Abstract

In the next few years, large-scale surveys with a time domain element, such as the ten-year Legacy Survey of Space and Time (LSST), will produce an immense data set to study variable and transient astronomical sources such as active galactic nuclei (AGN). AGN are located at the center of most galaxies and have five major components: a supermassive black hole (SMBH), an accretion disk, the broad-line region (BLR), a dusty circumnuclear torus, and the narrow-line region (NLR). The torus is believed to have a two-component structure: a geometrically thin circumnuclear disk and a hollow dusty cone along the polar axis. The torus absorbs the ultraviolet (UV)/optical light from the accretion disk and re-emits it in the infrared (IR). In order to study the properties of the torus, techniques such as dust reverberation mapping are needed since AGN, at large distances, cannot be resolved by direct imaging. Reverberation mapping uses the differences in the UV/optical and IR light travel times (lags) to determine the properties of the torus region. This thesis focuses on the use of the TOrus Reverberation MApping Code, TORMAC, to create simulations of the response of the IR dust emission to an input AGN light curve. Both an observed optical light curve, that of MCG-06-30-15, a narrow-line Seyfert 1 (NLS1) AGN, and a simulated AGN light curve were used as inputs. These simulations are used to determine how observing strategies (time baselines and observing cadences) and practical limitations (such as seasonal gaps, irregular sampling) affect how much information can be recovered about the properties of the torus region. In addition, I examined how various torus parameters affect the lags recovered from reverberation mapping. The work performed in this thesis will help inform the design of future optical-IR monitoring campaigns, as well as, to better understand the uncertainties in previous studies - especially those with sparse sampling and limited time duration.

Library of Congress Subject Headings

Active galactic nuclei; Dust--Analysis; Infrared astronomy; Ultraviolet astronomy

Publication Date

8-2023

Document Type

Thesis

Student Type

Graduate

Degree Name

Astrophysical Sciences and Technology (MS)

Department, Program, or Center

School of Physics and Astronomy (COS)

Advisor

Andrew Robinson

Advisor/Committee Member

Joel Kastner

Advisor/Committee Member

Michael Zemcov

Campus

RIT – Main Campus

Plan Codes

ASTP-MS

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