Relativistic effects in superluminal jets and neutron star winds

Abramowicz, Marek A.; Ellis, George; Lanza, A.

doi:10.1086/169211

Cited by 66 publications

(131 citation statements)

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“…We will now compute the stress-energy tensor T µν of such a radiation field at any point outside of the event horizon. This is a very symmetric problem, closely resembling one considered by Abramowicz et al [12], i.e., uniformly radiating static spherical object in the Schwarzschild spacetime. While some results can be deduced based on the findings of [12], we choose a systematic self-contained approach to our calculations, performing them from first principles.…”

Section: Cbr Stress-energy Tensormentioning

confidence: 88%

“…An interesting quantity is the saturation velocity β s , for which radial radiation drag is not only strong enough to dominate the radiation pressure term, but also balances the effective gravity. Thus, it is the radial velocity for which the particle does not instantaneously accelerate (strictly, dβ/dr = 0 is implied for β s = 0, see [12]). Obviously |β s | ≥ |β F 0 |.…”

Section: Radiation Flux and Saturation Velocitymentioning

confidence: 99%

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Cosmic background radiation in the vicinity of a Schwarzschild black hole: No classic firewall

et al. 2014

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The Cosmic Blackbody Background Radiation pervades the entire Universe, and so falls into every astrophysical black hole. The blueshift of the infalling photons, measured by a static observer, is infinite at the event horizon. This raises a question as to whether a "firewall" of high energy density may form just outside the horizon, or whether the effect can be attributed exclusively to a singular behavior of the static observer's frame at the horizon. In principle, the presence of such firewall may alter the motion of the infalling matter, influence the black hole evolution, or even invalidate the vacuum Einstein field equation solution as a realistic approximation for black holes. In this paper we show by means of analytic calculations that all these effects indeed exist, but their magnitude is typically negligibly small, even though the matter stress tensor is divergent in the static frame at r = 2M . That is not surprising because of the divergent relation of that frame to a freely falling frame as r → 2M ; however it represents a kind of classical analogue for the Black Hole Complementarity principle that has been proposed for quantum effects near a black hole. What is perhaps more surprising is the divergence of the radiation stress tensor for massive particles moving on circular geodesic orbits for values of r approaching r = 3M . However such orbits will not occur for infalling matter in realistic accretion discs.

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Section: Cbr Stress-energy Tensormentioning

confidence: 88%

Section: Radiation Flux and Saturation Velocitymentioning

confidence: 99%

Cosmic background radiation in the vicinity of a Schwarzschild black hole: No classic firewall

et al. 2014

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“…For a spherically symmetric radiation field, motion of a test-particle is restricted to one plane and we choose it to be the equatorial plane (θ = π/2). Abramowicz et al (1990) performed a rigorous analysis of purely radial motion of a test particle in the combined gravity and isotropic radiation fields of a spherical, non-rotating, compact star, and we shall use their stress energy tensor of radiation, T (μ)(ν) , calculated in a stationary observer's tetrad assuming isotropic emission from the surface of star, see also Stahl et al (2013). Numerical solutions of the equations of motion of test particle trajectories in a steady radiation field have been obtained e.g., by Bini et al (2009) andStahl et al (2012) in the Schwarzschild metric, and by Oh et al (2010); Bini et al (2011) in the Kerr metric.…”

Section: Equations Of Motionmentioning

confidence: 99%

Relativistic effects on radiative ejection of coronae in variable X-ray sources

Mishra

Kluźniak

2014

A&A

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Context. Optically thin coronae around neutron stars suffering an X-ray burst can be ejected as a result of rapid increase in stellar luminosity. In general relativity, radiation pressure from the central luminous star counteracts gravitational attraction more strongly than in Newtonian physics. However, motion near the neutron star is very effectively impeded by the radiation field. Aims. To explore the mechanisms leading to ejection of accretion disk coronae Methods. We perform a general relativistic calculation of the motion of a test particle in a spherically symmetric radiation field. Results. At every radial distance from the star larger than that of the innermost stable circular orbit (ISCO), and any initial luminosity of the star, there exists a luminosity change which leads to coronal ejection. The luminosity required to eject from the system the inner parts of the optically thin neutron-star corona is very high in the presence of radiation drag and always close to the Eddington luminosity. Outer parts of the corona, at a distance of 20 R G or more, will be ejected by a sub-Eddington outburst. Mildly fluctuating luminosity will lead to dissipation in the plasma and may explain the observed X-ray temperatures of coronae in low mass X-ray binaries. At large radial distances from the star (3 × 10 3 R G or more) the results do not depend on whether or not Poynting-Robertson drag is included in the calculation.

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“…In this and subsequent equations, hatted quantities such as are ur9 measured in a local tetrad, in contrast to unhatted quantities such as ur, which are measured in the global BoyerLindquist coordinate system. The components of the four-velocity in global Boyer-Lindquist coordinates are given by the transformation of these quantities from the local to global frames (see, e.g., Abramowicz, Ellis, & Lanza 1990 ;Miller & Lamb 1996) :…”

Section: Ight Deñectionmentioning

confidence: 99%

“…(see, e.g., Abramowicz et al 1990or Miller & Lamb 1996. Using this formula, we can determine the total deÑection /@ and rotate back from the temporary equatorial plane to the global coordinate system.…”

Section: Ight Deñectionmentioning

confidence: 99%

Attenuation of Beaming Oscillations near Neutron Stars

Miller

2000

ApJ

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Observations made with the Rossi X-Ray T iming Explorer have revealed kilohertz quasi-periodic brightness oscillations (QPOs) from nearly twenty di †erent neutron star low-mass X-ray binaries (LMXBs). These frequencies often appear as a pair of kilohertz QPOs in a given power density spectrum. It is extremely likely that the frequency of the higher frequency of these QPOs is the orbital frequency of gas at some radius near the neutron star. It is also likely that the QPOs are caused by the movement of bright arcs or luminous clumps around the star, which produce a modulation in the observed X-ray intensity as they are periodically occulted by the star or as they present a di †erent viewing aspect to the observer at inÐnity. If this picture is correct, it means that this type of QPO is a beaming oscillation. In such models it is expected that there will also be beaming oscillations at the stellar spin frequency and at overtones of the orbital frequency, but no strong QPOs have been detected at these frequencies.We therefore examine the processes that can attenuate beaming oscillations near neutron stars, and in doing so we extend the work on this subject that was initiated by the discovery of lower frequency QPOs from LMXBs. We consider attenuation by scattering, attenuation by light deÑection, and the decrease in modulation caused by integration over the visible surface of the neutron star. Our main results are (1) in a spherical scattering cloud, all overtones of rotationally modulated beaming oscillations are attenuated strongly, not just the even harmonics, (2) the amount of attenuation is diminished, and hence the observed modulation amplitude is increased, by the presence of a central, Ðnite-sized star, even if the scattering cloud is much larger than the star, and (3) if the speciÐc intensity of radiating points on the star has a large angular width, then even with zero optical depth from the stellar surface to the observer, and even in the approximation of straight-line photon propagation, the modulation amplitude seen at inÐnity is decreased signiÐcantly by integration over the visible portion of the surface. We also compare the modulation of Ñux as seen at inÐnity with the modulation near the star and show that (4) it is possible to have a relatively high-amplitude modulation near the star at, e.g., the stellar spin frequency, even if no peak at that frequency is detectable in a power density spectrum taken at inÐnity.

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Relativistic effects in superluminal jets and neutron star winds

Cited by 66 publications

References 0 publications

Cosmic background radiation in the vicinity of a Schwarzschild black hole: No classic firewall

Cosmic background radiation in the vicinity of a Schwarzschild black hole: No classic firewall

Relativistic effects on radiative ejection of coronae in variable X-ray sources

Attenuation of Beaming Oscillations near Neutron Stars

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