Distances at which AGNs enable prebiotic chemistry (d_O), facilitate potential extinction events (d_B), and permit photosynthesis (d_P) are depicted as a function of the mass of the SMBH (M_BH). The x-axis is truncated at 10⁴ M_⊙ because this value is quite close to some of the smaller central BHs known to date (Mezcua et al. 2018; Graham et al. 2019; Nguyen et al. 2019), and at 10¹¹ M_⊙ as SMBHs are not expected to exceed this theoretical limit at the current age of the universe (Inayoshi & Haiman 2016; King 2016; Pacucci et al. 2017). For Sagittarius A*, we obtain d_O ≈ 44 pc, d_B ≈ 2 pc, and d_P ≈ 340 pc after selecting an Eddington factor close to unity. Top panel: the solid and dashed curves correspond to Eddington factors of unity and 0.1, respectively; note that these two values are consistent with observational constraints that mostly favor average Eddington factors of ∼0.1–1 (Marconi et al. 2004). Bottom panel: the dotted–dashed and dotted curves correspond to Eddington factors of 10 and 0.01, respectively; these values are also consistent with observations and theory (see Section 2.1).