NGC 4826 Black Hole Mass Dataset

We present infrared photometry and \emph{Hubble Space Telescope} (\emph{HST}) imaging and spectroscopy of the Sab galaxy NGC 4826. Schwarzschild dynamical modeling is used to measure its central black hole mass $M$.  Photometric decomposition is used to enable a comparison of $M$
to published scaling relations between black hole masses and properties of host bulges.  
This decomposition implies that NGC 4826 contains classical and pseudo bulges of approximately equal mass.  The classical bulge has best-fit S{\'e}rsic index  $n = 3.27$.  The pseudobulge is made up of three parts, an inner lens ($n = 0.18$ at $r \lesssim 4\arcsec$), an outer lens ($n = 0.17$ at $r \lesssim 45\arcsec$), and a $n = 0.58$ S{\'e}rsic component required to match the surface brightness 
between the lens components.  The total $V$-band luminosity of the galaxy is $M_{VT} = -21.07$, the ratio of classical bulge to total light is $B/T \simeq 0.12$, and the ratio of pseudobulge to total light is $PB / T \simeq 0.13$.  The outer disk is exponential ($n = 1.07$) and makes up 
$D/T = 0.75$ of the light of the galaxy. 
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Our best-fit Schwarzschild model has a black hole mass with $1\sigma$ uncertainties of $M = 8.4^{+1.7}_{-0.6} \times 10^{6}\ \msun$ and a stellar population with a $K$-band mass-to-light ratio of $\Upsilon_K = 0.46 \pm 0.03\ \units{\msun\ L_{\scriptscriptstyle\odot}^{-1}}$ at the assumed distance of 7.27 Mpc.  Our modeling is marginally consistent with $M = 0$ at the $3\sigma$ limit.  These best-fit parameters were calculated assuming the black hole is located where the velocity dispersion is largest; this is offset from the maximum surface brightness, probably because of dust absorption.  
The black hole mass---one of the smallest measured by modeling stellar dynamics---satisfies the
well known correlations of $M$ with the $K$-band luminosity, stellar mass, and velocity dispersion of the classical bulge only.
In contrast, the black hole is undermassive with respect to the correlation of $M$ with total (classical plus pseudo) bulge luminosity.  
Thus the composite (classical bulge plus pseudobulge) galaxy NGC 4826 is consistent with previous results on black hole scaling
relations and helps to strengthen these results at low black hole masses.