Australian Sky & Telescope — January 01, 2018

36 AUSTRALIAN SKY & TELESCOPE January 2018

COSMIC COLLISION by Govert Schilling

T

SO THE RUMOURS WERE RIGHT

after all. On August 17, the Advanced

Laser Interferometer Gravitational-

Wave Observatory (LIGO) registered

tiny ripples in spacetime, produced by

a pair of frantically orbiting neutron

stars right before they collided. What’s

more: telescopes on the ground and in

space detected the fading glow of the

radioactive fireball that resulted from

the cosmic smash-up, all across the

electromagnetic spectrum.

“The detection of gravitational waves

from a binary neutron star merger is

something that we have spent decades

preparing for,” notes astrophysicist

Alan Weinstein (Caltech). “All of our

dreams came true.” According to his

colleague Barry Barish (also Caltech),

one of LIGO’s founding fathers and

co-recipient of the 2017 Nobel Prize in

Physics, the new discovery “establishes

gravitational-wave science as a new

emerging field.” Vicky Kalogera

(Northwestern University) adds, “I

couldn’t believe my eyes. It’s a lot more

exciting than the first gravitational-

wave detection” of colliding black holes,

in September 2015.

The excitement is fully justified.

Observing both gravitational waves

and electromagnetic radiation from

the catastrophic coalescence of two

hyper-dense neutron stars provides

astronomers with a wealth of new,

detailed information. The new buzzword

is ‘multi-messenger’ astronomy, the study

of the universe using fundamentally

different types of emission.

Rumours about the neutron star

event have circulated since August 18

when Craig Wheeler (University of

Texas at Austin) tweeted: “New LIGO.

Source with optical counterpart. Blow

your sox off!” Then, on September

Spacetime ripples from a neutron

star smash-up have ushered in a

new age of astronomy.