VLBA Continuum Observations of NGC 4258: Constraints on an Advection-Dominated Accretion Flow
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چکیده
We report a 3σ upper limit of 220μJy on any 22-GHz continuum emission coincident with the central engine in NGC 4258. If NGC 4258 is powered by an advection-dominated accretion flow, this radio upper limit implies that the inner advection-dominated flow cannot extend significantly beyond ∼ 10 Schwarzschild radii. Subject headings: accretion, accretion disks — galaxies: active — galaxies: nuclei — galaxies: individual (NGC 4258) — masers
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تاریخ انتشار 1998