The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A*

Abstract

Using a combination of general-relativistic magnetohydrodynamics simulations and ray tracing of synchrotron emission, we study the effect of modest (24 degrees) misalignment between the black hole spin and plasma angular momentum, focusing on the variability of total flux, image centroids, and image sizes. We consider both millimeter and infrared (IR) observables motivated by Sagittarius A* (Sgr A*), though our results apply more generally to optically thin flows. For most quantities, tilted accretion is more variable, primarily due to a significantly hotter and denser "coronal" region well off the disk midplane. We find (1) a 150% increase in millimeter light curve variability when adding tilt to the flow; (2) the tilted image centroid in the millimeter shifts on a scale of 3.7 microarcseconds over 28 hours (5000 gravitational times) for some electron temperature models; (3) tilted disk image diameters in the millimeter can be 10% larger (52 versus 47 microarcseconds) than those of aligned disks at certain viewing angles; (4) the tilted models produce significant IR flux, similar to that seen in Sgr A*, with comparable or even greater variability than observed; (5) for some electron models, the tilted IR centroid moves by more than 50 microarcseconds over several hours, in a similar fashion to the centroid motion detected by the GRAVITY interferometer.

Accepted for publication in ApJ; figures and numbers slightly updated from previous version with additional data, but conclusions are unchanged

References in corpus (26)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The Athena++ Adaptive Mesh Refinement Framework: Design and Magnetohydrodynamic Solvers
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• Global General Relativistic MHD Simulation of a Tilted Black-Hole Accretion Disk
• An Unambiguous Detection of Faraday Rotation in Sagittarius A*
• Numerical Simulation of Hot Accretion Flows (III): Revisiting wind properties using trajectory approach
• The Submillimeter Bump in Sgr A* from Relativistic MHD Simulations
• The Power of Imaging: Constraining the Plasma Properties of GRMHD Simulations using EHT Observations of Sgr A*
• Plasma diagnostic potential of 2p4f in N${}^{+}$ -- accurate wavelengths and oscillator strengths
• Flares in the Galactic center I: orbiting flux tubes in Magnetically Arrested Black Hole Accretion Disks
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• Electron and proton heating in trans-relativistic magnetic reconnection
• Modeling the orbital motion of Sgr A*'s near-infrared flares
• Ab Initio Horizon-Scale Simulations of Magnetically Arrested Accretion in Sagittarius A* Fed by Stellar Winds
• Sgr A* near-infrared flares from reconnection events in a magnetically arrested disc
• The Surprisingly Small Impact of Magnetic Fields On The Inner Accretion Flow of Sagittarius A* Fueled By Stellar Winds
• Epicyclic Motions and Standing Shocks in Numerically Simulated Tilted Black-Hole Accretion Disks
• A parameter survey of Sgr A* radiative models from GRMHD simulations with self-consistent electron heating
• How important is non-ideal physics in simulations of sub-Eddington accretion onto spinning black holes?
• Tilted Disks around Black Holes: A Numerical Parameter Survey for Spin and Inclination Angle
• A Plasmoid Model for the Sgr A* Flares Observed with GRAVITY and Chandra
• The origin of hotspots around Sgr A*: Orbital or pattern motion?

Cited by in corpus (5)

• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• A "coronal-mass-ejection'' model for flares in Sagittarius A*
• The turbulent variability of accretion discs observed at high energies
• Electron Heating in the Trans-Relativistic Perpendicular Shocks of Tilted Accretion Flows