An Early-warning System for Electromagnetic Follow-up of Gravitational-wave Events

Abstract

Binary neutron stars (BNSs) will spend ;10-15 minutes in the band of Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors at design sensitivity. Matched-filtering of gravitational-wave (GW) data could in principle accumulate enough signal-to-noise ratio (S/N) to identify a forthcoming event tens of seconds before the companions collide and merge. Here we report on the design and testing of an early-warning GW detection pipeline. Early-warning alerts can be produced for sources that are at low enough redshift so that a large enough S/N accumulates ∼10-60 s before merger. We find that about 7% (49%) of the total detectable BNS mergers will be detected 60 s (10 s) before the merger. About 2% of the total detectable BNS mergers will be detected before merger and localized to within 100 deg 2 (90% credible interval). Coordinated observing by several wide-field telescopes could capture the event seconds before or after the merger. LIGO-Virgo detectors at design sensitivity could facilitate observing at least one event at the onset of merger.

Early warning of coalescing neutron-star and neutron-star-black-hole binaries from the nonstationary noise background using neural networks

“…For example, Ref. [29] considered a similar early-warning problem using GstLAL and the designed aLIGO sensitivity. According to the associated data release [64], the authors of Ref.…”

“…According to the associated data release [64], the authors of Ref. [29] preformed 1,446 BNS injections with distance from 80 Mpc to 100 Mpc in total and they were able to detect 446 (or 31%) out of them at an upper cut-off frequency of 29 Hz and a FAR = (30 days) −1 . From the dotted traces in Fig.…”

“…See, e.g., Ref. [29] for further discussions on potential early-warning signals as well as a nice summary of the follow-up capacity of various EM obser-vatories.…”

“…There are presently four low-latency, matched-filter based pipelines that produce near real-time gravitationalwave alerts for BNS and NSBH mergers: GstLAL [30,31], PyCBC [32], MBTA [33], and SPIIR [34,35]. Several of these pipelines have already developed analyses capable of early warning detection [29,30,35]. See also Ref.…”

H.E.S.S. follow-up observations of Binary Black Hole Coalescence events during the second and third Gravitational Waves observing runs of Advanced LIGO and Advanced Virgo

“…4 and 5 moving to values of T − T 0 < 1000 s for around eight events yr −1 (not accounting for bad weather). For a fraction of GW events, this latency will become negligible or even negative (as measured from the merger time) as GW detector sensitivity improves with the implementation and improvement of the early-warning system (Nitz et al 2020;Sachdev et al 2020;Magee et al 2021).…”