Blazar candidates of uncertain type

Sources were classified based on the EW of emission lines. For spectra with broad emission lines, MBH was estimated using the virial method. For absorption line dominated spectra, MBH was derived from the stellar velocity dispersion of the host galaxy.

The delta was estimated for FSRQs using an empirical relation between their gamma-ray and broad-line region luminosities. We obtained and analyzed optical spectra for the candidate counterparts of 86 BCUs. Based on the spectral features, we confirmed 35 sources as FSRQs, 45 as BL Lacs, 3 as low-ionization narrow emission-line regions (LINERs), and 3 as regular elliptical galaxies, and we secured redshifts for 54 objects.

We corrected the erroneous SDSS redshift for the counterparts of 4FGL J1047.9+0055 from 0.252 to 0.642. The black hole masses in log[MBH/M_{sun}_)]range from 7.07 to 9.22. The derived delta for 35 FSRQs spans from 3.62 to 35.43, with a mean value (delta) of 13.41.

The distribution of our classified sources in the gamma-ray luminosity-photon index plane is consistent with that of the known blazars. Our spectroscopic analysis provides reliable classifications and key physical parameters for a large sample of BCUs. This work offers a crucial dataset for future statistical studies of blazars, their jet physics, and the connection between accretion processes and jet power.