Nāpōwawā‘enakaulua : A Close Quasar Pair at Cosmic Dawn in the Aether Survey

We present the discovery and first characterization of Nāpōwawā‘enakaulua , the most compact known quasar pair candidate in the Epoch of Reionization, with a projected separation of only 0 . ″ 98 (≈5.56 pkpc at z ∼ 6.08) and a velocity offset of Δ v ≃ 15km s −1 . Using spectroscopy from JWST/NIRSpec integral field unit, as part of the Aether survey , Gemini/GNIRS and GMOS, we characterize the continuum and emission line properties of the two quasars, enabling constraints on their black hole masses ( M BH ≃ 1.5 × 10 9 and 4.0 × 10 8 M ⊙ ), accretion states ( λ Edd ≃ 1.23 and 1.07), and systemic redshifts ( z sys ≃ 6.0781 and 6.0785). We place this pair in the cosmological context by comparing the chance of occurrence to extrapolations of high- z quasar clustering measurements at larger scales, resulting in a ∼2–3 order of magnitude excess with respect to expectations. This excess hints at an underlying population of merger-triggered quasar pairs at cosmic dawn or to a denser-than-average galactic environment. Nāpōwawā‘enakaulua thus represents a crucial signpost to investigate the mass assembly of the first massive galaxies and black holes.