The local interstellar medium (ISM) is suffused with "dark" gas, identifiedby excess infrared and gamma ray emission, yet undetected by standard ISMtracers such as neutral hydrogen (HI) or carbon monoxide emission. Based onobserved dust properties from Planck, recent studies have argued that HI mixedwith dust is strongly saturated and that dark gas is dominated byoptically-thick HI. We test this hypothesis by reproducing this model usingdata from Planck and new 21 cm emission maps from GALFA-HI -- the firstlarge-area 21cm emission survey with comparable angular resolution to Planck.We compare the results with those from a large sample of HI column densitiesbased on direct observations of HI optical depth, and find that the inferredcolumn density corrections are significantly lower than those inferred by thePlanck-based model. Further, we rule out the hypothesis that the pencil-beam HIabsorption sight lines preferentially miss opaque "blobs" with small coveringfraction, as these structures require densities and pressures which areincompatible with ISM conditions. Our results support the picture that excessdust emission in the local ISM is not dominated by optically-thick HI, but israther a combination of intrinsic changes in dust grain emissivities and H2missed by CO observations.

Mass and specific angular momentum are two fundamental physical parameters ofgalaxies. We present measurements of the baryonic mass and specific angularmomentum of 11 void dwarf galaxies derived from neutral hydrogen (H{\sc i})synthesis data. Rotation curves were measured using 3D and 2D tilted ringfitting routines, and the derived curves generally overlap within the errorbars, except in the central regions where, as expected, the 3D routines givesteeper curves. The specific angular momentum of void dwarfs is found to behigh compared to an extrapolation of the trends seen for higher mass bulge-lessspirals, but comparable to that of other dwarf irregular galaxies that lieoutside of voids. As such, our data show no evidence for a dependence of thespecific angular momentum on the large scale environment. Combining our datawith the data from the literature, we find a baryonic threshold of $\sim10^{9.1}~M_{\odot}$ for this increase in specific angular momentum.Interestingly, this threshold is very similar to the mass threshold below whichthe galaxy discs start to become systematically thicker. This providesqualitative support to the suggestion that the thickening of the discs, as wellas the increase in specific angular momentum, are both results of a commonphysical mechanism, such as feedback from star formation. Quantitatively,however, the amount of star formation observed in our dwarfs appearsinsufficient to produce the observed increase in specific angular momentum. Itis hence likely that other processes, such as cold accretion of high angularmomentum gas, also play a role in increasing the specific angular momentum.

Post-starburst or "E+A" galaxies are rapidly transitioning from star-formingto quiescence. While the current star formation rate of post-starbursts isalready at the level of early type galaxies, we recently discovered that manyhave large CO-traced molecular gas reservoirs consistent with normal starforming galaxies. These observations raise the question of why these galaxieshave such low star formation rates. Here we present an ALMA search for thedenser gas traced by HCN (1--0) and HCO+ (1--0) in two CO-luminous, quiescentpost-starburst galaxies. Intriguingly, we fail to detect either molecule. Theupper limits are consistent with the low star formation rates and withearly-type galaxies. The HCN/CO luminosity ratio upper limits are low comparedto star-forming and even many early type galaxies. This implied low dense gasmass fraction explains the low star formation rates relative to the CO-tracedmolecular gas and suggests the state of the gas in post-starburst galaxies isunusual, with some mechanism inhibiting its collapse to denser states. Weconclude that post-starbursts galaxies are now quiescent because little densegas is available, in contrast to the significant CO-traced lower density gasreservoirs that still remain.

Based on the stellar orbit distribution derived from orbit-superpositionSchwarzschild models, we decompose each of 250 representative present-daygalaxies into four orbital components: cold with strong rotation, warm withweak rotation, hot with dominant random motion and counter-rotating (CR). Werebuild the surface brightness ($\Sigma$) of each orbital component and wepresent in figures and tables a quantification of their morphologies using theSersic index \textit{n}, concentration $C =\log{(\Sigma_{0.1R_e}/\Sigma_{R_e})}$ and intrinsic flattening$q_{\mathrm{Re}}$ and $q_{\mathrm{Rmax}}$, with $R_e$ the half-light-radius and$R_{\mathrm{max}}$ the CALIFA data coverage. We find that: (1) kinematic hottercomponents are generally more concentrated and rounder than colder components,and (2) all components become more concentrated and thicker/rounder in moremassive galaxies; they change from disk-like in low mass late-type galaxies tobulge-like in high-mass early type galaxies. Our findings suggest that Sersic\textit{n} is not a good discriminator between rotating bulges and non-rotatingbulges. The luminosity fraction of cold orbits $f_{\rm cold}$ is wellcorrelated with the photometrically-decomposed disk fraction $f_{\rm disk}$ as$f_{\mathrm{cold}} = 0.14 + 0.23f_{\mathrm{\mathrm{disk}}}$. Similarly, the hotorbit fraction $f_{\rm hot}$ is correlated with the bulge fraction $f_{\rmbulge}$ as $f_{\mathrm{hot}} = 0.19 + 0.31f_{\mathrm{\mathrm{bulge}}}$. Thewarm orbits mainly contribute to disks in low-mass late-type galaxies, and tobulges in high-mass early-type galaxies. The cold, warm, and hot componentsgenerally follow the same morphology ($\epsilon = 1-q_{\rm Rmax}$) versuskinematics ($\sigma_z^2/\overline{V_{\mathrm{tot}}^2}$) relation as the thindisk, thick disk/pseudo bulge, and classical bulge identified from cosmologicalsimulations.

Several models have predicted that stars could form inside galactic outflowsand that this would be a new major mode of galaxy evolution. Observations ofgalactic outflows have revealed that they host large amounts of dense andclumpy molecular gas, which provide conditions suitable for star formation. Wehave investigated the properties of the outflows in a large sample of galaxiesby exploiting the integral field spectroscopic data of the large MaNGA-SDSS4galaxy survey. We find that star formation occurs inside at least half of thegalactic outflows in our sample. We also show that even if star formation isprominent inside many other galactic outflows, this may have not been revealedas the diagnostics are easily dominated by the presence of even faint AGN andshocks. If very massive outflows typical of distant galaxies and quasars followthe same scaling relations observed locally, then the star formation insidehigh-z outflows can be up to several 100 Msun/yr and could contributesubstantially to the early formation of the spheroidal component of galaxies.Star formation in outflows can also potentially contribute to establishing thescaling relations between black holes and their host spheroids. Moreover,supernovae exploding on large orbits can chemically enrich in-situ and heat thecircumgalactic and intergalactic medium. Finally, young stars ejected on largeorbits may also contribute to the reionization of the Universe.