Chandra X-Ray Observatory

Joint HST/Chandra Accepted Cycle 15 Targets and Abstracts

Proposal NumberSubject CategoryPI NameChandra TimeTitle
15700897BH AND NS BINARIESPeterson 20ksMapping the AGN Broad Line Region by Reverberation

Subject Category: BH AND NS BINARIES

Proposal Number:15700897

Title: Mapping the AGN Broad Line Region by Reverberation

PI Name: Peterson

We propose to make the first reverberation map of the detailed response of the broad UV emission lines, crucial to studies of the evolution of black hole masses across cosmic time, to the variable continuum using the Seyfert 1 galaxy NGC 5548. Reverberation mapping is the only direct method for measuring black hole masses beyond the local universe, using time resolution as a substitute for spatial resolution. This program will provide the first determination of the structure of a high-ionization broad-line region. NGC 5548 is known to vary on short time scales and has a short time lag between continuum and emission-line flux variations, assuring that physically meaningful, empirical, model-independent velocity-delay maps for the strong UV lines (C IV and Lyman alpha) can be recovered reliably given our experimental design. Realistic numerical simulations based on the known statistical properties of this source demonstrate that velocity-delay maps can be well-determined with 180 consecutive daily visits, even allowing for safing events or other occasional interruptions. Obtaining unique velocity-delay maps for strong emission lines will be a ground-breaking accomplishment for HST; these maps will clarify the nature of the broad-line region, its role in the apparently complicated accretion/outflow process, and determine definitively the veracity and accuracy of the AGN reverberation-based black hole masses that are now a key component of any study of black hole growth, evolution, and the role of feedback in the evolution of galaxies. We leverage this program with a well-designed public-domain extragalactic deep-field parallel program

Smithsonian Institute Smithsonian Institute

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