CLOUDY view of the warm corona. (arXiv:1901.02962v1 [astro-ph.HE])

CLOUDY view of the warm corona. (arXiv:1901.02962v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Panda_S/0/1/0/all/0/1">Swayamtrupta Panda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Czerny_B/0/1/0/all/0/1">Bo&#x17c;ena Czerny</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Done_C/0/1/0/all/0/1">Chris Done</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kubota_A/0/1/0/all/0/1">Aya Kubota</a>

Bright active galaxies show a range of properties but many of these
properties are correlated which has led to the concept of the Quasar Main
Sequence. We test whether our current understanding of the quasar structure
allows reproducing the pattern observed in the optical plane formed by the
kinematic line width of H$beta$ and the relative importance of the Fe II
optical emission. We performed simulations of the H$beta$ and Fe II production
using the code CLOUDY and well-justified assumptions about the broadband
spectra, distance of the emission line region, and the cloud properties. We
show that the presence of the warm corona is an important element of the
broadband spectrum which decreases the dependence of the relative Fe II
emissivity on the Eddington ratio, and allows to reproduce the rare cases of
the particularly strong Fe II emitters. Models are sensitive to the adopted
cloud distance, and strong Fe II emission can be obtained either by adopting
strongly super-solar metallicity, or much shorter distance than traditionally
obtained from reverberation mapping. We modelled in a similar way the UV plane
defined by the Mg II line and Fe II UV pseudo-continuum, but here the model is
less successful, in general overproducing the Fe II strength. We found that the
Fe II optical and UV emissivity depend in a different way on the turbulent
velocity and metallicity, and the best extension of the model in order to cover
both planes is to allow very large turbulent velocities in the Broad Line
Region clouds.

Bright active galaxies show a range of properties but many of these
properties are correlated which has led to the concept of the Quasar Main
Sequence. We test whether our current understanding of the quasar structure
allows reproducing the pattern observed in the optical plane formed by the
kinematic line width of H$beta$ and the relative importance of the Fe II
optical emission. We performed simulations of the H$beta$ and Fe II production
using the code CLOUDY and well-justified assumptions about the broadband
spectra, distance of the emission line region, and the cloud properties. We
show that the presence of the warm corona is an important element of the
broadband spectrum which decreases the dependence of the relative Fe II
emissivity on the Eddington ratio, and allows to reproduce the rare cases of
the particularly strong Fe II emitters. Models are sensitive to the adopted
cloud distance, and strong Fe II emission can be obtained either by adopting
strongly super-solar metallicity, or much shorter distance than traditionally
obtained from reverberation mapping. We modelled in a similar way the UV plane
defined by the Mg II line and Fe II UV pseudo-continuum, but here the model is
less successful, in general overproducing the Fe II strength. We found that the
Fe II optical and UV emissivity depend in a different way on the turbulent
velocity and metallicity, and the best extension of the model in order to cover
both planes is to allow very large turbulent velocities in the Broad Line
Region clouds.

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