About Me

Education: PhD from the Hebrew University of Jerusalem

Research Interests: Violent astophysical transients: Supernova, tidal disruption events, gamma ray burst, planetary collisions and fast radio bursts.

Publications: ADS, Google scholar


Despite decades of research, many questions regarding the nature of supernovae remains a mystery. These questions include what kinds of stars explode? What are their properties before the explosion? what is the process that powers these explosions? how does this explosion affect its environment and whether a compact object (i.e. a neutron star or a black hole) is born in the explosion, and if so, what are its properties.

In a recent work I studied how a supernova shock breakout would look like if the energy were injected close to the stellar surface rather then in the centre of the star. A simulation of this process is presented in the video below.

Explosions as Probes of Galactic Plasma
Some astrophysical explosions produce non thermal radio emission that can be used to probe the properties of the plasma in the environment in which they occur. In supernovae, this phenomenon can teach us about mass loss prior to the explosion, and in tidal disruption events, it can teach us about the properties of other galactic centres.

In a recent work I used the variation in radio intensity from supernova 1979C to infer the existence of companion to the progenitor, and estimate its pre explosion distance and mass. The animation below shows the spiral waves in the stellar winds due to the binary motion.

Planetary Collisions
Terrestrial planets are thought to form through the violent mergers of planetary embryos. Each one of these mergers involves an giant impact event on the growing planet, which can erode its atmosphere. My research involves developing a theoretical model to predict how much atmosphere will be lost in this process. Another open question in planet formation concerns the timescales for these collisions. The current thinking is that the planetary embryos all start out on circular, non intersecting orbits, and that dynamical instabilities modify these orbits, eventually bringing about collisions. Part of my research is developing a theoretical model to predict the timescale for the development of these instabilities.

The animation below demonstrates the evolution of dynamical instabilities in a three planet system. The circles represent the planets, and the arrows represent the direction and magnitude of the eccentricity vectors.

Numerical Hydrodynamics
I co developed, together with Elad Steinberg, a numerical hydrodynamic simulation based on a moving Voronoi mesh in c++. This hydrocode is the backbone to many of my works. It combines the strengths of grid based methods (like the Godunov scheme) and the flexibility of Lagrangian methods (like smooth particle hydrodynamics). The code is called RICH, which stands for Racah Institute (physics department at the Hebrew University) Computational Hydrodynamics. As far as I know, it is the only open source, object oriented hydrocode. As such, new physics can be incorporated in the simulation without modifying existing code.

The animation below shows a moving mesh hydrodynamic simulation of the Kelvin Helmholtz instability


Outreach: I maintain a wiki for back of the envelope calculations and toy models. The purpose of this wiki is to help other (especially early career) astrophysicists familiarise themselves with different theoretical concepts. Each entry is designed to be self contained, and to allow the reader to absorb the material within less than an hour. At the moment the website gets hunderds of views every week.

Teaching: As a PhD student, I was a TA for second year thermodynamics and lab instructor for a second year lab. As a postdoc, I gave 10+ graduate level blackboard talks and a lecture on defensive programming for undergraduates.

Refereeing: My Publons profile