Gamma Ray Astronomy at PeV Energies-Phase 3 (GRAPES-3) is a cosmic ray experiment located in Ooty, Tamil Nadu, featuring an array of extensive air shower detectors and a muon telescope. The primary objectives of GRAPES-3 are to precisely measure the cosmic ray energy spectrum, study its nuclear composition, and explore multi-TeV γ-ray astronomy. A key aspect of these studies is understanding...
Blazars are a class of active galactic nuclei (AGN) where the relativistic jet is pointed towards the observer. They are powerful sources of non-thermal radiation from radio to Very high energy(VHE) gamma-rays. Flat Spectrum Radio Quasars (FSRQs) are a subclass of blazars where there are broad absorption or emission lines present in the optical spectra.
The observed properties of FSRQs are...
It has long been observed that extensive air showers (EAS) produced by heavier mass primary cosmic rays (PCR) contained more muons than those created by lighter ones. As a result, muon multiplicities in EAS have been used as an indicator for estimating the PCR
composition. This points towards the importance of an accurate determination of the muon
multiplicity in an EAS. The GRAPES-3...
The GRAPES-3 experiment in Ooty, Tamil Nadu, operates the world's largest muon telescope, which consists of 3,776 proportional counters (PRCs) as its primary detectors. These PRCs are cuboidal iron tubes filled with P10 gas, a mixture of 90% Argon and 10% Methane. Each PRC has dimensions of 6m x 0.1m x 0.1m and contains a 100-micron diameter tungsten wire anode, placed exactly at the centre of...
Upon the interaction of primary cosmic rays with atmospheric nuclei, an Extensive Air Shower (EAS) is produced, generating secondary particles that offer an indirect method to study cosmic rays. The muonic component of these showers is crucial for understanding the mass composition of the primary cosmic rays. However, at higher energies, significant discrepancies persist between simulated and...
The HAWC observatory is an air-shower Cherenkov detector
installed at high altitudes (4100 m a.s.l.) with the mission of
studying the universe at TeV energies by means of the gamma and
cosmic rays that are received from the sky. The analyses of the
hadronic-induced events at HAWC have allowed to investigate the
sky maps, energy spectrum and the composition of cosmic rays at
energies from...
The Askaryan Radio Array (ARA) is an in-ice ultra high energy (UHE, >10 PeV) neutrino experiment at the South Pole that aims to detect UHE-neutrino induced radio emission in ice. ARA consists of five independent stations each consisting of a cubical lattice of in-ice antenna clusters with side length of ~10 m buried at about 200 m below the ice surface. All five independent ARA stations have...
Using AstroSat observations, we present spectral and temporal studies of the outburst of the black hole X-ray binary (BHXB) GX 339-4 that occurred during January-April 2021. We have also used X-ray data from Maxi and Swift. We have studied the rising phase of this outburst and its evolution in detail. In the power density spectrum (PDS). We found that quasi-periodic oscillation (QPO) increases...
The ultra-relativistic, highly collimated jets generated by Gamma-Ray Bursts (GRBs) provide crucial insights into particle emission. These jets also reveal the physical mechanisms driving the rapid release of high-energy gamma-ray photons. This presentation will discuss time-resolved and flux-resolved spectroscopy for the ultra-long GRB 220627A. The analysis spans a duration exceeding 1200...
We examine the impact of turbulent magnetic field diffusion on the ultra-high energy cosmic ray (UHECR) spectrum from a cosmological perspective. Specifically, we explore the effect of magnetic diffusion within the framework of one of the modified symmetric teleparallel gravity, known as $f(Q)$ gravity. In this modified alternative theory of gravity (MATG), the non-metricity scalar $Q$ and its...
High-energy cosmic rays are a significant aspect of the high-energy universe, but their origins and acceleration mechanisms are not fully understood. Neutrinos, generated through interactions of these cosmic rays, provide a unique means to study these energetic particles and their sources. This presentation focuses on how observations of neutrinos can inform our understanding of cosmic ray...
