GOALS-JWST: Small Neutral Grains and Enhanced 3.3 μm PAH Emission in the Seyfert Galaxy NGC 7469
Journal article, 2023
We present James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) integral field spectroscopy of the nearby luminous infrared galaxy NGC 7469. We take advantage of the high spatial/spectral resolution and wavelength coverage of JWST/NIRSpec to study the 3.3 μm neutral polycyclic aromatic hydrocarbon (PAH) grain emission on ∼200 pc scales. A clear change in the average grain properties between the star-forming ring and the central AGN is found. Regions in the vicinity of the AGN, with [Ne iii]/[Ne ii] > 0.25, tend to have larger grain sizes and lower aliphatic-to-aromatic (3.4/3.3) ratios, indicating that smaller grains are preferentially removed by photodestruction in the vicinity of the AGN. PAH emission at the nucleus is weak and shows a low 11.3/3.3 PAH ratio. We find an overall suppression of the total PAH emission relative to the ionized gas in the central 1 kpc region of the AGN in NGC 7469 compared to what has been observed with Spitzer on 3 kpc scales. However, the fractional 3.3 μm-to-total PAH power is enhanced in the starburst ring, possibly due to a variety of physical effects on subkiloparsec scales, including recurrent fluorescence of small grains or multiple photon absorption by large grains. Finally, the IFU data show that while the 3.3 μm PAH-derived star formation rate (SFR) in the ring is 27% higher than that inferred from the [Ne ii] and [Ne iii] emission lines, the integrated SFR derived from the 3.3 μm feature would be underestimated by a factor of 2 due to the deficit of PAHs around the AGN, as might occur if a composite system like NGC 7469 were to be observed at high redshift.
Author
Thomas Lai
California Institute of Technology (Caltech)
Lee Armus
California Institute of Technology (Caltech)
Marina Bianchin
University of California at Irvine (UCI)
T. Diaz-Santos
European University Cyprus
Foundation for Research and Technology-Hellas (FORTH)
S. T. Linden
University of Massachusetts
G. Privon
University of Virginia
National Radio Astronomy Observatory
University of Florida
H. Inami
Hiroshima University
U. Vivian
University of California at Irvine (UCI)
Thomas Bohn
Hiroshima University
Aaron S. Evans
University of Virginia
National Radio Astronomy Observatory
K. Larson
Space Telescope Science Institute (STScI)
Brandon S. Hensley
Princeton University
J. T. Smith
University of Toledo
M. A. Malkan
University of California
Y. Song
Atacama Large Millimeter-submillimeter Array (ALMA)
European Southern Observatory Santiago
S. Stierwalt
Occidental College
P. van der Werf
Leiden University
Jed McKinney
University of Massachusetts
Susanne Aalto
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Victorine A. Buiten
Leiden University
Jeff Rich
Carnegie Observatories
V. Charmandaris
European University Cyprus
University of Crete
Foundation for Research and Technology-Hellas (FORTH)
P. Appleton
California Institute of Technology (Caltech)
Loreto Barcos-Munoz
University of Virginia
National Radio Astronomy Observatory
T. Boker
European Space Agency (ESA)
Luke Finnerty
University of California
Justin A. Kader
University of California at Irvine (UCI)
David Law
Space Telescope Science Institute (STScI)
Anne M. Medling
University of Toledo
Michael J.I. Brown
Monash University
Christopher C. Hayward
Flatiron Institute
Justin Howell
California Institute of Technology (Caltech)
K. Iwasawa
Catalan Institution for Research and Advanced Studies
University of Barcelona
F. Kemper
Institute of Space Studies of Catalonia (IEEC)
Catalan Institution for Research and Advanced Studies
Institute of Space Sciences (ICE) - CSIC
Jason Marshall
Glendale Community College
J. Mazzarella
California Institute of Technology (Caltech)
Francisco Muller-Sanchez
University of Memphis
E. J. Murphy
National Radio Astronomy Observatory
D. B. Sanders
University of Hawaii
J. A. Surace
California Institute of Technology (Caltech)
Astrophysical Journal Letters
2041-8205 (ISSN) 2041-8213 (eISSN)
Vol. 957 2 L26Exploring the Hidden Dusty Nuclei of Galaxies (HIDDeN)
European Research Council (ERC) (789410), 2018-10-01 -- 2023-09-30.
Subject Categories
Subatomic Physics
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.3847/2041-8213/ad0387