Localizing Sagittarius A* and M87 on Microarcsecond Scales with Millimeter VLBI

Abstract

With the advent of the Event Horizon Telescope (EHT), a millimeter/sub-millimeter very-long baseline interferometer (VLBI), it has become possible to image a handful of black holes with sub-horizon resolutions. However, these images do not translate into microarcsecond absolute positions due to the lack of absolute phase information when an external phase reference is not used. Due to the short atmospheric coherence time at these wavelengths, nodding between the source and phase reference is impractical. However, here we suggest an alternative scheme which makes use of the fact that many of the VLBI stations within the EHT are arrays in their own right. With this we show that it should be possible to absolutely position the supermassive black holes at the centers of the Milky Way (Sgr A*) and M87 relative to nearby objects with precisions of roughly 1 microarcsecond. This is sufficient to detect the perturbations to Sgr A*'s position resulting from interactions with the stars and stellar-mass black holes in the Galactic cusp on year timescales, and severely constrain the astrophysically relevant parameter space for an orbiting intermediate mass black hole, implicated in some mechanisms for producing the young massive stars in the Galactic center. For M87, it allows the registering of millimeter images, in which the black hole may be identified by its silhouette against nearby emission, and existing larger scale radio images, eliminating present ambiguities in the nature of the radio core and inclination, opening angle, and source of the radio jet.

18 pages, 4 figures, Accepted for publication in ApJ

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Cited by in corpus (27)

• Dynamical Boson Stars
• Universal Interferometric Signatures of a Black Hole's Photon Ring
• Galactic Rotation and Solar Motion from Stellar Kinematics
• Constraining the spin and the deformation parameters from the black hole shadow
• Slowly-Rotating Black Holes in Einstein-Dilaton-Gauss-Bonnet Gravity: Quadratic Order in Spin Solutions
• Micro-Arcsecond Radio Astrometry
• Plasma diagnostic potential of 2p4f in N${}^{+}$ -- accurate wavelengths and oscillator strengths
• The Power of Imaging: Constraining the Plasma Properties of GRMHD Simulations using EHT Observations of Sgr A*
• The Novel Probes Project -- Tests of Gravity on Astrophysical Scales
• Imaging an Event Horizon: Mitigation of Scattering Toward Sagittarius A*
• Dynamical Imaging with Interferometry
• Modified gravity black hole lensing observables in weak and strong field of gravity
• Metrics and Motivations for Earth-Space VLBI: Time-Resolving Sgr A* with the Event Horizon Telescope
• Repeated Imaging of Massive Black Hole Binary Orbits with Millimeter Interferometry: measuring black hole masses and the Hubble constant
• Silhouettes of invisible black holes
• Modelling the black hole silhouette in Sgr A* with ion tori
• VLBI studies of DAGN and SMBHB hosting galaxies
• An accretion-jet model for M87: interpreting the spectral energy distribution and Faraday rotation measure
• Constraining a companion of the galactic center black hole, Sgr A*
• Constraining a black hole companion for M87* through imaging by the Event Horizon Telescope
• Gravitational Lensing of a star by a rotating black hole
• Can the Slow-Rotation Approximation be used in Electromagnetic Observations of Black Holes?
• Testing the Black Hole No-hair Theorem with Galactic Center Stellar Orbits
• Astrometric Detection of Intermediate-Mass Black Holes At the Galactic Centre
• Toward Astrometric Constraints on a Supermassive Black Hole Binary in the Early-Type Galaxy NGC\,4472
• Thermal equilibrium of an ideal gas in a free-floating box
• Visible shapes of black holes M87* and SgrA*