Title : Advances in Satellite Radar Imaging

Abstract

Recently, IIRS Dehradun conducted the Structured Training Program (STP). The theme of the STP was "Advances in Satellite Radar Imaging". 28 Scientists/Engineers from ISRO/DOS Centers participated in the program. The programme covered the basics of radar remote sensing and its applications like natural resources management, agriculture, and infrastructure planning, disaster management and planetary exploration. This seminar will cover a brief discussion based on the lectures given by various faculty members in the STP.

Title : An X-ray Perspective on Multi-scale Solar Flares: Spectroscopy to Polarimetry

Abstract

Solar flares have a wide range of intensity scales ranging from large X-class flares to microflares to hypothesized nanoflares that may be responsible for coronal heating. Investigations of multi-scale solar flares, from large flares to the smallest microflares, are key to the missing pieces in our understanding of the flaring process and coronal heating. As the flaring plasma and accelerated electrons emit profusely in soft and hard X-rays, X-ray spectroscopic observations offer the most direct diagnostics of the thermal and non-thermal particle populations in flares and, thus, insights into the energy release mechanisms in flares. Solar X-ray Monitor (XSM) onboard the Chandrayaan-2 mission provides disk-integrated X-ray spectral measurements of the Sun in the energy range of 1-15 keV, with a high dynamic range to observe sub-A class micro flares to large X-class flares. XSM has recently completed five years of continuous solar observations and in this talk I will highlight some of the major results using XSM observations on various aspects of multi-scale solar flares. I will also introduce other recently operational solar soft X-ray spectrometers on other missions and on the advantages of simultaneous analysis of soft X-ray spectra with the hard X-ray spectra from instruments such as Solar Orbiter STIX and Aditya L-1 HEL1OS. Going beyond spectroscopy, I will also discuss the potential of X-ray polarimetric observations of solar flares and our efforts towards a small satellite experiment, which would also be a pathfinder to an X-ray astronomy mission.

Title : Studying solar flares with the X-ray telescope STIX on Solar Orbiter

Abstract

Of the six remote-sensing instruments aboard ESA's Solar Orbiter spacecraft, the Spectrometer/Telescope for Imaging X-rays (STIX) is the one dedicated to the study of solar flares. It performs X-ray imaging spectroscopy in the hard X-ray regime, which provides key physical diagnostics on both the hot thermal plasma as well as on the accelerated energetic electrons. During its operation since launch in 2020, STIX has detected over 56,000 solar flares. I will discuss how the STIX data are used to study energy release and particle acceleration in solar flares. In particular, I will focus on studies that use STIX jointly with other observational assets, such as the other remote-sensing instruments on Solar Orbiter, various instruments on other spacecraft, and in-situ particle detectors.

Title : Unveiling the mechanism behind sign changes in the thermopower and Hall coefficient of strained Sr2RuO4

Abstract

Sr2RuO4 is a fascinating material in condensed matter physics, celebrated for its unconventional superconductivity and intricate electronic structure. A particularly intriguing aspect is its strain-induced Lifshitz transition, which profoundly influences transport properties. Notable among these effects are the sign changes observed in the thermopower and Hall coefficient under strain, a phenomenon that remains not fully understood. In this talk, I will explore these transport properties using the semiclassical Boltzmann transport formalism, examining both unstrained and strained (uniaxial and c-axis) systems. I will demonstrate that the sign changes are driven by the Van Hove singularity, which emerges as a direct consequence of the Lifshitz transition, offering deeper insights into the electronic structure and transport behavior of Sr2RuO4.

Title : Introduction to High-Energy Neutrino Astrophysics

Abstract

We will provide a pedagogical introduction to High-Energy Neutrino Astrophysics and the emerging field of Multimessenger Neutrino Astronomy. We will discuss how the high-energy neutrinos are produced, propagate and are detected and what they can tell us about the origins of cosmic rays, dark matter, and other fundamental puzzles of the Universe.