PDRs4All IV. An embarrassment of riches: Aromatic infrared bands in the Orion Bar
Creators: name: Chown, Ryan
name: Sidhu, Ameek
name: Peeters, Els
name: Tielens, Alexander G. G. M.
name: Cami, Jan
name: Berné, Olivier
name: Habart, Emilie
name: Alarcón, Felipe
name: Canin, Amélie
name: Schroetter, Ilane
name: Trahin, Boris
name: Van De Putte, Dries
name: Abergel, Alain
name: Bergin, Edwin A.
name: Bernard-Salas, Jeronimo
name: Boersma, Christiaan
name: Bron, Emeric
name: Cuadrado, Sara
name: Dartois, Emmanuel
name: Dicken, Daniel
name: El-Yajouri, Meriem
name: Fuente, Asunción
name: Goicoechea, Javier R.
name: Gordon, Karl D.
name: Issa, Lina
name: Joblin, Christine
name: Kannavou, Olga
name: Khan, Baria
name: Lacinbala, Ozan
name: Languignon, David
name: Gal, Romane Le
name: Maragkoudakis, Alexandros
name: Meshaka, Raphael
name: Okada, Yoko
name: Onaka, Takashi
name: Pasquini, Sofia
name: Pound, Marc W.
name: Robberto, Massimo
name: Röllig, Markus
name: Schefter, Bethany
name: Schirmer, Thiébaut
name: Vicente, Sílvia
name: Wolfire, Mark G.
name: Zannese, Marion
name: Aleman, Isabel
name: Allamandola, Louis
name: Auchettl, Rebecca
name: Baratta, Giuseppe Antonio
name: Bejaoui, Salma
name: Bera, Partha P.
name: Black, John H.
name: Boulanger, Francois
name: Bouwman, Jordy
name: Brandl, Bernhard
name: Brechignac, Philippe
name: Brünken, Sandra
name: Buragohain, Mridusmita
name: Burkhardt, Andrew
name: Candian, Alessandra
name: Cazaux, Stéphanie
name: Cernicharo, Jose
name: Chabot, Marin
name: Chakraborty, Shubhadip
name: Champion, Jason
name: Colgan, Sean W. J.
name: Cooke, Ilsa R.
name: Coutens, Audrey
name: Cox, Nick L. J.
name: Demyk, Karine
name: Meyer, Jennifer Donovan
name: Foschino, Sacha
name: García-Lario, Pedro
name: Gavilan, Lisseth
name: Gerin, Maryvonne
name: Gottlieb, Carl A.
name: Guillard, Pierre
name: Gusdorf, Antoine
name: Hartigan, Patrick
name: He, Jinhua
name: Herbst, Eric
name: Hornekaer, Liv
name: Jäger, Cornelia
name: Janot-Pacheco, Eduardo
name: Kaufman, Michael
name: Kemper, Francisca
name: Kendrew, Sarah
name: Kirsanova, Maria S.
name: Klaassen, Pamela
name: Kwok, Sun
name: Labiano, Álvaro
name: Lai, Thomas S. -Y.
name: Lee, Timothy J.
name: Lefloch, Bertrand
name: Petit, Franck Le
name: Li, Aigen
name: Linz, Hendrik
name: Mackie, Cameron J.
name: Madden, Suzanne C.
name: Mascetti, Joëlle
name: McGuire, Brett A.
name: Merino, Pablo
name: Micelotta, Elisabetta R.
name: Misselt, Karl
name: Morse, Jon A.
name: Mulas, Giacomo
name: Neelamkodan, Naslim
name: Ohsawa, Ryou
name: Omont, Alain
name: Paladini, Roberta
name: Palumbo, Maria Elisabetta
name: Pathak, Amit
name: Pendleton, Yvonne J.
name: Petrignani, Annemieke
name: Pino, Thomas
name: Puga, Elena
name: Rangwala, Naseem
name: Rapacioli, Mathias
name: Ricca, Alessandra
name: Roman-Duval, Julia
name: Roser, Joseph
name: Roueff, Evelyne
name: Rouillé, Gaël
name: Salama, Farid
name: Sales, Dinalva A.
name: Sandstrom, Karin
name: Sarre, Peter
name: Sciamma-O'Brien, Ella
name: Sellgren, Kris
name: Shenoy, Sachindev S.
name: Teyssier, David
name: Thomas, Richard D.
name: Togi, Aditya
name: Verstraete, Laurent
name: Witt, Adolf N.
name: Wootten, Alwyn
name: Zettergren, Henning
name: Zhang, Yong
name: Zhang, Ziwei E.
name: Zhen, Junfeng
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: (Abridged) Mid-infrared observations of photodissociation regions (PDRs) are dominated by strong emission features called aromatic infrared bands (AIBs). The most prominent AIBs are found at 3.3, 6.2, 7.7, 8.6, and 11.2 $μ$m. The most sensitive, highest-resolution infrared spectral imaging data ever taken of the prototypical PDR, the Orion Bar, have been captured by JWST. We provide an inventory of the AIBs found in the Orion Bar, along with mid-IR template spectra from five distinct regions in the Bar: the molecular PDR, the atomic PDR, and the HII region. We use JWST NIRSpec IFU and MIRI MRS observations of the Orion Bar from the JWST Early Release Science Program, PDRs4All (ID: 1288). We extract five template spectra to represent the morphology and environment of the Orion Bar PDR. The superb sensitivity and the spectral and spatial resolution of these JWST observations reveal many details of the AIB emission and enable an improved characterization of their detailed profile shapes and sub-components. While the spectra are dominated by the well-known AIBs at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 $μ$m, a wealth of weaker features and sub-components are present. We report trends in the widths and relative strengths of AIBs across the five template spectra. These trends yield valuable insight into the photochemical evolution of PAHs, such as the evolution responsible for the shift of 11.2 $μ$m AIB emission from class B$_{11.2}$ in the molecular PDR to class A$_{11.2}$ in the PDR surface layers. This photochemical evolution is driven by the increased importance of FUV processing in the PDR surface layers, resulting in a "weeding out" of the weakest links of the PAH family in these layers. For now, these JWST observations are consistent with a model in which the underlying PAH family is composed of a few species: the so-called 'grandPAHs'.
description: 25 pages, 10 figures, to appear in A&amp;A