Doppler boosting factor in the observer’s frame o relative to the hot spot’s moving frame hs, So ~ Shs × D, with D = (Γ(1 − β))−(3+α), for a moving hot spot at β = v/c, Γ = (1− β2)−1/2, and at an angle 90° −i relative to the line of sight (McCrea 1972). We show D for two radii, ISCO a = 0 (blue) and R = 10 Rg (red). Solid curves assume spectral index α = 0.6 (Sv ∝ v−α, appropriate for very bright flares) and dotted curves assume = 1.5 (S / − , appropriate for average bright states, Witzel et al. 2018). If one assumes that D < 2.5, the inclination has to be less than about 45°.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.