Extended Data Fig. 8: Comparison of the Hα emission line in observations and simple model calculations.

a, Observed (black line) and absorption-corrected (orange dotted line) broad Hα emission line spectra of J1035 + 1422, normalized to the continuum. Overplotted for comparison are the Hα emission lines predicted by photoionization models from the inflow (red dashed line), the outflow (blue dashed line), and both (green dotted line) (assuming a covering factor of 0.5 (Ω_i = Ω₀= 0.5 in Supplementary Table 1) and a radial velocity 5,000 km s⁻¹ for both inflow and outflow). Clearly, the observed Hα is much stronger than the model prediction. This may be due to the oversimplicity of the models, in which a much broader velocity range is missing. Alternatively, and more likely, the excess Hα flux might be contributed by the accretion disk. b, The residual line profile (cyan dotted line; the zigzag shape is caused by the oversimplified model assumption of a single velocity instead of the actual large velocity gradient), which largely resembles the Hα line observed in the well studied disk-emitting quasar 3C332 (ref. ⁴³; grey solid line). Note that 3C332 shows a substantial excess component with respect to the best-fit disk line model (violet dashed line), which is redshifted with a velocity range of roughly 0−5,000 km s⁻¹. This is reminiscent of the redshifted Hα broad absorption line found in J1035 + 1422 here, suggesting the interesting possibility that this excess Hα emission in 3C332 might originate from inflows.