The Discovery of a Hidden Broad Line AGN in a Bulgeless Galaxy: Keck NIR Spectroscopic Observations of SDSS J085153.64+392611.76. (arXiv:2007.08525v1 [astro-ph.GA])

The Discovery of a Hidden Broad Line AGN in a Bulgeless Galaxy: Keck NIR Spectroscopic Observations of SDSS J085153.64+392611.76. (arXiv:2007.08525v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bohn_T/0/1/0/all/0/1">Thomas Bohn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Canalizo_G/0/1/0/all/0/1">Gabriela Canalizo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Satyapal_S/0/1/0/all/0/1">Shobita Satyapal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pfeifle_R/0/1/0/all/0/1">Ryan W. Pfeifle</a>

We report the discovery of a buried, active supermassive black hole in SDSS
J085153.64+392611.76, a bulgeless Seyfert 2 (Sy2) galaxy. Keck near-infrared
observations reveal a hidden broad line region, allowing for the rare case
where strong constraints can be placed on both the black hole mass and bulge
component. Using virial mass estimators, we obtain a black hole mass of
log($M_{rm{BH}}/M_{odot}$) = $6.78 pm 0.50$. This is one of the only Sy2 AGN
hosted in a bulgeless galaxy with a virial black hole mass estimate and could
provide important constraints on the formation scenarios of the black hole seed
population. The lack of a bulge component suggests that the SMBH has grown
quiescently, likely caused by secular processes independent of major mergers.
In the absence of a detectable bulge component, we find the $M_{rm{BH}}$ –
$M_{rm{stellar}}$ relation to be more reliable than the $M_{rm{BH}}$ –
$M_{rm{bulge}}$ relation. In addition, we detect extended narrow Pa$alpha$
emission that allows us to create a rotation curve where we see
counter-rotating gas within the central kiloparsec (kpc). Possible causes of
this counter-rotation include a galactic bar or disruption of the inner gas by
a recent fly-by of a companion galaxy. This in turn could have triggered
accretion onto the central SMBH in the current AGN phase.

We report the discovery of a buried, active supermassive black hole in SDSS
J085153.64+392611.76, a bulgeless Seyfert 2 (Sy2) galaxy. Keck near-infrared
observations reveal a hidden broad line region, allowing for the rare case
where strong constraints can be placed on both the black hole mass and bulge
component. Using virial mass estimators, we obtain a black hole mass of
log($M_{rm{BH}}/M_{odot}$) = $6.78 pm 0.50$. This is one of the only Sy2 AGN
hosted in a bulgeless galaxy with a virial black hole mass estimate and could
provide important constraints on the formation scenarios of the black hole seed
population. The lack of a bulge component suggests that the SMBH has grown
quiescently, likely caused by secular processes independent of major mergers.
In the absence of a detectable bulge component, we find the $M_{rm{BH}}$ –
$M_{rm{stellar}}$ relation to be more reliable than the $M_{rm{BH}}$ –
$M_{rm{bulge}}$ relation. In addition, we detect extended narrow Pa$alpha$
emission that allows us to create a rotation curve where we see
counter-rotating gas within the central kiloparsec (kpc). Possible causes of
this counter-rotation include a galactic bar or disruption of the inner gas by
a recent fly-by of a companion galaxy. This in turn could have triggered
accretion onto the central SMBH in the current AGN phase.

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