July 18, 2012
Quasar Revealed In Unprecedented Detail
Lee Rannals for redOrbit.com - Your Universe OnlineAstronomers have made a crucial step towards a scientific goal by observing the heart of a distant quasar with angular resolution.
An international team of astronomers connected radio telescopes in Chile, Hawaii and Arizona for the first time using the technique of Very Long Baseline Interferometry (VLBI), enabling them to make the sharpest observation ever of the center of a distant galaxy, the bright quasar 3C 279.
This quasar contains a supermassive black hole with a mass of as much as a billion times the mass of the sun.
The observations show that the quasar's radio signals come from within a region only 28 micro-arcseconds in diameter, which is just 0.5 light-years within the nucleus of the quasar.
The team's observations represent a new milestone towards imaging supermassive black holes and the regions around them.
Astronomers plan in the future to connect even more telescopes in this way to create the Event Horizon Telescope, which will be able to image the shadow of the super-massive black hole in the center of our own Milky Way galaxy.
Using VLBI, the sharpest images can be achieved by making the separation between telescopes as large as possible. The team used the three telescopes to create an interferometer with intercontinental baseline lengths of about 5,800 miles from Chile to Hawaii, nearly 4,500 miles from Chile to Arizona and over 2,800 miles from Arizona to Hawaii.
To synchronize the measurements, each of the telescopes were equipped with an atomic clock. After observations, four terabytes of data recorded on large hard disks at each station were shipped to Germany and processed at the Max Planck Institute for Radio Astronomy in Bonn.
The jet from the quasar could be detected on all three baselines, with an angular resolution that corresponds to a telescope magnification of about 2.1 million. This is equivalent of being able to see a tennis ball on the surface of the moon. On Earth, this would allow someone to read a newspaper in Los Angeles from Frankfurt, Germany.
Adding the APEX telescope in Chile helped achieve sharp observations at millimeter wavelengths, marking an important step towards realizing an interferometer stretching across the globe.
The experiment is the result of three years of hard work at high altitude making APEX ready for VLBI observations. Scientists from Germany and Sweden have installed new digital data acquisition systems, a very precise atomic clock, and pressurized data recorders capable of recording 4 gigabits per second for many hours.
Once the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope is finally completed, it will help the network achieve observations with 10 times better sensitivity than today.
Image 2 (below): Astronomers connected the Atacama Pathfinder Experiment (APEX), in Chile, to the Submillimeter Array (SMA) in Hawaii, USA, and the Submillimeter Telescope (SMT) in Arizona, USA for the first time, to make the sharpest observation ever of the center of a distant galaxy, the bright quasar 3C 279. The telescopes were linked using a technique known as Very Long Baseline Interferometry (VLBI). Larger telescopes can make sharper observations, and interferometry allows multiple telescopes to act like a single telescope as large as the separation – or “baseline” – between them. The baseline length from Chile (APEX) to Hawaii (SMA) is 9447 km, from Chile to Arizona (SMT) 7174 km, and from Arizona to Hawaii 4627 km. Credit: ESO/L. CalÃ§ada