Optical caustics in a kerr spacetime and the origin of rapid X-ray variability in active galactic nuclei

We consider the e †ect of rapid rotation on the light curves of neutron stars with hot polar caps. For P B 3 ms spin periods, the pulse fractions can be as much as an order of magnitude larger than with simple, slowly rotating (Schwarzschild) estimates. Doppler boosting, in particular, leads to characteristic distortion and "" soft lags ÏÏ in the pulse proÐles, which are easily measurable in light curves with moderate energy resolution. With D105 photons it should also be possible to isolate the more subtle distortions of light travel time variations and frame dragging. Detailed analysis of high-quality millisecond pulsar data from upcoming X-ray missions must include these e †ects.

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“…Because of certain numerical integration advantages, we use the Kerr metric in a slightly modiÐed form (Rauch & Blandford 1994) :…”

Section: Kerr Propagationmentioning

confidence: 99%

Light Curves of Rapidly Rotating Neutron Stars

Braje

Romani

Rauch

2000

ApJ

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116

106

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“…This leaves only small acceleration terms which the numerical integration routine can process more rapidly. However, any simple forward integration method, including this one, is still slower than more elaborate methods, such as the semi-analytical method of Dexter & Agol (2009) or the numerical methods of Rauch & Blandford (1994) which increase computational efficiency through the use of elliptic integrals and clever changes of variables.…”

Section: Application: Magnification Map -Binary Systemmentioning

confidence: 99%

Rotating gravitational lenses: a kinematic approach

Walters¹,

Forbes²

2014

Monthly Notices of the Royal Astronomical Society

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This paper uses the Kerr geodesic equations for massless particles to derive an acceleration vector in both Boyer-Lindquist and Cartesian coordinates. As a special case, the Schwarzschild acceleration due to a non-rotating mass has a particularly simple and elegant form in Cartesian coordinates. Using forward integration, these equations are used to plot the caustic pattern due to a system consisting of a rotating point mass with a smaller non-rotating planet. Additionally, first and second order approximations to the paths are identified, which allows for fast approximations of paths, deflection angles and travel-time delays.

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“…[166]. For example, except for the case of motion in the equatorial plane, trajectories are non-planar (see Fig.…”

Section: The Motion Of Light In the Kerr Metricmentioning

confidence: 99%

“…16). Discussions of the techniques used to calculate photon geodesics near Kerr black holes may be found in [166] [167] [168] [169].…”

Section: The Motion Of Light In the Kerr Metricmentioning

confidence: 99%

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Atomic X-ray spectroscopy of accreting black holes

Liedahl¹,

Torres²

2005

Can. J. Phys.

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Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation across the electromagnetic spectrum, each energy band providing access to rather distinct regimes of physical conditions and geometric scale. X-ray emission probes the innermost regions of the accretion disk, where relativistic effects prevail. While this has been known for decades, it also has been acknowledged that inferring physical conditions in the relativistic regime from the behavior of the X-ray continuum is problematic and not satisfactorily constraining. With the discovery in the 1990s of iron X-ray lines bearing signatures of relativistic distortion came the hope that such emission would more firmly constrain models of disk accretion near black holes, as well as provide observational criteria by which to test general relativity in the strong field limit. Here we provide an introduction to this phenomenon. While the presentation is intended to be primarily tutorial in nature, we aim also to acquaint the reader with trends in current research. To achieve these ends, we present the basic applications of general relativity that pertain to X-ray spectroscopic observations of black hole accretion disk systems, focusing on the Schwarzschild and Kerr solutions to the Einstein field equations. To this we add treatments of the fundamental concepts associated with the theoretical and modeling aspects of accretion disks, as well as relevant topics from observational and theoretical X-ray spectroscopy. PACS Nos.: 32.30. Rj, 32.80.Hd, 95.30.Dr, 95.30.Sf, 95.85.Nv, 97.10.Gz. 97.80.Jp, 98.35.Mp, 98.62.Mw

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Optical caustics in a kerr spacetime and the origin of rapid X-ray variability in active galactic nuclei

Cited by 207 publications

References 0 publications

Light Curves of Rapidly Rotating Neutron Stars

Light Curves of Rapidly Rotating Neutron Stars

Rotating gravitational lenses: a kinematic approach

Atomic X-ray spectroscopy of accreting black holes

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