Speaker
Description
Blazars are among the most variable non-thermal sources in the Universe, exhibiting broadband emission from radio to $\gamma$-rays. With the new era of large-scale surveys such as the Vera C. Rubin Observatory, their optical variability can now be regularly monitored with unprecedented depth, paving the way to probe their emission mechanisms in a time-domain, multi-wavelength context.
In this work, we investigate the connection between optical and $\gamma$-ray emissions in a large sample of blazars using multi-year light curves from Fermi-LAT and Rubin’s predecessor, ZTF. We introduce a robust similarity metric to quantify cross-band correlations and implement a flare-detection pipeline based on the rise and fall structure of extreme-amplitude emission events. Building on this, we develop a real-time algorithm designed to identify extreme optical states and trigger follow-up observations.
We find a zero time lag between the optical and $\gamma$-ray band for most of the sources, and optical-$\gamma$-ray correlations beyond $>3\sigma$ for about 20% of them, which supports co-spatial emission regions.
Our real-time triggering strategy achieves a purity of over 70% for $\gamma$-ray flares and nearly 100% for optical low states, demonstrating that optical surveys can efficiently anticipate high-energy activity and confidently trigger spectroscopic observations of the host galaxy. These results highlight the growing potential of all-sky optical surveys as drivers of multi-wavelength follow-up, providing a powerful complement to current high-energy facilities such as $\textit{Fermi}$-LAT.