ABSTRACT
In such cases, however, talks do not suffice--one should have demonstrated the defects of the alternative approach (the radio-star hypothesis) and found some bright arguments in favor of the synchrotron mechanism. I may permit myself to express a supposition that I did not achieve a success on this way not so much for the lack of imagination as for almost a complete lack of knowledge of astronomy-it so happened that I was then unacquainted not only with the university but even with the school course in astronomy. The only astronomical object I had been acquainted with before was the Sun. Therefore, it was only to the Sun that G G Getmantsev3, my post graduate student of those days, and I applied the synchrotron theory [22]. But, in the case of the Sun, there were other possibilities as well and it was not easy to separate the synchrotron component from the total radiation. I would like to mention also the work by Getmantsev [23], performed at my suggestion, wherein he obtained an important result concerning synchrotron radiation for electrons with a power-law spectrum. The papers by Getmantsev [23, 24] and the analysis of the possibility of using radio-wave diffraction on the Moon to determine the dimensions of the sources [8, 25] promoted the development of radio astronomy but did not bring any change even into the minds of astronomers acquainted with our work. So, as late as 1952, I S Shklovsky not only continued advocating the radio-star hypothesis but also considered the synchrotron hypothesis inadmissible [11]. 4 As an argument confirming such a conclusion, Shklovsky 2 Quite recently (in 1996), I learnt about the paper by G W Hutchinson (1952 Phil. Mag. 80 847) which was also devoted to the relation between galactic radio emission and cosmic rays. The author knew and cited papers [19, 21] but, for some reason, paid no attention to paper [20] . The new suggestion from Hutchinson, compared to the previous papers, was a possible relation between radio emission and bremsstrahlung gamma radiation from the same relativistic electrons that enter in the composition of cosmic rays. Some interesting things concerning Hutchinson's work and generally the history of the synchrotron theory of cosmic radio emission can be found in book [79]. 3 Dr G G Getmantsev died on 30 April, 1980 in his 55th year. 4 In [11, p 445], we find: "Apart from the notion that the sources of galactic radio emission are the interstellar ionized gas and 'radio stars' (in the previously mentioned sense), there also exists another concept developed most extensively by V L Ginzburg [35] [this is paper [21] from the literature cited here, VLG]. According to [35], the source
On the birth and development of cosmic-ray astrophysics 97
The next very important step in this direction was made in 1952 by I M Gordon (due to some circumstances his paper [27] was published only in 1954 but he made reports in 1952 and the main content of [27] has been known in the USSR at least since the end of 1952). Gordon applied the synchrotron mechanism to optical radiation in solar flares and even discussed the possibility of synchrotron X-ray radiation. The main thing is that he paid attention to the importance and the feasibility of polarization measurements-the presence of polarization is rather characteristic of synchrotron radiation and, consequently, the detection of polarization could provide decisive evidence. To the particularly important results of this period one should refer the work by S B Pikelner [26] who, as a matter of fact, introduced the concept of the gas galactic halo and 'cosmic-ray halo'. He also stressed that the magnetic field with H ;:::; 3 X w-6 G exists in the entire Galaxy. Note, by the way, that, in my opinion, S B Pikelner, who died in 1975 in the 55th year of his life, was the most prominent Soviet astronomer-theoretician and he left a lasting trace in astrophysics (see the obituary [28]) . The contribution made by Pikelner is not limited to his publications, for he disinterestedly helped everybody who needed his advice and there was no end to those who came to this noble and kind man.
