Theory and Simulations of Refractive Substructure in Resolved Scatter-Broadened Images

Abstract

At radio wavelengths, scattering in the interstellar medium distorts the appearance of astronomical sources. Averaged over a scattering ensemble, the result is a blurred image of the source. However, Narayan & Goodman (1989) and Goodman & Narayan (1989) showed that for an incomplete average, scattering introduces refractive substructure in the image of a point source that is both persistent and wideband. We show that this substructure is quenched but not smoothed by an extended source. As a result, when the scatter-broadening is comparable to or exceeds the unscattered source size, the scattering can introduce spurious compact features into images. In addition, we derive efficient strategies to numerically compute realistic scattered images, and we present characteristic examples from simulations. Our results show that refractive substructure is an important consideration for ongoing missions at the highest angular resolutions, and we discuss specific implications for RadioAstron and the Event Horizon Telescope.

Equation numbering in appendix now matches published version. Two minor typos corrected

References in corpus (6)

• Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre
• RadioAstron -- a Telescope with a Size of 300 000 km: Main Parameters and First Observational Results
• Imaging the Supermassive Black Hole Shadow and Jet Base of M87 with the Event Horizon Telescope
• Imaging an Event Horizon: Mitigation of Scattering Toward Sagittarius A*
• Discovery of Substructure in the Scatter-Broadened Image of Sgr A*
• Relative Astrometry of Compact Flaring Structures in Sgr A* with Polarimetric VLBI

Cited by in corpus (68)

• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• High Resolution Linear Polarimetric Imaging for the Event Horizon Telescope
• Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*
• Testing General Relativity with the Shadow Size of Sgr A*
• How to tell an accreting boson star from a black hole
• Testing General Relativity with the Event Horizon Telescope
• Sgr A* and General Relativity
• The Scattering and Intrinsic Structure of Sagittarius A* at Radio Wavelengths
• Modeling Seven Years of Event Horizon Telescope Observations with Radiatively Inefficient Accretion Flow Models
• Testing the No-Hair Theorem with Observations of Black Holes in the Electromagnetic Spectrum
• RadioAstron Observations of the Quasar 3C273: a Challenge to the Brightness Temperature Limit
• Persistent Asymmetric Structure of Sagittarius A* on Event Horizon Scales
• Detection of intrinsic source structure at ~3 Schwarzschild radii with Millimeter-VLBI observations of SAGITTARIUS A*
• Radio observations of active galactic nuclei with mm-VLBI
• Probing the magnetic field structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations
• Simulations of imaging the event horizon of Sagittarius A* from space
• Event Horizon Telescope Observations as Probes for Quantum Structure of Astrophysical Black Holes
• Testing General Relativity with Accretion-Flow Imaging of Sgr A*
• Fast Variability and mm/IR flares in GRMHD Models of Sgr A* from Strong-Field Gravitational Lensing
• Toward determining the number of observable supermassive black hole shadows
• Dynamical Imaging with Interferometry
• Interstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB150418
• Milky Way scattering properties and intrinsic sizes of active galactic nuclei cores probed by very long baseline interferometry surveys of compact extragalactic radio sources
• The ALMA Phasing System: A Beamforming Capability for Ultra-High-Resolution Science at (Sub)Millimeter Wavelengths
• Magnetic reconnection and plasmoid formation in three-dimensional accretion flows around black holes
• Superresolution Interferometric Imaging with Sparse Modeling Using Total Squared Variation --- Application to Imaging the Black Hole Shadow
• The Effects of Accretion Flow Dynamics on the Black Hole Shadow of Sagittarius A${}^{\ast }$
• Imaging an Event Horizon: Mitigation of Source Variability of Sagittarius A*
• PSR B0329+54: Substructure in the scatter-broadened image discovered with RadioAstron on baselines up to 330,000 km
• Stochastic Optics: A Scattering Mitigation Framework for Radio Interferometric Imaging
• Probing the innermost accretion flow geometry of Sgr A* with Event Horizon Telescope
• Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron
• Detection statistics of the RadioAstron AGN survey
• The Optics of Refractive Substructure
• Deep Horizon; a machine learning network that recovers accreting black hole parameters
• The Intrinsic Shape of Sagittarius A* at 3.5-mm Wavelength
• The extreme blazar AO 0235+164 as seen by extensive ground and space radio observations
• Quantifying Intrinsic Variability of Sagittarius A* using Closure Phase Measurements of the Event Horizon Telescope
• Asymmetric structure in Sgr A* at 3mm from closure phase measurements with VLBA, GBT and LMT
• Testing General Relativity with the Black Hole Shadow Size and Asymmetry of Sagittarius A*: Limitations from Interstellar Scattering
• Bayesian techniques for comparing time-dependent GRMHD simulations to variable Event Horizon Telescope observations
• Wisps in the Galactic center: NIR triggered observations of the radio source Sgr A* at 43 GHz
• The intrinsic structure of Sagittarius A* at 1.3 cm and 7 mm
• Noodle Model for Scintillation Arcs
• Variability in GRMHD simulations of Sgr A${}^{\ast }$: Implications for EHT closure phase observations
• Persistent Non-Gaussian Structure in the Image of Sagittarius A* at 86 GHz
• The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering
• MeqSilhouette : A mm-VLBI observation and signal corruption simulator
• Polarization images of accretion flow around supermassive black holes: imprints of toroidal field structure
• Analysis of Orbital Configurations for Millimetron Space Observatory
• A Characterization of the ALMA Phasing System at 345 GHz
• MeqSilhouette v2: Spectrally-resolved polarimetric synthetic data generation for the Event Horizon Telescope
• An Event Horizon Imager (EHI) Mission Concept Utilizing Medium Earth Orbit Sub-mm Interferometry
• First Space-VLBI Observations of Sagittarius A*
• A multi-frequency study of sub-parsec jets with the Event Horizon Telescope
• Micro-arcsecond structure of Sagittarius A* revealed by high-sensitivity 86 GHz VLBI observations
• Substructure of visibility functions from scattered radio emission of pulsars through space VLBI
• Catalog of supermassive black holes for interferometric observations
• Expanding Sgr A* dynamical imaging capabilities with an African extension to the Event Horizon Telescope
• SYMBA: An end-to-end VLBI synthetic data generation pipeline
• Probing Accretion Turbulence in the Galactic Center with EHT Polarimetry
• PKS 1954-388: RadioAstron Detection on 80,000 km Baselines and Multiwavelength Observations
• On the prospects of imaging Sagittarius A* from space
• VLBA Observations of Strong Anisotripic Radio Scattering towards the Orion Nebula
• Multiobjective optimization for scattering mitigation and scattering screen reconstruction in VLBI observations of the Galactic Center
• Direct VLBI Detection of Interstellar Turbulence Imprint on a Quasar: TXS 2005+403
• Orbit design for mitigating interstellar scattering effects in Earth-space VLBI observations of Sgr A*