Ripples in space-time: Into the future

by Dougal Dobie

In the last two blog posts we’ve learnt what has been accomplished so far in the very short history of gravitational wave astronomy. In this final gravitational waves post we will discuss what the future holds.

The 6 gravitational wave detections so far. GW170814 and GW170817 were both detected with 3 detectors, allowing them to be localised more precisely. Image credit LIGO/Virgo/Nasa/Leo Singer/Axel Mellinger

In February 2019 the third LIGO-Virgo observing run, O3, is scheduled to start. The detectors will have been offline for over a year, undergoing significant upgrades to increase their sensitivity. These upgrades will allow gravitational wave astronomers to detect neutron star mergers out to a distance of 500 million light years from earth, double the range during the second observing run and over 4 times further away than the first neutron star merger, GW170817.

We expect to detect around 10 more neutron star mergers during the 12 month observing run, which will allow us to better understand the neutron star merger population and answer the question that has been on everyone’s mind - was GW170817 was a typical event, or was it extraordinary?

Looking further into the future, a fourth gravitational wave detector, KAGRA, is currently being commissioned in Japan, while there are plans for a fifth detector in India. Expanding the network of gravitational wave detectors improves their sensitivity and enables the detection of polarised gravitational waves. Due to our unique geographical location, a sixth detector has also been proposed for Australia.

Gravitational wave astronomy also expands beyond neutron star mergers.

The Parkes radio telescope (affectionately known as The Dish), is part of the International Pulsar Timing Array (IPTA) which aims to detect ultra-low frequency gravitational waves by precisely measuring the rotation period of pulsars which will change in the presence of gravitational waves.

LISA, the Laser Interferometer Space Antenna, will be able to detect gravitational waves in a frequency range between IPTA and LIGO. In fact, the five binary black hole mergers detected by LIGO so far would have been detectable by LISA a few weeks or months prior to the merger.

Gravitational wave astronomy has exploded over the past three years, but there’s still much, much more to come.

Further reading:

https://arxiv.org/abs/1304.0670

https://www.elisascience.org/articles/lisa-mission/lisa-mission-gravitational-universe