We present the first results from a Hubble Space Telescope WFC3/IR program,which obtained direct imaging and grism observations of galaxies near quasarsightlines with a high frequency of uncorrelated foreground Mg II absorption.These highly efficient observations targeted 54 Mg II absorbers along the lineof sight to nine quasars at $z_{qso}\sim2$. We find that 89% of the absorbersin the range $0.64< z < 1.6$ can be spectroscopically matched to at least onegalaxy with an impact parameter less than 200 kpc and $|\Delta z|/(1+z)<0.006$.We have estimated the star formation rates and measured structural parametersfor all detected galaxies with impact parameters in the range 7-200 kpc andstar formation rates greater than 1.3 M$_{\odot}$ yr$^{-1}$. We find thatgalaxies associated with Mg II absorption have significantly higher mean starformation rates and marginally higher mean star formation rate surfacedensities compared to galaxies with no detected Mg II. Nearly half of the Mg IIabsorbers match to more than one galaxy, and the mean equivalent width of theMg II absorption is found to be greater for groups, compared to isolatedgalaxies. Additionally, we observe a significant redshift evolution in thephysical extent of Mg II-absorbing gas around galaxies and evidence of anenhancement of Mg II within 50 degrees of the minor axis, characteristic ofoutflows, which persists to 80 kpc around the galaxies, in agreement withrecent predictions from simulations.

Turbulence has the potential for creating gas density enhancements thatinitiate cloud and star formation (SF), and it can be generated locally by SF.To study the connection between turbulence and SF, we looked for relationshipsbetween SF traced by FUV images, and gas turbulence traced by kinetic energydensity (KED) and velocity dispersion ($v_{disp}$) in the LITTLE THINGS sampleof nearby dIrr galaxies. We performed 2D cross-correlations between FUV and KEDimages, measured cross-correlations in annuli to produce correlationcoefficients as a function of radius, and determined the cumulativedistribution function of the cross correlation value. We also plotted on apixel-by-pixel basis the locally excess KED, $v_{disp}$, and HI mass surfacedensity, $\Sigma_{\rm HI}$, as determined from the respective values with theradial profiles subtracted, versus the excess SF rate density $\Sigma_{\rmSFR}$, for all regions with positive excess $\Sigma_{\rm SFR}$. We found that$\Sigma_{\rm SFR}$ and KED are poorly correlated. The excess KED associatedwith SF implies a $\sim0.5$% efficiency for supernova energy to pump local HIturbulence on the scale of resolution here, which is a factor of $\sim2$ toosmall for all of the turbulence on a galactic scale. The excess $v_{disp}$ inSF regions is also small, only $\sim0.37$ km s$^{-1}$. The local excess in$\Sigma_{\rm HI}$ corresponding to an excess in $\Sigma_{\rm SFR}$ isconsistent with an HI consumption time of $\sim1.6$ Gyr in the inner parts ofthe galaxies. The similarity between this timescale and the consumption timefor CO implies that CO-dark molecular gas has comparable mass to HI in theinner disks.

We derive the stellar-to-halo mass relation (SHMR), namely $f_\star\proptoM_\star/M_{\rm h}$ versus $M_\star$ and $M_{\rm h}$, for early-type galaxiesfrom their near-IR luminosities (for $M_\star$) and the position-velocitydistributions of their globular cluster systems (for $M_{\rm h}$). Ourindividual estimates of $M_{\rm h}$ are based on fitting a dynamical model witha distribution function expressed in terms of action-angle variables andimposing a prior on $M_{\rm h}$ from the concentration-mass relation in thestandard $\Lambda$CDM cosmology. We find that the SHMR for early-type galaxiesdeclines with mass beyond a peak at $M_\star\sim 5\times 10^{10}M_\odot$ and$M_{\rm h}\sim 10^{12}M_\odot$ (near the mass of the Milky Way). This result isconsistent with the standard SHMR derived by abundance matching for the generalpopulation of galaxies, and with previous, less robust derivations of the SHMRfor early types. However, it contrasts sharply with the monotonically risingSHMR for late types derived from extended HI rotation curves and the same$\Lambda$CDM prior on $M_{\rm h}$ as we adopt for early types. The SHMR formassive galaxies varies more or less continuously, from rising to falling, withdecreasing disc fraction and decreasing Hubble type. We also show that thedifferent SHMRs for late and early types are consistent with the similarscaling relations between their stellar velocities and masses (Tully-Fisher andFaber-Jackson relations). Differences in the relations between the stellar andhalo virial velocities account for the similarity of the scaling relations. Weargue that all these empirical findings are natural consequences of a picturein which galactic discs are built mainly by smooth and gradual inflow,regulated by feedback from young stars, while galactic spheroids are built by acooperation between merging, black-hole fuelling, and feedback from AGNs.