Astronomers using the Low-Frequency Array for Radio Astronomy (LOFAR) have captured a stunning image of a bubble of particles surrounding a supermassive black hole in the giant elliptical galaxy M87.
This false-color image shows the galaxy M87: optical light is shown in white/blue, the radio emission in yellow/orange (Francesco de Gasperin / LOFAR collaboration)
“The result is of great importance”, said Dr Francesco de Gasperin of the Max-Planck-Institut für Astrophysik in Garching, Germany, lead author of a paper in the journal Astronomy & Astrophysics (arXiv.org version).
“It shows the enormous potential of LOFAR, and provides compelling evidence of the close ties between black hole, host galaxy, and their surroundings.”
The astronomers used LOFAR to study the elliptical galaxy Messier 87 (M87) located at the centre of a galaxy cluster in the constellation of Virgo. The galaxy hosts one of the most massive black holes discovered so far, with a mass six billion times that of the Sun. Every few minutes this black hole swallows an amount of matter similar to that of the whole Earth, converting part of it into radiation and a larger part into powerful jets of ultra-fast particles.
“This is the first time such high-quality images are possible at these low frequencies”, explained co-author Prof Heino Falcke of the Radboud University in Nijmegen, the Netherlands. “This was a challenging observation – we did not expect to get such fantastic results so early in the commissioning phase of LOFAR.”
To determine the age of the bubble, the authors used data from the Very Large Array in New Mexico and the Effelsberg 100-m radio telescope in Bonn, Germany.
The team found that this bubble is surprisingly young, just about 40 million years. The low frequency observation does not reveal any relic emission outside the well-confined bubble boundaries. This means that the bubble is not just a relic of an activity that happened long ago but is constantly refilled with fresh particles ejected by the central black hole.
“What is particularly fascinating,” said co-author Dr Andrea Merloni of the Max-Planck Institute of Extraterrestrial Physics in Garching, “is that the results also provide clues on the violent matter-to-energy conversion that occurs very close to the black hole. In this case the black hole is particularly efficient in accelerating the jet, and much less effective in producing visible emission.”
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Bibliographic information: F. de Gasperin et al. 2012. M 87 at metre wavelengths: the LOFAR picture. Astronomy & Astrophysics 547, A56; doi: 10.1051/0004-6361/201220209
