Astronomy and Astrophysics Seminars

Nascent efforts towards Nano and Milli-Hertz GW Astronomy

by Dr. Prerna Rana (TIFR)

Tuesday, May 10, 2022 from to (Asia/Kolkata)
at Hybrid ( AG 66 ) Meeting ID: 898 0249 9816 Passcode: 479156
The routine detection of transient hecto hertz gravitational waves (GWs) from stellar-mass compact binaries by the LIGO-Virgo-KAGRA collaboration since 2015 has inaugurated the era of GW astronomy. The maturing Pulsar Timing Arrays (PTAs) and planned Laser Interferometer Space Antenna (LISA) and the third generation GW observatories are expected to establish Multi-Band GW Astronomy in the coming decades. The International PTA (IPTA) consortium plans to combine the data of 100 milli-second pulsars (MSPs) and resources from different PTA experiments to expedite the detection of nano-hertz GWs in the coming years. This is motivating the Indian PTA (InPTA), the latest entrant to the IPTA consortium, to make the first official data release (DR1) of 14 MSPs, observed simultaneously in 300-500 MHz (Band 3) and 1260-1460 MHz (Band 5) frequency bands using TIFR’s uGMRT. I will briefly discuss my contributions towards the InPTA DR1, particularly, in estimating a series of pulsar Time of Arrival (TOA) and Dispersion measure (DM), which covers a baseline of 3.5 years (2018-2021). Thereafter, I will sketch the uGMRT observations of an abrupt profile change event in PSR J1713+0747, one of the most precisely timed IPTA pulsars and its implications. I will also discuss our ongoing efforts to model the GW Burst with Memory (BWM) events produced by the massive black holes in general relativistic hyperbolic orbits with the help of the post Newtonian formulation and its IPTA implications. Towards the end, I will show how we can parameterize the extreme precession behavior, called the zoom-whirl behavior, of 3D periodic orbits in Kerr space-time. Such extreme precession should show an imprint on the GW signal from the extreme-mass-ratio inspirals, which are the prime milli-hertz GW sources for the planned LISA GW observatory.