The Nuclear Spectral Energy Distribution of NGC 4395, the Least Luminous Type 1 Seyfert Galaxy

We present X-ray (ROSAT), infrared, and radio observations of NGC 4395, whichharbors the optically least luminous type 1 Seyfert nucleus discovered thusfar. In combination with published optical and ultraviolet spectra, we haveused these data to assemble the broadband spectral energy distribution (SED) ofthe galaxy's nucleus. Interestingly, the SED of NGC 4395 differs markedly fromthe SEDs of both quasars and typical low-luminosity active galactic nuclei,which may be a manifestation of the different physical conditions (i.e., blackhole masses, accretion rates, and/or accretion modes) that exist in theseobjects. The nuclear X-ray source in NGC 4395 is variable and has an observedluminosity of just ~ 10^38 ergs/s. Although this emission could plausibly beassociated with either a weak active nucleus or a bright stellar-mass binarysystem, the optical and ultraviolet emission-line properties of the nucleusstrongly suggest that the X-rays arise from a classical AGN.