Unveiling the correlation between the UV 2175 Å dust attenuation bump, PAH emission, and gas-phase metallicity at cosmic noon

The UV 2175,Å attenuation bump is one of the most prominent yet poorly understood features of galaxy attenuation and extinction curves. It is observed from the local Universe up to z∼ 7, but its physical origin remains uncertain. Its main carrier candidate is polycyclic aromatic hydrocarbon (PAH) molecules, which are more prevalent in high-metallicity environments. We present the first systematic study of the relationship between the PAH abundance and the UV attenuation bump in 49 galaxies at cosmic noon (1.5<z<2.7), and we examine its dependence on the stellar mass (M_*), star formation rate (SFR), and V-band optical depth (τ_V). For 19 galaxies, we also explore the role of gas-phase metallicity via oxygen abundance measurements. We measured the UV bump amplitude using VLT/MUSE spectroscopy from the MUSE/HUDF survey. Galaxy properties, including the PAH-to-dust mass fraction q_̊m PAH, were derived via spectral energy distribution (SED) fitting with , combining JWST/NIRCam and JWST/MIRI photometry (λ_ Prospector ̊m rest at z=2). Oxygen abundances were obtained from strong-line diagnostics using Keck/MOSFIRE and JWST/NIRSpec data. We find a positive correlation between the UV bump amplitude E_̊m bump and q_̊m PAH (Spearman ̊ho=0.60); at low q_̊m PAH, UV bumps are rarely detected, supporting PAHs as the primary carriers. Both E_̊m bump and q_̊m PAH correlate with M_*, oxygen abundance, and τ_V, and they anticorrelate with the specific SFR (sSFR), indicating that PAHs and the UV bump are suppressed in low-metallicity, dust-poor, and/or intensely star-forming environments. This is consistent with the destruction of PAHs in regions with limited dust shielding and/or strong radiation fields produced by young stellar populations. A principal component analysis of E_̊m bump, q_̊m PAH, τ_V, sSFR, and oxygen abundance explains 97% of the data variance, supporting previous findings that reported correlations with M_* reflect an underlying correlation with metallicity. Finally, variations in dust geometry can explain the wide range of UV bump amplitudes (sim0-0.5,mag) at high q_̊m PAH.