Spectra taken with the Hubble Space Telescope ( HST ) reveal that NGC 4450 emits Balmer emission lines with displaced double peaks and extremely high-velocity wings .
This characteristic line profile , previously seen in a few nearby LINERs and in a small fraction of broad-line radio galaxies , can be interpreted as a kinematic signature of a relativistic accretion disk .
We can reproduce the observed profile with a model for a disk with a radial range of 1000–2000 gravitational radii and inclined by 27 degrees along the line of sight .
The small-aperture HST data also allow us to detect , for the first time , the featureless continuum at optical wavelengths in NGC 4450 ; the nonstellar nucleus is intrinsically very faint , with M _ { B } = –11.2 mag for D = 16.8 Mpc .

We have examined the multiwavelength properties of NGC 4450 collectively with those of other low-luminosity active nuclei which possess double-peaked broad lines and find a number of common features .
These objects are all classified spectroscopically as “ type 1 ” LINERs or closely related objects .
The nuclear luminosities are low , both in absolute terms and relative to the Eddington rates .
All of them have compact radio cores , whose strength relative to the optical nuclear emission places them in the league of radio-loud active nuclei .
The broad-band spectral energy distributions of these sources are most notable for their deficit of ultraviolet emission compared to those observed in luminous Seyfert 1 nuclei and quasars .
The double-peaked broad-line radio galaxies Arp 102B and Pictor A have very similar attributes .
We discuss how these characteristics can be understood in the context of advection-dominated accretion onto massive black holes .