers, and hence will change the number of LIGO events that are detected. There are claims that natal kicks that black holes and neutron stars receive could be similar, and observationally measuring black hole natal kicks could be a good test of that.

For more details about my academic life here are links to my CV and github repository.

Local time 17:00:00 – my:heart’s:content

I am heavily involved with outreach activities of ICRAR, which keeps me in touch with the world outside of my work desktop and gives me a chance to work with optical telescopes and stare at the night skies (a thing that people believe astronomers do all the time!!). I was also a part of a YouTube series called ‘Astro Morning tea’ that was made by the ICRAR outreach team for a few episodes. Open the links at your own risk and learn some about some (probably outdated) astronomy news and fun science facts.

Check out a few local news articles I managed to squeeze my face on-

  • Led the night sky observing at Astrofest Perth that had tens of thousands of people
  • Got to entertain an auditorium full of people at Battle of the brains
  • Another outback Astrofest night sky viewing


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