Astrochemistry

Polycyclic Aromatic Hydrocarbons (PAHs) In The High-redshift Universe: Prospect Of The PRIMA FIRESS Low-resolution Spectroscopy

By Keith Cowing

Status Report

astro-ph.GA

October 10, 2025

Filed under astro-ph.GA, astrochemistry, astronomy, biochemistry, biophysics, Interstellar, organic chemistry, Polycyclic Aromatic Hydrocarbons, protocluster, spectrometer, Spectroscopy

Polycyclic Aromatic Hydrocarbons (PAHs) In The High-redshift Universe: Prospect Of The PRIMA FIRESS Low-resolution Spectroscopy — Simulated PRIMA/FIRESS spectrum of the PAH emission based on the model spectrum for a galaxy with log(LIR/L_⊙)= 13.6 in Fig.7(b) for selective redshifts (z = 3, 5, 7, 10). In addition to q_PAH= 0.038, two lower q_PAH values (1.8 and 0.5%) are used for simulation. Dark blue, purple, and green solid lines represent the noiseless model spectrum with q_PAH= 0.038, 0.018, 0.005 respectively. — astro-ph.GA

The integrated luminosity from the features of the polycyclic aromatic hydrocarbons (PAHs) exceeds the luminosity from atomic and molecular emission lines in the star-forming regions in galaxies and is a potential tracer of galaxy-scale star formation and molecular gas content of the high-redshift universe.

We simulate the observable PAH spectra using the PRobe far-Infrared Mission for Astrophysics far-infrared enhanced survey spectrometer (FIRESS) and investigate the capability of the FIRESS low-resolution spectroscopy for observing PAH emission spectrum from high-redshift galaxies.

Our investigation suggests that (1) PRIMA observations of PAH emission are ≳10 times more efficient at detecting galaxies than the VLA observations of CO(1-0) for galaxies with the same infrared luminosity, (2) PRIMA/FIRESS can detect the PAH emission from galaxies with LIR∼1012L_⊙ up to the end of reionization (and possibly beyond, if LIR∼1013L_⊙), (3) the PAH band ratios measured from a full spectral fitting and from a simple flux “clipping” method are different and vary depending on the interstellar radiation field strength, and (4) PRIMA/FIRESS can also be used as the PAH mapping instrument to measure star formation and redshift of the galaxies in high-redshift protoclusters.

Ilsang Yoon, Brandon Hensley, Thomas S. -Y. Lai, Irene Shivaei, Ismael Garcia-Bernete, Grant P. Donnelly, Alexandra Pope, J. D. T. Smith, Paul Torrey

Comments: Comments: This paper is part of the JATIS special issue focused on the PRobe Infrared Mission for Astrophysics (PRIMA) probe mission concept. The issue is edited by Matt Griffin and Naseem Rangwala (JATIS VOL. 11, NO. 3 | July 2025)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2509.02470 [astro-ph.GA] (or arXiv:2509.02470v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2509.02470
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Journal reference: JATIS VOL. 11, NO. 3 | July 2025
Related DOI:
https://doi.org/10.1117/1.JATIS.11.3.031634
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Submission history
From: Ilsang Yoon
[v1] Tue, 2 Sep 2025 16:23:24 UTC (18,305 KB)
https://arxiv.org/abs/2509.02470
Astrochemistry, Astrobiology,

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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