Books : reviews

Wolfgang Sieber, Richard Wielebinski.
Pulsars: 13 years of research on neutron stars.
IAU/Reidel. 1981

rating : 3 : worth reading

When J. Bell and A. Hewish first discovered pulsars at Cambridge some thirteen years ago, they opened up a whole field of speculation to research. This research was at first rather hectic and the accumulation of knowledge, both observational and theoretical, through the years has been at the same time extensive and largely unordered.

This very crucial volume reflects the concern of the Scientific Organizing Committee of the IAU that a proper review of the data gathering, interpretation and theory on pulsars be undertaken.

Accepted research fields associated with neutron stars such as X-ray and γ-ray emission, pulse timing, neutron star properties, and neutron stars in binary systems are treated in some detail while an extensive collection of papers on radio observation of pulsars and optical radiation is also presented. Unresolved questions concerning pulsars on magnetospheric constitution, radio emission mechanism and their relation to supernovae are highlighted in an attempt to critically assess the developments in these fields.

[disclaimer: I received a free copy of the book, in order to write this review, published in Journal of the British Astronomical Association, 92(2):102, 1982]

Thirteen years ago Jocelyn Bell and Anthony Hewish discovered pulsars, giving for the first time observational evidence for neutron stars. It was soon accepted that pulsars are rapidly rotating neutron stars with misaligned magnetic and spin axes. Since their discovery much has been learnt about these strange objects, but much yet remains to be discovered. This book contains the proceedings of the IAU symposium on pulsars, held in the August of 1980. It consists of reviews of the state of the art and of papers on current research, theoretical and observational. Over 60 papers are included, covering nearly all aspects of pulsars.

On the observational side, there are reports of the pulsed emission at wavelengths ranging from radio to γ-rays. The emission is highly polarized and shows considerable structure at radio frequencies. Although the average pulse profile is remarkably unchanging, abrupt mode-switching can occur, as well as nulling—a complete cessation of all radiation. Subpulses can show systematic drifts in phase from pulse to pulse.

Originally it was the extreme regularity of the pulses which excited interest; today the emphasis is on studying the minute deviations from this regularity. Spindown gives information about pulsar ages, while glitches—sudden decreases in period—provide clues to the internal structure of neutron stars. Measurements of the orbit of the close binary pulsar are providing a check of general relativity.

The theorists have not been idle either. Many papers are devoted to models of the pulsar magnetosphere, which require a considerable range of physics. There is not yet agreement on the origin of the pulses themselves—from the polar caps or from the light cylinder?—although the weight of opinion seems to favour the former. Another problem addressed in this book is that of pulsar formation. Are they the remnants of supernovae? Unfortunately the inferred pulsar birth-rate is greater than the rate of supernova explosions, though the observational errors are sufficiently large not to rule out the idea. (More recent analysis of the observations has reduced this discrepancy.) Obviously binary evolution must be taken into consideration, to account for the binary pulsars.

This book covers the present view of pulsars, aimed at a professional audience. I would recommend it to anyone working in this area, and especially to research students wishing to enter the subject.