How do galaxies evolve? What happens when supermassive black holes merge? How did the Universe look like just after the Big Bang?
Published by the editorial team, 5 September 2023
The European Research Council (ERC) has awarded Dr. Aditya Parthasarathy a prestigious and extremely competitive grant to pursue his research at ASTRON, the Netherlands Institute for Radio Astronomy. Dr. Parthasarathy was awarded a Starting Grant of about 1.6 million Euros as part of the Horizon Europe funding programme while working at the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany. The grant will enable him and his team to address these fundamental questions in astrophysics through the project titled, “A Gamma-ray Infrastructure to Advance Gravitational Wave Astrophysics (GIGA)”.
“It is a very exciting time for low-frequency gravitational wave science. With GIGA, we will be pushing the state-of-the-art for pulsar timing arrays in both the gamma-ray and radio wavelengths” says Dr. Parthasarathy. Pulsars are formed from the inevitable gravitational collapse of massive stars, leaving behind a compact neutron star, denser than atomic nuclei and rotating hundreds of times a second. With every rotation, they emit beams of radiation that sweep across the Galaxy – acting as cosmic lighthouses. The incredible regularity of their pulses can be used to search for minute variations in their ticking, which encode a wealth of astrophysical information. A pulsar timing array uses a collection of these cosmic clocks to detect the faint sea of gravitational waves that permeates the Universe.
This gravitational wave background is expected to originate from pairs of supermassive black holes found in the centers of merging galaxies. A significant detection of this signal will advance our understanding of how galaxies evolve and the properties of the early Universe just after the Big Bang. Recently, an international team of astronomers announced the first compelling evidence for the gravitational wave background using many of the world’s most sensitive radio telescopes and with data collected for over 15 years. Although this milestone result has made the first inroads into probing low-frequency gravitational waves, there is much left to be understood.
Bent by electrons
“One of the biggest limitations in improving the sensitivity of radio pulsar timing arrays is our understanding of the intervening interstellar medium and how to model its effects on pulsar data,” says Dr. Parthasarathy. As radio waves propagate from the pulsar to our planet, they are bent by the electrons in the interstellar medium, which directly biases the measurement of the gravitational wave parameters. “GIGA will overcome this major limitation by using gamma-ray observations of pulsars from NASA’s Fermi space telescope. Since gamma rays are immune to the effects of the interstellar medium, a gamma-ray pulsar timing array will provide an independent and more direct detection of the gravitational wave background,” he adds.
“GIGA is an exciting idea that promises to deliver breakthrough results,” says Prof. Michael Kramer, who is one of the directors of the MPIfR, and leads the Fundamental Physics in Radio Astronomy group. “A combination of gamma-ray and radio data will not only boost our sensitivity to the gravitational wave background but will aid in understanding its astrophysical origins better” he adds.
Research group at ASTRON
Dr Parthasarathy will be joining ASTRON before the end of 2023 where he will use his ERC Starting Grant to establish his research group. “I am very excited to start my own research group while continuing to collaborate with my MPIfR colleagues, and I am grateful to the ERC for the funding”, concludes Dr. Parthasarathy.
