Talks

Fast radio bursts (FRBs) are brilliant short-duration flashes of radio emission originating at cosmological distances. Vast diversity in the properties of currently known FRBs and the fleeting nature of these events make it difficult to understand their progenitors and emission mechanisms. Some of the 'pulsar-like' properties of FRBs indicate their neutron star origin. Interestingly, the high-time-resolution properties of FRB 20210912A, a highly energetic event detected by the Australian Square Kilometre Array Pathfinder (ASKAP) in the Commensal Real-time ASKAP Fast Transients (CRAFT) survey, revealed remarkable resemblance with a previously reported CRAFT FRB, FRB 20181112A, including similar rest-frame emission timescales and polarization profiles. The observed properties of these two FRBs may be explained by emission from rapidly spinning neutron stars, with rest-frame spin periods of ∼ 1.1 ms — comparable to the shortest known period of a pulsar and close to the shortest possible rotation period of a neutron star. In this talk I will discuss the similarities between these two FRBs and their implications on FRB progenitor models.

This talk will explore our current understanding of the fast radio burst (FRB) radiation mechanism, highlighting key observational findings and the constraints they place on theoretical models. I will also discuss how FRBs can serve as powerful probes of the reionization era, providing unique insights into the early universe.

When large language models became the dominant machine learning paradigm in 2002, their performance surprised almost everyone, including many experts. LLMs showed “emergent” behavior—bigger models could do tasks that identically-trained smaller models had failed at. Empirical scaling laws suggested that models would get predictably better with increasing model size, more training data and more training-time compute. But these laws began to saturate, only for a new scaling regime to enter the picture. In this talk, Anil Ananthaswamy will chart the ongoing transition to so-called large reasoning models, which use more compute during inference and ostensibly “think” and “reason” before answering, by using extra compute to explore multiple pathways to the final answer.

"FRB 20240114A (R147) is a hyperactive repeating FRB discovered by CHIME/FRB in January 2024. Since its discovery, it has been extensively followed up across the electromagnetic spectrum, including X-ray and optical observations . Several telescopes like FAST, Parkes, Meerkat, etc. have detected hundreds to thousands of bursts from the source. Our uGMRT monitoring campaign (300–1460 MHz) started from 1st February 2024, with our recent study (Kumar et. al. 2024) reporting 60 bursts observed between 300–750 MHz. These bursts exhibit narrow emission bandwidths (~10%) and probe the lower end of the energy distribution. We also observe variations in burst activity, including a coincident burst storm reported by FAST. Preliminary indications suggest possible chromaticity in its burst activity, which, if confirmed, could provide crucial insights into the emission mechanisms of repeating FRBs.
Continued monitoring until March 2025 has yielded in detection of more than 100 additional bursts in Band-4 (550-750 MHz) with uGMRT after entering a quiet phase in August last year. Notably, we recently detected a bright burst in S-band (2–3 GHz) with the VLA on 31st March 2025, following renewed activity reported by the Hyperflash team earlier this year. We have also been observing with VLA across S-band to X-band (2–12 GHz) to study the spectral properties of the potential PRS associated with the FRB source. We will discuss our results, on bursts as well as the PRS, in the context of other recent multi-wavelength observations of FRB 20240114A and its associated candidate PRS, to provide a comprehensive picture of its activity and emission mechanisms."
 

Roughly one in 20 FRB sources have been confirmed to be repeating. Their repeating nature opens up a wide range of follow-up observations and detections. In this talk I will briefly describe the status of our knowledge of repeaters and highlight some of the analyses that are possible, especially for highly active sources. Finally I will connect what we know observationally to possible source models.

CRACO is the new Commensal Realtime ASKAP Fast Transient COherent upgrade searching in the image domain for FRBs with an expected 5 times higher sensitivity than the incoherent sum survey. During commissioning, CRACO probed a new parameter space of long FRB durations from 14 ms to 110 ms time resolution. We found two slower FRBs at the high end of the search range. The detections demonstrate the presence of a detectable population of not-so-fast radio bursts at timescales of hundreds of milliseconds. The scattering times of ~70 ms and 700 ms at 0.8 GHz are among the highest observed so far. The second FRB also shows scintillation from the Milky Way restricting the scattering screen to be close to the source. These highly scattered events at moderate to low distances (z=0.3247 and 0.04973, respectively) extend the observed scattering timescales to 7 orders of magnitude. This extent together with the placement of one scattering screen in the host galaxy questions the applicability of a proposed scattering-distance relation. The vastly different estimated host dispersion measures of ~120 and ~220 pc/cm3 also question the transferability of the pulsar scattering-DM relationship to FRBs.
 

The Bustling Universe Radio Survey Telescope in Taiwan (BURSTT) is a pioneering array designed to detect and precisely localize bright, nearby fast radio bursts (FRBs) in the 300–800 MHz band. Its key features include wide-area coverage of ~10,000 square degrees using multiple beams, along with continuous 24/7 operation. These capabilities significantly enhance the likelihood of detecting nearby FRBs and provide important clues for investigating the repetition rates and potential counterparts of FRBs. The first phase, BURSTT-256 (comprising 256 antennas) is currently fully operational, with a real-time FRB search running around the clock. Daily detections of giant pulses from the Crab pulsar demonstrate the system’s performance, and localization tests with multiple outrigger stations are currently underway. In this presentation, we will report the current status of BURSTT, along with results from our monitoring and localization efforts.

The Murchison Widefield Array (MWA) is a low-frequency interferometer telescope located in the Western Australian outback, operating in the 70 – 300 MHz band, and comprised of 8096 dual-polarisation dipole antennas that are arranged in groups of 16 (tiles), with a maximum baseline out to ~6 km. Even though the array was originally designed and built primarily as an imaging telescope, the eventual development of a voltage capture system (VCS) functionality, whereby unprocessed voltage data can be recorded from all operating tiles opened up opportunities for pulsar and fast transient exploration in the southern skies with this next-generation telescope. Over the past decade, a series of capability enhancements around the VCS and associated software subsystems for post processing (on HPC platforms) has enabled a wide range of pulsar science, provided triggering/shadowing opportunities for GRBs/FRBs, and even facilitated non-astronomical applications involving passive radar or tracking space debris. These efforts have also led to the conception and undertaking of the Southern-sky MWA Rapid Two-metre (SMART) survey – an ambitious project that aims to conduct sensitive searches for pulsars and fast transients in the low-frequency southern skies. With the imminent transition of the array to Phase III by the end of the year, real-time processing and beamforming will replace the data-intensive VCS. I will present an overview of some key technical/science accomplishments in the past years, including new pulsar discoveries flowing on from the SMART project, ongoing efforts to develop a fast-imaging capability (offline processing) to realise large sky surveys for FRBs, and new opportunities now on the horizon for monitoring science in the areas of pulsars and fast transients.