Linking Characteristics of the Polycyclic Aromatic Hydrocarbon Population with Galaxy Properties: A Quantitative Approach Using the NASA Ames PAH IR Spectroscopic Database

Abstract

Utilizing the data and tools provided through the NASA Ames PAH IR Spectroscopic Database (PAHdb), we study the PAH component of over 900 Spitzer-IRS galaxy spectra. Employing a database-fitting approach, the average PAH size, the PAH size distribution, and PAH ionization fraction are deduced. In turn, we examine their connection with the properties of the host galaxy. We found that PAH population within galaxies consists of middle-sized PAHs with an average number of carbon atoms of $\overline{N_C}$ = 55, and a charge state distribution of $\sim$40% ionized - 60% neutral. We describe a correlation between the 6.2/11.2 $\mu$m PAH ratio with the ionization parameter ($\gamma \equiv (G_0/n_{\mathrm{e}})(T_{\mathrm{gas}}/1\mathrm{K}{)}^{0.5}$), a moderate correlation between the 8.6/11.2 $\mu$m PAH ratio and specific star-formation rate, and a weak anti-correlation between $\gamma$ and M${}_{\ast }$. From the PAHdb decomposition we provide estimates for the 3.3 $\mu$m PAH band, not covered by Spitzer observations, and establish a correlation between the 3.3/11.2 $\mu$m PAH ratio with N${}_{\mathrm{C}}$. We further deliver a library of mid-IR PAH template spectra parameterized on PAH size and ionization fraction, which can be used in galaxy spectral energy distribution fitting codes for the modeling of the mid-IR PAH emission component in galaxies.

28 pages, 19 figures, 4 tables. Accepted for publication in ApJ

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Cited by in corpus (15)

• PHANGS-JWST First Results: Variations in PAH Fraction as a Function of ISM Phase and Metallicity
• A Framework for Modeling Polycyclic Aromatic Hydrocarbon Emission in Galaxy Evolution Simulations
• Polycyclic Aromatic Hydrocarbon Emission in the Central Regions of Three Seyferts the Implication for Underlying Feedback Mechanisms
• JWST MIRI and NIRCam observations of NGC 891 and its circumgalactic medium
• Spectral variations among different scenarios of PAH processing or formation
• Polycyclic Aromatic Hydrocarbon Size Tracers
• PDRs4All XVI. Tracing aromatic infrared band characteristics in photodissociation region spectra with PAHFIT in the JWST era
• PDRs4All: XVIII. The evolution of the PAH ionisation and PAH size distribution across the Orion Bar
• The Background Interstellar Medium as Observed from Off-Order Low-Resolution Spitzer-IRS Spectra
• The Calibration of Polycyclic Aromatic Hydrocarbon Dust Emission as a Star Formation Rate Indicator in the AKARI NEP Survey
• SPHEREx: Aromatics, Aliphatics and PAH Size across the Iris Nebula
• Aromatic Species in the Molecular Universe
• Anharmonic infrared spectra of cationic pyrene and superhydrogenated derivatives
• PDRs4All XIX. The 6 to 9 $\mu$m region as a probe of PAH charge and size in the Orion Bar
• Star Formation Beyond the Optical Disk : The Low-Density Outskirts of NGC2090