The X-ray variability of Seyfert 1.8/1.9 galaxies
  Seyfert 1.8/1.9 are sources showing weak broad H-alpha components in their
optical spectra. We aim at testing whether Seyfert 1.8/1.9 have similar
properties at UV and X-ray wavelengths to Seyfert 2. We use the 15 Seyfert
1.8/1.9 in the Veron Cetty and Veron catalogue with public data available from
the Chandra and/or XMM-Newton archives at different dates, with timescales
between observations ranging from days to years. Our results are homogeneously
compared with a previous work using the same methodology applied to a sample of
Seyfert 2 (Hernandez-Garcia et al. 2015). X-ray variability is found in all 15
nuclei over the aforementioned ranges of timescales. The main variability
pattern is related to intrinsic changes in the sources, which are observed in
ten nuclei. Changes in the column density are also frequent, as they are
observed in six nuclei, and variations at soft energies, possibly related to
scattered nuclear emission, are detected in six sources. X-ray intraday
variations are detected in six out of the eight studied sources. Variations at
UV frequencies are detected in seven out of nine sources. A comparison between
the samples of Seyfert 1.8/1.9 and 2 shows that, even if the main variability
pattern is due to intrinsic changes of the sources in the two families, these
nuclei exhibit different variability properties in the UV and X-ray domains. In
particular, variations in the broad X-ray band on short time-scales
(days/weeks), and variations in the soft X-rays and UV on long time-scales
(months/years) are detected in Seyfert 1.8/1.9 but not in Seyfert 2. Overall,
we suggest that optically classified Seyfert 1.8/1.9 should be kept separated
from Seyfert 2 galaxies in UV/X-ray studies of the obscured AGN population
because their intrinsic properties might be different.
