Abstract:
Stars host extreme conditions that are difficult to achieve on Earth, and provide a natural lab to conduct important tests of fundamental physics. I will discuss two remarkable examples -- a novel search for heavy dark matter using observations of neutron stars and/or black holes, and a search for neutrino-neutrino interactions (a Standard Model interaction that has not been directly tested) using supernovae. In each case, we will see how improved knowledge of the astrophysical conditions paves the way for deeper probes of fundamental physics. read more...

Abstract:
Everything in the universe is made up of a few basic building blocks called fundamental particles governed by four fundamental forces. The Standard Model (SM) of particle physics, developed in the nineteen seventies, beautifully encapsulates how the fundamental particles and the three forces (electromagnetic, strong and weak) are related to each other. The SM has been a well-tested physics theory so far yet some questions remain both within the realm of SM and beyond such as why there are three generations of fundamental particles and why their masses are different, explanation of the observed matter-antimatter asymmetry in the universe, the existence of dark matter, and hint of non-zero neutrino masses etc. We will introduce the elusive subatomic particles, the neutrinos and highlight the role they play in our understanding of the universe. The first part of the talk will comprise of an introduction to neutrino physics along with historical account of important discoveries. We will discuss the current status and open questions in this field. Towards the end, we will discuss some of our current theoretical efforts and their connection to experiments at Fermilab. read more...

Abstract:
Directly imaging rocky exoplanets is one of the key science goals of current and upcoming large telescopes. Direct imaging has emerged as a powerful technique for studying distant worlds beyond our solar system. Modern large telescopes are capable of imaging young Jupiter-mass planets at wide separations from the host star. However, the challenge of imaging rocky planets remains due to the high contrast requirement. The mid-infrared (mid-IR) regime offers the optimum contrast to directly detect the thermal signatures of exoplanets in our solar neighborhood. Upcoming mid-IR instruments such as METIS (Mid-infrared ELT Imager and Spectrograph) on the Extremely Large Telescope (ELT) will be able to detect rocky exoplanets. In this talk, I will cover fundamental principles, challenges, and recent advancements in the direct imaging of exoplanets. Key topics include innovative instrumentation, such as coronagraphs and adaptive optics, utilized to suppress starlight and enhance the detection of exoplanets. I will also discuss the results from the first discovery of a cold giant exoplanet using direct imaging from James Webb Space Telescope and the ground-based VLT telescope. read more...

Abstract:
In this talk we would discuss the major broad observational features of black hole astrophysics and discuss how various disc models arose, starting from Bondi flow, thin Keplerian (Shakura Sunyaev; Novikov Thorne) disc, thick disc or the POLISH donuts, ADAF, TCAF and also the modern popular disc models. We will discuss the pros and cons of them. We would end by point out the challenges that lie ahead.read more...

Abstract:
Fundamental laws of physics are symmetric under time reversal (T) symmetry, but T symmetry is strongly broken in the macroscopic world. In this talk, I will present several mechanisms for determining the arrow of time (or breaking T symmetry), including the second law of thermodynamics, multi-scale energy flux, asymmetric macroscopic objects such as rockets, open systems, and causality. In this talk, I will also discuss hydrodynamic entropy that captures multi-scale order in hydrodynamic flows.read more...