Martin Bureau

Abstract:

As a part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project, we present an estimate of the mass of the supermassive black hole (SMBH) in the nearby fast-rotator early-type galaxy NGC 3665. We obtained the Combined Array for Research in Millimeter Astronomy (CARMA) B and C array observations of the 12CO(J = 2 − 1) emission line with a combined angular resolution of 0.59 arcsec. We analysed and modelled the three-dimensional molecular gas kinematics, obtaining a best-fitting SMBH mass MBH=5.75+1.49−1.18×10^8 M⊙, a mass-to-light ratio at H-band (M/L)H = 1.45 ± 0.04 (M/L)⊙,H and other parameters describing the geometry of the molecular gas disc (statistical errors, all at 3σ confidence). We estimate the systematic uncertainties on the stellar M/L to be ≈0.2 (M/L)⊙,H, and on the SMBH mass to be ≈0.4 × 108 M⊙. The measured SMBH mass is consistent with that estimated from the latest correlations with galaxy properties. Following our older works, we also analysed and modelled the kinematics using only the major-axis position–velocity diagram, and conclude that the two methods are consistent.

Abstract:

We present dynamical measurements for 586 Hα-detected star-forming galaxies from the KMOS (K-band Multi-Object Spectrograph) Redshift One Spectroscopic Survey (KROSS). The sample represents typical star-forming galaxies at this redshift (z = 0.6-1.0), with a median star formation rate of ≈7 M ⊙ yr -1 and a stellar mass range of log (M * [M ⊙ ]) ≈ 9-11. We find that the rotation velocity-stellar mass relationship (the inverse of the Tully- Fisher relationship) for our rotationally dominated sources (v C /σ 0 > 1) has a consistent slope and normalization as that observed for z = 0 discs. In contrast, the specific angular momentum (j * angular momentum divided by stellar mass) is ≈0.2-0.3 dex lower on average compared to z = 0 discs. The specific angular momentum scales as j s ∝ M * 0.6±0.2 , consistent with that expected for dark matter (i.e. j DM ∝ M DM 2/3 ). We find that z≈ 0.9 star-forming galaxies have decreasing specific angular momentum with increasing Sérsic index. Visually, the sources with the highest specific angular momentum, for a given mass, have the most disc-dominated morphologies. This implies that an angular momentum-mass-morphology relationship, similar to that observed in local massive galaxies, is already in place by z ≈ 1.

Abstract:

We revisit the filamentary structures of galaxies around the Virgo cluster, exploiting a larger dataset based on the HyperLeda database than previous studies. In particular, this includes a large number of low-luminosity galaxies, resulting in better sampled individual structures. We confirm seven known structures in the distance range 4 h^-1 Mpc < SGY < 16 h^-1 Mpc, now identified as filaments, where SGY is the axis of the supergalactic coordinate system roughly along the line of sight. The Hubble diagram of the filament galaxies suggests they are infalling toward the main-body of the Virgo cluster. We propose that the collinear distribution of giant elliptical galaxies along the fundamental axis of the Virgo cluster is smoothly connected to two of these filaments (Leo II A and B). Behind the Virgo cluster (16 h^-1 Mpc < SGY < 27 h^-1 Mpc), we also identify a new filament elongated toward the NGC 5353/4 group ("NGC 5353/4 filament") and confirm a sheet that includes galaxies from the W and M clouds of the Virgo cluster ("W-M sheet"). In the Hubble diagram, the NGC 5353/4 filament galaxies show infall toward the NGC 5353/4 group, whereas the W-M sheet galaxies do not show hints of gravitational in uence from the Virgo cluster. The filamentary structures identified can now be used to better understand the generic role of filaments in the build-up of galaxy clusters at z ≈ 0.