Work

Insights for Early Massive Black Hole Growth from JWST Detection of the [Ne v] λ3427 Emission Line

Year: 2025

Type: article

Abstract: We use the narrow [Ne v] λ3427 emission line detected in the recently published JWST spectra of two galaxies, at z ≃ 6.9 and 5.6, to study the key properties of the active galactic nuclei (AGN) and the supermassive black holes (SMBHs) in their centers. Using a new empirical scaling linking the Ne V line emission with AGN accretion-driven (continuum) emission, derived from a highly complete low-redshift AGN sample, we show that the Ne V emission in the two z > 5 galaxies implies total (bolometric) AGN luminosities of order L bol ≈ (4–8) × 1045 erg s−1. Assuming that the radiation emitted from these systems is Eddington limited, the (minimal) black hole (BH) masses are of order M BH ≳ 107 M ⊙. Combined with the published stellar masses of the galaxies, estimated from dedicated fitting of their spectral energy distributions, the implied BH-to-stellar mass ratios are of order M BH/M host ≈ 0.1–1. This is considerably higher than what is found in the local Universe, but is consistent with the general trend seen in some other z ≳ 5 AGN. Given the intrinsic weakness of the Ne V line and the nature of the Ne V –to–L bol scaling, any (rare) detection of the [Ne v] λ3427 line at z > 5 would translate to similarly high AGN luminosities and SMBH masses, thus providing a unique observational path for studying luminous AGN well into the epoch of reionization, including obscured sources.

Source: The Astrophysical Journal Letters

DOI: 10.3847/2041-8213/ae0d8c