On the
left of the image the central LOFAR antennas. On the right the peaked signals
of the two discovered pulsars. Credit: LOFAR Pulsar Working Group
The
radio telescope LOFAR has discovered two new pulsars - fast-spinning neutron
stars, remnants of massive supernova explosions. Two of these weak but quickly
flashing radio sources were spotted for the first time during the ‘warm-up' for
the LOFAR all-sky survey. The results are described in the PhD thesis that
astronomer Thijs Coenen will defend November 20 at the University of Amsterdam.
The
International LOFAR Telescope (ILT), designed and built by ASTRON, is a radio
telescope centered in the Netherlands and spread across Europe. The telescope
consists of a network of thousands of individual dipole antennas, connected
over a fast network to a central supercomputer. The high sensitivity of this
software telescope means it is extraordinarily suited for pulsar
research.
The
international team of astronomers looking for new pulsars with LOFAR is led by
Jason Hessels, from ASTRON and the University of Amsterdam, and Ben Stappers,
from the University Manchester. The discovery highlighted by Coenen's PhD
research showcases the pulsar capabilities of LOFAR, and hints at new
possibilities with its successor, the Square Kilometre Array
(SKA). Hessels says: "SKA will take LOFAR technology one step further, and
these discoveries show we can expect to detect a large fraction of the pulsars
in our Galaxy with SKA."
Pulsars
act as cosmic lighthouses, emitting radio beams that sweep the Galaxy. Their
signals allow scientists to study the behaviour of gravity and matter in
circumstances so extreme that they cannot be reproduced on Earth, not even in
the most advanced facility. Pulsars are important because of this - they are
true cosmic laboratories. So far, about 2,000 pulsars have been
identified, but astronomers think there must be about 50,000 active pulsars in
our Galaxy.
Using computing
resources provided by the European Grid Infrastructure, Coenen and the team
needed only a month to search through a set of 2010-2013 LOFAR images that
would have occupied a single computer for more than a century. Coenen says:
"Analysing all that data was a huge challenge, but then to find two new pulsars
with this powerful telescope was very special."
These
first results show how LOFAR, with its flexible configuration, can produce more
than a 1,000 images per second of a large part of the sky. That means the
pulsar survey will be the most sensitive ever in this radio regime.
Joeri
van Leeuwen, Coenen's PhD co-supervisor, concludes: "With these first tests so
successfully wrapped up, the hunt for new pulsars is on."
More
information
PhD
thesis:
Searching for Pulsars with LOFAR, Thijs Coenen MSc.,
Public defence: 20 November 2013 at 10am in the Agnietenkapel, Amsterdam.
Supervisor: Prof. dr. M.B.M. van der Klis
Co-supervisor: Dr. A.G.J. van Leeuwen
Co-supervisor: Dr. J.W.T. Hessels
Searching for Pulsars with LOFAR, Thijs Coenen MSc.,
Public defence: 20 November 2013 at 10am in the Agnietenkapel, Amsterdam.
Supervisor: Prof. dr. M.B.M. van der Klis
Co-supervisor: Dr. A.G.J. van Leeuwen
Co-supervisor: Dr. J.W.T. Hessels
Pulsar
Working Group:
A. Alexov, A. Bilous, R. Breton, T. Coenen, H. Falcke, J.M Griessmeier, T. Hassall, J. Hessels, A. Karastergiou, E. Keane, V. Kondratiev, M. Kramer, M. Kuniyoshi, J. van Leeuwen, A. Noutsos, M. Serylak, M. Pilia, C. Sobey, B. Stappers, S. ter Veen, J. Verbiest, P. Weltevrede, K. Zagkouris.
A. Alexov, A. Bilous, R. Breton, T. Coenen, H. Falcke, J.M Griessmeier, T. Hassall, J. Hessels, A. Karastergiou, E. Keane, V. Kondratiev, M. Kramer, M. Kuniyoshi, J. van Leeuwen, A. Noutsos, M. Serylak, M. Pilia, C. Sobey, B. Stappers, S. ter Veen, J. Verbiest, P. Weltevrede, K. Zagkouris.
