Bonn, Oct 6 : Researchers at the Max-Planck-Institut for Radio Astronomy in Germany have observed the central region of the Active Galaxy M87 with 50 times more clarity than before, as viewed with the Hubble Space Telescope.

Yuri Kovalev and his colleagues observed M87, the central galaxy of the Virgo cluster at a distance of only 50 million light years, with the VLBA (Very Long Baseline Array) at two cm wavelength.

M87 is a very massive galaxy (2 to 3 x 1012 solar masses) at the centre of the Virgo cluster of galaxies at a distance of only 16 Megaparsec (approximately 50 million light years).

Kovalev said the resulting images provide details down to a resolution of one milli-arcsecond, corresponding to a linear resolution of only three light months.

The new image of the inner radio jet of M87 shows a highly collimated jet, which appears limb-brightened, and also a faint counter-jet, unprecedented in its combination of sensitivity and spatial resolution, he said.

He said the central gap in the jets was also found to be consistent with the presence of a fast inner jet as well.

“The first jet-like structure, emanating from the nucleus of a galaxy, was found in M87,” said NRAO co-author Ken Kellermann, former MPIfR director and currently external member of the institute.

In 1918, US astronomer Heber Curtis was the first to discover a nuclear jet extending at least 5000 light years from the centre of M87. This galaxy was also among the first to be recognized as a powerful source of radio emission.

Then, in 1949, Australian scientist John Bolton and his colleagues used the sea cliff interferometer in Sydney to identify the strong radio source Virgo A with the galaxy M87.

Kovalev said the scientists were now planning to increase the spatial resolution and provide an even more detailed image of the M87 jet.

“The observations were performed with the Very Long Baseline Array (VLBA) of the National Radio Astronomy Observatory (NRAO), consisting of ten radio antennas in North America including Hawaii and Virgin Island and an additional telescope from the Very Large Array (VLA) near Socorro, New Mexico. The Effelsberg 100m radio telescope is regularly used for transatlantic baselines extending the VLBA observations,” said Kovalev.

“With the 100m radio telescope, we plan to increase the spatial resolution and provide an even more detailed image of the M87 jet,” he said.

Researchers believe the energy of such powerful radio galaxies result from their "central engines".

Active Galactic Nuclei or AGN are thought to consist of a very massive black hole in the centre of the galaxy, in case of M87, it is a black hole of approximately three billion (3 x 109) solar masses.

A disk of rapidly rotating gas around the nucleus (accretion disk) “feeds” the black hole and matter is ejected from the nucleus in jets orthogonal to the disk.

The paper: ‘The Inner Jet of Radio Galaxy M87’, appears in the October 10 issue of the Astrophysical Journal Letters. (ANI)