Space Telescope and Optical Reverberation Mapping Project. IX. Velocity-Delay Maps for Broad Emission Lines in NGC 5548

Understand

We report velocity-delay maps for prominent broad emission lines, Ly_alpha, CIV, HeII and H_beta, in the spectrum of NGC5548.

• The emission-line responses inhabit the interior of a virial envelope.
• The velocity-delay maps reveal stratified ionization structure.
• The HeII response inside 5-10 light-days has a broad single-peaked velocity profile.