2024-12-17 チャルマース工科大学
＜関連情報＞
- https://news.cision.com/chalmers/r/event-horizon-telescope–moving-towards-a-close-up-of-a-black-hole-and-its-jets,c4083768
- https://www.aanda.org/articles/aa/full_html/2024/12/aa50898-24/aa50898-24.html
NGC 1052の推定中心 The putative center in NGC 1052
Antonios Nathanail,, Santiago Navarro Fuentes, Joey Neilsen, Roberto Neri, Chunchong Ni,,, Aristeidis Noutsos, Michael A. Nowak, Junghwan Oh, Hiroki Okino,, Héctor Raúl Olivares Sánchez, Gisela N. Ortiz-León,, Tomoaki Oyama, Feryal Özel, Daniel C. M. Palumbo,, Georgios Filippos Paraschos, Jongho Park,, Harriet Parsons,, 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, Giacomo Principe,,, Dimitrios Psaltis, Hung-Yi Pu,,, Venkatessh Ramakrishnan,,, Ramprasad Rao, Mark G. Rawlings,,, Alexander W. Raymond,, Angelo Ricarte,, Bart Ripperda,,,, Freek Roelofs,,, Alan Rogers, 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, León David Sosapanta Salas, Kamal Souccar, Joshua S. Stanway, He Sun,, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede,, Remo P. J. Tilanus,,,, Michael Titus, Pablo Torne,, Teresa Toscano, 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, Jasmin E. Washington, Jonathan Weintroub,, Robert Wharton, Kaj Wiik, Gunther Witzel, Michael F. Wondrak,, George N. Wong,, Qingwen Wu, Nitika Yadlapalli, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, André Young, Ken Young, Ziri Younsi,, Wei Yu, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang and Guang-Yao Zhao,
Astronomy & Astrophysics Published:17 December 2024
DOI:https://doi.org/10.1051/0004-6361/202450898
Abstract
Context. Many active galaxies harbor powerful relativistic jets, however, the detailed mechanisms of their formation and acceleration remain poorly understood.
Aims. To investigate the area of jet acceleration and collimation with the highest available angular resolution, we study the innermost region of the bipolar jet in the nearby low-ionization nuclear emission-line region (LINER) galaxy NGC 1052.
Methods. We combined observations of NGC 1052 taken with VLBA, GMVA, and EHT over one week in the spring of 2017. Our study is focused on the size and continuum spectrum of the innermost region containing the central engine and the footpoints of both jets. We employed a synchrotron-self absorption model to fit the continuum radio spectrum and we combined the size measurements from close to the central engine out to ∼1 pc to study the jet collimation.
Results. For the first time, NGC 1052 was detected with the EHT, providing a size of the central region in-between both jet bases of 43 μas perpendicular to the jet axes, corresponding to just around 250 RS (Schwarzschild radii). This size estimate supports previous studies of the jets expansion profile which suggest two breaks of the profile at around 3 × 103 RS and 1 × 104 RS distances to the core. Furthermore, we estimated the magnetic field to be 1.25 Gauss at a distance of 22 μas from the central engine by fitting a synchrotron-self absorption spectrum to the innermost emission feature, which shows a spectral turn-over at ∼130 GHz. Assuming a purely poloidal magnetic field, this implies an upper limit on the magnetic field strength at the event horizon of 2.6 × 104 Gauss, which is consistent with previous measurements.
Conclusions. The complex, low-brightness, double-sided jet structure in NGC 1052 makes it a challenge to detect the source at millimeter (mm) wavelengths. However, our first EHT observations have demonstrated that detection is possible up to at least 230 GHz. This study offers a glimpse through the dense surrounding torus and into the innermost central region, where the jets are formed. This has enabled us to finally resolve this region and provide improved constraints on its expansion and magnetic field strength.
