The Search for Orphan Gamma-Ray Bursts with Rubin/LSST and the Fink broker

* Orphan gamma-ray burst (GRB) afterglows occur when the gamma-ray emission from a GRB is not directed towards Earth, making the initial burst invisible. However, the afterglow, produced by the interaction of the GRB's blast wave with surrounding material, can be observed. * Studying orphan afterglows provides valuable insights into GRB physics and their progenitors, and can enhance multi-messenger analyses with gravitational waves. * The Vera C. Rubin Observatory, with its exceptional sensitivity and wide field of view, is expected to play a crucial role in detecting orphan afterglows. * The anticipated high volume of alerts from the Rubin Observatory necessitates the use of alert brokers like Fink to filter and categorize events. * Researchers are developing a machine learning classifier within Fink to identify orphan afterglows based on their distinct light curve characteristics. * This classifier uses features like the duration, rise and decay rates, color, and fitted parameters of the light curve to distinguish orphan afterglows from other transient events. * Initial tests using simulated data show promising results, with the classifier effectively excluding most non-orphan events while retaining a significant portion of orphan afterglows. Reference: Masson, M., & Bregeon, J. (2024). Search for orphan gamma-ray burst afterglows with the Vera C. Rubin Observatory and the alert broker Fink. arXiv preprint arXiv:2412.05061v1. Acknowledements: Podcast prepared with Google/NotebookLM. Illustration credits: LSST project/NSF/AURA