We revisit the HI size-mass (D$_{\rm HI}$-M$_{\rm HI}$) relation of galaxieswith a sample of more than 500 nearby galaxies covering over five orders ofmagnitude in HI mass and more than ten $B$-band magnitudes. The relation isremarkably tight with a scatter $\sigma \sim$0.06 dex, or 14%. The scatter doesnot change as a function of galaxy luminosity, HI richness or morphologicaltype. The relation is linked to the fact that dwarf and spiral galaxies have ahomogenous radial profile of HI surface density in the outer regions when theradius is normalised by D$_{\rm HI}$. The early-type disk galaxies typicallyhave shallower HI radial profiles, indicating a different gas accretionhistory. We argue that the process of atomic-to-molecular gas conversion orstar formation cannot explain the tightness of the D$_{\rm HI}$-M$_{\rm HI}$relation. This simple relation puts strong constraints on simulation models forgalaxy formation.

Recently, Li et al. (2016) claimed to have found evidence for multiplegenerations of stars in the intermediate age clusters NGC 1783, NGC 1696 andNGC 411 in the Large and Small Magellanic Clouds (LMC/SMC). Here we show thatthese young stellar populations are present in the field regions around theseclusters and are not likely associated with the clusters themselves. Using thesame datasets, we find that the background subtraction method adopted by theauthors does not adequately remove contaminating stars in the small numberPoisson limit. Hence, we conclude that their results do not provide evidence ofyoung generations of stars within these clusters.

We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 3observations of CO(2-1) emission from the circumnuclear disk in the E/S0 galaxyNGC 1332 at 0.044" resolution. The disk exhibits regular rotational kinematicsand central high-velocity emission (+/-500 km/s) consistent with the presenceof a compact central mass. We construct models for a thin, dynamically colddisk in the gravitational potential of the host galaxy and black hole, and fitthe beam-smeared model line profiles directly to the ALMA data cube. Model fitssuccessfully reproduce the disk kinematics out to r=200 pc. Fitting models justto spatial pixels within projected r=50 pc of the nucleus (two times largerthan the black hole's gravitational radius of influence), we findM_BH=6.64(-0.63,+0.65)*10^8 solar masses. This observation demonstrates ALMA'spowerful capability to determine the masses of supermassive black holes byresolving gas kinematics on small angular scales in galaxy nuclei.

To investigate what drives the reversal of the morphology-density relation atintermediate/high redshift, we present a multi-wavelength analysis of 27 dustystarburst galaxies in the massive cluster Cl 0024+17 at z = 0.4. We combineH-alpha dynamical maps from the VLT/FLAMES multi-IFU system with far-infraredimaging using Herschel SPIRE and millimetre spectroscopy from IRAM/NOEMA, inorder to measure the dynamics, star formation rates and gas masses of thissample. Most galaxies appear to be rotationally supported, with a median ratioof rotational support to line-of-sight velocity dispersion v/sigma ~ 5 +/- 2,and specific angular momentum lambda_R = 0.83 +/- 0.06 - comparable to fieldspirals of a similar mass at this redshift. The star formation rates of 3 - 26M_solar/yr and average 12 CO derived gas mass of 1 x 10^10 M_solar suggest gasdepletion timescales of ~ 1Gyr (~ 0.25 of the cluster crossing time). We derivecharacteristic dust temperatures (mean T_dust = 26 +/- 1 K) consistent withlocal galaxies of similar far-infrared luminosity, suggesting that the lowdensity gas is yet to be stripped. Taken together, these results suggest thatthese starbursts have only recently accreted from the field, with starformation rates likely enhanced due to the effects of ram pressure. In order tomake the transition to cluster S0s these galaxies must lose ~ 40% of theirspecific angular momentum. We suggest this must occur > 1 Gyr later, after themolecular gas has been depleted and/or stripped, via multiple tidalinteractions with other cluster members.