The Astrophysical Journal (Jan 2023)
Unraveling Twisty Linear Polarization Morphologies in Black Hole Images
- Razieh Emami,
- Angelo Ricarte,
- George N. Wong,
- Daniel Palumbo,
- Dominic Chang,
- Sheperd S. Doeleman,
- Avery E. Broderick,
- Ramesh Narayan,
- Maciek Wielgus,
- Lindy Blackburn,
- Ben S. Prather,
- Andrew A. Chael,
- Richard Anantua,
- Koushik Chatterjee,
- Ivan Marti-Vidal,
- Jose L. Gómez,
- Kazunori Akiyama,
- Matthew Liska,
- Lars Hernquist,
- Grant Tremblay,
- Mark Vogelsberger,
- Charles Alcock,
- Randall Smith,
- James Steiner,
- Paul Tiede,
- Freek Roelofs
Affiliations
- Razieh Emami
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- Angelo Ricarte
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- George N. Wong
- ORCiD
- School of Natural Sciences, Institute for Advanced Study, 1 Einstein Drive , Princeton, NJ 08540, USA; Princeton Gravity Initiative, Princeton University , Princeton, NJ 08544, USA
- Daniel Palumbo
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Dominic Chang
- ORCiD
- Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Sheperd S. Doeleman
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Avery E. Broderick
- ORCiD
- Perimeter Institute for Theoretical Physics , 31 Caroline Street North, Waterloo, ON, N2L 2Y5, Canada; Department of Physics and Astronomy, University of Waterloo , 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
- Ramesh Narayan
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Maciek Wielgus
- ORCiD
- Max-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, Germany
- Lindy Blackburn
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Ben S. Prather
- ORCiD
- Department of Physics, University of Illinois , 1110 West Green Street, Urbana, IL 61801, USA
- Andrew A. Chael
- ORCiD
- Princeton Gravity Initiative, Jadwin Hall, Princeton University , Princeton, NJ 08544, USA
- Richard Anantua
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA; Department of Physics & Astronomy, The University of Texas at San Antonio , One UTSA Circle, San Antonio, TX 78249, USA
- Koushik Chatterjee
- ORCiD
- Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Ivan Marti-Vidal
- ORCiD
- Departament d’Astronomia i Astrofísica, Universitat de València , C/Dr. Moliner 50, E-46100 Burjassot Spain; Observatori Astronòmic, Universitat de València , C/Catedràtico Beltrán 2, E-46980 Paterna, Spain
- Jose L. Gómez
- ORCiD
- Instituto de Astrofísica de Andalucía-CSIC , Glorieta de la Astronomía s/n, Spain
- Kazunori Akiyama
- ORCiD
- Massachusetts Institute of Technology Haystack Observatory , 99 Millstone Road, Westford, MA 01886, USA; Mizusawa VLBI Observatory, National Astronomical Observatory of Japan , 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan; Black Hole Initiative, Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Matthew Liska
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- Lars Hernquist
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- Grant Tremblay
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- Mark Vogelsberger
- ORCiD
- Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
- Charles Alcock
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- Randall Smith
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- James Steiner
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]
- Paul Tiede
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- Freek Roelofs
- ORCiD
- Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA ; [email protected]; Black Hole Initiative at Harvard University , 20 Garden Street, Cambridge, MA 02138, USA
- DOI
- https://doi.org/10.3847/1538-4357/acc8cd
- Journal volume & issue
-
Vol. 950,
no. 1
p. 38
Abstract
We investigate general relativistic magnetohydrodynamic simulations to determine the physical origin of the twisty patterns of linear polarization seen in spatially resolved black hole images and explain their morphological dependence on black hole spin. By characterizing the observed emission with a simple analytic ring model, we find that the twisty morphology is determined by the magnetic field structure in the emitting region. Moreover, the dependence of this twisty pattern on spin can be attributed to changes in the magnetic field geometry that occur due to the frame dragging. By studying an analytic ring model, we find that the roles of Doppler boosting and lensing are subdominant. Faraday rotation may cause a systematic shift in the linear polarization pattern, but we find that its impact is subdominant for models with strong magnetic fields and modest ion-to-electron temperature ratios. Models with weaker magnetic fields are much more strongly affected by Faraday rotation and have more complicated emission geometries than can be captured by a ring model. However, these models are currently disfavoured by the recent EHT observations of M87*. Our results suggest that linear polarization maps can provide a probe of the underlying magnetic field structure around a black hole, which may then be usable to indirectly infer black hole spins. The generality of these results should be tested with alternative codes, initial conditions, and plasma physics prescriptions.
Keywords
