학술논문
GOALS-JWST: Small neutral grains and enhanced 3.3 micron PAH emission in the Seyfert galaxy NGC 7469
Document Type
Working Paper
Author
Lai, Thomas S. -Y.; Armus, Lee; Bianchin, Marina; Diaz-Santos, Tanio; Linden, Sean T.; Privon, George C.; Inami, Hanae; U, Vivian; Bohn, Thomas; Evans, Aaron S.; Larson, Kirsten L.; Hensley, Brandon S.; Smith, J. -D. T.; Malkan, Matthew A.; Song, Yiqing; Stierwalt, Sabrina; van der Werf, Paul P.; McKinney, Jed; Aalto, Susanne; Buiten, Victorine A.; Rich, Jeff; Charmandaris, Vassilis; Appleton, Philip; Barcos-Munoz, Loreto; Boker, Torsten; Finnerty, Luke; Kader, Justin A.; Law, David R.; Brown, Michael J. I.; Hayward, Christopher C.; Howell, Justin; Iwasawa, Kazushi; Kemper, Francisca; Marshall, Jason; Mazzarella, Joseph M.; Muller-Sanchez, Francisco; Murphy, Eric J.; Sanders, David; Surace, Jason
Source
Subject
Language
Abstract
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 um neutral polycyclic aromatic hydrocarbon (PAH) grain emission on ~60 pc scales. We find a clear change in the average grain properties between the star-forming ring and the central AGN. Regions in the vicinity of the AGN, with [NeIII]/[NeII]>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 photo-destruction in the vicinity of the AGN. 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 um to total PAH power is enhanced in the starburst ring, possibly due to a variety of physical effects on sub-kpc scales, including recurrent fluorescence of small grains or multiple photon absorption by large grains. Finally, the IFU data show that while the 3.3 um PAH-derived star formation rate (SFR) in the ring is 8% higher than that inferred from the [NeII] and [NeIII] emission lines, the integrated SFR derived from the 3.3 um feature would be underestimated by a factor of two 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.
Comment: 14 pages, 5 figures, 2 tables, Submitted to ApJL
Comment: 14 pages, 5 figures, 2 tables, Submitted to ApJL