ASTROSAT: Some Key Science Prospects

ASTROSAT is an astronomy satellite designed for simultaneous multi-wavelength studies in the Optical/UV and a broad X-ray energy range. With four X-ray instruments and a pair of UV-Optical telescopes, ASTROSAT will provide unprecendented opportunity for simultaneous multi-wavelength observations, which is of immense value in study of highly variable sources, especially X-ray binaries and Active Galactic Nuclei. The Large Area X-ray Proportional Counters (LAXPC) of ASTROSAT, which has the largest effective area in the hard X-ray band compared to all previous X-ray missions, will enable high time resolution X-ray measurements in the 2-80 keV band with moderate energy resolution. Here we give a brief summary of the payload characteristics of ASTROSAT and discuss some of the main science topics that will be addressed with the LAXPC, and with simultaneous observations with the UVIT telescopes, with particular emphasis on X-ray binaries and compact objects. The possibility of aiding gravitational wave experiments is also briefly mentioned.Comment: Invited Review to International Journal of Modern Physics D (based on a talk in ASTROD-5 symposium at RRI, Bangalore

A method for testing the cosmic homogeneity with Shannon entropy

We propose a method for testing cosmic homogeneity based on the Shannon entropy in Information theory and test the potentials and limitations of the method on Monte Carlo simulations of some homogeneous and inhomogeneous 3D point process in a finite region of space. We analyze a set of N-body simulations to investigate the prospect of determining the scale of homogeneity with the proposed method and show that the method could serve as an efficient tool for the study of homogeneity.Comment: 7 pages, 3 figures, Accepted for publication in MNRA

Development of Nanostructure based Corrosion-Barrier Coatings on Steel for Transmutation Applications: Quaterly Report

During the past quarter, this project employed one graduate student and two undergraduate student researchers and made the following accomplishments : • Acquisition of steel samples for experiments • Design and fabrication of specialized anodization apparatus to accommodate steel samples • Investigation of adhesiveness of aluminum on steel • Investigation of effects of anodizing acids on steel to identify most appropriate acid and a suitable barrier materia