Our group’s research seeks to combine new and rich cutting-edge astronomical data sets and tools from the growing field of big-data science and high-performance computing, in order to address outstanding open questions in the field of transient astrophysics and to discover new types of astrophysical phenomena.

Solving the "Supernovae progenitors puzzle" from multiple angles

Stars more massive than eight solar masses go through a process called “core collapse”, in which they run out of fuel for nuclear burning, collapse under the effect of their own gravity and end their lives in spectacular supernova explosions. The details of the mechanism governing core-collapse explosions and the nature and characteristics of the SN “progenitors” – the stars dying as Supernovae – remain mysterious. This lacuna in scientists’ understanding is called the “supernova progenitor puzzle” and constitutes one of the outstanding open questions in transient astrophysics.

Our research tackles this puzzle from multiple, complementary angles. 

The NERSC supercomputer hosted at LBNL

Hunting the shortest X-ray transients

One of the key steps in solving the supernova-explosion mystery is understanding the very earliest and most elusive stages of such explosions, some of which are theorized to have characteristic signatures in the UV and X-ray.  However, very few of these early signatures have been observed and characterised to date. Using the NERSC supercomputer and novel data analysis techniques, we mine the X-ray archival data from large space telescopes to find these lost events and discover new types of short X-ray astronomical transients.

Understanding the earliest stages of Supernova explosions

Some of the progenitor’s best kept secrets may be hiding in the first hours of the UV radiation from the explosion. In recent years, a lot of effort has been put in modelling this early radiation (e.g. Sapir & Waxman 2017). Using data from ZTF, Swift, and soon ULTRASAT and LS4 as well as novel modelling codes, we compare theoretical models and refine our understanding of the early stages of stellar explosion.

Link to our related publications

The multiple-bands light curve of 2018fif, from Soumagnac et al 2020.
Eta Carinae, imaged by WFPC2 at red and near-UV wavelengths; Credit: Jon Morse & NASA HST

Uncovering the secrets of Interacting Supernovae

A lot remains to be understood about “interacting supernovae”, supernovae that result from the explosion of a star within a dense cocoon of circumstellar material. These energetic objects provide a unique opportunity to learn about the environment surrounding massive stars shortly before their explosive death, the latest stages of stellar evolution and the initial conditions of such explosions.

Using instruments like ZTF and soon ULTRASAT and LS4, we perform surveys of these objects in search for their hidden secrets. 

Link to our related publications.

 

Exploring Host Galaxies properties

Understanding the properties of the galaxies in which stars explode provide important clues about the identity and nature of Supernovae progenitor stars.

Using DESI, we are currently computing the MOST Hosts survey, the largest spectroscopic sample of transient host galaxies to date and a mine of information to study correlations between supernovae and their host galaxies.

The Kitt Peak Observatory hosting the DESI instrument. Credit: Bryan Alen.