Fundamental physics with the Square Kilometre Array

Abstract

The Square Kilometre Array (SKA) is a planned large radio interferometer designed to operate over a wide range of frequencies, and with an order of magnitude greater sensitivity and survey speed than any current radio telescope. The SKA will address many important topics in astronomy, ranging from planet formation to distant galaxies. However, in this work, we consider the perspective of the SKA as a facility for studying physics. We review four areas in which the SKA is expected to make major contributions to our understanding of fundamental physics: cosmic dawn and reionisation; gravity and gravitational radiation; cosmology and dark energy; and dark matter and astroparticle physics. These discussions demonstrate that the SKA will be a spectacular physics machine, which will provide many new breakthroughs and novel insights on matter, energy, and spacetime.

New sensitivity curves for gravitational-wave signals from cosmological phase transitions

“…We specifically consider the following ground-based and space-based interferometer experiments: aLIGO, aVirgo, the Kamioka Gravitational-Wave Detector (KAGRA) [95][96][97][98][99], Cosmic Explorer (CE) [100,101], Einstein Telescope (ET) [102][103][104][105], DECIGO, BBO, and LISA. Furthermore, we also consider the following pulsar timing array (PTA) experiments [106]: the North American Nano-Hertz Observatory for Gravitational Waves (NANOGrav) [107][108][109][110], the Parkes Pulsar Timing Array (PPTA) [111,112], the European Pulsar Timing Array (EPTA) [113][114][115], the International Pulsar Timing Array (IPTA) [116][117][118][119], and the Square Kilometre Array (SKA) [120][121][122]. The purpose of appendix A is to make our presentation self-contained and to facilitate the generalization of our results in section 3 to other experiments and potentially also other types of signals.…”

Gravitational wave probes of dark matter: challenges and opportunities

“…GW observations of such a system could provide a measurement of the DM density (through the dephasing effect), fixing the normalization of the expected radio signal [132]. Joint observations of these systems using LISA and the Square Kilometer Array [133] would thus probe the natural parameter space of the QCD axion in the mass range m a ∈ [10 −7 , 10 −5 ] eV.…”

The Science of Fundamental Catalogs

“…A practical realization of sub-microarcsecond fundamental catalogs can be achieved with a number of different astronomical techniques in various ranges of the electromagnetic spectrum. In particular, radio astrometry at this level of accuracy adhering to the time-tested concept of absolute measurements requires technical facilities like VLBA (https://science.nrao.edu/facilities/vlba/docs/manuals/oss), VERA (Nagayama et al, 2020) and the Square Kilometer Array (SKA) (Fomalont and Reid, 2004;Godfrey et al, 2012;Reid and Honma, 2014;Weltman et al, 2020) with baselines ranging from the Earth's radius to the size of the lunar orbit. First successful steps in this direction have been recently taken with the space radio-interferometric mission RadioAstron (Kardashev et al, 2012;Popov, 2019;Gurvits, 2020) which proved to be very productive (http://www.asc.rssi.ru/radioastron/ publications/publ.html).…”