Radio Pulse Shapes, Flux Densities, and Dispersion of Pulsar NP 0532

Crab giant pulses at low frequencies

“…At 116.75 MHz this feature is ∼40% of the peak mainpulse intensity. Previous studies have revealed the presence of an emission bridge (Rankin et al 1970;Manchester et al 1972;Vandenberg et al 1973), although it was not very evident as the signals were affected by dispersion smearing.…”

“…Additionally, in this band the pulse emission occurs over a large fraction of the pulse period resulting in an insufficient off-pulse region contributing to flux estimation uncertainties. Alternatively, the drastic turn over in the spectrum of the pulsar at ∼100 MHz (Rankin et al 1970;and Fig. 2 in Sect.…”

“…The Crab pulsar has a rather steep spectrum with a spectral index α = −3 (Rankin et al 1970;Maron et al 2000). This implies that a large number of giant pulses should be detectable at low radio frequencies, if their occurence rate remains the same as that reported at higher frequencies (Lundgren et al 1995).…”

“…Other than the first order comparision, more observations are necessary to ascertain the nature of these components. For example, the mainpulse precursor is linearly polarized (Campbell & Heiles 1970) and its intensity varies in time on the order of a few tens of minutes (Rankin et al 1970). Our observations show that the precursor to the interpulse is devoid of any giant pulse emission and therefore consists of normal pulses only.…”

“…At radio frequencies, the pulsar emission shows a variety of features of which the evolution of the average pulse profile with increasing radio frequency is readily noticed. For example, in addition to the main-and interpulse emission visible at most frequencies, other emission components appear at certain frequencies; the precursor emission component is visibile only at low frequencies (Rankin et al 1970); the low-frequency component appears between 600-4800 MHz and two high-frequency components in the 4000-8400 MHz frequency range (Moffett & Hankins 1996). In the latter work, it is also seen that no interpulse emission is present at 2700 MHz, and reappears slightly earlier in phase above 4700 MHz.…”