I am an Astronomer, and an Instrument Scientist for the WFC3 instrument on board the Hubble Space Telescope. My research efforts have focused on applying microlensing, transit, and relativistic deflection techniques to detect and study exoplanets, nearby stars and black holes. I currently lead two HST projects to detect isolated, stellar-mass black holes and determine their masses through gravitational lensing.
Back in 1994, I had shown that the microlensing events detected towards the Magellanic Clouds are mainly caused by the stars within the Magellanic Clouds, and not by MACHOs (Sahu, 1994, Nature, 370, 275). This naturally led to the idea that microlensing can be used to detect planets around the lensing stars. So I co-founded the PLANET (Probing Lensing Anomalies NETwork) collaboration to detect planets around the lensing stars through frequent monitoring of microlensing events. This project has led to the discovery of several exoplanets, including terrestrial planets.
I led a program of HST observations which showed, for the first time, that a Gamma Ray Burst (GRB 970228) was associated with an external galaxy, and that the GRB phenomenon is unrelated to the nuclear activity of the host galaxy (Sahu et al. 1997, Nature, 387, 479).
One of my favorite research programs was to search for exoplanets in the Galactic bulge, through a large HST program called SWEEPS (Sagittarius Window Eclipsing Extrasolar Planet Search). Through this program, we monitored about 300,000 stars towards the Galactic bulge using the Advanced Camera System (ACS) on board HST, to search for transiting exoplanets. This led to the discovery of 16 planet candidates, including 5 ultra-short-period planets. These results were published as a full Article in Nature (Sahu et al. 2006, Nature, 443, 1038), (also available through astro-ph). The NASA Science Update, held on 4 October 2006, gives some details on these results.
Recently, I led the first ever measurement of relativistic deflection caused by a star outside the solar system (the nearby white dwarf Stein 2051 B), as predicted by Einstein just over a century ago. The relativistic deflection was used to measure the mass of the white dwarf, the first such measurement through this technique (Sahu et al. 2017, Science, 356, 1046). Click here for the Abstract, and click here for the full Article. This work was listed by Discover magazine as one of the "Top 100 Science Stories" of 2017.
Many of my scientific publications (over 300 in total, including 9 in Nature and one in Science) have received extensive coverage in national news media (including The Washington Post, New York Times, LA Times, and National Geographic), as well as international press (such as De Volkskrant, Times of India, etc.).
My hobbies include tennis, long-distance running, biking, and trekking in the mountains (highlights: Everest Basecamp and Annapurna Circuit in Nepal, Rainbow Mountains and Canyon del Colca in Peru, Grand Teton and Red Rock Canyon in the US...).
|Research Interests||HST-Support Activities|
|Curriculum Vita (pdf format)||Online Recent Seminars|
|Publications (pdf format)||Related Sites|
|Revised LHS Catalogue|