TY - JOUR
T1 - The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A
AU - White, Christopher J.
AU - Quataert, Eliot
N1 - Funding Information:
This research was supported in part by the National Science Foundation under grants NSF AST 1715054 and NSF PHY 1748958 and by a Simons Investigator award from the Simons Foundation (E.Q.). This work used the Extreme Science and Engineering Discovery Environment (XSEDE) cluster Stampede2 at the Texas Advanced Computing Center (TACC) through allocations AST170012 and AST200005, as well as the Princeton Research Computing cluster Tiger managed and supported by the Princeton Institute for Computational Science and Engineering (PICSciE) and the Office of Information Technology’s High Performance Computing Center and Visualization Laboratory at Princeton University.
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Using a combination of general-relativistic magnetohydrodynamics simulations and ray tracing of synchrotron emission, we study the effect of modest (24°) 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 μas over 28 hr (5000 gravitational times) for some electron temperature models; (3) tilted disk image diameters in the millimeter can be 10% larger (52 versus 47 μas) 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; and (5) for some electron models, the tilted IR centroid moves by more than 50 μas over several hours, in a similar fashion to the centroid motion detected by the GRAVITY interferometer.
AB - Using a combination of general-relativistic magnetohydrodynamics simulations and ray tracing of synchrotron emission, we study the effect of modest (24°) 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 μas over 28 hr (5000 gravitational times) for some electron temperature models; (3) tilted disk image diameters in the millimeter can be 10% larger (52 versus 47 μas) 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; and (5) for some electron models, the tilted IR centroid moves by more than 50 μas over several hours, in a similar fashion to the centroid motion detected by the GRAVITY interferometer.
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U2 - 10.3847/1538-4357/ac423c
DO - 10.3847/1538-4357/ac423c
M3 - Article
AN - SCOPUS:85125744409
SN - 0004-637X
VL - 926
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 136
ER -