| Classical simulations of the formation and evolution of the Oort cloud generally encounter two problems. The most severe one is simulations systematically predicting an Oort cloud to Scattered Disc population ratio that is much lower than inferred from observations. The analysis was traditionally done for long-period comets (LPCs) with total absolute magnitude HT < 9 or HT < 11, but recent studies show that the absolute magnitude distribution of LPCs is very shallow beyond HT ~ 7, the reasons for which are not yet known. Here we calculate the flux of LPCs with HT < 6.5 and q < 2.5 based on existing works, and infer a corresponding Oort cloud population for comets with HT < 6.5. Using the flux of Jupiter-family comets (JFCs) we estimate the number of Scattered Disc objects with HT < 6.5 and find the Oort cloud to Scattered Disc population ratio to be even higher than previous estimates based on smaller comets. The implications of this finding, along with several possible remedies, are discussed. |
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