Space Telescope and Optical Reverberation Mapping Project 2: Broad line lags from UV emission line reverberation mapping of Mrk817

Reliable measurements of the geometry and kinematics of the high-ionization gas in the inner regions of AGN are among the foremost requirements for identifying the location of disk winds and the nature of gas outflows, which ultimately are essential for understanding the role of black hole feedback in black hole-galaxy co-evolution. I will present the first velocity-resolved reverberation mapping measurements for the prominent ultraviolet broad emission lines in the inner regions of Mrk 817 from a year-long campaign using the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultraviolet observations are accompanied by X-ray, optical, and near-IR observations as part of the AGN Space Telescope and Optical Reverberation Mapping Program 2 (AGN STORM 2). Our reverberation mapping techniques use the light echoes from the broad-emission-line region and the accretion disk to measure the location and kinematics of the highly-ionized gas in this AGN. This work summarizes the ultraviolet monitoring of the broad-line region in Mrk817 that includes a newly-found “broad-line holiday” state in the first portion of the campaign.