The Event Horizon Telescope: exploring strong gravity and accretion physics

Abstract

The Event Horizon Telescope (EHT), a global sub-millimeter wavelength very long baseline interferometry array, is now resolving the innermost regions around the supermassive black holes Sgr A* and M87. Using black hole images from both simple geometric models and relativistic magnetohydrodynamical accretion flow simulations, we perform a variety of experiments to assess the promise of the EHT for studying strong gravity and accretion physics during the stages of its development. We find that (1) the addition of the LMT and ALMA along with upgraded instrumentation in the "Complete" stage of the EHT allow detection of the photon ring, a signature of Kerr strong gravity, for predicted values of its total flux; (2) the inclusion of coherently averaged closure phases in our analysis dramatically improves the precision of even the current array, allowing (3) significantly tighter constraints on plausible accretion models and (4) detections of structural variability at the levels predicted by the models. While observations at 345 GHz circumvent problems due to interstellar electron scattering in line-of-sight to the galactic center, short baselines provided by CARMA and/or the LMT could be required in order to constrain the overall shape of the accretion flow. Given the systematic uncertainties in the underlying models, using the full complement of two observing frequencies (230 and 345 GHz) and sources (Sgr A* and M87) may be critical for achieving transformative science with the EHT experiment.

arXiv comment17 pages, 7 figures, 10 tables. Accepted by MNRAS 10 October 2014

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• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• Asymptotically flat black holes in Horndeski theory and beyond
• Phenomenological aspects of black holes beyond general relativity
• BlackHoleCam: fundamental physics of the Galactic center
• A Quantitative Test of the No-Hair Theorem with Sgr A* using stars, pulsars, and the Event Horizon Telescope
• Sgr A* and General Relativity
• The Milky Way's Supermassive Black Hole: How good a case is it? A Challenge for Astrophysics & Philosophy of Science
• Binary black hole shadows, chaotic scattering and the Cantor set
• Persistent Asymmetric Structure of Sagittarius A* on Event Horizon Scales
• Ring-down gravitational waves and lensing observables: How far can a wormhole mimic those of a black hole?
• Observational signature of near-extremal Kerr-like black holes in a modified gravity theory at the Event Horizon Telescope
• Probing the magnetic field structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations
• Strong field gravitational lensing by a charged Galileon black hole
• Assessments of Ali, Dome A, and Summit Camp for Mm-wave Observations Using MERRA-2 Reanalysis
• Strong gravitational field time delay for photons coupled to Weyl tensor in a Schwarzschild black hole
• Absorption of electromagnetic and gravitational waves by Kerr black holes: Shadows, superradiance and the spin-helicity effect
• Probing the innermost accretion flow geometry of Sgr A* with Event Horizon Telescope
• Millimeter-Wave Broadband Anti-Reflection Coatings Using Laser Ablation of Sub-Wavelength Structures
• Horndeski theories confront the Gravity Probe B experiment
• Constraint on the black-hole spin of M87 from the accretion-jet model
• Superradiance in the sky
• Particle energization in relativistic plasma turbulence: solenoidal versus compressive driving
• Self-gravitating black hole scalar wigs
• Testing General Relativity's No-Hair Theorem with X-Ray Observations of Black Holes
• An accretion-jet model for M87: interpreting the spectral energy distribution and Faraday rotation measure
• Numerical black hole initial data and shadows in dynamical Chern-Simons gravity
• On the Possibility that Ultra-Light Boson halos host and form Super-massive Black Holes
• Relative depolarization of the black hole photon ring in GRMHD models of Sgr A* and M87*
• Bondi-Hoyle-Lyttleton accretion in the presence of small rigid bodies around a black hole
• Accelerating black holes in the low energy heterotic string theory
• Profiled spectral lines generated by Keplerian discs orbiting in the Bardeen and Ayon-Beato-Garcia spacetimes
• First 230 GHz VLBI Fringes on 3C 279 using the APEX Telescope
• A Black Hole Mass-Variability Time Scale Correlation at Submillimeter Wavelengths
• Observable Emission Features of Black Hole GRMHD Jets on Event Horizon Scales
• Qualifying ringdown and shadow of black holes under general parametrized metrics with photon orbits
• Probing spacetime around Sagittarius A* using modeled VLBI closure phases
• Non Axisymmetric Relativistic Wind Accretion with Velocity Gradients onto a Rotating Black Hole
• A catalogue sample of low mass galaxies observed in X-rays with central candidate black holes
• Generalized no-hair theorems without horizons
• Towards a Full MHD Jet Model of Spinning Black Holes--I: Framework and a split monopole example
• Solar system tests in constraining parameters of dyon black holes
• Strong-field gravitational lensing by black holes
• Orbits in a stochastic Schwarzschild geometry
• Wind accretion onto compact objects
• Orbit design for mitigating interstellar scattering effects in Earth-space VLBI observations of Sgr A*