CARAMEL-gas: A Step toward Fast Empirical Models of the Broad-line-emitting Gas

Williams, Peter; Treu, Tommaso

doi:10.3847/1538-4357/ac8164

Cited by 5 publications

(3 citation statements)

References 29 publications

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“…In contrast, CARAMEL utilizes a more prescriptive parameterization of BLR properties. For example, CARAMEL treats the clouds as particles that are representative of a gas density field and approximates the responding emission by setting the emissivity as a radial power-law function (Williams & Treu 2022). CARAMEL includes a parameter estimation procedure to recover the best-matching model for a time series data set, which is not yet implemented in BELMAC.…”

Section: Modeling Reverberation Responsesmentioning

confidence: 99%

Modeling the Reverberation Response of the Broad-line Region in Active Galactic Nuclei

Rosborough,

Robinson,

Almeyda

et al. 2024

ApJ

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The variable continuum emission of an active galactic nucleus (AGN) produces corresponding responses in the broad emission lines, which are modulated by light travel delays, and contain information on the physical properties, structure, and kinematics of the emitting gas region. The reverberation mapping technique, a time series analysis of the driving light curve and response, can recover some of this information, including the size and velocity field of the broad-line region (BLR). Here we introduce a new forward-modeling tool, the Broad Emission Line MApping Code, which simulates the velocity-resolved reverberation response of the BLR to any given input light curve by setting up a 3D ensemble of gas clouds for various specified geometries, velocity fields, and cloud properties. In this work, we present numerical approximations to the transfer function by simulating the velocity-resolved responses to a single continuum pulse for sets of models representing a spherical BLR with a radiatively driven outflow and a disklike BLR with Keplerian rotation. We explore how the structure, velocity field, and other BLR properties affect the transfer function. We calculate the response-weighted time delay (reverberation “lag”), which is considered to be a proxy for the luminosity-weighted radius of the BLR. We investigate the effects of anisotropic cloud emission and matter-bounded (completely ionized) clouds and find the response-weighted delay is only equivalent to the luminosity-weighted radius when clouds emit isotropically and are radiation-bounded (partially ionized). Otherwise, the luminosity-weighted radius can be overestimated by up to a factor of 2.

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Section: Modeling Reverberation Responsesmentioning

confidence: 99%

Modeling the Reverberation Response of the Broad-line Region in Active Galactic Nuclei

Rosborough,

Robinson,

Almeyda

et al. 2024

ApJ

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“…One major class of models assumes that the BLR consists of many discrete clouds (e.g., Rees et al 1989;Baldwin et al 1995;Czerny & Hryniewicz 2011;Baskin & Laor 2018;Rosborough et al 2023). The cloud model offers advantages in flexibly parameterizing the geometry, kinematics, and photoionization physics, enabling interpretation of observations, particularly recent high-quality RM and interferometric data (Korista & Goad 2004;Pancoast et al 2011Pancoast et al , 2014aLi et al 2013Li et al , 2018Williams & Treu 2022;GRAVITY Collaboration 2018, 2020. However, the physics of the cloud model may be oversimplified.…”

Section: Broad-line Region Dynamical Model and The Inferencementioning

confidence: 99%

“…Their arguments make it clear that photoionization physics are needed in the application of RM modeling. Indeed, there has been recent progress in addressing this problem (Williams & Treu 2022;Rosborough et al 2023). Nevertheless, recent studies of NGC 3783 have shown that the modeling using GRAVITY and RM data is remarkably consistent (Bentz et al 2021b;GRAVITY Collaboration 2021a,b), which supports the application of this simple model, at least for the particular case of NGC 3783.…”

Section: Parametermentioning

confidence: 99%

Broad-line region geometry from multiple emission lines in a single-epoch spectrum

Kuhn,

Shangguan,

Davies

et al. 2024

A&A

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The broad-line region (BLR) of active galactic nuclei (AGNs) traces gas close to the central supermassive black hole (BH). Recent reverberation mapping (RM) and interferometric spectro-astrometry data have enabled detailed investigations of the BLR structure and dynamics as well as estimates of the BH mass. These exciting developments have motivated comparative investigations of BLR structures using different broad emission lines. In this work, we have developed a method to simultaneously model multiple broad lines of the BLR from a single-epoch spectrum. We applied this method to the five strongest broad emission lines ( and lambda 5876) in the UV-to-near-IR spectrum of NGC 3783, a nearby Type I AGN that has been well studied by RM and interferometric observations. Fixing the BH mass to the published value, we fit these line profiles simultaneously to constrain the BLR structure. We find that the differences between line profiles can be explained almost entirely as being due to different radial distributions of the line emission. We find that using multiple lines in this way also enables one to measure some important physical parameters, such as the inclination angle and virial factor of the BLR. The ratios of the derived BLR time lags are consistent with the expectation of theoretical model calculations and RM measurements.

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Strong lensed QSOs with variability detectable by LSST: How many are there?

Taak

Treu

2023

Monthly Notices of the Royal Astronomical Society

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Strong lensed quasi-stellar objects (QSOs) are valuable probes of the universe in numerous aspects. Two of these applications, reverberation mapping and measuring time delays for determining cosmological parameters, require the source QSOs to be variable with sufficient amplitude. In this paper, we forecast the number of strong lensed QSOs with sufficient variability to be detected by the Vera C. Rubin Telescope Legacy Survey of Space and Time (LSST). The damped random walk model is employed to model the variability amplitude of lensed QSOs taken from a mock catalog by Oguri & Marshall (2010). We expect 30–40 % of the mock lensed QSO sample, which corresponds to ∼1000, to exhibit variability detectable with LSST. A smaller subsample of 250 lensed QSOs will show larger variability of >0.15 mag for bright lensed images with i < 21 mag, allowing for monitoring with smaller telescopes. We discuss systematic uncertainties in the prediction by considering alternative prescriptions for variability and mock lens catalog with respect to our fiducial model. Our study shows that a large-scale survey of lensed QSOs can be conducted for reverberation mapping and time delay measurements following up on LSST.

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CARAMEL-gas: A Step toward Fast Empirical Models of the Broad-line-emitting Gas

Cited by 5 publications

References 29 publications

Modeling the Reverberation Response of the Broad-line Region in Active Galactic Nuclei

Modeling the Reverberation Response of the Broad-line Region in Active Galactic Nuclei

Broad-line region geometry from multiple emission lines in a single-epoch spectrum

Strong lensed QSOs with variability detectable by LSST: How many are there?

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