Characterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI

Avery E. Broderick , Roman Gold , Boris Georgiev , Dominic W. Pesce , Paul Tiede , Chunchong Ni , Kotaro Moriyama , Kazunori Akiyama , Antxon Alberdi , Walter Alef , Juan Carlos Algaba , Richard Anantua , Keiichi Asada , Rebecca Azulay , Uwe Bach , Anne-Kathrin Baczko , David Ball , Mislav Baloković , John Barrett , Michi Bauböck , Bradford A. Benson , Dan Bintley , Lindy Blackburn , Raymond Blundell , Katherine L. Bouman , Geoffrey C. Bower , Hope Boyce , Michael Bremer , Christiaan D. Brinkerink , Roger Brissenden , Silke Britzen , Dominique Broguiere , Thomas Bronzwaer , Sandra Bustamante , Do-Young Byun , John E. Carlstrom , Chiara Ceccobello , Andrew Chael , Chi-Kwan Chan , Koushik Chatterjee , Shami Chatterjee , Ming-Tang Chen , Yongjun Chen , Xiaopeng Cheng , Ilje Cho , Pierre Christian , Nicholas S. Conroy , John E. Conway , James M. Cordes , Thomas M. Crawford , Geoffrey B. Crew , Alejandro Cruz-Osorio , Yuzhu Cui , Jordy Davelaar , Mariafelicia de Laurentis , Roger Deane , Jessica Dempsey , Gregory Desvignes (1) , Jason Dexter , Vedant Dhruv , Sheperd S. Doeleman , Sean Dougal , Sergio A. Dzib , Ralph P. Eatough , Razieh Emami , 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 García , Olivier Gentaz , Ciriaco Goddi , Arturo I. Gómez-Ruiz , José L. Gómez , Minfeng Gu , Mark Gurwell , Kazuhiro Hada , Daryl Haggard , Kari Haworth , Michael H. Hecht , Ronald Hesper , Dirk Heumann , Luis C. Ho , Paul Ho , Mareki Honma , Chih-Wei L. Huang , Lei Huang , David H. Hughes , Shiro Ikeda , C. M. Violette Impellizzeri , Makoto Inoue , Sara Issaoun , David J. James , Buell T. Jannuzi , Michael Janssen , Britton Jeter , Wu Jiang , Alejandra Jiménez-Rosales , Michael D. Johnson , Svetlana Jorstad , Abhishek V. Joshi , 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 , Prashant Kocherlakota , Yutaro Kofuji , Patrick M. Koch , Shoko Koyama , Carsten Kramer , Michael Kramer , Thomas P. Krichbaum , Cheng-Yu Kuo , Noemi La Bella , Tod R. Lauer , Daeyoung Lee , Sang-Sung Lee , Po Kin Leung , Aviad Levis , Zhiyuan Li , Rocco Lico , Greg Lindahl , Michael Lindqvist , Mikhail Lisakov , Jun Liu , Kuo Liu , Elisabetta Liuzzo , Wen-Ping Lo , Andrei P. Lobanov , Laurent Loinard , Colin J. Lonsdale , Ru-Sen Lu , Jirong Mao , Nicola Marchili , Sera Markoff , Daniel P. Marrone , Alan P. Marscher , Iván Martí-Vidal , Satoki Matsushita , Lynn D. Matthews , Karl M. Menten , Daniel Michalik , Izumi Mizuno , Yosuke Mizuno , James M. Moran , Monika Moscibrodzka , Cornelia Müller , Alejandro Mus , Gibwa Musoke , Ioannis Myserlis , Andrew Nadolski , Hiroshi Nagai , Neil M. Nagar , Masanori Nakamura , Ramesh Narayan , Gopal Narayanan , Iniyan Natarajan , Antonios Nathanail , Santiago Navarro Fuentes , Joey Neilsen , Roberto Neri , Aristeidis Noutsos , Michael A. Nowak , Junghwan Oh , Hiroki Okino , Héctor Olivares , Gisela N. Ortiz-León , Tomoaki Oyama , Daniel C. M. Palumbo , Georgios Filippos Paraschos , Jongho Park , Harriet Parsons , Nimesh Patel , Ue-Li Pen , Vincent Piétu , Richard Plambeck , Aleksandar Popstefanija , Oliver Porth , Felix M. Pötzl , Ben Prather , Jorge A. Preciado-López , Hung-Yi Pu , Venkatessh Ramakrishnan , Ramprasad Rao , Mark G. Rawlings , Alexander W. Raymond , Luciano Rezzolla , Angelo Ricarte , Bart Ripperda , Freek Roelofs , Alan Rogers , Eduardo Ros , Cristina Romero-Cañizales , Arash Roshanineshat , Helge Rottmann , Alan L. Roy , Ignacio Ruiz , Chet Ruszczyk , Kazi L. J. Rygl , Salvador Sánchez , David Sánchez-Argüelles , Miguel Sánchez-Portal , Mahito Sasada , Kaushik Satapathy , Tuomas Savolainen , F. Peter Schloerb , Jonathan Schonfeld , Karl-Friedrich Schuster , Lijing Shao , Zhiqiang Shen , Des Small , Bong Won Sohn , Jason Soohoo , Kamal Souccar , He Sun , Fumie Tazaki , Alexandra J. Tetarenko , Remo P. J. Tilanus , Michael Titus , Pablo Torne , Efthalia Traianou , Tyler Trent , Sascha Trippe , Matthew Turk , Ilse van Bemmel , Huib Jan van Langevelde , Daniel R. van Rossum , Jesse Vos , Jan Wagner , Derek Ward-Thompson , John Wardle , Jonathan Weintroub , Norbert Wex , Robert Wharton , Maciek Wielgus , Kaj Wiik , Gunther Witzel , Michael F. Wondrak , George N. Wong , Qingwen Wu , Paul Yamaguchi , Doosoo Yoon , André Young , Ken Young , Ziri Younsi , Feng Yuan , Ye-Fei Yuan , J. Anton Zensus , Guang-Yao Zhao , Shuo Zhang , Shan-Shan Zhao

1 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics

The extraordinary physical resolution afforded by the Event Horizon Telescope has opened a window onto the astrophysical phenomena unfolding on horizon scales in two known black holes, M87* and Sgr A*. However, with this leap in resolution has come a new set of practical complications. Sgr A* exhibits intraday variability that violates the assumptions underlying Earth aperture synthesis, limiting traditional image reconstruction methods to short timescales and data sets with very sparse (u, v) coverage. We present a new set of tools to detect and mitigate this variability. We develop a data-driven, model-agnostic procedure to detect and characterize the spatial structure of intraday variability. This method is calibrated against a large set of mock data sets, producing an empirical estimator of the spatial power spectrum of the brightness fluctuations. We present a novel Bayesian noise modeling algorithm that simultaneously reconstructs an average image and statistical measure of the fluctuations about it using a parameterized form for the excess variance in the complex visibilities not otherwise explained by the statistical errors. These methods are validated using a variety of simulated data, including general relativistic magnetohydrodynamic simulations appropriate for Sgr A* and M87*. We find that the reconstructed source structure and variability are robust to changes in the underlying image model. We apply these methods to the 2017 EHT observations of M87*, finding evidence for variability across the EHT observing campaign. The variability mitigation strategies presented are widely applicable to very long baseline interferometry observations of variable sources generally, for which they provide a data-informed averaging procedure and natural characterization of inter-epoch image consistency.

Keywords: Galactic center; Black holes; Radio astronomy; Very long baseline interferometry; Time domain astronomy; Astronomy data analysis; Computational astronomy

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

Avery E. Broderick, Roman Gold, Boris Georgiev, Dominic W. Pesce, Paul Tiede, et al.. Characterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI. The Astrophysical Journal Letters, 2022, 930, ⟨10.3847/2041-8213/ac6584⟩. ⟨insu-03713306⟩