A small and vigorous black hole in the early Universe

Abstract

Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang1–3. Models consider different seeding and accretion scenarios4–7, which require the detection and characterization of black holes in the first few hundred million years after the Big Bang to be validated. Here we present an extensive analysis of the JWST-NIRSpec spectrum of GN-z11, an exceptionally luminous galaxy at z = 10.6, revealing the detection of the [Neiv]λ2423 and CII*λ1335 transitions (typical of active galactic nuclei), as well as semi-forbidden nebular lines tracing gas densities higher than 109 cm−3, typical of the broad line region of active galactic nuclei. These spectral features indicate that GN-z11 hosts an accreting black hole. The spectrum also reveals a deep and blueshifted CIVλ1549 absorption trough, tracing an outflow with velocity 800−1,000 km s−1, probably driven by the active galactic nucleus. Assuming local virial relations, we derive a black hole mass of $$\log ({M}_{{\rm{BH}}}/{M}_{\odot })=6.2\pm 0.3$$ log ( M BH / M ⊙ ) = 6.2 ± 0.3 , accreting at about five times the Eddington rate. These properties are consistent with both heavy seeds scenarios and scenarios considering intermediate and light seeds experiencing episodic super-Eddington phases. Our finding explains the high luminosity of GN-z11 and can also provide an explanation for its exceptionally high nitrogen abundance.

GN-z11 in Context: Possible Signatures of Globular Cluster Precursors at Redshift 10

“…Even assuming a conservatively low T e = 0.5 × 10 4 K, the 99% confidence upper limit on the F 1483 /F 1486 flux ratio implies n e  10 5 -10 6 cm −3 in the N IVemitting gas. We note that the results of this analysis are consistent with those derived from deeper follow-up spectra by Maiolino et al (2024); though their more stringent upper limit of F 1483 /F 1486 < 0.15 (3σ) implies densities at the upper end of this range, n e  10 6 cm −3 .…”

“…In this section, we present the photoionization modeling we perform and comparisons to the observed line fluxes; we reserve some additional details and plots including the line fluxes actually fit for Appendix B. Note that while we compare to AGN models, our model line fitting assumes that the nebular emission is powered by star formation; we return to discuss the possibility of a broad-line AGN contribution (Maiolino et al 2024) in Section 3.3.…”

“…In Section 5, we combine the inferences from the previous section into a picture of GN-z11 that we consider in a broader context. In this work, we primarily seek to understand this spectrum in the context of the assumption that the nebular emission is powered by star formation, but as argued from follow-up spectroscopy by Maiolino et al (2024) during the refereeing of this manuscript, part of this emission could be produced instead by a small accreting black hole. We compare to this subsequent analysis where relevant, and return to comment on this in more detail in Section 3.3.…”

A Candidate Supermassive Black Hole in a Gravitationally Lensed Galaxy at Z ≈ 10

“…Until recently, the high-redshift SMBH population has remained hidden. However, Chandra and JWST observations have started to reveal the presence of a handful of candidate active galactic nuclei (AGN) in the very early Universe (Bogdán et al 2024;Larson et al 2023;Maiolino et al 2024).…”

Fast Outflows and Luminous He ii Emission in Dwarf Galaxies with Active Galactic Nuclei (AGN)

“…Therefore, it is interesting to also consider the possible impact of AGN feedback in dwarf galaxies. Moreover, low-z dwarf galaxies likely possess properties close to those of moderate AGN host galaxies in the early universe (e.g., Maiolino et al 2024;Matthee et al 2023). Such AGN feedback may also regulate the growth of (super)massive black hole seeds and first galaxies (e.g., Silk 2017).…”