Gravitationally distorted P-Cygni profiles from outflows near compact objects

Abstract

We consider resonant absorption in a spectral line in the outflowing plasma within several tens of Schwarzschild radii from a compact object. We take into account both Doppler and gravitational shifting effects and re-formulate the theory of P-Cygni profiles in these new circumstances. It is found that a spectral line may have multiple absorption and emission components depending on how far the region of interaction is from the compact object and what is the distribution of velocity and opacity. Profiles of spectral lines produced near a neutron star or a black hole can be strongly distorted by Doppler blue-, or red-shifting, and gravitational red-shifting. These profiles may have both red- and blue-shifted absorption troughs. The result should be contrasted with classical P-Cygni profiles which consist of red-shifted emission and blue-shifted absorption features. We suggest this property of line profiles to have complicated narrow absorption and emission components in the presence of strong gravity may help to study spectroscopically the innermost parts of an outflow.

34 pages, 12 figures, accepted by MNRAS; minor corrections

References in corpus (7)

• Gravitationally redshifted absorption lines in the X-ray burst spectra of a neutron star
• The Cores of the Fe K Lines in Seyfert I Galaxies Observed by the Chandra High Energy Grating
• Evidence for Gravitational Infall of Matter onto the Super-Massive Black Hole in the quasar PG 1211+143?
• Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?
• A changing inner radius in the accretion disc of Q0056-363?
• On the structure of line-driven winds near black holes
• Line-driven winds in presence of strong gravitational fields