On the Origin of X-ray Emission From Millisecond Pulsars in 47 Tuc

Abstract

The observed spectra and X-ray luminosities of millisecond pulsars in 47 Tuc can be interpreted in the context of theoretical models based on strong, small scale multipole fields on the neutron star surface. For multipole fields that are relatively strong as compared to the large scale dipole field, the emitted X-rays are thermal and likely result from polar cap heating associated with the return current from the polar gap. On the other hand, for weak multipole fields, the emission is nonthermal and results from synchrotron radiation of $e^{\pm }$ pairs created by curvature radiation. The X-ray luminosity, $L_x$, is related to the spin down power, $L_{sd}$, expressed in the form $L_x\propto L_{sd}^{\beta }$ with $\beta \sim 0.5$ and $\sim 1$ for strong and weak multipole fields respectively. If the polar cap size is of the order of the length scale of the multipole field, $s$ and $\beta \sim 0.5$, the polar cap temperature is $\sim 3\times 10^{6}K(\frac{L_{sd}}{10^{34}erg{s}^{-1}}{)}^{1/8}(\frac{s}{3\times 10^{4}cm}{)}^{-1/2}$. A comparison of the X-ray properties of millisecond pulsars in globular clusters and in the Galactic field suggests that the emergence of relatively strong small scale multipole fields from the neutron star interior may be correlated with the age and evolutionary history of the underlying neutron star.

25 pages, 2 figures, accepted for publication in ApJ

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Cited by in corpus (14)

• Chandra X-Ray Observations of Nineteen Millisecond Pulsars in the Globular Cluster 47 Tucanae
• Dynamical Formation of Millisecond Pulsars in Globular Clusters
• Fermi Discovery of Gamma-ray Emission from the Globular Cluster Terzan 5
• Pulsar Wind Nebulae and the Non-thermal X-Ray Emission of Millisecond Pulsars
• The Origin of Gamma-Rays from Globular Clusters
• Contribution to diffuse gamma-rays in the Galactic center region from unresolved millisecond pulsars
• The Fundamental Plane of Gamma-ray Globular Clusters
• Constraining A General-Relativistic Frame-Dragging Model for Pulsed Radiation from a Population of Millisecond Pulsars in 47 Tucanae using GLAST/LAT
• Recycled pulsars with multipolar magnetospheres from accretion-induced magnetic burial
• Variability of Nineteen Millisecond Pulsars in 47 Tucanae with CHANDRA/HRC-S
• Gamma-ray emission from globular clusters
• A comparison of millisecond pulsar populations between globular clusters and the Galactic field
• Magnetically Threaded Thin Disks in the Presence of the Quadrupole Magnetic Field
• On kHz oscillations and characteristic frequencies of accreting magnetospheres