Unveiling the correlation between the UV 2175 Å dust attenuation bump, PAH emission, and gas-phase metallicity at cosmic noon
Abstract
The UV 2175 Å attenuation bump is one of the most prominent yet poorly understood features of galaxy attenuation curves. Its main candidate carrier is polycyclic aromatic hydrocarbon (PAH) molecules, which are more prevalent in high-metallicity environments. We present the first systematic study of the relationship between PAH abundance and the UV bump in 49 galaxies at cosmic noon (1.5 < z < 2.7), examining its dependence on stellar mass, star formation rate (SFR), and V-band optical depth. For 19 galaxies, we also investigate gas-phase metallicity using oxygen abundances. We measure the bump amplitude from VLT/MUSE spectroscopy and derive galaxy properties, including the PAH-to-dust mass fraction qPAH, through spectral energy distribution fitting with Prospector, combining JWST/NIRCam and JWST/MIRI photometry. Oxygen abundances are derived from strong-line diagnostics using Keck/MOSFIRE and JWST/NIRSpec data. We find a positive correlation between bump amplitude Ebump and qPAH (Spearman ρ= 0.60). UV bumps are rarely detected at low qPAH, supporting PAHs as their primary carriers. Both Ebump and qPAH correlate with stellar mass, oxygen abundance, and optical depth, and anticorrelate with specific SFR, suggesting that PAHs and the UV bump are suppressed in low-metallicity, dust-poor, and/or intensely star-forming environments. This is consistent with PAH destruction in environments with limited dust shielding and/or strong radiation fields. A principal component analysis of Ebump, qPAH, optical depth, specific SFR, and oxygen abundance explains 97% of the variance, suggesting that previously reported correlations with stellar mass reflect an underlying dependence on metallicity. Finally, variations in dust geometry may explain the wide range of bump amplitudes (0-0.5 mag) at high qPAH.
Related
- The JWST/PASSAGE Survey: Metallicity Radial Gradients in Emission-Line Galaxy Pairs at Cosmic Noon with NIRISS
- Unveiling star formation at sub-solar metallicity with ALMA2040
- ALMA Chemical Evolution (ACE) survey: The gas fundamental metallicity relation at cosmic noon
- Unveiling the Dark Ages: A New Pathway Using Tomographical 21 cm Cosmic Microwave Background Cross-correlations
- Theoretical emission lines and metallicity calibrations of H II regions in ASTRID simulation
BibTeX
@misc{arriscado2026unveiling,
title = {{Unveiling the correlation between the UV 2175 Å dust attenuation bump, PAH emission, and gas-phase metallicity at cosmic noon}},
author = {L. Arriscado and I. Shivaei and L. A. Boogaard and A. Mizener and D. Calzetti and P. G. Pérez-González and F. Rodríguez Montero and G. H. Rieke and Y. Zhu and A. Battisti and A. J. Bunker and E. Curtis-Lake and T. Díaz-Santos and Z. Ji and P. Rinaldi and B. Rodríguez del Pino and S. Tacchella and A. Varo-O'Ferrall and C. C. Williams and J. Witstok},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28743},
eprint = {2610.28743},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28743},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Unveiling the correlation between the UV 2175 Å dust attenuation bump, PAH emission, and gas-phase metallicity at cosmic noon
AU - L. Arriscado
AU - I. Shivaei
AU - L. A. Boogaard
AU - A. Mizener
AU - D. Calzetti
AU - P. G. Pérez-González
AU - F. Rodríguez Montero
AU - G. H. Rieke
AU - Y. Zhu
AU - A. Battisti
AU - A. J. Bunker
AU - E. Curtis-Lake
AU - T. Díaz-Santos
AU - Z. Ji
AU - P. Rinaldi
AU - B. Rodríguez del Pino
AU - S. Tacchella
AU - A. Varo-O'Ferrall
AU - C. C. Williams
AU - J. Witstok
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28743
UR - https://arxiv.org/abs/2610.28743
AB - The UV 2175 Å attenuation bump is one of the most prominent yet poorly understood features of galaxy attenuation curves. Its main candidate carrier is polycyclic aromatic hydrocarbon (PAH) molecules, which are more prevalent in high-metallicity environments. We present the first systematic study of the relationship between PAH abundance and the UV bump in 49 galaxies at cosmic noon (1.5 < z < 2.7), examining its dependence on stellar mass, star formation rate (SFR), and V-band optical depth. For 19 galaxies, we also investigate gas-phase metallicity using oxygen abundances. We measure the bump amplitude from VLT/MUSE spectroscopy and derive galaxy properties, including the PAH-to-dust mass fraction q_PAH, through spectral energy distribution fitting with Prospector, combining JWST/NIRCam and JWST/MIRI photometry. Oxygen abundances are derived from strong-line diagnostics using Keck/MOSFIRE and JWST/NIRSpec data. We find a positive correlation between bump amplitude E_bump and q_PAH (Spearman ρ= 0.60). UV bumps are rarely detected at low q_PAH, supporting PAHs as their primary carriers. Both E_bump and q_PAH correlate with stellar mass, oxygen abundance, and optical depth, and anticorrelate with specific SFR, suggesting that PAHs and the UV bump are suppressed in low-metallicity, dust-poor, and/or intensely star-forming environments. This is consistent with PAH destruction in environments with limited dust shielding and/or strong radiation fields. A principal component analysis of E_bump, q_PAH, optical depth, specific SFR, and oxygen abundance explains 97% of the variance, suggesting that previously reported correlations with stellar mass reflect an underlying dependence on metallicity. Finally, variations in dust geometry may explain the wide range of bump amplitudes (0-0.5 mag) at high q_PAH.
ER -