361 research outputs found
Structure in the polarized Galactic synchrotron emission, in particular ``depolarization canals''
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
LOFAR: A new radio telescope for low frequency radio observations: Science and project status
LOFAR, the Low Frequency Array, is a large radio telescope consisting about
100 soccer field sized antenna stations spread over a region of 400 km in
diameter. It will operate in the frequency range from ~10 to 240 MHz, with a
resolution at 240 MHz of better than an arcsecond. Its superb sensitivity will
allow for a broad range of astrophysical studies. In this contribution we first
discuss four major areas of astrophysical research in which LOFAR will
undoubtedly make important contributions: reionisation, distant galaxies and
AGNs, transient radio sources and cosmic rays. Subsequently, we will discuss
the technical concept of the instrument and the status of the LOFAR projectComment: 8 pages, 2 figures, to appear in the proceedings of the XXI Texas
Symposium on Relativistic Astrophysics held on December 9--13 2002, in
Florence, Ital
A new sample of giant radio galaxies from the WENSS survey. I. Sample definition, selection effects and first results
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
The curve of GRB 970508
Submitted to: Astrophys. J. Abstract: We report on Westerbork 1.4 GHz radio observations of the radio counterpart to -ray burst GRB~970508, between 0.80 and 138 days after this event. The 1.4 GHz light curve shows a transition from optically thick to thin emission between 39 and 54 days after the event. We derive the slope of the spectrum of injected electrons () in two independent ways which yield values very close to . This is in agreement with a relativistic dynamically near-adiabatic blast wave model whose emission is dominated by synchrotron radiation and in which a significant fraction of the electrons cool fast
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