In the conventional picture of a core-collapse supernova, the iron core collapses into a neutron star or a black hole, and a shockwave unbinds the star. In rare cases, accretion onto a rapidly rotating black hole acts as an "engine" that launches a jet. If that jet tunnels through the star, breaks out, and is pointed at the Earth, we detect a long-duration gamma-ray burst (GRB). There have been thousands of GRBs discovered, almost always by high-energy satellites such as Fermi or Swift. However, recent discoveries by optical surveys hint at diverse outcomes that are invisible to GRB satellites, such as baryon-loaded jets (“dirty fireballs”) or jets choked inside the star. With the Zwicky Transient Facility (ZTF) we are conducting a systematic exploration of the broader landscape of engine-driven explosions, including dirty fireballs, choked jets and off-axis afterglows (“orphan afterglows”). I will show how unexpected arrivals to the landscape (such as AT2018cow) complicate the picture, revealing that some engine-driven explosions take place embedded in dense circumstellar material that was likely ejected in eruptive pre-explosion mass-loss episodes. I will emphasize the synergy between eROSITA and optical surveys like ZTF: a distinguishing feature of both dirty fireballs and AT2018cow-like transients is luminous X-ray emission.
|Presenter status||Graduate student at Caltech|