Polarimetric Properties of Event Horizon Telescope Targets from ALMA

Ciriaco Goddi, Iván Martí-Vidal, Hugo Messias, Geoffrey C. Bower, Avery E. Broderick, Jason Dexter, Daniel P. Marrone, Monika Moscibrodzka, Hiroshi Nagai, Juan Carlos Algaba, Keiichi Asada, Geoffrey B. Crew, José L. Gómez, C. M.Violette Impellizzeri, Michael Janssen, Matthias Kadler, Thomas P. Krichbaum, Rocco Lico, Lynn D. Matthews, Antonios NathanailAngelo Ricarte, Eduardo Ros, Ziri Younsi, Kazunori Akiyama, Antxon Alberdi, Walter Alef, Richard Anantua, Rebecca Azulay, Anne Kathrin Baczko, David Ball, Mislav Baloković, John Barrett, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Wilfred Boland, Katherine L. Bouman, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Dominique Broguiere, Thomas Bronzwaer, Do Young Byun, John E. Carlstrom, Andrew Chael, Chi Kwan Chan, Shami Chatterjee, Koushik Chatterjee, Ming Tang Chen, Yongjun Chen, Paul M. Chesler, Ilje Cho, Pierre Christian, John E. Conway, James M. Cordes, Thomas M. Crawford, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Sheperd S. Doeleman, Ralph P. Eatough, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garciá, Olivier Gentaz, Boris Georgiev, Roman Gold, Arturo I. Gómez-Ruiz, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Michael H. Hecht, Ronald Hesper, Luis C. Ho, Paul Ho, Mareki Honma, Chih Wei L. Huang, Lei Huang, David H. Hughes, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Svetlana Jorstad, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong Jin Kim, Jae Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Michael Kramer, Carsten Kramer, Cheng Yu Kuo, Tod R. Lauer, Sang Sung Lee, Aviad Levis, Yan Rong Li, Zhiyuan Li, Michael Lindqvist, Greg Lindahl, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin Lonsdale, Ru Sen Lu, Nicholas R. Macdonald, Jirong Mao, Nicola Marchili, Sera Markoff, Alan P. Marscher, Satoki Matsushita, Lia Medeiros, Karl M. Menten, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Cornelia Müller, Gibwa Musoke, Alejandro Mus Mejiás, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Michael A. Nowak, Hiroki Okino, Héctor Olivares, Gisela N. Ortiz-León, Tomoaki Oyama, Feryal zel, Daniel C.M. Palumbo, Jongho Park, Nimesh Patel, Ue Li Pen, Dominic W. Pesce, Vincent Piétu, Richard Plambeck, Aleksandar Popstefanija, Oliver Porth, Felix M. Pötzl, Ben Prather, Jorge A. Preciado-López, Dimitrios Psaltis, Hung Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Bart Ripperda, Freek Roelofs, Alan Rogers, Mel Rose, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Chet Ruszczyk, Kazi L.J. Rygl, Salvador Sánchez, David Sánchez-Arguelles, Mahito Sasada, Tuomas Savolainen, F. Peter Schloerb, Karl Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason Soohoo, He Sun, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede, Remo P.J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Tyler Trent, Efthalia Traianou, Sascha Trippe, Ilse Van Bemmel, Huib Jan Van Langevelde, Daniel R. Van Rossum, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, George N. Wong, Qingwen Wu, Doosoo Yoon, André Young, Ken Young, Feng Yuan, Ye Fei Yuan, J. Anton Zensus, Guang Yao Zhao, Shan Shan Zhao, Gabriele Bruni, A. Gopakumar, Antonio Hernández-Gómez, Ruben Herrero-Illana, Adam Ingram, S. Komossa, Y. Y. Kovalev, Dirk Muders, Manel Perucho, Florian Rösch, Mauri Valtonen

Research output: Contribution to journalArticlepeer-review

Abstract

We present the results from a full polarization study carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) during the first Very Long Baseline Interferometry (VLBI) campaign, which was conducted in 2017 April in the λ3 mm and λ1.3 mm bands, in concert with the Global mm-VLBI Array (GMVA) and the Event Horizon Telescope (EHT), respectively. We determine the polarization and Faraday properties of all VLBI targets, including Sgr A∗, M87, and a dozen radio-loud active galactic nuclei (AGNs), in the two bands at several epochs in a time window of 10 days. We detect high linear polarization fractions (2%-15%) and large rotation measures (RM > 103.3-105.5 rad m-2), confirming the trends of previous AGN studies at millimeter wavelengths. We find that blazars are more strongly polarized than other AGNs in the sample, while exhibiting (on average) order-of-magnitude lower RM values, consistent with the AGN viewing angle unification scheme. For Sgr A∗ we report a mean RM of (-4.2 0.3) 105 rad m-2 at 1.3 mm, consistent with measurements over the past decade and, for the first time, an RM of (-2.1 0.1) 105 rad m-2 at 3 mm, suggesting that about half of the Faraday rotation at 1.3 mm may occur between the 3 mm photosphere and the 1.3 mm source. We also report the first unambiguous measurement of RM toward the M87 nucleus at millimeter wavelengths, which undergoes significant changes in magnitude and sign reversals on a one year timescale, spanning the range from -1.2 to 0.3 105 rad m-2 at 3 mm and -4.1 to 1.5 105 rad m-2 at 1.3 mm. Given this time variability, we argue that, unlike the case of Sgr A∗, the RM in M87 does not provide an accurate estimate of the mass accretion rate onto the black hole. We put forward a two-component model, comprised of a variable compact region and a static extended region, that can simultaneously explain the polarimetric properties observed by both the EHT (on horizon scales) and ALMA (which observes the combined emission from both components). These measurements provide critical constraints for the calibration, analysis, and interpretation of simultaneously obtained VLBI data with the EHT and GMVA.

Original languageEnglish (US)
Article numberL14
JournalAstrophysical Journal Letters
Volume910
Issue number1
DOIs
StatePublished - Mar 20 2021

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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