The Origin and Evolution of the Normal Type Ia SN 2018aoz with Infant-phase Reddening and Excess Emission

SN~2018aoz is a Type Ia SN with $B$-band plateau and excess emission in the infant-phase light curves $\lesssim$ 1 day after first light, evidencing an over-density of surface iron-peak elements as shown our previous study. Here, we advance constraints on nature origin based its evolution until nebular phase. Near-peak spectroscopic features show intermediate between two subtypes normal Ia: Core-Normal Broad-Line. The could have contributions from radioactive decay well ejecta interaction either binary companion or small torus circumstellar material. Nebular-phase limits H$\alpha$ He~I favour white dwarf companion, consistent size constrained by low early luminosity, while absence [O~I] disfavours violent merger progenitor. Of main explosion mechanisms proposed to explain distribution SN~2018aoz, asymmetric Chandrasekhar-mass less progenitor observed blueshifts nebular-phase [Fe~II] [Ni~II]. helium-shell double-detonation compatible lack C spectral features, but current 1-D models are incompatible emission, $B_{\rm max}-V_{\rm max}$ color, [Ca~II]. Although processes still need be more precisely understood, same produce significant fraction SNe that appear $\sim$ day.