Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A232 | |
Number of page(s) | 13 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202450133 | |
Published online | 10 October 2024 |
Joint ALMA/X-ray monitoring of the radio-quiet type 1 active galactic nucleus IC 4329A
1
Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Santiago 8370191, Chile
2
Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
3
Joint ALMA Observatory, Avenida Alonso de Cordova 3107, Vitacura, Santiago 7630355, Chile
4
INAF – Astronomical Observatory of Rome, Via Frascati 33, 00040 Monte Porzio Catone, Italy
5
Department of Space, Earth and Environment, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
6
RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
7
Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
8
X-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
9
Yale Center for Astronomy & Astrophysics, 52 Hillhouse Avenue, New Haven, CT 06511, USA
10
Instituto de Astrofísica and Centro de Astroingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Campus San Joaquín, Av. Vicuña Mackenna 4860, Macul, Santiago 7820436, Chile
11
Millennium Institute of Astrophysics, Nuncio Monseñor Sótero Sanz 100, Of 104 Providencia, Santiago, Chile
12
Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, Colorado 80301, USA
13
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
14
Department of Astronomy, School of Physics, Peking University, Beijing 100871, China
15
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
16
MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MD 02139, USA
17
Eureka Scientific, 2452 Delmer Street Suite 100, Oakland, CA 94602-3017, USA
18
Department of Physics and Astronomy, West Virginia University, P.O. Box 6315 Morgantown, WV 26506, USA
19
Center for Research and Exploration in Space Science and Technology, NASA/GSFC, Greenbelt, MD 20771, USA
20
Department of Astronomy, University of Maryland, College Park, MD 20742, USA
21
Joint Space-Science Institute, University of Maryland, College Park, MD 20742, USA
22
Department of Astronomy, University of Geneva, ch. d’Écogia 16, CH-1290 Versoix, Switzerland
23
National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
24
Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
25
Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
26
Department of Physics and Astronomy, Texas A&M University, College Station, TX 77845, USA
27
Department of Physics, Southern Methodist University, 3215 Daniel Ave., Dallas, TX 75205, USA
28
Physics Department, Tor Vergata University of Rome, Via della Ricerca Scientifica 1, 00133 Rome, Italy
29
INFN – Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
30
School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
Received:
26
March
2024
Accepted:
12
July
2024
The origin of a compact millimeter (mm, 100–250 GHz) emission in radio-quiet active galactic nuclei (RQ AGN) remains debated. Recent studies propose a connection with self-absorbed synchrotron emission from the accretion disk X-ray corona. We present the first joint ALMA (∼100 GHz) and X-ray (NICER/XMM-Newton/Swift; 2–10 keV) observations of the unobscured RQ AGN, IC 4329A (z = 0.016). The time-averaged mm-to-X-ray flux ratio aligns with recently established trends for larger samples, but with a tighter scatter (∼0.1 dex) compared to previous studies. However, there is no significant correlation on timescales of less than 20 days. The compact mm emission exhibits a spectral index of −0.23 ± 0.18, remains unresolved with a 13 pc upper limit, and shows no jet signatures. Notably, the mm flux density varies significantly (by factor of 3) within four days, exceeding the contemporaneous X-ray variability and showing the largest mm variations ever detected in RQ AGN over daily timescales. The high amplitude variability rules out scenarios of heated dust and thermal free–free emission, pointing toward a synchrotron origin for the mm radiation in a source of ∼1 light day (∼120 gravitational radii) size. While the exact source is not yet certain, an X-ray corona scenario emerges as the most plausible compared to a scaled-down jet or outflow-driven shocks.
Key words: galaxies: individual: IC 4329A / submillimeter: galaxies / X-rays: galaxies
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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