Multi-messenger and time-domain astronomy in the 2040s

TL;DR

The paper discusses how multi-messenger astronomy in the 2040s will be revolutionized by vast new data from advanced observatories, requiring enhanced optical/infrared spectroscopy and dedicated facilities to maximize scientific discoveries.

Contribution

It highlights the need for a major upgrade in spectroscopic capabilities and dedicated facilities to fully leverage the upcoming multi-messenger data in the 2040s.

Findings

Next-generation observatories will detect unprecedented multi-messenger signals.

Enhanced spectroscopic capabilities are essential for scientific breakthroughs.

Dedicated large-aperture facilities are crucial for maximizing scientific return.

Abstract

Multi-messenger astronomy will be transformed in the 2040s by an unprecedented volume of detections from next-generation gravitational wave, high-energy, and ultra-high energy neutrino, cosmic ray, and time domain observatories. This white paper, prepared for the European Southern Observatory (ESO) Expanding Horizons call, outlines the key science questions enabled by this emerging multi-messenger ecosystem, ranging from nucleosynthesis and dense matter physics to cosmology, fundamental physics, and the growth of black holes across cosmic time. We demonstrate that fully exploiting these discoveries requires a step change in optical to near infrared spectroscopic capability, including low latency response, high throughput, and flexible time domain operations across both hemispheres. We argue that without a dedicated large-aperture time domain facility, the scientific return of multi-messenger astronomy in the 2040s will be considerably limited.