English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The only relativistic reflection model that implements a parameter relatingthe intensity incident on an accretion disk to the observed intensity isrelxill. The parameter used in earlier versions of this model, referred to asthe reflection strength, is unsatisfactory, and it has been superseded by aparameter that provides insight into the accretion geometry, namely thereflection fraction. The reflection fraction is defined as the ratio of thecoronal intensity illuminating the disk to the coronal intensity that reachesthe observer. The relxill model combines a general relativistic ray-tracingcode and a photoionization code to compute the component of radiation reflectedfrom an accretion that is illuminated by an internal source. The reflectionfraction is a particularly important parameter for relativistic models withwell-defined geometry, such as the lamppost model, which is a focus of thispaper. Relativistic spectra are compared for three inclinations and for fourvalues of the key parameter of the lamppost model, namely the height above theblack hole of the illuminating, on-axis point source. In all cases, thestrongest reflection is produced for low source heights and high spin. Alow-spin black hole is shown to be incapable of producing enhanced relativisticreflection. Results for the relxill model are compared to those obtained withother models and a Monte Carlo simulation. Fitting data using the relxill modeland the recently implemented parameter the reflection fraction, one canconstrain the geometry of a system, under the assumption of a lamppost-likeaccretion geometry. The reflection fraction is independent of such systemparameters as inclination and black hole spin. The reflection fractionparameter was implemented with the name refl_frac in all flavors of the relxillmodel, and the nonrelativistic reflection model xillver, in v0.4a (18 January2016).

Normalizing a Relativistic Model of X-ray Reflection: The Definition of the Reflection Fraction and its Implementation in relxill