Pavan Hebbar

Gamma Ray Bursts(GRBs) are large explosions of very high energy in the sky that last for short durations(from one-tenths of second to tens of seconds). The fast-rise and slow-decay profile of GRB, makes it extremely important to detect GRBs in their early stages.
Under the guidance of Prof. Varun Bhalerao, I implemented efficient algorithms to detect GRBs from AstroSAT CZTI data. After proper processing of the raw data, the light curves of the four independent quadrants were compared to calculate the significance of the peaks to decide whether a given peak is a GRB or not. To account for the changing noise profiles, an adaptive cutoff threshold was implemented which depend on the user defined false-alarm-rate

Bogdanov et al. 2005 reported the presence of transits in 47 Tuc W, which lasted for about one-third of its binary orbit around a main sequence star. These transits couldn't be observed in the 2005-06 HRC observations of Chandra Telescope.
Under the guidance of Prof. Craig Heinke, I analyzed the data from the 2014-15 Chandra Observations to verify the nature of the X-ray variable star. We looked into the light curves under different energy regimes and verified the presence of the transits. At the same time we also showed that the absence of the transits in 2005-06 observations were due to the fact that the variation of photon count rate is more dominant in the high energy X-rays.
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Cosmic Microwave Background Radiation is the earliest source of radiation in this universe. Though extremely isotropic, it has small anisotropies of the order of 10^-5 which are responsible for the formation of large scale structures in the universe. These anisotropies in CMBR not only help us study the universe today but also to probe the times before the epoch of recombination.
Inflation refers to the time after Big Bang during which the universe expanded exponentially. The theory of inflation helps us answer several questions regarding the structure and composition of the present day universe
My work involved the study of various types of anisotropies especially the polarization anisotropies and validate the inflation models using B-mode polarization spectrum of CMBR. We also estimated the values of different parameters in each of the inflation models. You can find more details over here

MOTIVE was proposal for payload to be sent on Venus by ISRO(Indian Space Research Organization) with a purpose to study Venusian Gamma ray Flashes(VGFs) and solar flares, while monitoring the sky in search of GRBs and High Energy Counterparts of Gravitational Waves. Along with Prof. Varun Bhalerao, I specifically looked into VGFs and localization of GRBs.
Currently, position of GRBs is found using the IPN (InterPlanetary Network) satellites that typically locate the GRB to an accuracy of 100 arcmin². We intended to increase this accuracy by trilateration of gamma ray detectors on Mars, Venus and Earth. I was involved in the calculation of increase in the accuracy through this method and found that the error could be decreased to about 1 arcmin².
We also studied about VGFs and verified if they could be observed from the proposed altitude of satellite. We looked into the probability of a VGF occurring at a given altitude and the range of altitudes for which it would be visible due to the atmosphere of Venus.