Multi-messenger astrophysics
Multi-messenger astrophysics
Multi-messenger astronomy has been identified as a priority in most major astrophysics planning exercises and will be mainstream in the WST era.
Electromagnetic counterparts' detection for Next-Generation Gravitational-Wave Events
Third-generation gravitational wave (GW) observatories such as the Einstein Telescope (ET) and Cosmic Explorer (CE), are expected to revolutionise the future of multi-messenger astrophysics by detecting ∼ 10^5 binary neutron star (BNS) mergers per year, reaching redshifts well beyond the star formation peak.
The detection and characterisation of the electromagnetic counterparts of these events is crucial to understanding the extreme physics at play. The WST will be ideally suited to perform this task.
On the one hand, WST ’s extragalactic and cosmology surveys will create an unprecedented catalogue of galaxy redshifts out to z < 2, allowing the correlation with a majority of GW events, even without optical counterparts. On the other hand, GW events with EM counterparts will be followed in timely fashion as Targets of Opportunities (ToOs) with rapid reaction times. The wide-field of view and high multiplexing of WST is ideally suited to the several square degrees uncertainty on the location on sky of the EM counterpart of such events.
Insight into neutrino mass
Another multi-messenger area in which the WST will provide original contributions would be in the determination of the neutrino mass.
The observation of flavour oscillations of atmospheric and solar neutrinos, as well as oscillation studies at reactors and accelerators, unequivocally proves neutrinos to possess non-zero rest masses, contradicting the Standard Model expectation of them being massless.
A massive neutrino has a direct effect on how primordial perturbations in the early universe propagate. The WST will therefore be able through its cosmological surveys to put stringent upper limits on the neutrino mass.
Synergies
The WST will fill a critical gap in the global astronomical infrastructure of the 2040s.
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New frontiers in cosmology
Understanding how dark matter, dark energy, and gravity shape structure across the Universe requires measurements that span from the smallest galaxies to the largest cosmic environments.
Interview with Sofia Bisero
Issue #2 The WST Chronicle"The WST Is An Ambitious Facility With a Big Potential"