Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 X-ray polarimetry: historical remarks and other considerations
- Part I Polarimetry techniques
- Part II Polarized emission in X-ray sources
- 14 Probing strong gravity effects with X-ray polarimetry
- 15 X-ray polarization from black holes in the thermal state
- 16 Strong-gravity effects acting on polarization from orbiting spots
- 17 Polarization of thermal emission from accreting black holes
- 18 X-ray polarimetry and radio-quiet AGN
- 19 The soft X-ray polarization in obscured AGN
- 20 The polarization of complex X-ray sources
- 21 Polarization of Compton X-rays from jets in AGN
- 22 Polarization of X-ray lines from galaxy clusters and elliptical galaxies
- 23 Polarization characteristics of rotation-powered pulsars
- 24 Polarized X-rays from magnetized neutron stars
- 25 Polarization properties of X-ray millisecond pulsars
- 26 X-ray polarization signatures of neutron stars
- 27 Polarization from the oscillating magnetized accretion torus
- 28 X-ray polarization from accreting white dwarfs and associated systems
- 29 Polarization of pulsar wind nebulae
- 30 X-ray polarization of gamma-ray bursts
- 31 Central engine afterglow from GRBs and the polarization signature
- 32 GRB afterglow polarimetry past, present and future
- 33 Gamma-ray polarimetry with SPI
- 34 INTEGRAL/IBIS observations of the Crab nebula and GRB 041219A polarization
- 35 Fermi results on the origin of high-energy emission in pulsars
- 36 Diagnostics of the evolution of spiral galaxies in a cluster environment
- Part III Future missions
- Author index
- Subject index
18 - X-ray polarimetry and radio-quiet AGN
from Part II - Polarized emission in X-ray sources
Published online by Cambridge University Press: 06 July 2010
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 X-ray polarimetry: historical remarks and other considerations
- Part I Polarimetry techniques
- Part II Polarized emission in X-ray sources
- 14 Probing strong gravity effects with X-ray polarimetry
- 15 X-ray polarization from black holes in the thermal state
- 16 Strong-gravity effects acting on polarization from orbiting spots
- 17 Polarization of thermal emission from accreting black holes
- 18 X-ray polarimetry and radio-quiet AGN
- 19 The soft X-ray polarization in obscured AGN
- 20 The polarization of complex X-ray sources
- 21 Polarization of Compton X-rays from jets in AGN
- 22 Polarization of X-ray lines from galaxy clusters and elliptical galaxies
- 23 Polarization characteristics of rotation-powered pulsars
- 24 Polarized X-rays from magnetized neutron stars
- 25 Polarization properties of X-ray millisecond pulsars
- 26 X-ray polarization signatures of neutron stars
- 27 Polarization from the oscillating magnetized accretion torus
- 28 X-ray polarization from accreting white dwarfs and associated systems
- 29 Polarization of pulsar wind nebulae
- 30 X-ray polarization of gamma-ray bursts
- 31 Central engine afterglow from GRBs and the polarization signature
- 32 GRB afterglow polarimetry past, present and future
- 33 Gamma-ray polarimetry with SPI
- 34 INTEGRAL/IBIS observations of the Crab nebula and GRB 041219A polarization
- 35 Fermi results on the origin of high-energy emission in pulsars
- 36 Diagnostics of the evolution of spiral galaxies in a cluster environment
- Part III Future missions
- Author index
- Subject index
Summary
Active galactic nuclei (AGN) are definitely not spherical objects, but rather have an axisymmetric morphology. This, together with the fact that the primary X-ray emission is due to Comptonization, and that there are several circumnuclear regions which may scatter the primary radiation, implies that most, if not all, of the X-ray spectral components observed in radio-quiet AGN should be significantly polarized. Moreover, the polarization properties of the radiation emitted very close to the black hole are modified by Special and General Relativity effects, which therefore can be probed with X-ray polarimetry.
Introduction
AGN have a complex morphology (see Figure 18.1). The nucleus, where a super-massive (106–109M⊙) black hole accretes matter from an accretion disc, is surrounded by optically and geometrically thick matter, possibly clumpy and probably in a toroidal (or at least axisymmetric) configuration. If the line of sight intercepts this ‘torus’, the nucleus is not visible and the source is classified as of type 2. For type 1 sources, instead, the line of sight does not intercept the ‘torus’, and the nucleus can be directly seen. Outside the ‘torus’, ionized matter, responsible for scattering and polarizing the nuclear radiation in type 2 sources is present. A jet is also present in ‘radio-loud’ sources, which are not discussed in this contribution, devoted to ‘radio-quiet’ AGN.
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- X-ray PolarimetryA New Window in Astrophysics, pp. 122 - 129Publisher: Cambridge University PressPrint publication year: 2010
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