First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass

Abstract

In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. We find that the Sgr A* data exhibit variability that exceeds what can be explained by the uncertainties in the data or by the effects of interstellar scattering. The magnitude of this variability can be a substantial fraction of the correlated flux density, reaching $\sim$100\% on some baselines. Through an exploration of simple geometric source models, we demonstrate that ring-like morphologies provide better fits to the Sgr A* data than do other morphologies with comparable complexity. We develop two strategies for fitting static geometric ring models to the time-variable Sgr A* data; one strategy fits models to short segments of data over which the source is static and averages these independent fits, while the other fits models to the full dataset using a parametric model for the structural variability power spectrum around the average source structure. Both geometric modeling and image-domain feature extraction techniques determine the ring diameter to be $51.8\pm 2.3$ $\mu$as (68\% credible intervals), with the ring thickness constrained to have an FWHM between $\sim$30\% and 50\% of the ring diameter. To bring the diameter measurements to a common physical scale, we calibrate them using synthetic data generated from GRMHD simulations. This calibration constrains the angular size of the gravitational radius to be $4.8_{-0.7}^{+1.4}$ \mathrm{μas}, which we combine with an independent distance measurement from maser parallaxes to determine the mass of Sgr A* to be $4.0_{-0.6}^{+1.1}\times 10^6$ M${}_{\odot }$.

arXiv comment65 pages, 35 figures, published in The Astrophysical Journal Letters on May 12, 2022. See the published paper for the full authors list

References in corpus (56)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• Rank-normalization, folding, and localization: An improved $\hat{R}$ for assessing convergence of MCMC
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Viewing the Shadow of the Black Hole at the Galactic Center
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• DiFX2: A more flexible, efficient, robust and powerful software correlator
• Relativistic redshift of the star S0-2 orbiting the Galactic center supermassive black hole
• First M87 Event Horizon Telescope Results. VII. Polarization of the Ring
• 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
• Universal Interferometric Signatures of a Black Hole's Photon Ring
• General relativistic magnetohydrodynamical simulations of the jet in M87
• Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes
• Variable Infrared Emission from the Supermassive Black Hole at the Center of the Milky Way
• High Resolution Linear Polarimetric Imaging for the Event Horizon Telescope
• Interferometric Imaging Directly with Closure Phases and Closure Amplitudes
• The Shadow of a Spherically Accreting Black Hole
• Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*
• 1.3 mm Wavelength VLBI of Sagittarius A*: Detection of Time-Variable Emission on Event Horizon Scales
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• Evidence for Low Black Hole Spin and Physically Motivated Accretion Models from Millimeter VLBI Observations of Sagittarius A*
• Imaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope using Sparse Modeling
• Frequency-Dependent Shift in the Image Centroid of the Black Hole at the Galactic Center as a Test of General Relativity
• On The Nature of the Compact Dark Mass at the Galactic Center
• A rapidly-changing jet orientation in the stellar-mass black hole V404 Cygni
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• Polarimetric properties of Event Horizon Telescope targets from ALMA
• Super-resolution Full Polarimetric Imaging for Radio Interferometry with Sparse Modeling
• 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
• The Event Horizon of M87
• Variable structures in M87* from space, time and frequency resolved interferometry
• Dynamical Imaging with Interferometry
• Non-Reversible Parallel Tempering: a Scalable Highly Parallel MCMC Scheme
• The ALMA Phasing System: A Beamforming Capability for Ultra-High-Resolution Science at (Sub)Millimeter Wavelengths
• Closure statistics in interferometric data
• Hybrid Very Long Baseline Interferometry Imaging and Modeling with Themis
• Calibration of ALMA as a phased array: ALMA observations during the 2017 VLBI campaign
• EHT-HOPS pipeline for millimeter VLBI data reduction
• Selective Dynamical Imaging of Interferometric Data
• Variational Image Feature Extraction for the Event Horizon Telescope
• Dual differential polarimetry. A technique to recover polarimetric information from dual polarization observations
• Relativistic accretion disk reflection in AGN X-ray spectra at z=0.5--4: a study of four \textit{Chandra} deep fields

Cited by in corpus (168)

• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A${}^{\ast }$
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• 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
• Tests of Loop Quantum Gravity from the Event Horizon Telescope Results of Sgr A${}^{\ast }$
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• Testing Rotating Regular Metrics with EHT Results of Sgr A*
• H-AMR: A New GPU-accelerated GRMHD Code for Exascale Computing With 3D Adaptive Mesh Refinement and Local Adaptive Time-stepping
• Orbital motion near Sagittarius A* -- Constraints from polarimetric ALMA observations
• Superradiant evolution of the shadow and photon ring of Sgr A${}^{\star }$
• The Black Hole Explorer: Motivation and Vision
• Analytical study of gravitational lensing in Kerr-Newman black-bounce spacetime
• An Upper Limit on the Charge of the Black Hole Sgr A* from EHT Observations
• Shadows of black holes with dark matter halo
• Rings and images of Horndeski hairy black hole illuminated by various thin accretions
• Investigating Loop Quantum Gravity with EHT Observational Effects of Rotating Black holes
• Shape of higher-order images of equatorial emission rings around a Schwarzschild black hole: Analytical description with polar curves
• The Image of the M87 Black Hole Reconstructed with PRIMO
• A review on analytical studies in Gravitational Lensing
• Bumblebee black holes in light of Event Horizon Telescope observations
• Images from disk and spherical accretions of hairy Schwarzschild black holes
• Hunting extra dimensions in the shadow of Sgr A*
• Black Holes with Multiple Photon Spheres
• Gravitational lensing of a Schwarzschild-like black hole in Kalb-Ramond gravity
• Asymptotically locally flat and AdS higher-dimensional black holes of Einstein-Horndeski-Maxwell gravity in the light of EHT observations: shadow behavior and deflection angle
• Photon Ring Astrometry for Superradiant Clouds
• Multi-frequency Black Hole Imaging for the Next-Generation Event Horizon Telescope
• Observational Signatures of Frame Dragging in Strong Gravity
• Images of hairy Reissner-Nordström black hole illuminated by static accretions
• Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode
• Selective Dynamical Imaging of Interferometric Data
• Testing EGB gravity coupled to bumblebee field and black hole parameter estimation with EHT observations
• The Galactic Center as a laboratory for theories of gravity and dark matter
• Effective Potential and Topological Photon Spheres: A Novel Approach to Black Hole Parameter Classification
• Influence of accretion disk on the optical appearance of the Kazakov-Solodukhin black hole
• Using Machine Learning to Link Black Hole Accretion Flows with Spatially Resolved Polarimetric Observables
• Strong deflection limit analysis of black hole lensing in inhomogeneous plasma
• The Event Horizon Telescope Image of the Quasar NRAO 530
• Shadows of rotating Einstein-Maxwell-dilaton black holes surrounded by a plasma
• Probing spacetime and accretion model for the Galactic Center: Comparison of Kerr and dilaton black hole shadows
• Shadow of regular black hole in scalar-tensor-vector gravity theory
• Constraining spherically symmetric metrics by the gap between photon rings
• Optical features of rotating quintessential charged black holes in de-Sitter spacetime
• Circular orbits and thin accretion disk around a quantum corrected black hole
• The effect of scalar hair on the charged black hole with the images from accretions disk
• Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration
• AGN Feeding and Feedback in M84: From Kiloparsec Scales to the Bondi Radius
• Bayesian Accretion Modeling: Axisymmetric Equatorial Emission in the Kerr Spacetime
• Signatures of regular black holes from the shadow of Sgr A* and M87*
• Schrödinger and Klein-Gordon theories of black holes from the quantization of the Oppenheimer and Snyder gravitational collapse
• Rotation in Event Horizon Telescope Movies
• Enabling Transformational ngEHT Science via the Inclusion of 86 GHz Capabilities
• Kerr-Newman Black Holes in Weyl-Cartan Theory: Shadows and EHT constraints
• M87: a cosmic laboratory for deciphering black hole accretion and jet formation
• Light trajectory and shadow shape in the rotating naked singularity
• Quantum gravity lights up spinning black holes
• Axial gravitational quasinormal modes of a self-dual black hole in loop quantum gravity
• General relativistic effects and the near-infrared and X-ray variability of Sgr A* I
• Testing black hole equatorial reflection symmetry using Sgr A* shadow images
• A Characterization of the ALMA Phasing System at 345 GHz
• Constraints on the Galactic Centre environment from \textit{Gaia} hypervelocity stars III: Insights on a possible companion to Sgr A*
• Shadow Geometry of Kerr Naked Singularities
• Strong deflection of massive particles in spherically symmetric spacetimes
• Observational Appearance of a Freely-falling Star in an Asymmetric Thin-shell Wormhole
• Energy extraction from rotating regular black hole via Comisso-Asenjo mechanism
• Gravitoelectromagnetic coupled perturbations and quasinormal modes of a charged black hole with scalar hair
• How Spatially Resolved Polarimetry Informs Black Hole Accretion Flow Models
• Shadow thermodynamics of the Hayward-AdS black hole
• Probing Plasma Physics with Spectral Index Maps of Accreting Black Holes on Event Horizon Scales
• Scalar Hairy Black Holes with Inverted Mexican Hat Potential
• Non-commutativity in Hayward spacetime
• The future ability to test theories of gravity with black-hole shadows
• Shadow behavior of an EMSG charged black hole
• Shadows and quasinormal modes of a charged non-commutative black hole by different methods
• Optical appearance of numerical black hole solutions in higher derivative gravity
• Determination of the spin parameter and the inclination angle by the relativistic images in black hole image
• Constraining modified gravity theories with scalar fields using black-hole images
• A multi-frequency study of sub-parsec jets with the Event Horizon Telescope
• Revisiting the black hole mass of M87* using VLT/MUSE Adaptive Optics Integral Field Unit data I: Ionized gas kinematics
• Distinguishing black holes with and without spontaneous scalarization in Einstein-scalar-Gauss-Bonnet theories via optical features
• Bayesian Black Hole Photogrammetry
• The Next Generation Event Horizon Telescope Collaboration: History, Philosophy, and Culture
• Constraints on the black-hole charges of M87* and Sagittarius A* by changing rates of photon spheres can be relaxed
• Novel regular black holes: geometry, source and shadow
• A first search of transients in the Galactic Center from 230 GHz ALMA observations
• Spins of supermassive black holes M87* and SgrA* revealed from the size of dark spots in Event Horizon Telescope Images
• Dynamics and Emission Properties of Flux Ropes from Two-Temperature GRMHD Simulations with Multiple Magnetic Loops
• The ring-shaped shadow of rotating naked singularity with a complete photon sphere
• Shadows and parameter estimation of rotating quantum corrected black holes and constraints from EHT observation of M87* and Sgr A*
• Shadows aspect of rotating black holes in the Einstein-AdS SU(N)-nonlinear sigma model
• Exploring the shear viscosity in four-dimensional planar black holes beyond General Relativity
• Measuring Black Hole Light Echoes with Very Long Baseline Interferometry
• Scalar Perturbation Around Rotating Regular Black Hole: Superradiance Instability and Quasinormal Modes
• Interferometric signature of higher-order images in a parametrized framework
• Free-falling test particles in a charged Kalb-Ramond black hole: gravitational Doppler effect and tidal forces
• Discovery of a Planar Black Hole Mass Scaling Relation for Spiral Galaxies
• Extreme lensing induces spectro-temporal correlations in black-hole signals
• Gravitational Lensing and Image Distortion by Buchdahl Inspired Metric in ${\mathcal{R}}^2$ Gravity
• SgrA${}^{\ast }$ spin and mass estimates through the detection of an extremely large mass-ratio inspiral
• Effects of a global monopole on thermodynamic phase transition of the charged AdS black hole
• Forward Ray Tracing and Hot Spots in Kerr Spacetime
• Polarized signatures of adiabatically expanding hotspots in Sgr A*'s accretion flow
• Physics of Pair Producing Gaps in Black Hole Magnetospheres: Two Dimensional General Relativistic Particle-in-cell Simulations
• Evolution of eccentric stellar disks around supermassive black holes: the complex disk disruption dynamics and the milliparsec stars
• The $\text{q}$-metric naked singularity: A viable explanation for the nature of the central object in the Milky Way
• An independent hybrid imaging of Sgr A* from the data in EHT 2017 observations
• Gravitational lens on a static optical constant-curvature background: Its application to Weyl gravity model
• First polarization study of the M87 jet and active galactic nuclei at submillimeter wavelengths with ALMA
• Photon ring polarimetry with next-generation black hole imaging I. M87*
• General Relativistic effects and the NIR variability of Sgr A* II: A systematic approach to temporal asymmetry
• Optical appearance of the Schwarzschild black hole in the string cloud context
• Imaging fermionic dark matter cores at the center of galaxies
• Thin Accretion Disk Around Rotating Hairy Black Hole: Radiative Property and Optical Appearance
• Imaging the event horizon of M87* from space on different timescales
• Modified Kerr black holes surrounded by dark matter spike
• Remarks on the light ring images and the optical appearance of hairy black holes in Einstein-Maxwell-dilaton gravity
• Image of Quantum Improved Regular Kerr Black Hole and Parameter Constraints from EHT Observations
• Probing Accretion Turbulence in the Galactic Center with EHT Polarimetry
• Deep learning inference with the Event Horizon Telescope I. Calibration improvements and a comprehensive synthetic data library
• Deep learning inference with the Event Horizon Telescope II. The Zingularity framework for Bayesian artificial neural networks
• Determining parameters of a spherical black hole with a thin accretion disk by observing its shadow
• Fate of initially bound timelike geodesics in spherical boson stars
• Prospects for probing small-scale dark matter models with pulsars around Sagittarius A*
• Correspondence between two gravitational lens equations in a static and spherically symmetric spacetime
• Circular orbits and accretion disk around a deformed-Schwarzschild black hole in loop quantum gravity
• Fractal signatures of non-Kerr spacetimes in the shadow of light-ring bifurcations
• Shadow and thin accretion disk around Ayón-Beato-García black hole coupled with cloud of strings
• Impact of the nonthermal electron radiation effects on the horizon scale image structure of Sagittarius A*
• Shadows of a generic class of spherically symmetric, static spacetimes
• The surface geometry and shadow of a Schwarzschild black hole with halo
• Overlapping of photon rings in black hole imaging
• Synchrotron emitting Komissarov torus with magnetic polarization around Kerr black holes
• Not all spacetime coordinates for general-relativistic ray tracing are created equal
• Quantum Gravitational Hair in Gravastars and Observational Tests
• Synthetic gravitational lens image of the Sagittarius A${}^{\ast }$ black hole with a thin disk model
• Shadow of quadrupole-deformed compact objects in a local dark matter shell
• Morphology of Relativistically Broadened Line Emission from Axisymmetric Equatorial Accretion Disks
• Determining parameters of Kerr black holes at finite distance by shadow observation
• Radiative properties of thin accretion disks around rotating short-hairy black holes
• Regular black hole solutions in $(2+1)$-dimensional $f(R,T)$ gravity coupled to nonlinear electrodynamics
• GALLIFRAY -- A geometric modeling and parameter estimation framework for black hole images using bayesian techniques
• Non-thermal Synchrotron Emission and Polarization Signatures during Black Hole Flux Eruptions
• Imprints of non-commutativity on charged black holes
• Determining parameters of Kerr-Newman black holes by shadow observation from finite distance and spatial infinity
• SgrA* spin and mass estimates through the detection of multiple extremely large mass-ratio inspirals
• Limiting the Yukawa Gravity through the Black Hole Shadows of Sgr A* and M87*
• Exploring black hole shadows in axisymmetric spacetimes with coordinate-independent methods and neural networks
• Charge constraint on M87* with twisted light
• Deciphering signatures of Kerr-Sen black holes in presence of plasma from the Event Horizon Telescope data
• Characterization of black hole accretion through image moment invariants
• Assessing the Role of Intrinsic Variability in Black Hole Parameter Inference using Multi-Epoch EHT Data
• Auto- and cross-correlations for multiple images of corotating hotspots in accretion disks
• Shadow of topologically charged rotating braneworld black hole
• Gravitational signatures beyond Newton: exploring hierarchical three-body dynamics
• Shadows cast by a class of rotating black bounces with an anisotropic fluid
• Exploring black holes with multiple photon spheres by interferometric signatures
• Perturbations of Einstein--Maxwell--phantom spacetime: Instabilities of charged Ellis--Bronnikov wormholes and quasinormal modes of black holes
• Optical appearance of regularized compact objects without an exterior photon sphere
• Macroscopic backreaction of the trace anomaly on classical vacuum backgrounds
• Shaving off soft hairs and the black hole image memory effect
• Investigating the interplay of the braneworld gravity and the plasma environment on the black hole shadow
• The Cohesive Object Sequence: The Mass-Density Distribution of Astronomical Objects from Asteroids to Stars
• Nonthermal hotspot orbiting the supermassive black hole Sgr A*
• Multiobjective optimization for scattering mitigation and scattering screen reconstruction in VLBI observations of the Galactic Center
• Constraints on horizonless objects after the EHT observation of Sagittarius A*
• Constructing a gravitational wave analysis pipeline for extremely large mass ratio inspirals