ASTRO-H X-ray telescope aims to solve black hole mysteries
Device made by Ottawa's Neptec will sharpen telescope's view of supernovas, galaxy clusters
A Japanese space telescope with X-ray vision sharpened by Canadian technology heads into orbit on Friday.
JAXA's ASTRO-H is scheduled to launch at 3:25 a.m. Friday from the Tanegashima Space Center in Japan.
The X-ray telescope, which will orbit about 550 kilometres above the Earth, is designed to help solve mysteries about extreme space objects such as black holes, supernovas and neutron stars. It could also reveal new information about how galaxies form and how stars end their lives.
Stars such as the sun, which is about 5500 C, give off visible and ultraviolet light that we can see with a normal telescope from the ground here on Earth.
But much hotter objects like supernovas and black holes, which are about a million to 10 million C, emit higher energy light in the form of X-rays, says Luigi Gallo, principal investigator for the Canadian science working group for ASTRO-H and an astronomy professor at St. Mary's University in Halifax.
That makes space X-rays invisible from Earth.
"We're actually lucky in that the atmosphere protects us from X-rays [which can damage DNA] reaching the ground," Gallo told CBC News.
It means that ASTRO-H must be launched into space in order see anything.
While other X-ray telescopes, such as NASA's Chandra observatory, are already in orbit around the Earth, ASTRO-H has a couple of unique and valuable features.
'Like wearing glasses'
For one thing, it has a detector that can distinguish the chemical fingerprints of elements in supernovae and their remnants, which take the form of coloured lines unique to each element.
With other telescopes, such lines were all blurred together. With ASTRO-H, the detector is sharp enough to let scientists distinguish each one, said Samar Safi-Harb, a professor and Canada research chair in supernova astrophysics at the University of Manitoba.
"It's kind of like wearing glasses," added Safi-Harb, another member of the Canadian science working group for ASTRO-H.
Heavy elements in our bodies such as oxygen, calcium and iron all originally came from a supernova, an exploded star. Safi-Harb wants to use ASTRO-H to figure out the proportion of each element in different kinds of supernovas. That should reveal what kind of star exploded – how massive it was, for example – and offer new insights about the origins of heavy elements.
It might also answer one of the big questions in astrophysics, Safi-Harb said: Do most massive stars become black holes or some exotic neutron stars?
Another advantage of ASTRO-H is its four different telescopes, which allow it to see a much broader range of X-ray colours representing different energy levels. That means heavy elements such as calcium and iron, which give off light at lower X-ray energies, and decaying radioactive elements, which give of light at higher energies, can be seen at the same time.
Safi-Harb said that's important for understanding processes in the remnants left behind by a supernova explosion, which give off both types of X-rays.
Previously, astronomers needed to use two different telescopes at separate times to see both types of colours, leaving open the possibility they might have changed between the two observations and making it hard to relate the two images.
ASTRO-H's ability to see a huge range of X-ray colours is made possible, in part, by the Canadian-made ASTRO-H Metrology System (CAMS).
It's difficult for a telescope to see a broad range of colours because they require different focal lengths. ASTRO-H achieves the long focal lengths required to see higher-energy or "hard" X-rays by being literally telescopic – the hard X-ray detectors are mounted on the end of an arm six metres long that will slide out of the telescope's body once it's in space so it won't get in the way during the launch, Gallo said.
Of course, the boom does sway a bit, causing the equivalent of camera shake that could blur the telescope's images. The CAMS system uses lasers and detectors to measure the amount and direction that the boom moves. The measurement is used to correct the image so it's sharp again.
The CAMS system was built by Ottawa-based Neptec in consultation with the Canadian researchers.
The third Canadian researcher involved in the project is Brian McNamara, professor and university research chair in astrophysics at the University of Waterloo. He hopes to use the instrument to study collections of hundreds of galaxies called galaxy clusters.
"These are the largest concentrations of mass in the universe," said McNamara, who's interested in the role the supermassive black holes at the centre of galaxies play in the formation of galaxy clusters.
If all goes well, Gallo, Safi-Harb and McNamara should be able to start using ASTRO-H very soon. They helped generate the data needed to design the telescope and decide what it should look at first.
In return for Canada's contribution, they are among the small group scientists around the world who will get exclusive access to the data for the first year of operation. After that, other scientists will be able to book time as well.
"It's a lot of fun, a lot of work, but it's well worth it if everything goes well," McNamara said.
He has been working on X-ray telescopes since he first graduated in the early 1990s, and has seen a couple of failures, including one lost to a rocket failure and another to a problem with the cooling system.
He'll be watching this launch online.
Gallo is heading to Japan to see the launch in person, but has no role in the launch itself.
"I'm a spectator at this point," said. "Did everything we can do. Now we're going to sit back and watch."