arXiv subjects

Kenil Ajudiya

Publications and source records attributed to Kenil Ajudiya.

4 recordsLinked to original sources

arXiv2026

Interpreting Galaxy Physical Properties Using Stellar Population Synthesis

Galaxy formation and evolution is one of the most active areas of research in astronomy. In recent times there have been several developments on the observational fronts particularly with the discovery of several relations between galaxy physical properties. The exact details of how they come about still remains to be understood. Such a development has been primarily possible due to a deluge of multi-wavelength data ranging from the ultra-violet (UV) to the radio, mainly due to wide field surveys e.g., the Sloan Digital Sky Survey (SDSS) in the optical. Meanwhile, simultaneous theoretical developments like a better understanding of dust attenuation and emission led to the development of techniques to extract information from the SEDs of galaxies, exploiting information from the far-ultraviolet (FUV) to the far-infrared (FIR). The substantial progress made in stellar evolution theory in the 1980s and 1990s paved the way for the latter approach to become the de facto standard in modeling the SEDs of galaxies. It became possible to synthesise a population of stars with a certain distribution and evolve it in time, keeping track of the emission from the stars, new star formation activity, gas enrichment with elements heavier than hydrogen and helium, and the absorption and re-emission from the interstellar dust. This technique, known as the stellar population synthesis (SPS), makes use of these multi-wavelength (UV to IR) data to generate a library of model SEDs. The observed SEDs can then be compared with such a library using statistical fitting techniques like the Bayesian statistics to infer the physical properties of galaxies. The main focus of this thesis is on the reliability of stellar population synthesis modelling when only limited photometry of a small number of wavelength bands is available. It is divided in two parts: elaborate understanding of SPS modelling (Part I) and...

astro-ph.GA↗

arXiv2026

Searching For Fast Radio Transients And Radio Pulsars Using SPOTLIGHT

Our initial impressions of astronomical objects was that they are inherently "static" over the course of any reasonably long observation. However, with the discovery of quasars and their scintillation in 1963-64, we learnt that there are transient phenomena even at the astronomical scales. The world of known transients has been expanding ever since then. Objects and phenomena like quasars, gamma ray bursts (GRBs), pulsars, rotating radio transients (RRATs), fast radio bursts (FRBs) and ultra long period transients (ULPTs) have answered several unanswered questions about the end states of stellar collapse, i.e, the formation and properties of back holes, neutron stars and white dwarfs. Even more interestingly, they have made us better realise how little we know about the universe. Even after more than 5 decades of research, many lurking questions about neutron stars await answers. In the current work, I explored the arena of FRB and radio pulsar astronomy by joining and contributing to the efforts of the SPOTLIGHT collaboration. The recent decades have witnessed huge leaps in radio instrumentation and high performance computing (HPC) technologies driven by the development of high throughput Graphics Processing Units (GPUs). These major technological advancements are conducive to probing extremely small time scales (up to microseconds) of astronomical events. Modern and next generation radio transients surveys at existing and upcoming radio telescopes worldwide are designed to make optimal use of the available resources to push the research frontiers with the sheer volume of data they produce (hence the terminology, data-driven astronomy). There is an urgent need to upgrade the existing time-domain radio astronomy software to keep up with the pace of the technological revolution on the hardware side. Although pulsar phenomena has been studied in great detail...

astro-ph.HE↗

arXiv2026

The SPOTLIGHT Pulsar Search Pipeline: A GPU-Accelerated FFT Approach

We present the pulsar search component of SPOTLIGHT (Survey for sPoradic radiO bursTs via a commensaL multI-beam Gpu-powered Hpc at the gmrT), a GPU-accelerated commensal backend operating at the upgraded Giant Metrewave Radio Telescope (uGMRT). While SPOTLIGHT is primarily designed for real-time detection and localisation of fast radio bursts (FRBs), it simultaneously records a subset of beamformed data products for periodicity searches without requiring dedicated telescope time. To process the large data volumes generated by the survey, we have developed a scalable FFT-based pulsar search pipeline that combines radio-frequency interference mitigation, GPU-accelerated dedispersion and periodicity searches, multi-beam candidate sifting, efficient folding and machine-learning classification. Using population synthesis and archival uGMRT observations, we estimate that a fully operational SPOTLIGHT survey with 160 PC and one IA beam could discover $\sim$ 450 new pulsars, probing both high-sky coverage and faint pulsars over three and a half years of commensal observations. The pipeline has been validated on GMRT Cycle 48 and 49 observations (i.e. April 2025 to Mar 2026), successfully re-detecting numerous known pulsars with a wide range of Period, DM and flux densities, and is currently operational for SPOTLIGHT commensal data processing. We describe the SPOTLIGHT observing system, pulsar survey design, search parameter space, candidate-selection strategy, current status, and future developments. SPOTLIGHT demonstrates the scientific potential of commensal pulsar surveys and serves as a pathfinder for real-time, large-scale pulsar and transient searches in the SKA era.

astro-ph.HE↗

arXiv2026

The SPOTLIGHT Multibeam Real-Time Transient Detection System

Fast Radio Bursts (FRBs) are among the most enigmatic transient phenomena in the Universe. In order to unravel the mystery behind these events, one requires instruments that possess the ability to search, detect, localise, and capture these events in high resolution over large fields-of-view in real-time. The SPOTLIGHT project is one such backend, leveraging the upgraded Giant Metrewave Radio Telescope (uGMRT) to conduct a commensal search for FRBs and other radio transients, using a dedicated high-performance computing facility, comprised of 90 NVIDIA A100 GPUs and 60 compute servers. Here we present the design, implementation, and performance of SPOTLIGHT's real-time transient search pipeline, a GPU-accelerated system capable of processing up to 2000 post-correlation beams in real time. The pipeline combines AstroAccelerate-powered brute-force dedispersion and single pulse search, with a multi-stage and robust candidate optimisation framework, as well as a triggering system for automatic capture of high-resolution visibility and baseband data. To ensure continuous validation of pipeline performance, we have also developed a real-time signal injection framework capable of injecting synthetic bursts directly into SPOTLIGHT's beamformed data stream. The system operates commensally with routine uGMRT observations, processing data streams in real-time while maintaining high sensitivity to ms-duration transients across dispersion measures extending up to 2000 pc cm$^{-3}$. During its initial deployment in uGMRT Cycle 49 and Cycle 50, the pipeline detected 2870 bursts from 42 known sources, and demonstrated sensitivity consistent with the predicted survey threshold of $\sim$ 0.2 Jy ms. The SPOTLIGHT system establishes a scalable framework for wide-field, low-frequency transient discovery and localisation, and provides a key technological foundation for next-generation radio transient surveys.

astro-ph.IM↗