English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In October 1997, radio pulses from the Crab Pulsar underwent abnormal delay.This was reported by two radio observatories, both of which explained thisfrequency dependent and time varying delay as being due to refractive effectsof ionized shells in the Crab Nebula. Both groups also noted that, curiouslyand confusingly coincident with the frequency dependent delay, the Crab Pulsaralso underwent an unusual slowing down, which they believed to be unrelated tothe Crab Nebula and instead intrinsic to the Crab Pulsar, resulting in anadditional delay that was frequency independent. However, it now appears thatone of the groups attributes the frequency independent delay also to refractiveeffects. This work aims to verify whether at least a part of the frequencyindependent delay is indeed due to intrinsic slowing down of the Crab Pulsar.Timing analysis of the Crab Pulsar's October 1997 event has been done inX-rays, which are not delayed by the refractive and diffractive effects thataffect radio waves; at X-rays only the intrinsic slowing down should contributeto any observed delay. Data mainly from the PCA instrument aboard the RXTEsatellite have been used, along with a small amount of data from the PDSinstrument aboard the BeppoSAX satellite. Analysis of the X-ray data, using thevery accurate reference timing mode derived at radio frequencies, stronglysupports the intrinsic slowing down hypothesis. Analysis using the referencetiming model derived self-consistently from the limited X-ray data, which isless accurate, is not completely unambiguous regarding the above twohypotheses, but provides reasonable support for the intrinsic slowing downhypothesis. A significant fraction of the frequency independent delay duringthe October 1997 event is indeed due to intrinsic slowing down of the CrabPulsar.

The 1997 Event in the Crab Pulsar in X-rays