X-ray/GeV emissions from Crab-like pulsars in LMC

Abstract

We discuss X-ray and gamma-ray emissions from Crab-like pulsars, PSRs~J0537-6910 and~J0540-6919, in Large Magellanic Cloud. Fermi-LAT observations have resolved the gamma-ray emissions from these two pulsars and found the pulsed emissions from PSR~J0540-6919. The total pulsed radiation in the X-ray/gamma-ray energy bands of PSR~J0540-6919 is observed with the efficiency ${\eta }_{J0540}\sim 0.06$ (in 4$\pi$ sr), which is about a factor of ten larger than ${\eta }_{Crab}\sim 0.006$ of the Crab pulsar. Although PSR~J0537-6910 has the highest spin-down power among currently known pulsars, the efficiency of the observed X-ray emissions is about two orders of magnitude smaller than that of PSR~J0540-6919. This paper mainly discusses what causes the difference in the radiation efficiencies of these three energetic Crab-like pulsars. We discuss electron/positron acceleration and high-energy emission processes within the outer gap model. By solving the outer gap structure with the dipole magnetic field, we show that the radiation efficiency decreases as the inclination angle between the magnetic axis and the rotation axis increases. To explain the difference in the pulse profile and in the radiation efficiency, our model suggests that PSR~J0540-6919 has an inclination angle much smaller than the that of Crab pulsar (here we assume the inclination angles of both pulsars are $\alpha <90^{\circ }$). On the other hand, we speculate that the difference in the radiation efficiencies between PSRs~J0537-6910 and J0549-6919 is mainly caused by the difference in the Earth viewing angle, and that we see PSR~J0537-6910 with an Earth viewing angle $\zeta >>90^{\circ }$ (or $<<90^{\circ }$) measured from the spin axis, while we see PSR~J0540-6919 with $\zeta \sim 90^{\circ }$.

arXiv comment23 pages, 7 figures, ApJ in press

References in corpus (32)

• The ATNF Pulsar Catalogue
• The ATNF Pulsar Catalogue
• Time-dependent force-free pulsar magnetospheres: axisymmetric and oblique rotators
• The Second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• Fermi Large Area Telescope Observations of the Crab Pulsar and Nebula
• Modeling of Gamma-Ray Pulsar Light Curves with Force-Free Magnetic Field
• Fitting Pulsar Wind Tori
• Discovery of an Ultra-fast X-ray Pulsar in the Supernova Remnant N157B
• Observation of Pulsed Gamma-rays Above 25 GeV from the Crab Pulsar with MAGIC
• Detection of Pulsed Gamma Rays Above 100 GeV from the Crab Pulsar
• High-Altitude Emission from Pulsar Slot Gaps: The Crab Pulsar
• Fitting Pulsar Wind Tori. II. Error Analysis and Applications
• Enhanced Optical Emission During Crab Giant Radio Pulses
• Morphological and spectral properties of the W51 region measured with the MAGIC telescopes
• The Galactic Population of Young Gamma-ray Pulsars
• Observations of the Crab pulsar between 25 GeV and 100 GeV with the MAGIC I telescope
• A re-visit of the phase-resolved X-ray and γ-ray spectra of the Crab pulsar
• Pulse Profiles, Spectra and Polarization Characteristics of Non-Thermal Emissions from the Crab-Like Pulsars
• Synchrotron Self-Compton Emission from the Crab and Other Pulsars
• Discovery of a highly energetic pulsar associated with IGR J14003-6326 in a young uncataloged Galactic supernova remnant G310.6-1.6
• Outer gap accelerator closed by magnetic pair-creation process
• Radio and X-ray Observations of PSR B0540-69
• Detection of bridge emission above 50 GeV from the Crab pulsar with the MAGIC telescopes
• Gamma-ray spectral properties of mature pulsars: a two-layer model
• Hard X-ray timing and spectral properties of PSR B0540-69
• Three-dimensional non-vacuum pulsar outer-gap model: Localized acceleration electric field in the higher altitudes
• Probing gamma-ray emissions of Fermi-LAT pulsars with a non-stationary outer gap model
• X-ray observations of the Large Magellanic Cloud pulsar PSR B0540-69 and its PWN
• The optical light curve of the LMC pulsar B0540-69 in 2009
• Outer-magnetospheric model for Vela-like pulsars:formation of sub-GeV spectrum
• Population study for gamma-ray pulsars: (III) Radiation characteristics and viewing geometry
• The X-ray emission of the Crab-like pulsar PSR J0537-6910

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