Multi-Messenger Windows on the Universe: detecting precursor emission to compacts' mergers

Abstract

We provide an overview of various mechanisms, and corresponding powers, of precursor emission to compacts' mergers to be detected by LIGO-Virgo-KAGRA (LVK) collaboration. Expected peak powers, $\leq 10^{43}$ erg s$^{-1}$, are not sufficiently high to be detected by all-sky high-energy satellites (unless beamed). The best chance is the detection of possible coherent radio emission, producing observable signals up to $\sim$ Jansky of flux density. Low-frequency phased array telescopes like LOFAR, the MWA and DSA-2000 are best suited due to their large instantaneous sky coverage. Time-wise, in addition to LIGO early warning alerts up to a minute before the merger, the dispersive delay at lower frequencies of $\sim$ 300 MHz can be of the order of minutes. Optical detections are the most challenging.