The putative center in NGC 1052

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.

Publication Details

Journal
Springer Link (Chiba Institute of Technology)
Published
2024-12-17
DOI
https://doi.org/10.1051/0004-6361/202450898/pdf
Primary Topic
Genetic and Environmental Crop Studies
Type
article
Field-Weighted Citation Impact
0.00

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article

The putative center in NGC 1052

Springer Link (Chiba Institute of Technology)
Genetic and Environmental Crop Studies
article

The putative center in NGC 1052

article en

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.

Springer Link (Chiba Institute of Technology)
National Science Foundation, Smithsonian Institution, U.S. Department of Energy, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, National Center for Theoretical Sciences, CERN, Space Telescope Science Institute, Ministerio de Ciencia, Innovación y Universidades, National Radio Astronomy Observatory, Associated Universities, International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Joint Institute for Computational Fundamental Science, Flatiron Health, Government of Canada, Leverhulme Trust, European Commission, National Research Foundation, University of Pretoria, Deutsche Forschungsgemeinschaft, Ministry of Education, Culture, Sports, Science and Technology, Fundação de Amparo à Pesquisa do Estado de São Paulo, National Natural Science Foundation of China, Academia Sinica, Chinese Academy of Sciences, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Generalitat Valenciana, Nuclear Safety and Security Commission, Korea Astronomy and Space Science Institute, National Research Foundation of Korea, Max-Planck-Gesellschaft, Vetenskapsrådet, Ministry of Education, India, European Southern Observatory, Ministerio de Ciencia e Innovación, National Astronomical Observatory of Japan, Recruitment Program of Global Experts, Istituto Nazionale di Fisica Nucleare, Ministry of Science and ICT, South Korea, Instituto de Astrofísica de Andalucía, Agencia Nacional de Investigación y Desarrollo, National Science and Technology Council, Institut Périmètre de physique théorique, East Asian Core Observatories Association, Toray Science Foundation, Office of Science, National Nuclear Security Administration, Physics Division, National Center for Theoretical Sciences, HORIZON EUROPE Framework Programme, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council, Japan Society for the Promotion of Science, Fundação para a Ciência e a Tecnologia, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, National Institutes of Natural Sciences, Agencia Estatal de Investigación, National Key Research and Development Program of China, Office of International Science and Engineering, Oak Ridge National Laboratory, Los Alamos National Laboratory
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Genetic and Environmental Crop Studies
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