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Observational test for the existence of a rotating black hole in Cyg X-1. [Gravitatinal effects, polarization properties]

Journal Article:

Abstract

It is stated that the degree and plane of linear polarisation of the radiation from Cyg X-1 are being investigated by X-ray satellite experiments. This radiation can be explained as coming from an accretion disk around a black hole, the polarisation of the X-rays being due to electron scattering in the hotter inner regions of the disk. Existing predictions of the polarisation properties, as a function of energy, have been based on a Newtonian approximation, thus neglecting gravitational effects on the rays as they propagate from the surface of the disk to an observer at infinity. Preliminary results are here given of a full general relativistic calculation that shows that gravitational effects completely alter the polarisation properties, and provide a sensitive test of the existence of a black hole. It is found that for a rapidly rotating black hole the general relativistic effects on the polarisation properties are an order of magnitude greater than for a slowly rotating black hole, or for a neutron star. The degree of linear polarisation of the rays as they leave the disk will also differ from the Newtonian value, and gravitational bending of the light will alter the angle at which a ray leaves  More>>
Authors:
Stark, R F; Connors, P A [1] 
  1. Oxford Univ. (UK). Dept. of Astrophysics
Publication Date:
Mar 31, 1977
Product Type:
Journal Article
Reference Number:
AIX-08-311902; EDB-77-102461
Resource Relation:
Journal Name: Nature (London); (United Kingdom); Journal Volume: 266:5601
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BLACK HOLES; X-RAY SPECTRA; BINARY STARS; COSMIC RADIO SOURCES; COSMIC X-RAY SOURCES; GENERAL RELATIVITY THEORY; KERR FIELD; KERR METRIC; POLARIZATION; ROTATION; COSMIC RAY SOURCES; FIELD THEORIES; GRAVITATIONAL FIELDS; METRICS; MOTION; SPECTRA; STARS; 640103* - Astrophysics & Cosmology- Quasi-Stellar, Radio, & X-Ray Sources- (-1987); 640102 - Astrophysics & Cosmology- Stars & Quasi-Stellar, Radio & X-Ray Sources
OSTI ID:
7310677
Country of Origin:
United Kingdom
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: NATUA
Submitting Site:
INIS
Size:
Pages: 429-430
Announcement Date:

Journal Article:

Citation Formats

Stark, R F, and Connors, P A. Observational test for the existence of a rotating black hole in Cyg X-1. [Gravitatinal effects, polarization properties]. United Kingdom: N. p., 1977. Web. doi:10.1038/266429a0.
Stark, R F, & Connors, P A. Observational test for the existence of a rotating black hole in Cyg X-1. [Gravitatinal effects, polarization properties]. United Kingdom. doi:10.1038/266429a0.
Stark, R F, and Connors, P A. 1977. "Observational test for the existence of a rotating black hole in Cyg X-1. [Gravitatinal effects, polarization properties]." United Kingdom. doi:10.1038/266429a0. https://www.osti.gov/servlets/purl/10.1038/266429a0.
@misc{etde_7310677,
title = {Observational test for the existence of a rotating black hole in Cyg X-1. [Gravitatinal effects, polarization properties]}
author = {Stark, R F, and Connors, P A}
abstractNote = {It is stated that the degree and plane of linear polarisation of the radiation from Cyg X-1 are being investigated by X-ray satellite experiments. This radiation can be explained as coming from an accretion disk around a black hole, the polarisation of the X-rays being due to electron scattering in the hotter inner regions of the disk. Existing predictions of the polarisation properties, as a function of energy, have been based on a Newtonian approximation, thus neglecting gravitational effects on the rays as they propagate from the surface of the disk to an observer at infinity. Preliminary results are here given of a full general relativistic calculation that shows that gravitational effects completely alter the polarisation properties, and provide a sensitive test of the existence of a black hole. It is found that for a rapidly rotating black hole the general relativistic effects on the polarisation properties are an order of magnitude greater than for a slowly rotating black hole, or for a neutron star. The degree of linear polarisation of the rays as they leave the disk will also differ from the Newtonian value, and gravitational bending of the light will alter the angle at which a ray leaves the surface of the disk. The large general relativistic variation of the polarisation plane with energy is illustrated graphically. The very large general relativistic rotations in the plane of polarisation provide an opportunity for testing the black hole hypothesis for Cyg X-1. In order to observe these effects X-ray satellite experiments will be required with more sensitive polarimetry across a wider energy range than is available at present.}
doi = {10.1038/266429a0}
journal = {Nature (London); (United Kingdom)}
volume = {266:5601}
journal type = {AC}
place = {United Kingdom}
year = {1977}
month = {Mar}
}