Searching for Compact Obscured Nuclei in Compton-thick Active Galactic Nuclei
Abstract Compact obscured nuclei (CONs) are heavily obscured infrared cores that have been found in local (ultra-)luminous infrared galaxies. They show bright emission from vibrationally excited rotational transitions of HCN, known as HCN-vib, and are thought to harbor Compton-thick (CT, N H ≥ 10 24 cm −2 ) active galactic nuclei (AGNs) or extreme compact starbursts. We explore the potential evolutionary link between CONs and CT-AGNs by searching for CONs in hard-X-ray-confirmed CT-AGNs from the Great Observatories All-sky LIRG Survey (GOALS). Here, we present new Atacama Large Millimeter/submillimeter Array Band 6 observations that targeted HCN-vib emission in four hard-X-ray-confirmed CT-AGNs. We analyze these objects together with literature HCN-vib measurements of five additional hard-X-ray-confirmed CT-AGNs from the GOALS sample. We do not detect any CONs in this combined sample of nine CT-AGNs. We then explore a proposed evolutionary sequence in which CONs evolve into X-ray-detectable CT-AGNs once outflows and feedback reduce the column densities of the enshrouding gas. We find, however, no evidence of well-developed dense molecular outflows in the observed CT-AGNs. While this could suggest that CT-AGNs are not universally linked to CONs, it could also be explained by a short duty cycle for molecular outflows.
Authors
- Kara N. Green
- Ezequiel Treister (ORCID: https://orcid.org/0000-0001-7568-6412)
- Laura Blecha (ORCID: https://orcid.org/0000-0002-2183-1087)
- K. L. Emig (ORCID: https://orcid.org/0000-0001-6527-6954)
- S. König (ORCID: https://orcid.org/0000-0001-6174-8467)
- Cláudio Ricci (ORCID: https://orcid.org/0000-0001-5231-2645)
- F. E. Bauer (ORCID: https://orcid.org/0000-0002-8686-8737)
- S. Aalto
- L. Armus (ORCID: https://orcid.org/0000-0003-3498-2973)
- George C. Privon (ORCID: https://orcid.org/0000-0003-3474-1125)
- Ilsang Yoon (ORCID: https://orcid.org/0000-0001-9163-0064)
- J. S. Gallagher (ORCID: https://orcid.org/0000-0001-8608-0408)
- Cosima Eibensteiner (ORCID: https://orcid.org/0000-0002-1185-2810)
- Alejandro Saravia (ORCID: https://orcid.org/0000-0003-4546-3810)
- Makoto A. Johnstone (ORCID: https://orcid.org/0000-0001-7690-3976)
- A. Evans (ORCID: https://orcid.org/0000-0003-2638-1334)
- D. Kunneriath (ORCID: https://orcid.org/0000-0002-1568-579X)
- Loreto Barcos-Muñoz (ORCID: https://orcid.org/0000-0003-0057-8892)
- Jaya Nagarajan-Swenson
Institutions
- California Institute of Technology (US)
- Florida Museum of Natural History (US)
- University of Wisconsin–Madison (US)
- Pontificia Universidad Católica de Chile (CL)
- Peking University (CN)
- National Radio Astronomy Observatory (US)
- University of Florida (US)
- Millennium Institute of Astrophysics (CL)
- McCormick (United States) (US)
- Kavli Institute for Theoretical Sciences (CN)
- Infrared Processing and Analysis Center (US)
- University of Virginia (US)
- Macalester College (US)
- Chalmers University of Technology (SE)
- Universidad Diego Portales (CL)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-05-29
- DOI
- https://doi.org/10.3847/1538-4357/adcecb
- Primary Topic
- Astrophysical Phenomena and Observations
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Aeronautics and Space Administration
- Fulbright Chile