New Features in Two Radio Pulsars: PSR 1541+09 and PSR 1133+16

Abstract

view Abstract Citations (15) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS New Features in Two Radio Pulsars: PSR 1541+09 and PSR 1133+16 Nowakowski, Leszek A. Abstract We present an analysis of single pulses from two radio pulsars, PSR 1541+09 and PSR 1133+16. We find the following new features: Both pulsars exhibit mode switching that can occur for several consecutive pulses at a time. We call this phenomenon a short-term mode switching, to distinguish it from a similar phenomenon previously known in other pulsars, where different modes are typically several hundred or thousand pulses long. In PSR 1541+09, the intensity of the central component often decreases dramatically for several pulses that form at least three different average profiles. In the normal mode, in which the pulsar is most of the time, the central (fourth) component dominates the profile, and other components are usually very weak. In other modes, the profile is dominated by components located in the leading part of the profile. PSR 1133+16 exhibits a similar phenomenon: single pulses appear in short sequences in which the first or the second conal component dominates in a few consecutive pulses. Occasionally, segments of pulses appear that have three components, in which the middle component may drift across the entire pulse window independently from the other two components. Evidence is presented that average profiles of the two pulsars contain more components than previously thought. We show that the average profile of PSR 1541+09 at 430 MHz consists of at least five components. Possible existence of other components in the average profile is also indicated. Complexity of the leading part of the average profile may explain why the width of the leading component was reported earlier by other authors to increase with radio frequency. We argue that morphology and modulation characteristics of the saddle region between two components in the average profile of the pulsar PSR 1133+16 over a wide frequency range are a manifestation of the existence of a third, weak component. At 430 and 1418 MHz, that component can be seen separately only occasionally, mostly in series of several (3-17) consecutive pulses that have three subpulses or when the first component decreases its brightness. We find also that the average profile of PSR 1133+16 is intensity dependent. We suggest that morphological differences between the average profile of weak and strong pulses can be explained by assuming slightly different emission heights of these profiles. We suggest that the emitting region of PSR 1133+16 consists of two roughly concentric rings. The two conal components are produced by the line of sight's crossing the outer cone of emission far away from its center, and the third (middle) component results from cutting the edge of the inner cone. Publication: The Astrophysical Journal Pub Date: February 1996 DOI: 10.1086/176782 Bibcode: 1996ApJ...457..868N Keywords: STARS: PULSARS: INDIVIDUAL ALPHANUMERIC: PSR 1133+16 full text sources ADS | data products SIMBAD (7)