Astrochemistry

The Calibration of Polycyclic Aromatic Hydrocarbon Dust Emission as a Star Formation Rate Indicator in the AKARI NEP Survey

By Keith Cowing
Status Report
astro-ph.GA
August 28, 2024
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The Calibration of Polycyclic Aromatic Hydrocarbon Dust Emission as a Star Formation Rate Indicator in the AKARI NEP Survey
Example of a typical PAHfit result for a main-sequence galaxy at z=0.36 (ID: J180123.2+654950.0; The SED is shown in Figure 5(a)), fit to the model SED (circle points). The solid red line shows the best-fit result. Drude profile fits to the PAH dust emission features are shown in blue. The solid purple line underlying the emission represents the continuum, which is the summation of the individual blackbody components shown in yellow. — astro-ph.GA

Polycyclic aromatic hydrocarbon (PAH) dust emission has been proposed as an effective extinction-independent star formation rate (SFR) indicator in the mid-infrared (MIR), but this may depend on conditions in the interstellar medium.

The coverage of the AKARI/Infrared Camera (IRC) allows us to study the effects of metallicity, starburst intensity, and active galactic nuclei on PAH emission in galaxies with fν(L18W)≲19 AB mag. Observations include follow-up, rest-frame optical spectra of 443 galaxies within the AKARI North Ecliptic Pole survey that have IRC detections from 7-24 μm.

We use optical emission line diagnostics to infer SFR based on Hα and [O II]λλ3726,3729 emission line luminosities. The PAH 6.2 μm and PAH 7.7 μm luminosities (L(PAH 6.2 μm) and L(PAH 7.7 μm), respectively) derived using multi-wavelength model fits are consistent with those derived from slitless spectroscopy within 0.2 dex. L(PAH 6.2 μm) and L(PAH 7.7 μm) correlate linearly with the 24 μm-dust corrected Hα luminosity only for normal, star-forming “main-sequence” galaxies.

Assuming multi-linear correlations, we quantify the additional dependencies on metallicity and starburst intensity, which we use to correct our PAH SFR calibrations at 0<z<1.2 for the first time.

We derive the cosmic star formation rate density (SFRD) per comoving volume from 0.15≲z≲1. The PAH SFRD is consistent with that of the far-infrared and reaches an order of magnitude higher than that of uncorrected UV observations at z∼1. Starburst galaxies contribute ≳0.7 of the total SFRD at z∼1 compared to main-sequence galaxies.

Helen Kyung Kim, Matthew A. Malkan, Toshinobu Takagi, Nagisa Oi, Denis Burgarella, Takamitsu Miyaji, Hyunjin Shim, Hideo Matsuhara, Tomotsugu Goto, Yoichi Ohyama, Veronique Buat, Seong Jin Kim

Comments: Accepted for publication in The Astrophysical Journal. 50 pages, 27 figures, 9 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2408.14005 [astro-ph.GA] (or arXiv:2408.14005v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2408.14005
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Submission history
From: Helen Kim
[v1] Mon, 26 Aug 2024 04:15:12 UTC (1,698 KB)
https://arxiv.org/abs/2408.14005

Astrobiology, astrochemistry,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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