We compare the set of local galaxies having dynamically measured black holes with a large, unbiased sample of galaxies extracted from the Sloan Digital Sky Survey. We confirm earlier work showing that the majority of black hole hosts have significantly higher velocity dispersions σ than local galaxies of similar stellar mass. We use Monte-Carlo simulations to illustrate the effect on black hole scaling relations if this bias arises from the requirement that the black hole sphere of influence must be resolved to measure black hole masses with spatially resolved kinematics. We find that this selection effect artificially increases the normalization of the M bh -σ relation by a factor of at least ∼ 3; the bias for the M bh -M star relation is even larger. Our Monte Carlo simulations and analysis of the residuals from scaling relations both indicate that σ is more fundamental than M star or effective radius. In particular, the M bh -M star relation is mostly a consequence of the M bh -σ and σ-M star relations, and is heavily biased by up to a factor of 50 at small masses. This helps resolve the discrepancy between dynamically-based black hole-galaxy scaling relations versus those of active galaxies. Our simulations also disfavour broad distributions of black hole masses at fixed σ. Correcting for this bias suggests that the calibration factor used to estimate black hole masses in active galaxies should be reduced to values of f vir ∼ 1. Black hole mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/black hole spins. Reducing black hole masses also reduces the gravitational wave signal expected from black hole mergers.

We report the discovery of DGSAT I, an ultra-diffuse, quenched galaxy located 10. • 4 degrees in projection from the Andromeda galaxy (M31). This low-surface brightness galaxy (µ V = 24.8 mag arcsec −2 ), found with a small amateur telescope, appears unresolved in sub-arcsecond archival Subaru/Suprime-Cam images, and hence has been missed by optical surveys relying on resolved star counts, in spite of its relatively large effective radius (R e (V ) = 12 ) and proximity (15 ) to the well-known dwarf spheroidal galaxy And II. Its red color (V − I = 1.0), shallow Sérsic index (n V = 0.68), and the absence of detectable Hα emission are typical properties of dwarf spheroidal galaxies and suggest that it is mainly composed of old stars.Initially interpreted as an interesting case of an isolated dwarf spheroidal galaxy in the local universe, our radial velocity measurement obtained with the BTA 6-meter telescope (V h = 5450 ± 40 km s −1 ) shows that this system is an M31-background galaxy associated with the filament of the Pisces-Perseus supercluster. At the distance of this cluster (∼ 78 Mpc), DGSAT I would have an R e ∼ 4.7 kpc and M V ∼ −16.3. Its properties resemble those of the ultra-diffuse galaxies recently discovered in the Coma cluster. DGSAT I is the first case of these rare ultra-diffuse galaxies found in this galaxy cluster. Unlike the ultra-diffuse galaxies associated with the Coma and Virgo clusters, DGSAT I is found in a much lower density environment, which provides a fresh constraint on the formation mechanisms for this intriguing class of galaxy.

We present an investigation of the scaling relations between Supermassive Black Hole (SMBH) masses, M • , and their host galaxies' K-band bulge (L bul ) and total (L tot ) luminosities. The widefield WIRCam imager at the Canada-France-Hawaii-Telescope (CFHT) was used to obtain the deepest and highest resolution near infrared images available for a sample of 35 galaxies with securely measured M • , selected irrespective of Hubble type. For each galaxy, we derive bulge and total magnitudes using a two-dimensional image decomposition code that allows us to account, if necessary, for large-and small-scale disks, cores, bars, nuclei, rings, envelopes and spiral arms. We find that the present-day M • − L bul and M • − L tot relations have consistent intrinsic scatter, suggesting that M • correlates equally well with bulge and total luminosity of the host. Our analysis provides only mild evidence of a decreased scatter if the fit is restricted to elliptical galaxies. The log-slopes of the M • − L bul and M • − L tot relations are 0.75 ± 0.10 and 0.92 ± 0.14, respectively. However, while the slope of the M • − L bul relation depends on the detail of the image decomposition, the characterization of M • − L tot does not. Given the difficulties and ambiguities of decomposing galaxy images into separate components, our results indicate that L tot is more suitable as a tracer of SMBH mass that L bul , and that the M • − L tot relation should be used when studying the co-evolution of SMBHs and galaxies.

We use new precision measurements of black hole (BH) masses from water megamaser disks to investigate scaling relations between macroscopic galaxy properties and supermassive BH mass. The megamaser-derived BH masses span 10 6 -10M , while all the galaxy properties that we examine (including total stellar mass, central mass density, and central velocity dispersion) lie within a narrower range. Thus, no galaxy property correlates tightly with M BH in ∼L * spiral galaxies as traced by megamaser disks. Of them all, stellar velocity dispersion provides the tightest relation, but at fixed * s the mean megamaser M BH are offset by −0.6 ± 0.1 dex relative to early-type galaxies. Spiral galaxies with non-maser dynamical BH masses do not appear to show this offset. At low mass, we do not yet know the full distribution of BH mass at fixed galaxy property; the non-maser dynamical measurements may miss the low-mass end of the BH distribution due to an inability to resolve their spheres of influence and/or megamasers may preferentially occur in lower-mass BHs.