arXiv subjects

Avery Broderick

Publications and source records attributed to Avery Broderick.

22 records · Page 2Linked to original sources

arXiv2003

Covariant Magnetoionic Theory II: Radiative Transfer

Accretion onto compact objects plays a central role in high energy astrophysics. In these environments, both general relativistic and plasma effects may have significant impacts upon the spectral and polarimetric properties of the accretion flow. In paper I we presented a fully general relativistic magnetoionic theory, capable of tracing rays in the geometric optics approximation through a magnetised plasma in the vicinity of a compact object. In this paper we discuss how to perform polarised radiative transfer along these rays. In addition we apply the formalism to a barotropic thick disk model, appropriate for low luminosity active galactic nuclei. We find that it is possible to generate large fractional polarisations over the innermost portions of the accretion flow, even when the emission mechanism is unpolarised. This has implications for accreting systems ranging from pulsars and X-ray binaries to AGN.

astro-ph↗

arXiv2003

Covariant Magnetoionic Theory I: Ray Propagation

Accretion onto compact objects plays a central role in high energy astrophysics. In these environments, both general relativistic and plasma effects may have significant impacts upon the propagation of photons. We present a full general relativistic magnetoionic theory, capable of tracing rays in the geometric optics approximation through a magnetised plasma in the vicinity of a compact object. We consider both the cold and warm, ion and pair plasmas. When plasma effects become large the two plasma eignemodes follow different ray trajectories resulting in a large observable polarisation. This has implications for accreting systems ranging from pulsars and X-ray binaries to AGN.

astro-ph↗

arXiv2002

General Relativistic Magnetoionic Theory

We have developed methods for tracing rays and performing radiative transfer through a magnetoactive plasma in a general relativistic environment. The two electromagnetic plasma modes propagate differently due to a combination of dispersive and gravitational effects. We have found that, when given an appropriate environment surrounding the central black hole, it is indeed possible to generate a significant degree of circular polarisation without an appreciable amount of linear polarisation due to these effects alone.

astro-ph↗

arXiv2001

Compact Objects and Accretion Disks

Recent developments in the spectropolarimetric study of compact objects, specifically black holes (stellar and massive) and neutron stars are reviewed. The lectures are organized around five topics: disks, jets, outflows, neutron stars and black holes. They emphasize physical mechanisms and are intended to bridge the gap between the fundamentals of polarimetry and the phenomenology of observed cosmic sources of polarized radiation, as covered by the other lecturers. There has been considerable recent progress in spectropolarimetry from radio through optical frequencies and this is producing some unique diagnostics of the physical conditions around compact objects. It is argued that there is a great need to develop a correspondingly sensitive polarimetric capability at ultraviolet through gamma-ray energies.

astro-ph↗