Scientists yesterday discovered a vast supply of gold on the far side of the universe. The extraordinary hoard is the result of a huge collision between two ultra-dense neutron stars. The resulting gravitational waves and radiation flash were picked up by powerful detectors and telescopes on Earth and in orbit.
The explosion
happened 130 million years ago in the Hydra constellation, which is so far away
that the light and the ripples in space and time have only just reached us.
The gold created
by the blast is estimated to weigh more than the whole of the Earth’s mass.
Huge quantities of platinum, uranium and other heavy elements such as lead were
also created.
Scientists not
only 'heard' the phenomenon by measuring vibrations in space-time, they also
used satellite and ground-based telescopes to see light and radiation pouring
out of the stellar fireball, dubbed a 'kilonova'. Excited
astronomers talked of opening a 'new chapter in astrophysics' and unlocking a
'treasure trove' of new science.
The discovery
will help scientists better understand the inner workings and emissions of
neutron stars, as well as more fundamental physics such as general relativity
and the expansion of our universe.
One scientists
suggests the event 'will be remembered as one of the most studied astrophysical
events in history.'
At a press conference in
Washington today, researcher Dr David Reitze, Executive Director at the Ligo
Laboratory at Caltech, said: 'This is the first time the cosmos has provided us
with a talking movie rather than a silent movie.' 'The audio is the
gravitation waves, the video is the light that came afterwards.'
Every other gravitational
wave detection has been traced to black holes crashing together in remote
regions of the universe more than a billion light years away. The new event -
though still very distant - was much closer and completely different in nature.
It was caused by colliding
neutron stars - burned out remnants of giant stars so dense that a teaspoon of
their material on Earth would weigh a billion tons.
Professor David Blair, a
gravitational wave scientist at the University of Western Australia, said: 'I
started working on the first high sensitivity gravitational wave detectors in
the USA in 1973.
'We pinned our hopes on
gravitational waves from neutron stars. This was our holy grail, but it eluded
us even when gravity waves from black holes had been detected.
'Forty four years later we
have found the holy grail!' The two objects, each about
12 miles in diameter, stretched and distorted space-time as they spiralled
towards each other and finally collided.
Like ripples from a stone
thrown in a pond, the gravitational waves fanned out across the universe at the
speed of light.
They were picked up on Earth
by two incredibly sensitive detectors in Washington and Louisiana run by the
Laser Interferometer Gravitational-Wave Observatory (Ligo).
It was here the first
discovery of gravitational waves was made in September 2015, confirming a
prediction made by Albert Einstein 100 years ago and earning three pioneers of
the project a Nobel Prize.
Two seconds after the Ligo
detection, a burst of gamma rays from the neutron star collision was captured
by NASA’s Fermi space telescope.
After Ligo notified
astronomers around the world of the possible detection of gravitational waves
from the merger of two neutron stars, the race was on to detect a visible
counterpart.
This is because unlike the
colliding black holes responsible for Ligo's four previous detections of
gravitational waves, this event was expected to produce a brilliant explosion
of visible light and other types of radiation.
Astronomers around the world
quickly turned their telescopes and dishes towards a small patch in the
southern sky and saw a flash across the visible and invisible light spectrum.
'This is a huge discovery,'
said researcher Dr Ryan Foley, an assistant professor of astronomy and
astrophysics at University of California Santa Cruz.
'We're finally connecting
these two different ways of looking at the universe, observing the same thing in
light and gravitational waves, and for that alone this is a landmark event.
'It's like being able to see
and hear something at the same time.' Analysis of the light
revealed something astonishing - the manufacture of gold on a cosmic scale, as
well as other heavy elements.
Dr Joe Lyman from the
University of Warwick, one of many British scientists involved, said: 'The
exquisite observations obtained in a few days showed we were observing a
kilonova, an object whose light is powered by extreme nuclear reactions.
'This tells us that the
heavy elements, like the gold or platinum in jewellery, are the cinders, forged
in the billion degree remnants of a merging neutron star.'
The origins of gold and
other heavy elements have been a long-standing mystery, but recent evidence has
suggested colliding neutron stars could have a hand in their creation. A third
gravitational wave facility called Virgo near Pisa, Italy, also registered a
faint signal from the event, allowing scientists to triangulate its position.
The neutron star collision
took place 130 million light years away in a relatively old galaxy called NGC
4993. When the gravitational waves began their journey across space, dinosaurs
roamed the Earth.
The gravitational wave
signal, named GW170817, was detected at 1.41pm BST (6.41pm ET) on August 17. Ligo's
detectors, consisting of L-shaped tunnels with arms 2.5 miles (4km) long, use
laser beams bouncing off mirrors to measure movement across a distance 10,000
times smaller than the width of a proton, the kernel of an atom.
A tight lid was kept on the
findings until the publication of a series of papers in journals including
Nature, Nature Astronomy, and Physical Review Letters. The international researchers expect to spend
many months trawling through the mountain of data.
One finding relates to what
happens during the merging of two neutron stars. The stars consist almost entirely of neutrons
and are so dense that a sugar cube of neutron star material would weigh about a
billion tons.
The violent merger of two
neutron stars ejects a huge amount of this neutron-rich material, powering the
creation of heavy elements in a process called rapid neutron capture, or the
'r-process.' The radiation this emits looks nothing like an ordinary supernova
or exploding star, and scientists have created many models to simulate the
process.
This is the first time one
has actually been observed in such detail, and the data fits remarkably well
with Another question already answered by the new data is the origin of
short-duration gamma ray bursts. Gamma ray bursts (GRBs), marked by an eruption
of gamma rays lasting milliseconds to several minutes, are the most powerful
explosions known.
Scientists now know that one
type of GRB is generated when neutron stars collide. Dr Samantha Oates, also
from the University of Warwick, said: 'This discovery has answered three
questions that astronomers have been puzzling for decades: What happens when
neutron stars merge? What causes the short duration gamma-ray bursts? Where are
the heavy elements, like gold, made?
'In the space of about a
week all three of these mysteries were solved.' Colleague Dr Danny Steeghs
said: 'This is a new chapter in astrophysics.'
British Ligo scientist
Professor BS Sathyaprakash, from the University of Cardiff, described the new
discovery as 'truly a eureka moment'. He added: 'The 12 hours that followed are
inarguably the most exciting hours of my scientific life.
'This event marks a turning
point in observational astronomy and will lead to a treasure trove of scientific
results.' Professor Bernard Schutz, also from the University of Cardiff, told
how his team used the gravitational wave detections to measure the expansion of
the universe more accurately than had ever been achieved before.
'What has amazed me ... is that
with just this one measurement, we got a result right in the middle between the
two rather different values that astronomers have measured recently,' he said. Dr
David Shoemaker, spokesman for the Ligo scientific collaboration and senior
research scientist at the US Massachusetts Institute of Technology's Kavli
Institute for Astrophysics and Space Research, said: 'From informing detailed
models of the inner workings of neutron stars and the emissions they produce,
to more fundamental physics such as general relativity, this event is just so
rich.
'It is a gift that will keep
on giving.' Ligo colleague Professor Laura Cadonati, from Georgia Institute of
Technology, US, said: 'This detection has genuinely opened the doors to a new
way of doing astrophysics. 'I expect it will be remembered as one of the most
studied astrophysical events in history.'
Via Dailymail