Krill Prize Laureate 2015
Weizmann Institute of Science
Supernovae and Exploring the sky
at high temporal frequencies
My research focuses on two topics – Super- novae and their progenitors, and exploring the sky at high temporal frequencies. Supernovae: I am currently studying Type IIn supernovae (SNe). For many years we know that there is a large amount of circum stellar ma- terial around these SNe. Recently, we showed that it is common for these SNe to eject this cir-cum stellar material in energetic outbursts taking place only months to years prior to the SNe ex-plosion (Ofek et al. 2013b; 2014b). The fact that these curious outbursts are synchronized with the stellar explosion is not well understood and gave rise to a large number of theoretical models. Fur- thermore, we recently showed that this mass-loss phenomena just prior to explosion is common for many types of SN progenitors (although smaller mass-loss involved; Gal-Yam et al. 2014; Yaronet al. in prep.). My current effort include bet-ter understanding the spectra of these SNe, and inferring the physical conditions at the extended envelopes around these progenitors (Ofek et al.2013a; 2013c; 2014a). Continue doing cutting edge science depends on the availability of new instruments. There-fore, I am deeply involved in the design of two future facilities for early SNe observations. These are the Zwicky Transient Factory (ZTF) and the ULTRASAT UV space observatory (Sagiv et al.2013). ZTF will use the Oschin-Schmidt Camera at Mount Palomar with a new mosaic camera with an unprecedented field of view of 47 deg2. First light is expected at early 2017. ULTRASAT is a joint program between the Israel Space Agency, NASA/JPL, Weizmann Institute of science and Caltech. The goal is to send into orbit a 30-cm aperture UV space telescope with an instanta-neous field of view of about 250 deg2. These two instruments are expected to revolutionize our un-derstanding of transients phenomena in general. One major goal of these instruments is the rou-tine discovery of SN shock breakout, that will be used to study SN progenitors and how stars die. Exploring the sky at high temporal fre-quencies – the Kuiper belt and the Oort cloud: A large phase space of the transient sky remains unexplored – specifically, until recently it was difficult to study high temporal frequencies. We are designing and building an array of two 55-cm large field of view Schmidt telescopes (each with a corrected field of 20 deg2). Besides, their extreme field, these telescopes will be equipped with high speed readout, low readnoise CMOS de- vices and optical multiplexrs. The multiplexer – a new instrument we conceived, designed and built a prototype, enlarges the effective field of a small camera devices (Ben-Ami et al. 2014). These two telescopes are designed for the detection of occul-tations of stars by small rocks in our own solar system – specifically 1-km sized Kuiper belt ob- ject (KBO), and the still unseen (but predicted) Oort cloud. I note that only two such KBO oc- cultations were detected, using the Hubble Space Telescope, in the past by our team (Schlichting et al. 2009; 2013). Such observations will provide important information to models of the formation of our solar system. They will provide, the size distribution (and hence the material strength) of small KBOs, and most excitingly they may pro- vide the first-ever direct detection of Oort cloud objects. Moreover, we know that high temporal frequency optical transient exist (e.g., Kasliwal et al. 2008), and these telescopes will enable us to study the transient and variable sky on time scales never explored before.