Shantanu Basu

a few words about my resesarch

I am fortunate that my career as an academic teacher and researcher allows for constant personal and professional growth, and brings me into touch with some of the brigthest minds of many generations. My past and present students and postdocs have come from many corners of the world and enriched my life immensely.

I am motivated by the ability to apply physics, mathematics, and computational techniques to unlocking the secrets of the cosmos. In our group we have developed a new paradigm for the evolution of protoplanetary disks around young stars. The Migrating Embryo model can explain the luminosity bursts of young stars, binary star and giant planet formation, and the ejection of low mass objects into the interstellar medium. Magnetic fields in the cosmos add a richness and complexity to all interstellar gas dynamics and we have demonstrated its effect in creating a broad distribution of protostellar core masses and in protostellar collapse by controlling disk formation and evolution and launching powerful outflows.

I am most recently interested in studying the formation of collapsed objects in the early universe, i.e., the first stars and black holes in the universe. A recent paper has explained the shape of the mass distribution of supermassive black holes in the early universe. We have also shown that magnetic fields enhance the formation of supermassive stars that quickly collapse into supermassive black holes.

There are many avenues available for a bright and motivated student or postdoc to make major progress in theoretical astrophysics using physical insight and numerical simulations.

Through a series of papers with rigorous self-consistent calculations of the formation and evolution of protostellar disks, we are promoting a new view of disk evolution. This Migrating Embryo model has implications for many aspects of star and planet formation, including the formation of stellar and substellar (brown dwarf and planet) systems, luminous outbursts of young stellar objects, and the growth of dust and high-temperature processing of materials.

Work in our group is one of the few in the world that has solved the equations of non-ideal magnetohydrodynamics to calculate the evolution of such processes as they affect gravitational fragmentation. This is interesting because magnetic fields can explain the observed very low efficiency of formation of molecular gas into stars. Only a few percent of molecular cloud mass is converted into stars in typical observed star-forming regions. Recent work shows that magnetic fields provide a natural explanation for filamentary structure (Auddy, Basu, and Kudoh 2016) and can explain the probability density function (pdf) of column densities in molecular clouds; both the steep slopes seen in regions of low star formation (Auddy, Basu and Kudoh 2018), as well as the transition from a lognormal pdf at low densities to a power law at higher densities (Auddy, Basu, and Kudoh 2019).

There are many disciplines in which a desired distribution is one that is like a lognormal at low and intermediate values, with a characteristic peak and turnover, but transitions to a power law distribution at high values. Besides astronomy, this need has arisen in fields as diverse as biology, computer science, ecology, and financel. We have analyzed and characterized the properties of a hybrid three-parameter probability density function (Basu, Gil, and Auddy 2015; Basu and Jones 2004) that can be used to fruitfully model data sets that exhibit both lognormal-like and power-law behavior. It is a natural first step when fitting data that may look like a modified lognormal, and its relatively compact analytic closed-form expression makes it easy to use with common fitting techniques (see Madaan, Lianou, and Basu 2020).