Search Talks

Radio observations are essential for studying galaxy formation and evolution, yet analyzing low-frequency interferometric data is challenging due to radio frequency interference (RFI) contamination and other system issues. To streamline this process, we developed GARUDA, an automated pipeline for analyzing GMRT data, employing AI/ML-based algorithms for efficient RFI identification and artifact removal. GARUDA enables fast and consistent data reduction, handling ~10-12 GB GSB data in 20-30 minutes and ~400 GB GWB data in under three hours on standard servers. In this presentation, I will discuss GARUDA’s capabilities and showcase results, including some of the deepest GMRT radio continuum images at the L-band, HI emission in galaxies, and one of the most sensitive galactic HI absorption lines (using frequency switching observation with GWB).

Measurements of magnetic fields at the outskirts of galaxy clusters provide crucial insights into the evolution of cosmic magnetic fields. Radio relics are known to trace merger shocks in galaxy clusters propagating in the periphery of galaxy clusters. Many relics show a very high linear polarisation, which is puzzlingly aligned with the orientation of the relics. In this talk we will briefly review current research on radio relics and what these observations tell us about the structure and evolution of magnetic fields. We use Rotation Measure (RM) synthesis and QU fitting methods to spatially resolve the properties of the dominant components in Faraday space. I will show how these methods allow us to constrain the properties of the magnetic fields in the cluster outskirts through a combined analysis of Faraday depths and depolarisation.

In this talk, I will provide an update on the current status of the SKA Observatory, which is currently under construction. I will also describe the role of India in this project, and summarise the various activities going on in India, coordinated by the SKA India Consortium, towards India's participation in the SKAO.   

I will review few basic questions which can be addressed by future and present intensity mapping experiments in the post-reionization era. Most importantly: dark energy, neutrino masses and galaxy formation aspects.

Radio continuum emission is a highly promising tool for tracing star formation activity across cosmic time and environments, by virtue of being unbiased by dust and reaching high angular resolution in interferometric imaging. I will discuss recent results, but also some of the challenges associated with using GHz continuum surveys to characterize the evolution of the star-forming galaxy population from the final Gyr of the EoR to the present day.

Galaxy clusters and superclusters are among the youngest structures forming in the Universe. The intra-cluster medium (ICM) and inter-galactic medium (IGM) are both unique plasmas that host magnetic fields and cosmic rays. Radio band observations provide the probes to these, so-called non thermal components, via the detectable synchrotron radiation. The particle acceleration mechanisms involve the role of shocks and turbulence in the magnetized plasma that can be probed with radio band continuum and polarization observations. I will present our work on studying turbulence and shocks in the high redshift, massive galaxy cluster El Gordo and the Saraswati supercluster with the precursors and pathfinders of the SKA. I will discuss our findings on the evolution of radio galaxies in superclusters and the properties of intra-cluster turbulence using radio and X-ray observations and provide a perspective on the exciting possibilities with the SKA.

With the increased sensitivity and field of view of SKA pathfinders, dynamic radio imaging (imaging the time axis) is becoming a burgeoning field, yielding rich new discoveries of transients and variable sources. MeerKAT is capable of reaching sub-150 uJy image rms in an 8s integration, which opens up studies of variability on much shorter timescales than was possible with previous radio interferometers. This also has important implications for interferometric SETI, since any potential technosignatures would be a subset of such transient events.

At the same time, imaging at such short timescales introduces its own substantial challenges. Instrumental effects that tend to average out in a traditional long synthesis observation can become limiting for dynamic imaging if not addressed correctly. I will discuss these challenges and present MeerKAT dynamic imaging of Jupiter’s radiation belts, which have led to the serendipitous discovery of a pulsar-class object named the PARROT (pulsar with abnormal refraction recurring on odd timescales).

This work has led to the development of (and given the name to) a more general dynamic imaging pipeline, developed in collaboration with the Breakthrough Listen initiative. The PARROT pipeline is capable of detecting short-duration transients in imaging data, and yielding light curves and dynamic spectra for thousands of field sources en masse. We are already starting to use it to “mine” existing archival MeerKAT data, yielding a couple of new discoveries. The longer-term plan is to develop the PARROT pipeline to a state where it can be run in real-time, commensally with any MeerKAT imaging observation. This would open the door to transient event triggers -- something that has never been done with a radio interferometer before.