Joint ALMA/X-ray monitoring of the radio-quiet type 1 active galactic nucleus IC 4329A
Journal article, 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.
X-rays: galaxies
Galaxies: individual: IC 4329A
Submillimeter: galaxies
Author
E. Shablovinskaya
Diego Portales University
C. Ricci
Beijing University of Technology
Diego Portales University
Chin Shin Chang
Atacama Large Millimeter-submillimeter Array (ALMA)
A. Tortosa
Osservatorio Astronomico di Roma
Santiago Del Palacio
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Taiki Kawamuro
RIKEN
Susanne Aalto
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Z. Arzoumanian
National Aeronautics and Space Administration (NASA)
Mislav Baloković
Yale University
F. E. Bauer
Pontificia Universidad Catolica de Chile
Millennium Institute of Astrophysics
Space Science Institute
K. C. Gendreau
National Aeronautics and Space Administration (NASA)
Luis C. Ho
Beijing University of Technology
D. Kakkad
Space Telescope Science Institute (STScI)
E. Kara
Massachusetts Institute of Technology (MIT)
Michael J. Koss
Eureka Scientific
Space Science Institute
T. Liu
West Virginia University
M. Loewenstein
University of Maryland
National Aeronautics and Space Administration (NASA)
Richard Mushotzky
University of Maryland
S. Paltani
University of Geneva
G. Privon
University of Virginia
National Radio Astronomy Observatory
University of Florida
Krista L. Smith
Texas A&M University
Southern Methodist University
Francesco Tombesi
Osservatorio Astronomico di Roma
University of Rome Tor Vergata
National Institute for Nuclear Physics
Benny Trakhtenbrot
Tel Aviv University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 690 A232Exploring the Hidden Dusty Nuclei of Galaxies (HIDDeN)
European Research Council (ERC) (789410), 2018-10-01 -- 2023-09-30.
Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.1051/0004-6361/202450133