The work is organized in three interlinked work packages addressing 1) how black holes burp out their energy 2) what are the cosmic factories forging metals heavier than iron, and 3) how these stellar mergers can teach us more about fundametal physics and cosmology. Over the first period, the PI devoted most of her efforts in setting up the group and securing the observational resources. Nonetheless, progress has been made in all three main areas.
The project was inaugurated by the discovery of GRB211211A, a minute-long explosion followed by a glow of red light known as kilonova. The kilonova is the telltale signature for the production of radioactive heavy nuclei via rapid neutron capture processes (WP2). However, a kilonova is a rare event that only happens with a neutron star encounters another compact object such as another neutron star or a black hole. The association of a kilonova with a long GRB shows that not all long GRBs are the product of the explosive death of a massive star, challenging our long-established beliefs about how long GRBs and their progenitors.
The PI had a central role in the discovery and characterization of the kilonova, the results of her research were published on December 7 in the journal Nature.
A few months later we were surprised by the brightest gamma-ray burst (GRB) ever observed, GRB221009A, which pushed our models to the extreme. This titanic explosion surpassed in brightness any previous gamma-ray burst and was so bright it effectively blinded most gamma-ray instruments in space. All this energy was shot into space in the form of a jet by a black hole, born in the GRB explosion. In just about every previously observed gamma-ray burst, the jet remained remarkably compact and there was little to no stray light or material outside the narrow beam. By contrast, in GRB 221009A the jet had a narrow core with wider, sloping sides. These properties, also shared by a small group of insanely bright bursts, allow us a better understanding of how black holes release their power through ultra-fast jets (WP1).
The PI and her team had a central role in this study, which was published on June 7 in the journal Science Advances.
Finally, we have been using the peculiar explosion dubbed GRB230307A to probe the interior of neutron stars (WP3) and to provide direct evidence for the production for heavy metals (WP2).
We investigated what happens before two compact objects collide, what sort of electromagnetic radiation may become visible and how its brightness and duration depend on the behavior of matter in extreme conditions.
