Kaydedildi:
| Asıl Yazarlar: | , , |
|---|---|
| Materyal Türü: | Preprint |
| Baskı/Yayın Bilgisi: |
2025
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| Konular: | |
| Online Erişim: | https://arxiv.org/abs/2507.03349 |
| Etiketler: |
Etiketle
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İçindekiler:
- Fermi-LAT observations revealed that each GeV phase-folded light-curve (aka. phaseogram) of the Crab, Geminga, Dragonfly and Vela pulsars consists of two pulses (P1 & P2) and a "Bridge" between them. There is clearly a "bump" at the Bridge phase of Vela's pulse profiles, that could also be regarded as the third pulse (P3). Differently, the Crab's, Geminga's & Dragonfly's Bridges relatively resemble a "valley floor". Despite such an apparent difference, it is interesting to investigate whether their Bridge emissions are still within the same general picture as Vela's. Assuming the north-south symmetry, we would expect the fourth component (Bridge2/P4) to exist as well. However, such a hypothetical Bridge2/P4 is not intuitively identified on $γ$-ray phaseograms of the Crab, Geminga, Dragonfly and Vela pulsars. It is also intriguing to hint at the rationale for the non-discovery of Bridge2/P4. Our prototypical toy model is free of assumptions on emission regions or radiation mechanisms. Instead, it assumes a north-south symmetric geometry and one circularly symmetric beam per hemisphere, while taking into account Doppler shifts (the most innovative element), time delays and energy-dependent beam shapes. Tentative compatibility of our fitting results with wind models is reported. Notably, for the Crab pulsar, we found a preliminary qualitative correlation between our model predictions and the IXPE results on X-ray polarisation. The softer $γ$-ray pulsation of the Geminga pulsar is found to span over its full phase. Prompted by systematic evaluations, we outline some potential improvements for our toy model.