The most detailed images ever made of faint, distant radio galaxies located billions of light years from Earth reveal that many of them harbor central massive black holes.
These new images add further support to the belief that super-massive black holes are inextricably linked with the way galaxies formed in the early universe.
Because the radio images are three times sharper than the optical images from the Hubble Space Telescope, the new pictures give a fresh insight into what's happening in the center of some of these galaxies.
Generated by the recently upgraded European VLBI Network (EVN), the images are particularly valuable because they penetrate the dust that often blocks the view of even the most powerful optical telescopes.
The pioneering observations were conducted by an international team of radio astronomers from Europe and the USA. The radio signals were received by the giant 100-m telescope in Effelsberg, Germany; the 76-m Lovell Telescope in the UK; the 70-m NASA/DSN antenna near Madrid in Spain and six other large radio telescopes located across Europe.
Data at each of the radio telescopes were archived on high speed magnetic tape recorders, generating almost 25,000 Gigabytes of data in total. By means of a special purpose-built supercomputer (operated by the National Radio Astronomy Observatory in Socorro, USA), the magnetic tapes were later played back and combined to form a super-sensitive giant radio telescope of continental dimensions.
For this experiment, the network focused on a small region of sky devoid of bright nearby stars or local galaxies, a sort of window on the distant universe. Since the Hubble Space Telescope peered at this same region, this otherwise unremarkable patch of sky has become famous as the "Hubble Deep Field" and is now known to contain thousands of galaxies.
The scientific team that initiated the new radio observations is led by Dr. Michael Garrett of the Joint Institute for VLBI in Europe, Dwingeloo, the Netherlands (JIVE), together with Drs. Simon Garrington and Tom Muxlow of the MERLIN National Facility, Jodrell Bank Observatory, UK.
Three radio sources were detected in an area of sky no bigger than that covered by a grain of sand held up to the night sky. The results appear in the latest issue of the European journal, Astronomy and Astrophysics.
According to Garrett, the team had not expected to detect this many radio sources.
(Reference: Astronomy & Astrophysics (Springer-verlag) February 1, vol. 366 number 2.)