skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Search for: All records

Creators/Authors contains: "Humphrey, Daniel"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract The broad emission lines (BELs) emitted by active galactic nuclei respond to variations in the ionizing continuum emission from the accretion disk surrounding the central supermassive black hole (SMBH). This reverberation response provides insights into the structure and dynamics of the broad-line region (BLR). In 2024, we introduced a new forward-modeling tool, the Broad Emission Line Mapping Code (BELMAC), which simulates the velocity-resolved reverberation response of the BLR to an input light curve. In this work, we describe a new version of BELMAC, which uses photoionization models to calculate the cloud luminosities for selected BELs. We investigated the reverberation responses of Hα, Hβ, MgIIλ2800, and CIVλ1550 for models representing a disk-like BLR with Keplerian rotation, radiatively driven outflows, and inflows. The line responses generally provide a good indication of the respective luminosity-weighted radii. However, there are situations where the BLR exhibits a negative response to the driving continuum, causing overestimates of the luminosity-weighted radius. The virial mass derived from the models can differ dramatically from the actual SMBH mass, depending mainly on the disk inclination and velocity field. In single-zone models, the BELs exhibit similar responses and profile shapes; two-zone models, such as a Keplerian disk and a biconical outflow, can reproduce observed differences between high- and low-ionization lines. Radial flows produce asymmetric line profile shapes due to both anisotropic cloud emission and electron scattering in an intercloud medium. These competing attenuation effects complicate the interpretation of profile asymmetries. 
    more » « less
    Free, publicly-accessible full text available September 23, 2026