New Zealand opens its eye on our universe
New American ambassador Mark Gilbert, with wife Nancy, are among an elite group of Obama financial backers known as ‘‘bundlers’’. Pinpointing a supermassive black hole in a distant galaxy by the Warkworth Radio Astronomical Observatory has confirmed New Zealand as a serious contributor to international radio astronomy.
‘‘Identification of a gamma-ray source with a radioactive object is an important scientific event, as it allows us to learn a lot about the nature of this mysterious and extremely powerful object,’’ says Sergei Gulyaev, director of the Institute for Radio Astronomy and Space Research (IRASR) at Auckland University of Technology.
Hundreds of gamma ray sources have been picked up by the Fermi Gamma– ray Space Telescope as it scans distant space. The observatory in low earth orbit since 2008 is a joint venture by Nasa, the United States Department of Energy, and government agencies in France, Germany, Italy, Spain and Japan.
Gamma-rays are part of the electromagnetic spectrum, as are visible light and radio waves. Sources Fermi is picking up are often from distant galaxies with much brighter centres than usual called active galactic nuclei (AGN) which emit high levels of radiation.
Supermassive black holes at the centres of those galaxies eject the radiation as they suck in surrounding gas, dust and other material.
This strong and distinctive radiation being shot out into space, can cover the entire electromagnetic spectrum, and helps to identify some very distant sources as galaxies, even if not visible.
One type of AGN shoots out two jets of radiation including strong radio waves from the centre of the black hole like a spinning top. They can be picked up by radio telescopes.
The Warkworth 30m radio telescope was hooked up with two radio telescopes in Australia in December, at Hobart and Ceduna. For 24 hours the team of astronomers ran through a series of 225 radio sources Fermi had confirmed were also emitting gamma-rays.
Called ‘‘very long base interferometry’’ (LVBI), radio telescopes work in unison across long distances synthesising a single massive telescope. It gives very fine resolution and means scientists can pinpoint radio sources with extreme accuracy not possible with a single telescope. The base line for the three telescopes is 3700km.
They were able to improve angular resolution by a factor of 30,000 and instantly confirmed an unidentified source as coming from a nearby AGN at least 3 billion light-years from earth.
‘‘The gamma-ray source 2FGL J1032.9-8401 cannot be seen from the northern hemisphere. The emergence of a world-class radio telescope in New Zealand is very important news for many applications, for example unveiling the nature of gamma-ray sources,’’ Gulyaev said.
The Warkworth team were able to pinpoint their own position to within 1cm, and the 30m telescope will be used for monitoring plate tectonic motion and Earth rotation.
Formerly launched as a telecommunications antenna in 1984 by New Zealand Post Office and later Telecom, the facility near Warkworth was transferred to IRASR in 2010 with the conversion to the radio telescope completed in 2014.