A multi-frequency study of sub-parsec jets with the Event Horizon Telescope
Abstract
The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed: the main science targets, Sgr A* and M87 along with various calibrators. We investigated the morphology of the sixteen AGN in the EHT 2017 data set, focusing on the properties of the VLBI cores: size, flux density, and brightness temperature. We studied their dependence on the observing frequency in order to compare it with the Blandford-K\"onigl (BK) jet model. We modeled the source structure of seven AGN in the EHT 2017 data set using linearly polarized circular Gaussian components and collected results for the other nine AGN from dedicated EHT publications, complemented by lower frequency data in the 2-86 GHz range. Then, we studied the dependences of the VLBI core flux density, size, and brightness temperature on the frequency measured in the AGN host frame. We compared the observations with the BK jet model and estimated the magnetic field strength dependence on the distance from the central black hole. Our results indicate a deviation from the standard BK model, particularly in the decrease of the brightness temperature with the observing frequency. Either bulk acceleration of the jet material, energy transfer from the magnetic field to the particles, or both are required to explain the observations.
Keywords
Cite
@article{arxiv.2501.05518,
title = {A multi-frequency study of sub-parsec jets with the Event Horizon Telescope},
author = {Jan Röder and Maciek Wielgus and Andrei P. Lobanov and Thomas P. Krichbaum and Dhanya G. Nair and Sang-Sung Lee and Eduardo Ros and Vincent L. Fish and Lindy Blackburn and Chi-kwan Chan and Sara Issaoun and Michael Janssen and Michael D. Johnson and Sheperd S. Doeleman and Geoffrey C. Bower and Geoffrey B. Crew and Remo P. J. Tilanus and Tuomas Savolainen and C. M. Violette Impellizzeri and Antxon Alberdi and Anne-Kathrin Baczko and José L. Gómez and Ru-Sen Lu and Georgios F. Paraschos and Efthalia Traianou and Ciriaco Goddi and Daewon Kim and Mikhail Lisakov and Yuri Y. Kovalev and Petr A. Voitsik and Kirill V. Sokolovsky and Kazunori Akiyama and Ezequiel Albentosa-Ruíz and Walter Alef and Juan Carlos Algaba and Richard Anantua and Keiichi Asada and Rebecca Azulay and Uwe Bach 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 Michael Bremer and Christiaan D. Brinkerink and Roger Brissenden and Silke Britzen and Avery E. Broderick and Dominique Broguiere and Thomas Bronzwaer and Sandra Bustamante and Do-Young Byun and John E. Carlstrom and Chiara Ceccobello and Andrew Chael and Dominic O. Chang and Koushik Chatterjee and Shami Chatterjee and Ming-Tang Chen and Yongjun Chen and Xiaopeng Cheng and Ilje Cho and Pierre Christian and Nicholas S. Conroy and John E. Conway and James M. Cordes and Thomas M. Crawford and Alejandro Cruz-Osorio and Yuzhu Cui and Brandon Curd and Rohan Dahale and Jordy Davelaar and Mariafelicia De Laurentis and Roger Deane and Jessica Dempsey and Gregory Desvignes and Jason Dexter and Vedant Dhruv and Indu K. Dihingia and Sean Taylor Dougall and Sergio A. Dzib and Ralph P. Eatough and Razieh Emami and Heino Falcke and Joseph Farah 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 Boris Georgiev and Roman Gold and Arturo I. Gómez-Ruiz and Minfeng Gu and Mark Gurwell and Kazuhiro Hada and Daryl Haggard and Kari Haworth and Michael H. Hecht 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 Makoto Inoue and David J. James and Buell T. Jannuzi and Britton Jeter and Wu Jiang and Alejandra Jiménez-Rosales and Svetlana Jorstad and Abhishek V. Joshi and Taehyun Jung and Mansour Karami 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 Jun Yi Koay and Prashant Kocherlakota and Yutaro Kofuji and Shoko Koyama and Carsten Kramer and Joana A. Kramer and Michael Kramer and Cheng-Yu Kuo and Noemi La Bella and Tod R. Lauer and Daeyoung Lee and Po Kin Leung and Aviad Levis and Zhiyuan Li and Rocco Lico and Greg Lindahl and Michael Lindqvist and Jun Liu and Kuo Liu and Elisabetta Liuzzo and Wen-Ping Lo and Laurent Loinard and Colin J. Lonsdale and Amy E. Lowitz 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 Daniel Michalik and Izumi Mizuno and Yosuke Mizuno and James M. Moran and Kotaro Moriyama and Monika Moscibrodzka and Wanga Mulaudzi and Cornelia Müller and Hendrik Müller and Alejandro Mus and Gibwa Musoke and Ioannis Myserlis and Andrew Nadolski and Hiroshi Nagai and Neil M. Nagar and Masanori Nakamura and Gopal Narayanan and Iniyan Natarajan and Antonios Nathanail and Santiago Navarro Fuentes and Joey Neilsen and Roberto Neri and Chunchong Ni and Aristeidis Noutsos and Michael A. Nowak and Junghwan Oh and Hiroki Okino and Héctor R. Olivares Sánchez and Gisela N. Ortiz-León and Tomoaki Oyama and Feryal özel and Daniel C. M. Palumbo and Jongho Park and Harriet Parsons and Nimesh Patel and Ue-Li Pen and Dominic W. Pesce and Vincent Piétu and Richard Plambeck and Aleksandar PopStefanija and Oliver Porth and Felix M. Pötzl and Ben Prather and Jorge A. Preciado-López and Giacomo Principe and Dimitrios Psaltis and Hung-Yi Pu and Venkatessh Ramakrishnan and Ramprasad Rao and Mark G. Rawlings and Angelo Ricarte and Bart Ripperda and Freek Roelofs and Alan Rogers and Cristina Romero-Cañizales and Arash Roshanineshat and Helge Rottmann and Alan L. Roy and Ignacio Ruiz and Chet Ruszczyk and Kazi L. J. Rygl and Salvador Sánchez and David Sánchez-Argüelles and Miguel Sánchez-Portal and Mahito Sasada and Kaushik Satapathy and F. Peter Schloerb and Jonathan Schonfeld and Karl-Friedrich Schuster and Lijing Shao and Zhiqiang Shen and Des Small and Bong Won Sohn and Jason SooHoo and León David Sosapanta Salas and Kamal Souccar and Joshua S. Stanway and He Sun and Fumie Tazaki and Alexandra J. Tetarenko and Paul Tiede and Michael Titus and Pablo Torne and Teresa Toscano and Tyler Trent and Sascha Trippe and Matthew Turk and Ilse van Bemmel and Huib J. 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 Qingwen Wu and Nitika Yadlapalli and Paul Yamaguchi and Aristomenis Yfantis and Doosoo Yoon and André Young and Ken Young and Ziri Younsi and Wei Yu and Feng Yuan and Ye-Fei Yuan and J. Anton Zensus and Shuo Zhang and Guang-Yao Zhao and Shan-Shan Zhao},
journal= {arXiv preprint arXiv:2501.05518},
year = {2025}
}