Spin-Induced Disk Precession in Sagittarius A*

Abstract

In Sgr A* at the Galactic center, by far the closest and easiest supermassive black hole we can study, the observational evidence is increasingly pointing to the presence of a compact, hot, magnetized disk feeding the accretor. In such low-Mach-number plasmas, forces arising, e.g., from pressure gradients in the plasma, can altogether negate the warping of disks around Kerr black holes caused by the Bardeen-Petterson effect and can lead to coherent precession of the entire disk. In this Letter, we present for the first time highly detailed 3D SPH simulations of the accretion disk evolution in Sgr A*, guided by observational constraints on its physical characteristics, and conclude that indeed the Bardeen-Petterson effect is probably absent in this source. Given what we now understand regarding the emission geometry in this object, we suggest that a ~ 50-500-day modulation in Sgr A*'s spectrum, arising from the disk precession, could be an important observational signature; perhaps the ~ 106-day period seen earlier in its radio flux, if confirmed, could be due to this process. On the other hand, if future observations do not confirm this long modulation in Sgr A*'s spectrum, this would be an indication that either the disk size or orientation is very different from current estimates, or that the black hole is not spinning at all (unlikely), or that our current understanding of how it produces its radiative output is incorrect.

14 pages, 3 figures; small changes to sections 2.1 and 3; accepted for publication in ApJ

References in corpus (15)

• Stellar Orbits Around the Galactic Center Black Hole
• Detection of the Intrinsic Size of Sagittarius A* through Closure Amplitude Imaging (includes Online Supporting Material)
• Where is the Inner Edge of an Accretion Disk Around a Black Hole?
• Hydrodynamic Simulations of the Bardeen-Petterson Effect
• Hydrodynamic Simulations of Tilted Thick-Disk Accretion onto a Kerr Black Hole
• Hydrodynamical Accretion Onto Sgr A* From Distributed Point Sources
• Polarimetric Imaging of the Massive Black Hole at the Galactic Center
• An Accretion-Induced X-ray Flare in Sgr A*
• Three-Dimensional Magnetohydrodynamic Simulations of Spherical Accretion
• Radio Variability of Sagittarius A* - A 106 Day Cycle
• Spin-Induced Disk Precession in the Supermassive Black Hole at the Galactic Center
• Polarized mm And sub-mm Emission From Sgr A* At The Galactic Center
• New Constraints on the Nature of Radio Emission in Sagittarius A*
• A Magnetic Dynamo Origin For The Sub-mm Excess In Sgr A*
• Long-Term Radio Modulation in Sagittarius A* from Spin-Induced Disk Precession

Cited by in corpus (10)

• Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
• A Precessing Ring Model for Low-Frequency Quasi-periodic Oscillations
• SNSPH: A Parallel 3-D Smoothed Particle Radiation Hydrodynamics Code
• Tilted black hole accretion disc models of Sagittarius A*: time-variable millimetre to near-infrared emission
• The pattern of accretion flow onto Sgr A*
• The X-ray Ridge Surrounding Sgr A* at the Galactic Center
• Magnetic layers and neutral points near rotating black hole
• Motion of Spinning Particles around Electrically Charged Black Hole in Eddington-inspired Born-Infeld Gravity
• Motion of test particle in rotating boson star
• SgrA* emission at 7mm: variability and periodicity