Monte Carlo radiative transfer

Noebauer, U. M.; Sim, Stuart

doi:10.1007/s41115-019-0004-9

Cited by 76 publications

(52 citation statements)

References 202 publications

(455 reference statements)

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“…Here we provide a brief overview of the techniques with the relevant references and discuss some of the more unique aspects of the work. The general principles behind MCRT are described in a series of papers by Abbott & Lucy (1985), Lucy & Abbott (1993) and Lucy (1999bLucy ( , 2002Lucy ( , 2003, and are reviewed by Noebauer & Sim (2019).…”

Section: Numerical Modelmentioning

confidence: 99%

Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

Matthews

Knigge

Higginbottom

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The origin, geometry and kinematics of the broad line region (BLR) gas in quasars and active galactic nuclei (AGN) are uncertain. We demonstrate that clumpy biconical disc winds illuminated by an AGN continuum can produce BLR-like spectra. We first use a simple toy model to illustrate that disc winds make quite good BLR candidates, because they are selfshielded flows and can cover a large portion of the ionizing flux-density (φ H -n H ) plane. We then conduct Monte Carlo radiative transfer and photoionization calculations, which fully account for self-shielding and multiple scattering in a non-spherical geometry. The emergent model spectra show broad emission lines with equivalent widths and line ratios comparable to those observed in AGN, provided that the wind has a volume filling factor of f V 0.1. Similar emission line spectra are produced for a variety of wind geometries (polar or equatorial) and for launch radii that differ by an order of magnitude. The line emission arises almost exclusively from plasma travelling below the escape velocity, implying that 'failed winds' are important BLR candidates. The behaviour of a line-emitting wind (and possibly any 'smooth flow' BLR model) is similar to that of the locally optimally-emitting cloud (LOC) model originally proposed by Baldwin et al (1995), except that the gradients in ionization state and temperature are large-scale and continuous, rather than within or between distinct clouds. Our models also produce UV absorption lines and X-ray absorption features, and the stratified ionization structure can partially explain the different classes of broad absorption line quasars.

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Section: Numerical Modelmentioning

confidence: 99%

Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

Matthews

Knigge

Higginbottom

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The method must take into account the adverse consequences of Monte Carlo noise in the simulation results. This noise can be reduced, e.g., by corrective measurements [31]. Using a similar concept, in this paper, we show a new model of light pollution based on Monte Carlo simulation of multiple photon scattering.…”

Section: Modelling Of Alanmentioning

confidence: 94%

Measurements and Modelling of Aritificial Sky Brightness: Combining Remote Sensing from Satellites and Ground-Based Observations

2021

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In recent decades, considerable research has been carried out both in measuring and modelling the brightness of the sky. Modelling is highly complex, as the properties of light emission (spatial and spectral distribution) are generally unknown, and the physical state of the atmosphere cannot be determined independently. The existing radiation transfer models lack the focus on light pollution and model only a narrow spectral range or do not consider realistic atmospheric circumstances. In this paper, we introduce a new Monte Carlo simulation for modelling light pollution, including the optical density of the atmosphere and multiple photon scattering, then we attempt to combine the available information of satellite and ground-based measurements to check the extent to which it is possible to verify our model. It is demonstrated that we need all the separate pieces of information to interpret the observations adequately.

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“…In general, Monte-Carlo radiative transfer (Hood et al 2008;Whitney 2011;Steinacker et al 2013;Stolker et al 2017;Lee et al 2017Lee et al , 2019Noebauer & Sim 2019) relies on photon packets, which perform a random walk throughout a 3D medium of interest. Every time the packet undergoes an interaction, its attributes (e.g.…”

Section: Monte-carlo Radiative Transfer With Hires-mcrtmentioning

confidence: 99%

Modelling high-resolution transmission spectra of the ultra-hot jupiter wasp-76b with 3D Monte-Carlo radiative transfer

Wardenier¹,

Parmentier²,

Lee³

2024

Preprint

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<div class="c-message_kit__gutter"> <div class="c-message_kit__gutter__right" data-qa="message_content"> <div class="c-message_kit__blocks c-message_kit__blocks--rich_text"> <div class="c-message__message_blocks c-message__message_blocks--rich_text"> <div class="p-block_kit_renderer" data-qa="block-kit-renderer"> <div class="p-block_kit_renderer__block_wrapper p-block_kit_renderer__block_wrapper--first"> <div class="p-rich_text_block" dir="auto"> <div class="p-rich_text_section">Ultra-hot Jupiters are tidally-locked gas giants with two chemical regimes: on the scorching dayside molecular species are dissociated and metals are ionised, while the permanent nightside is cool enough for cloud formation to occur. This means that the abundances of particular chemical species, such as iron, will exhibit a sharp gradient across the terminator region, which can be probed by transmission spectroscopy. We present a state-of-the-art 3D Monte-Carlo radiative transfer framework, adapted from Lee et al. (2017, 2019), that allows for the 3D modelling of high-resolution spectra of ultra-hot Jupiters. We use this tool to post-process the output of the SPARC/MITgcm global circulation model, with the aim to better understand how inhomogeneous chemistry, clouds and Doppler shifts due to atmospheric dynamics impact the appearance of a transit spectrum and its cross-correlation signal.</div> <div class="p-rich_text_section">&#160;</div> <div class="p-rich_text_section">In this talk, we apply our model to the transit of WASP-76b, for which Ehrenreich et al. (2020) recently presented a time-varying iron signature at high spectral resolution. The observation suggests that iron condenses on the nightside of the planet. We show that different parts of the limb lead to very different cross-correlation signals and we show that the relative contributions from the east and west limb change during the transit, resulting in a time-varying cross-correlation signal. Finally, we explore different atmospheric scenarios for WASP-76b and we demonstrate that the occurrence of iron condensation, combined with the specific time-varying geometry during the transit, can quantitatively reproduce the Ehrenreich et al. (2020) result.</div> </div> </div> </div> </div> </div> </div> </div> <div class="c-message_actions__container c-message__actions" role="group" aria-label="Message shortcuts" data-qa="message-actions">&#160;</div>

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Monte Carlo radiative transfer

Cited by 76 publications

References 202 publications

Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

Measurements and Modelling of Aritificial Sky Brightness: Combining Remote Sensing from Satellites and Ground-Based Observations

Modelling high-resolution transmission spectra of the ultra-hot jupiter wasp-76b with 3D Monte-Carlo radiative transfer

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