Hot spots on neutron stars - The near-field gravitational lens

Pechenick, Kay R.; Ftaclas, C.; Cohen, J. M.

doi:10.1086/161498

Cited by 282 publications

(367 citation statements)

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“…This toy model provides an example of the significance refraction can have on the self-lensing of a compact object. The basic model and viewing geometry used here were thoroughly discussed by Pechenick, Ftaclas & Cohen (1983), and the interested reader should consult that work for full details. Let us define the observer's coordinate system with respect to a plane perpendicular to the line of sight (the 'detector') which collects the rays from a distant object.…”

Section: Effects On Pulse Profiles and Timingmentioning

confidence: 99%

Frequency-dependent effects of gravitational lensing within plasma

Rogers

2015

Monthly Notices of the Royal Astronomical Society

125

120

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The interaction between refraction from a distribution of inhomogeneous plasma and gravitational lensing introduces novel effects to the paths of light rays passing by a massive object. The plasma contributes additional terms to the equations of motion, and the resulting ray trajectories are frequency-dependent. Lensing phenomena and circular orbits are investigated for plasma density distributions N ∝ 1/r h with h ≥ 0 in the Schwarzschild space-time. For rays passing by the mass near the plasma frequency refractive effects can dominate, effectively turning the gravitational lens into a mirror. We obtain the turning points, circular orbit radii, and angular momentum for general h. Previous results have shown that light rays behave like massive particles with an effective mass given by the plasma frequency for a constant density h = 0. We study the behaviour for general h and show that when h = 2 the plasma term acts like an additional contribution to the angular momentum of the passing ray. When h = 3 the potential and radii of circular orbits are analogous to those found in studies of massless scalar fields on the Schwarzschild background. As a physically motivated example we study the pulse profiles of a compact object with antipodal hotspots sheathed in a dense plasma, which shows dramatic frequency-dependent shifts from the behaviour in vacuum. Finally, we consider the potential observability and applications of such frequency-dependent plasma effects in general relativity for several types of neutron star.

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Section: Effects On Pulse Profiles and Timingmentioning

confidence: 99%

Frequency-dependent effects of gravitational lensing within plasma

Rogers

2015

Monthly Notices of the Royal Astronomical Society

125

120

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“…The high density of MSPs in GCs, and their well-known distances and reddening make them ideal targets to study the relation of thermal radiation from MSPs to other pulsar parameters (Kargaltsev et al 2012). Additionally, a more complete study of MSPs is possible from X-ray observations, as compared to other wavelengths, because X-rays from surface hot spots of these highly compact MSPs will be bent by gravity to allow observers to see ∼75% of the neutron star surface (Pechenick, Ftaclas & Cohen 1983;Beloborodov 2002;Bogdanov et al 2006), so that a significant number of MSPs whose radio beams do not intercept the Earth should still be detectable in X-rays.…”

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confidence: 99%

Chandra studies of the globular cluster 47 Tucanae: a deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars and new constraints to r-mode instability window

Bhattacharya

Heinke

Chugunov

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We combined Chandra ACIS observations of the globular cluster 47 Tucanae (hereafter, 47 Tuc) from 2000, 2002, and 2014-15 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. We have detected 370 X-ray sources within the half-mass radius (2 .79) of the cluster, 81 of which are newly identified, by including new data and using improved source detection techniques. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. (2001). We present alternative positions derived from two methods, centroiding and image reconstruction, for faint, crowded sources. We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are well fit by black body or neutron star atmosphere models, with temperatures, luminosities and emitting radii similar to those of other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities. We limit X-ray emission from the full surface of the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as α < 2.5 × 10 −9 and constrain the shape of the r-mode instability window.

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“…The light curve produced by this rotation is influenced by effects such as special relativistic aberration and general relativistic light deflection, hence detailed observation of light curves can produce constraints on neutron star structure. However, these effects are imprinted primarily in harmonic ratios, so if only the fundamental of the oscillation is detected (as it is in most burst oscillations), then the information content is minimal (Pechenick, Ftaclas, & Cohen 1983;Strohmayer 1992;Braje, Romani, & Rauch 2000;Psaltis,Özel, & DeDeo 2000;Weinberg, Miller, & Lamb 2001;Muno,Özel, & Chakrabarty 2002;Nath, Strohmayer, & Swank 2002). Therefore, the recent report of significant harmonic content in the millisecond pulsar XTE J1814-338 opens up exciting new ways to constrain neutron star structure.…”

Section: Light Curve Profilesmentioning

confidence: 99%

Constraints on Superdensematter From X-Ray Binaries

Miller

2006

NATO Science Series II: Mathematics, Physics and Chemistry

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From the earliest measurements of the masses of binary pulsars, observations of neutron stars have placed interesting constraints on the properties of high-density matter. The last few years have seen a number of observational developments that could place strong new restrictions on the equilibrium state of cold matter at supranuclear densities. We review these astronomical constraints and their context, and speculate on future prospects.

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Hot spots on neutron stars - The near-field gravitational lens

Cited by 282 publications

References 0 publications

Frequency-dependent effects of gravitational lensing within plasma

Frequency-dependent effects of gravitational lensing within plasma

Chandra studies of the globular cluster 47 Tucanae: a deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars and new constraints to r-mode instability window

Constraints on Superdensematter From X-Ray Binaries

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