Hidden Double-Peaked Emitters in Seyfert 2 Galaxies
  We present the detection of extremely broad, double-peaked, highly polarized
Halpha emission lines in the nuclei of the well-known Seyfert 2 galaxies NGC
2110 and NGC 5252. These hidden broad Halpha emission lines, visible only in
scattered light, are shown to display significant variability in strength and
profile on timescales of <~ 1 yr. That the broad emission line exhibits
variability in polarized flux also suggests that the scattering region must be
very compact, possibly confined in a small number of electron clouds <~ 1 lt-yr
in size. Our observational constraints place these clouds within ~10 pc of the
nucleus with temperatures < 10^6 K and densities ~ 10^7 cm^-3, consistent with
a region just outside the obscuring torus between the broad-line region and
narrow-line region. These scattering clouds could arise from the clumpy torus
itself. These findings and other properties indicate that NGC 2110 and NGC 5252
are the hidden counterparts to the broad-line double-peaked emission-line AGNs,
whose examples include Arp 102B and 3C 332.
