A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN Hosted by NGC 404

Journal Article · Thu Aug 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA7ECF· OSTI ID:22663272

Nyland, Kristina; Lacy, Mark ^[1]; Davis, Timothy A. ^[2]; Nguyen, Dieu D.; Seth, Anil ^[3]; Wrobel, Joan M. ^[4]; Kamble, Atish; Karovska, Margarita; Maksym, W. Peter ^[5]; Alatalo, Katherine ^[6]; Mukherjee, Dipanjan ^[7]

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1. National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
2. School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom)
3. Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States)
4. National Radio Astronomy Observatory, Socorro, NM 87801 (United States)
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States)
6. The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
7. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia)

The nearby dwarf galaxy NGC 404 harbors a low-luminosity active galactic nucleus powered by the lowest-mass (<150,000 M {sub ⊙}) central massive black hole (MBH), with a dynamical mass constraint, currently known, thus providing a rare low-redshift analog to the MBH “seeds” that formed in the early universe. Here, we present new imaging of the nucleus of NGC 404 at 12–18 GHz with the Karl G. Jansky Very Large Array (VLA) and observations of the CO(2–1) line with the Atacama Large Millimeter/Submillimeter Array (ALMA). For the first time, we have successfully resolved the nuclear radio emission, revealing a centrally peaked, extended source spanning 17 pc. Combined with previous VLA observations, our new data place a tight constraint on the radio spectral index and indicate an optically thin synchrotron origin for the emission. The peak of the resolved radio source coincides with the dynamical center of NGC 404, the center of a rotating disk of molecular gas, and the position of a compact, hard X-ray source. We also present evidence for shocks in the NGC 404 nucleus from archival narrowband HST imaging, Chandra X-ray data, and Spitzer mid-infrared spectroscopy, and discuss possible origins for the shock excitation. Given the morphology, location, and steep spectral index of the resolved radio source, as well as constraints on nuclear star formation from the ALMA CO(2–1) data, we find the most likely scenario for the origin of the radio source in the center of NGC 404 to be a radio outflow associated with a confined jet driven by the active nucleus.

• OSTI ID: 22663272
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 845; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION SPECTROSCOPY
CARBON
CARBON MONOXIDE
EMISSION
EXCITATION
GALAXIES
GALAXY NUCLEI
HARD X RADIATION
INFRARED SPECTRA
LUMINOSITY
MASS
STARS
SYNCHROTRON RADIATION
WAVELENGTHS
X-RAY SOURCES