Locating the missing large-scale emission in the jet of M87* with short EHT baselines
High Energy Astrophysical Phenomena
2026-05-06 v1 Instrumentation and Methods for Astrophysics
Abstract
In Very-Long Baseline Interferometric arrays, nearly co-located stations probe the largest scales and typically cannot resolve the observed source. In the absence of large-scale structure, closure phases constructed with these stations are zero and, since they are independent of station-based errors, they can be used to probe data issues. Here, we show with an expansion about co-located stations, how these trivial closure phases become non-zero with brightness distribution on smaller scales than their short baseline would suggest. When applied to sources that are made up of a bright compact and large-scale diffuse component, the trivial closure phases directly measure the centroid relative to the compact source and higher-order image moments. We present a technique to measure these image moments with minimal model assumptions and validate it on synthetic Event Horizon Telescope (EHT) data. We then apply this technique to 2017 and 2018 EHT observations of M87* and find a weak preference for extended emission in the direction of the large-scale jet. We also apply it to 2021 EHT data and measure the source centroid about 1 mas northwest of the compact ring, consistent with the jet observed at lower frequencies.
Cite
@article{arxiv.2601.13356,
title = {Locating the missing large-scale emission in the jet of M87* with short EHT baselines},
author = {Boris Georgiev and Paul Tiede and Sebastiano D. von Fellenberg and Michael Janssen and Iniyan Natarajan and Lindy Blackburn and Jongho Park and Erandi Chavez and Andrew T. West and Kotaro Moriyama and Jun Yi Koay and Hendrik Müller and Dhanya G. Nair and Avery E. Broderick and Maciek Wielgus and Kazunori Akiyama and Ezequiel Albentosa-Ruíz and Antxon Alberdi and Walter Alef and Juan Carlos Algaba and Richard Anantua and Keiichi Asada and Rebecca Azulay and Uwe Bach and Anne-Kathrin Baczko and David Ball and Mislav Baloković and Bidisha Bandyopadhyay and John Barrett and Michi Bauböck and Bradford A. Benson and Dan Bintley and Raymond Blundell and Katherine L. Bouman and Geoffrey C. Bower and Michael Bremer and Roger Brissenden and Silke Britzen and Dominique Broguiere and Thomas Bronzwaer and Sandra Bustamante and Douglas F. Carlos and John E. Carlstrom and Andrew Chael and Chi-kwan Chan and Dominic O. Chang and Koushik Chatterjee and Shami Chatterjee and Ming-Tang Chen and Yongjun Chen and Xiaopeng Cheng and Paul Chichura and Ilje Cho and Pierre Christian and Nicholas S. Conroy and John E. Conway and Thomas M. Crawford and Geoffrey B. Crew and Alejandro Cruz-Osorio and Yuzhu Cui and Brandon Curd and Rohan Dahale and Jordy Davelaar and Mariafelicia De Laurentis and Roger Deane and Gregory Desvignes and Jason Dexter and Vedant Dhruv and Indu K. Dihingia and Sheperd S. Doeleman and Sergio A. Dzib and Ralph P. Eatough and Razieh Emami and Heino Falcke and Joseph Farah and Vincent L. Fish and Edward Fomalont and H. Alyson Ford and Marianna Foschi and Raquel Fraga-Encinas and William T. Freeman and Per Friberg and Christian M. Fromm and Antonio Fuentes and Peter Galison and Charles F. Gammie and Roberto García and Olivier Gentaz and Ciriaco Goddi and Roman Gold and Arturo I. Gómez-Ruiz and José L. Gómez and Minfeng Gu and Mark Gurwell and Kazuhiro Hada and Daryl Haggard and Ronald Hesper and Dirk Heumann and Luis C. Ho and Paul Ho and Mareki Honma and Chih-Wei L. Huang and Lei Huang and David H. Hughes and Shiro Ikeda and C. M. Violette Impellizzeri and Makoto Inoue and Sara Issaoun and David J. James and Buell T. Jannuzi and Britton Jeter and Wu Jiang and Alejandra Jiménez-Rosales and Michael D. Johnson and Svetlana Jorstad and Adam C. Jones and Abhishek V. Joshi and Taehyun Jung and Ramesh Karuppusamy and Tomohisa Kawashima and Garrett K. Keating and Mark Kettenis and Dong-Jin Kim and Jae-Young Kim and Jongsoo Kim and Junhan Kim and Motoki Kino and Prashant Kocherlakota and Yutaro Kofuji and Patrick M. Koch and Shoko Koyama and Carsten Kramer and Joana A. Kramer and Michael Kramer and Thomas P. Krichbaum and Cheng-Yu Kuo and Noemi La Bella and Deokhyeong Lee and Sang-Sung Lee and Aviad Levis and Shaoling Li and Zhiyuan Li and Rocco Lico and Greg Lindahl and Michael Lindqvist and Mikhail Lisakov and Jun Liu and Kuo Liu and Elisabetta Liuzzo and Wen-Ping Lo and Andrei P. Lobanov and Laurent Loinard and Colin J. Lonsdale and Amy E. Lowitz and Ru-Sen Lu and Nicholas R. MacDonald and Jirong Mao and Nicola Marchili and Sera Markoff and Daniel P. Marrone and Alan P. Marscher and Iván Martí-Vidal and Satoki Matsushita and Lynn D. Matthews and Lia Medeiros and Karl M. Menten and Izumi Mizuno and Yosuke Mizuno and Joshua Montgomery and James M. Moran and Monika Moscibrodzka and Wanga Mulaudzi and Cornelia Müller and Alejandro Mus and Gibwa Musoke and Ioannis Myserlis and Hiroshi Nagai and Neil M. Nagar and Masanori Nakamura and Gopal Narayanan and Antonios Nathanail and Santiago Navarro Fuentes and Joey Neilsen and Chunchong Ni and Michael A. Nowak and Junghwan Oh and Hiroki Okino and Héctor Raúl Olivares Sánchez and Tomoaki Oyama and Feryal Özel and Daniel C. M. Palumbo and Georgios Filippos Paraschos and Harriet Parsons and Nimesh Patel and Ue-Li Pen and Dominic W. Pesce and Vincent Piétu and Alexander Plavin and Aleksandar PopStefanija and Oliver Porth and Ben Prather and Giacomo Principe and Dimitrios Psaltis and Hung-Yi Pu and Alexandra Rahlin and Venkatessh Ramakrishnan and Ramprasad Rao and Mark G. Rawlings and Angelo Ricarte and Luca Ricci and Bart Ripperda and Jan Röder and Freek Roelofs and Cristina Romero-Cañizales and Eduardo Ros and Arash Roshanineshat and Helge Rottmann and Alan L. Roy and Ignacio Ruiz and Chet Ruszczyk and Kazi L. J. Rygl and León D. S. Salas and Salvador Sánchez and David Sánchez-Argüelles and Miguel Sánchez-Portal and Mahito Sasada and Kaushik Satapathy and Saurabh and Tuomas Savolainen and F. Peter Schloerb and Jonathan Schonfeld and Karl-Friedrich Schuster and Lijing Shao and Zhiqiang Shen and Sasikumar Silpa and Des Small and Randall Smith and Bong Won Sohn and Jason SooHoo and Kamal Souccar and Joshua S. Stanway and He Sun and Fumie Tazaki and Alexandra J. Tetarenko and Remo P. J. Tilanus and Michael Titus and Kenji Toma and Pablo Torne and Teresa Toscano and Efthalia Traianou and Tyler Trent and Sascha Trippe and Matthew Turk and Ilse van Bemmel and Huib Jan van Langevelde and Daniel R. van Rossum and Jesse Vos and Jan Wagner and Derek Ward-Thompson and John Wardle and Jasmin E. Washington and Jonathan Weintroub and Robert Wharton and Kaj Wiik and Gunther Witzel and Michael F. Wondrak and George N. Wong and Jompoj Wongphexhauxsorn and Qingwen Wu and Nitika Yadlapalli and Paul Yamaguchi and Aristomenis Yfantis and Doosoo Yoon and André Young and Ziri Younsi and Wei Yu and Feng Yuan and Ye-Fei Yuan and Ai-Ling Zeng and J. Anton Zensus and Shuo Zhang and Guang-Yao Zhao and Shan-Shan Zhao},
journal= {arXiv preprint arXiv:2601.13356},
year = {2026}
}
Comments
15 pages, 8 figures, Submitted to Astronomy & Astrophysics