Saurabh W. Jha
Department of Physics and Astronomy
Rutgers, the State University of New Jersey
136 Frelinghuysen Road
Piscataway, NJ 08854
office: Serin 315, Busch campus
tel: (848) 445-8962
fax: (732) 445-4343
I joined the Rutgers astrophysics group in September 2007. Previously, I was a Panofsky Fellow at the Kavli Institute for Particle Astrophysics and Cosmology at the Stanford Linear Accelerator Center, a Miller Fellow in the University of California, Berkeley Department of Astronomy, and a graduate student at the Harvard-Smithsonian Center for Astrophysics.
Research interests and collaborations
My main research focus is the observational study of Type Ia supernovae (SN Ia). I am interested in understanding the properties of these exploding white dwarf stars: their progenitor systems, how they explode, and using this knowledge to turn them into tools with which to survey the Universe.
This work is done in collaboration with a variety of groups:
The High-z Supernova Search Team first published strong evidence from observations of distant SN Ia that we live in an accelerating Universe. Along with the results of the Supernova Cosmology Project, this work was called the Breakthrough of the Year by Science in 1998, and was awarded the 2007 Gruber Cosmology Prize, the 2015 Breakthrough Prize in Fundamental Physics, and the 2011 Nobel Prize in Physics.
The ESSENCE project followed up this earlier work, in an attempt to characterize the dark energy that is driving the accelerating expansion of the Universe, by measuring its equation of state to 10% accuracy. The SDSS-II Supernova Survey filled a gap in previous work, by finding and analyzing hundreds of SN Ia in the redshift range between z=0.1 and z=0.3.
As part of the CANDELS and CLASH Multi-Cycle Treasury Programs on the Hubble Space Telescope, and the Frontier Fields and RELICS programs, we are searching for SN Ia beyond redshifts z > 1.5 using the WFC3/IR instrument. We have also found and analyzed three gravitationally lensed supernovae behind CLASH galaxy clusters in a project led by former graduate student Brandon Patel, and have continued studying other lensed supernovae.
In the future, the Large Synoptic Survey Telescope will find thousands of SN Ia. This huge number of objects means we will need new methods to make best use of the data. I am a member of the LSST Transients & Variable Stars Science Collaboration and currently the co-convener of the Supernova Working Group in the LSST Dark Energy Science Collaboration. The highest quality data for distant supernovae will come from space and I am part of a supernova Science Investigation Team for the Wide Field Infrared Survey Telescope (WFIRST).
While distant SN Ia have driven our understanding of the history of the expansion of the Universe, nearby SN Ia are the crucial underpinning to this enterprise. Not only do they anchor the Hubble diagram for cosmology, they provide the samples which show the utility of SN Ia as distance indicators. They are also the ones which we can study the best, from observations at many wavelengths to data at late times when more distant objects are too faint to be measured. We are currently working with the Foundation Supernova Survey using the Pan-STARRS PS1 telescope to observe and follow-up nearby supernovae, including spectroscopic analysis by graduate student Kyle Dettman.
MLCS2k2 is the development of the multi-color light curve shape method to turn SN Ia optical light curves into precise distances. This analysis tool continues to grow and be refined, and is in use by many SN Ia projects. The CfA II sample of SN Ia, presented in my doctoral thesis, comprises 44 objects homogeneously observed and analyzed, including the largest collection of near-ultraviolet U-band light curves published at the time.
We are also trying to understand the progenitors and explosion mechanism for SN Ia. In particular, we are interested in studying objects that are "peculiar cousins" to normal SN Ia, like the recently identified class of type Iax supernovae, named after the prototype SN 2002cx. Our recent work, led by former graduate student Curtis McCully, suggests these are thermonuclear explosions of white dwarfs that do not completely unbind the star. A most exciting development is our discovery of the progenitor system of the type Iax SN 2012Z with the Hubble Space Telescope; this is the first time that a progenitor system for a white dwarf supernova has ever been seen in pre-explosion images. Graduate student Yssavo Camacho is leading a spectroscopic analysis of SN 2014dt in M61, the nearest type-Iax SN known.
I am also interested in the detection and characterization of planets around other stars. With the AFOE group, we discovered the planetary companion to rho Coronae Borealis in 1997. In addition, colleagues and I have shown that a few of the transiting companions discovered by the OGLE survey are planets, including OGLE-TR-56b (the first planet discovered first by its transit), OGLE-TR-113b, and OGLE-TR-10b.
Rutgers is a partner in the Southern African Large Telescope. SALT is one of the world's largest optical telescopes and I have been using it in many facets of my research to observe supernovae near and far. I also recently chaired the SALT Science Committee.