GOALS-JWST: Small Neutral Grains and Enhanced 3.3 μm PAH Emission in the Seyfert Galaxy NGC 7469

Creators: Lai 賴, Thomas S.-Y. 劭愉^{1, 2}; Armus, Lee^{1, 2}; Bianchin, Marina³; Díaz-Santos, Tanio⁴; Linden, Sean T.⁵; Privon, George C.^{6, 7, 8}; Inami, Hanae⁹; U, Vivian³; Bohn, Thomas⁹; Evans, Aaron S.^{6, 7}; Larson, Kirsten L.¹⁰; Hensley, Brandon S.¹¹; Smith, J.-D. T.¹²; Malkan, Matthew A.¹³; Song, Yiqing^{14, 15}; Stierwalt, Sabrina¹⁶; van der Werf, Paul P.¹⁷; McKinney, Jed⁵; Aalto, Susanne¹⁸; Buiten, Victorine A.¹⁷; Rich, Jeff¹⁹; Charmandaris, Vassilis^{4, 20}; Appleton, Philip^{1, 2}; Barcos-Muñoz, Loreto^{6, 7}; Böker, Torsten¹⁰; Finnerty, Luke¹³; Kader, Justin A.³; Law, David R.¹⁰; Medling, Anne M.¹²; Brown, Michael J. I.²¹; Hayward, Christopher C.²²; Howell, Justin^{1, 2}; Iwasawa, Kazushi^{23, 24}; Kemper, Francisca^{25, 24, 26}; Marshall, Jason²⁷; Mazzarella, Joseph M.^{1, 2}; Müller-Sánchez, Francisco²⁸; Murphy, Eric J.⁶; Sanders, David²⁹; Surace, Jason^{1, 2}

1. Infrared Processing and Analysis Center
2. California Institute of Technology
3. University of California, Irvine
4. European University Cyprus
5. University of Massachusetts Amherst
6. National Radio Astronomy Observatory
7. University of Virginia
8. University of Florida
9. Hiroshima University
10. Space Telescope Science Institute
11. Princeton University
12. University of Toledo
13. University of California, Los Angeles
14. European Southern Observatory
15. Atacama Large Millimeter Submillimeter Array
16. Occidental College
17. Leiden University
18. Chalmers University of Technology
19. Carnegie Observatories
20. University of Crete
21. Monash University
22. Flatiron Institute
23. University of Barcelona
24. Institució Catalana de Recerca i Estudis Avançats
25. Spanish National Research Council
26. Institut d'Estudis Espacials de Catalunya
27. Glendale Community College
28. University of Memphis
29. University of Hawaii at Manoa

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 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.

Copyright and License

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

The authors thank A. Witt and E. Peeters for helpful discussions. This work is based on observations made with the NASA/ESA/CSA JWST. T.S.-Y.L. acknowledges funding support from NASA grant JWST-ERS-01328. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program No. 1328 and can be accessed via doi:10.17909/vq6q-sd19. Research at UCI by M.B. and V.U. was supported by funding from program No. JWST-GO-01717, which was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. V.U. further acknowledges partial funding support from NASA Astrophysics Data Analysis Program (ADAP) grant Nos. 80NSSC20K0450 and 80NSSC23K0750 and HST grant Nos. HST-AR-17063.005-A and HST-GO-17285.001. The Flatiron Institute is supported by the Simons Foundation. H.I. and T.B. acknowledge support from JSPS KAKENHI grant No. JP21H01129 and the Ito Foundation for Promotion of Science. A.M.M. acknowledges support from the National Science Foundation under grant No. 2009416. A.S.E. and S.L. acknowledge support from NASA grants HST-GO15472 and HST-GO16914. S.A. gratefully acknowledges support from ERC Advanced grant 789410, the Swedish Research Council, and the Knut and Alice Wallenberg (KAW) Foundation. K.I. acknowledges support by the Spanish MCIN under grant PID2019-105510GB-C33/AEI/10.13039/501100011033. F.M.-S. acknowledges support from NASA through ADAP award 80NSSC19K1096. Finally, this research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Facilities

JWST (NIRSpec & MIRI) - , MAST - , NED - .

Software References

Astropy (Astropy Collaboration et al. 2013, 2018, 2022), CAFE (Marshall et al. 2007), JWST Science Calibration Pipeline (Bushouse et al. 2022), lmfit (Newville et al. 2014), Matplotlib (Hunter 2007), Numpy (van der Walt et al. 2011; Harris et al. 2020), QFitsView (Ott 2012), SciPy (Virtanen et al. 2020).

Files

Lai_2023_ApJL_957_L26.pdf

Files (1.9 MB)

Name	Size	Download all
Lai_2023_ApJL_957_L26.pdf md5:cc9def35f762e844d9c4e831be7f9c1c	1.9 MB	Preview Download

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes