TY - JOUR
T1 - PHANGS-JWST First Results
T2 - Variations in PAH Fraction as a Function of ISM Phase and Metallicity
AU - Chastenet, Jérémy
AU - Sutter, Jessica
AU - Sandstrom, Karin
AU - Belfiore, Francesco
AU - Egorov, Oleg V.
AU - Larson, Kirsten L.
AU - Leroy, Adam K.
AU - Liu, Daizhong
AU - Rosolowsky, Erik
AU - Thilker, David A.
AU - Watkins, Elizabeth J.
AU - Williams, Thomas G.
AU - Barnes, Ashley T.
AU - Bigiel, Frank
AU - Boquien, Médéric
AU - Chevance, Mélanie
AU - Chiang, I. Da
AU - Dale, Daniel A.
AU - Kruijssen, J. M.Diederik
AU - Emsellem, Eric
AU - Grasha, Kathryn
AU - Groves, Brent
AU - Hassani, Hamid
AU - Hughes, Annie
AU - Kreckel, Kathryn
AU - Meidt, Sharon E.
AU - Rickards Vaught, Ryan J.
AU - Sardone, Amy
AU - Schinnerer, Eva
N1 - Funding Information:
We present maps of R ≡ (F770W + F1130W)/F2100W in these first four targets. This ratio traces the relative fraction of PAHs (the F770W and F1130W bands) to small dust grains (from the F2100W band). The ratio R decreases in H ii regions, showing that the PAH fraction drops there, which is further discussed in Egorov et al. (). We track the variations of the abundance ratio as a function of the ISM content as traced by CO, H α, H i , and metallicity measurements. We find that R as a function of ionized gas fraction (traced by , Figure , bottom left panel) shows a similar trend in all the targets: a rather flat distribution up to a value of for all galaxies, at which the abundance ratio systematically decreases. The variations with the fraction of molecular gas (Figure , bottom right panel) are rather small. This work sets the stage for future research to refine how the local environment influences the relative PAH fraction. As JWST data reduction methods are improved and the sample of galaxies with this coverage expands, the conditions in which PAHs are found will be better established. This early study provides insights into how global metallicity and ISM environment can effect the relative PAH population and shows the improvements that JWST observations bring to determining the answers to these questions. PAH PAH PAH J.M.D.K. gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program via the ERC Starting Grant MUSTANG (grant agreement number 714907). T.G.W. and E.S. acknowledge funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement No. 694343). M.B. acknowledges support from FONDECYT regular grant 1211000 and by the ANID BASAL project FB210003. I.C. thanks the National Science and Technology Council for support through grants 108-2112-M-001-007-MY3 and 111-2112-M-001-038-MY3, and the Academia Sinica for Investigator Award AS-IA-109-M02. K.K., O.E. gratefully acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the form of an Emmy Noether Research Group (grant number KR4598/2-1, PI Kreckel). F.B. would like to acknowledge funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement No.726384/Empire). E.R. and H.H. acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), funding reference number RGPIN-2022-03499. K.G. is supported by the Australian Research Council through the Discovery Early Career Researcher Award (DECRA) Fellowship DE220100766 funded by the Australian Government. K.G. is supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. A.S. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903834. A.K.L. gratefully acknowledges support by grants 1653300 and 2205628 from the National Science Foundation, by award JWST-GO-02107.009-A, and by a Humboldt Research Award from the Alexander von Humboldt Foundation.
Funding Information:
J.C. acknowledges support from ERC starting grant #851622 DustOrigin. E.J.W. acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project-ID 138713538—SFB 881 (“The Milky Way System,” subproject P1). M.C. gratefully acknowledges funding from the DFG through an Emmy Noether Research Group (grant number CH2137/1-1). COOL Research DAO is a Decentralized Autonomous Organization supporting research in astrophysics aimed at uncovering our cosmic origins. 28
Funding Information:
We thank the anonymous referee for careful reading and comments that helped improve the clarity of the paper. This work was carried out as part of the PHANGS collaboration, associated with JWST program 2107. This work is based on observations made with the NASA/ESA/CSA JWST. Some/all of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST) 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. The specific observations analyzed can be accessed via doi:10.17909/9bdf-jn24. Based on observations collected at the European Southern Observatory under ESO programmes 094.C-0623 (PI: Kreckel), 095.C-0473, 098.C-0484 (PI: Blanc), 1100.B-0651 (PHANGS-MUSE; PI: Schinnerer), as well as 094.B-0321 (MAGNUM; PI: Marconi), 099.B-0242, 0100.B-0116, 098.B-0551 (MAD; PI: Carollo) and 097.B-0640 (TIMER; PI: Gadotti). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2012.1.00650.S, ADS/JAO.ALMA#2013.1.01161.S, ADS/JAO.ALMA#2015.1.00925.S, ADS/JAO.ALMA#2015.1.00956.S, ADS/JAO.ALMA#2017.1.00392.S, ADS/JAO.ALMA#2017.1.00766.S, ADS/JAO.ALMA#2017.1.00886.L, ADS/JAO.ALMA#2018.1.01651.S. ADS/JAO.ALMA#2018.A.00062.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/2/1
Y1 - 2023/2/1
N2 - We present maps tracing the fraction of dust in the form of polycyclic aromatic hydrocarbons (PAHs) in IC 5332, NGC 628, NGC 1365, and NGC 7496 from JWST/MIRI observations. We trace the PAH fraction by combining the F770W (7.7 μm) and F1130W (11.3 μm) filters to track ionized and neutral PAH emission, respectively, and comparing the PAH emission to F2100W, which traces small, hot dust grains. We find the average R PAH = (F770W + F1130W)/F2100W values of 3.3, 4.7, 5.1, and 3.6 in IC 5332, NGC 628, NGC 1365, and NGC 7496, respectively. We find that H ii regions traced by MUSE Hα show a systematically low PAH fraction. The PAH fraction remains relatively constant across other galactic environments, with slight variations. We use CO+Hi +Hα to trace the interstellar gas phase and find that the PAH fraction decreases above a value of I H α / Σ H I + H 2 ∼ 10 37.5 erg s − 1 kpc − 2 ( M ⊙ pc − 2 ) − 1 in all four galaxies. Radial profiles also show a decreasing PAH fraction with increasing radius, correlated with lower metallicity, in line with previous results showing a strong metallicity dependence to the PAH fraction. Our results suggest that the process of PAH destruction in ionized gas operates similarly across the four targets.
AB - We present maps tracing the fraction of dust in the form of polycyclic aromatic hydrocarbons (PAHs) in IC 5332, NGC 628, NGC 1365, and NGC 7496 from JWST/MIRI observations. We trace the PAH fraction by combining the F770W (7.7 μm) and F1130W (11.3 μm) filters to track ionized and neutral PAH emission, respectively, and comparing the PAH emission to F2100W, which traces small, hot dust grains. We find the average R PAH = (F770W + F1130W)/F2100W values of 3.3, 4.7, 5.1, and 3.6 in IC 5332, NGC 628, NGC 1365, and NGC 7496, respectively. We find that H ii regions traced by MUSE Hα show a systematically low PAH fraction. The PAH fraction remains relatively constant across other galactic environments, with slight variations. We use CO+Hi +Hα to trace the interstellar gas phase and find that the PAH fraction decreases above a value of I H α / Σ H I + H 2 ∼ 10 37.5 erg s − 1 kpc − 2 ( M ⊙ pc − 2 ) − 1 in all four galaxies. Radial profiles also show a decreasing PAH fraction with increasing radius, correlated with lower metallicity, in line with previous results showing a strong metallicity dependence to the PAH fraction. Our results suggest that the process of PAH destruction in ionized gas operates similarly across the four targets.
UR - http://www.scopus.com/inward/record.url?scp=85148734720&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/acadd7
DO - 10.3847/2041-8213/acadd7
M3 - Article
AN - SCOPUS:85148734720
SN - 2041-8205
VL - 944
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L11
ER -