Bibcode
Runco, Jordan; Malkan, Matthew; Fernández-Ontiveros, J. A.; Spinoglio, Luigi
Referencia bibliográfica
American Astronomical Society, AAS Meeting #233, id.#434.07
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1
2019
Número de citas
0
Número de citas referidas
0
Descripción
We select a sample of 179 local (0 ≤ z < 0.35) galaxies from the
Hershel Science Archive to investigate possible relationships between
the 65μm, 71μm, 79μm, 84μm, 119μm, and 163μm OH lines
and the central region of the galaxy. The sample was observed using the
PACS instrument, and contains a wide range of Seyfert galaxies, LINERs,
and non-active star-forming galaxies. We fit the profiles of the six OH
lines when available in each galaxy to obtain the equivalent width (EW).
We find 24 galaxies with some P-Cygni or reverse P-Cygni line profiles,
which indicate outflows and inflows. We find a significant correlation
between the EW of the 79μm and 119μm OH lines and both the optical
spectral type, and the dust temperature measured by 25μm/60μm
slope. The more powerful the AGN, the more likely the OH lines are in
emission. OH emission is more common in Seyfert-1's than in Seyfert-2's.
The other four OH lines have fewer observations; they do not show these
correlations. This could be related to the process by which the OH lines
go into emission. For the 79μm and 119μm lines, this is thought to
be from collisional excitation in the dense AGN environment. Emission in
the other four lines is probably generated by radiative pumping, since
they arise from much higher energy levels (E/k = 300-600K). Bivariate
linear regressions reveal that the correlations are strongest with
optical spectral type, and that the correlation with dust temperature is
secondary, due to the warmer dust in Seyfert nuclei. Lastly, we use the
[NUV – H] color to estimate the amount of dust obscuration. We
find that more dust obscuration makes the 119μm line more likely to
be in absorption, but not the other five OH lines. This additional
correlation with EW(OH119) is driven by P-Cygni features in outflows
which are particularly prominent in ULIRGs, where the absorption
component often dominates the emission component.