On the puzzling high-energy pulsations of the energetic radio-quiet γ-ray pulsar J1813–1246
- INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133 Milano (Italy)
- Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
- Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)
We have analyzed the new deep XMM-Newton and Chandra observations of the energetic, radio-quiet pulsar J1813–1246. The X-ray spectrum is nonthermal, very hard, and absorbed. Based on spectral considerations, we propose that J1813 is located at a distance further than 2.5 kpc. J1813 is highly pulsed in the X-ray domain, with a light curve characterized by two sharp, asymmetrical peaks, separated by 0.5 in phase. We detected no significant X-ray spectral changes during the pulsar phase. We extended the available Fermi ephemeris to five years. We found two glitches. The γ-ray light curve is characterized by two peaks, separated by 0.5 in phase, with a bridge in between and no off-pulse emission. The spectrum shows clear evolution in phase, being softer at the peaks and hardening toward the bridge. Surprisingly, both X-ray peaks lag behind the γ-ray ones by a quarter of phase. We found a hint of detection in the 30-500 keV band with INTEGRAL, which is consistent with the extrapolation of both the soft X-ray and γ-ray emission of J1813. The unique X-ray and γ-ray phasing suggests a singular emission geometry. We discuss some possibilities within the current pulsar emission models. Finally, we develop an alternative geometrical model where the X-ray emission comes from polar cap pair cascades.
- OSTI ID:
- 22370220
- Journal Information:
- Astrophysical Journal, Vol. 795, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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