We combine optical and near-infrared adaptive optics-assisted integral field observations of the merging ultraluminous infrared galaxies IRAS F17207-0014 from the Wide-Field Spectrograph and Keck/OH-Suppressing Infra-Red Imaging Spectrograph (OSIRIS). The optical emission line ratios [N II]/H alpha, [S II]/H alpha, and [O I]/H alpha reveal a mixing sequence of shocks present throughout the galaxy, with the strongest contributions coming from large radii (up to 100 per cent at similar to 5 kpc in some directions), suggesting galactic-scale winds. The near-infrared observations, which have approximately 30 times higher spatial resolution, show that two sorts of shocks are present in the vicinity of the merging nuclei: low-level shocks distributed throughout our field-of-view evidenced by an H-2/Br gamma line ratio of similar to 0.6-4, and strong collimated shocks with a high H-2/Br gamma line ratio of similar to 4-8, extending south from the two nuclear discs approximately 400 pc (similar to 0.5 arcsec). Our data suggest that the diffuse shocks are caused by the collision of the interstellar media associated with the two progenitor galaxies and the strong shocks trace the base of a collimated outflow coming from the nucleus of one of the two discs.

The classification of galaxy mergers and isolated disks is key for understanding the relative importance of galaxy interactions and secular evolution during the assembly of galaxies. Galaxy kinematics as traced by emission lines have been used to suggest the existence of a significant population of high-z star-forming galaxies consistent with isolated rotating disks. However, recent studies have cautioned that post-coalescence mergers may also display disk-like kinematics. To further investigate the robustness of merger/disk classifications based on kinematic properties, we carry out a systematic classification of 24 local (U) LIRGs spanning a range of morphologies: from isolated spiral galaxies, ongoing interacting systems, to fully merged remnants. We artificially redshift the Wide Field Spectrograph observations of these local (U) LIRGs to z = 1.5 to make a realistic comparison with observations at high-z, and also to ensure that all galaxies have the same spatial sampling of similar to 900 pc. Using both kinemetry-based and visual classifications, we find that the reliability of kinematic classification shows a strong trend with the interaction stage of galaxies. Mergers with two nuclei and tidal tails have the most distinct kinematics compared to isolated disks, whereas a significant population of the interacting disks and merger remnants are indistinguishable from isolated disks. The high fraction of mergers displaying disk-like kinematics reflects the complexity of the dynamics during galaxy interactions. Additional merger indicators such as morphological properties traced by stars or molecular gas are required to further constrain the merger/disk classifications at high-z.

We present CO(1-0) maps of 12 warm H-2-selected Hickson Compact Groups (HCGs), covering 14 individually imaged warm H-2 bright galaxies, with the Combined Array for Research in Millimeter Astronomy. We found a variety of molecular gas distributions within the HCGs, including regularly rotating disks, bars, rings, tidal tails, and possibly nuclear outflows, though the molecular gas morphologies are more consistent with spirals and earlytype galaxies than mergers and interacting systems. Our CO-imaged HCG galaxies, when plotted on the Kennicutt-Schmidt relation, shows star formation (SF) suppression of < S > = 10 +/- 5, distributed bimodally, with five objects exhibiting suppressions of S greater than or similar to 10 and depletion timescales greater than or similar to 10 Gyr. This SF inefficiency is also seen in the efficiency per freefall time of Krumholz et al. We investigate the gas-to-dust ratios of these galaxies to determine if an incorrect L-CO-M(H-2) conversion caused the apparent suppression and find that HCGs have normal gas-to-dust ratios. It is likely that the cause of the apparent suppression in these objects is associated with shocks injecting turbulence into the molecular gas, supported by the fact that the required turbulent injection luminosity is consistent with the bright H-2 luminosity reported by Cluver et al. Galaxies with high SF suppression (S greater than or similar to 10) also appear to be those in the most advanced stages of transition across both optical and infrared color space. This supports the idea that at least some galaxies in HCGs are transitioning objects, where a disruption of the existing molecular gas in the system suppresses SF by inhibiting the molecular gas from collapsing and forming stars efficiently. These observations, combined with recent work on poststarburst galaxies with molecular reservoirs, indicates that galaxies do not need to expel their molecular reservoirs prior to quenching SF and transitioning from blue spirals to red early-type galaxies. This may imply that SF quenching can occur without the need to starve a galaxy of cold gas first.

We present an integral field spectroscopic study of radiative shocks in 27 nearby ultraluminous and luminous infrared galaxies (U/LIRGs) from the Great Observatory All-sky LIRG Survey, a subset of the Revised Bright Galaxy Sample. Our analysis of the resolved spectroscopic data from the Wide Field Spectrograph focuses on determining the detailed properties of the emission-line gas, including a careful treatment of multicomponent emission-line profiles. The resulting information obtained from the spectral fits is used to map the kinematics of the gas, sources of ionizing radiation, and feedback present in each system. The resulting properties are tracked as a function of merger stage. Using emission-line flux ratios and velocity dispersions, we find evidence for widespread, extended shock excitation in many local U/LIRGs. These low-velocity shocks become an increasingly important component of the optical emission lines as a merger progresses. We find that shocks may account for as much as half of the Ha luminosity in the latest-stage mergers in our sample. We discuss some possible implications of our result and consider the presence of active galactic nuclei. and their effects on the spectra in our sample.

Using Spitzer observations of classical Cepheids we have measured the true average distance modulus of the Small Magellanic Cloud (SMC) to be 18.96 +/- 0.01(stat) +/- 0.03(sys) mag (corresponding to 62 +/- 0.3 kpc), which is 0.48 +/- 0.01 mag more distant than the LMC. This is in agreement with previous results from Cepheid observations, as well as with measurements from other indicators such as RR Lyrae stars and the tip of the red giant branch. Utilizing the properties of the mid-infrared Leavitt Law we measured precise distances to individual Cepheids in the SMC, and have confirmed that the galaxy is tilted and elongated such that its eastern side is up to 20 kpc closer than its western side. This is in agreement with the results from red clump stars and dynamical simulations of the Magellanic Clouds and Stream.

We compare mid-infrared (IR) 3.6 and 4.5 mu m Warm Spitzer observations for Cepheids in the Milky Way and the Large and Small Magellanic Clouds. Using models, we explore in detail the effect of the CO rotation-vibration band-head at 4.6 mu m on the mid-IR photometry. We confirm the temperature sensitivity of the CO band-head at 4.6 mu m and find no evidence for an effect at 3.6 mu m. We compare the ([3.6]-[4.5]) period-colour relations in the MW, LMC and SMC. The slopes of the period-colour relations for the three galaxies are in good agreement, but there is a trend in zero-point with metallicity, with the lowest metallicity Cepheids having redder mid-IR colours. Finally, we present a colour-[Fe/H] relation based on published spectroscopic metallicities. This empirical relation, calibrated to the metallicity system of Genovali et al., demonstrates that the ([3.6]-[4.5]) colour provides a reliable metallicity indicator for Cepheids, with a precision comparable to current spectroscopic determinations.

There are many mechanisms by which galaxies can transform from blue, star-forming spirals, to red, quiescent early-type galaxies, but our current census of them does not form a complete picture. Recent observations of nearby case studies have identified a population of galaxies that quench "quietly." Traditional poststarburst searches seem to catch galaxies only after they have quenched and transformed, and thus miss any objects with additional ionization mechanisms exciting the remaining gas. The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify transforming galaxies, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the Oh-Sarzi-Schawinski-Yi (OSSY) measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1067 SPOG candidates (SPOGs*) within z = 0.2. SPOGs* represent 0.2% of the OSSY sample galaxies that exceed the continuum signal-to-noise cut (and 0.7% of the emission line galaxy sample). SPOGs* colors suggest that they are in an earlier phase of transition than OSSY galaxies that meet an "E+A" selection. SPOGs* have a 13% 1.4 GHz detection rate from the Faint Images of the Radio Sky at Twenty Centimeters Survey, higher than most other subsamples, and comparable only to low-ionization nuclear emission line region hosts, suggestive of the presence of active galactic nuclei (AGNs). SPOGs* also have stronger Na I D absorption than predicted from the stellar population, suggestive of cool gas being driven out in galactic winds. It appears that SPOGs* represent an earlier phase in galaxy transformation than traditionally selected poststarburst galaxies, and that a large proportion of SPOGs* also have properties consistent with disruption of their interstellar media, a key component to galaxy transformation. It is likely that many of the known pathways to transformation undergo a SPOG phase. Studying this sample of SPOGs* further, including their morphologies, AGN properties, and environments, has the potential for us to build a more complete picture of the initial conditions that can lead to a galaxy evolving.

We provide evidence that UGC. 1382, long believed to be a passive elliptical galaxy, is actually a giant low surface brightness (GLSB) galaxy that rivals the archetypical GLSB Malin. 1 in size. Like other GLSB galaxies, it has two components: a high surface brightness disk galaxy surrounded by an extended low surface brightness (LSB) disk. For UGC. 1382, the central component is a lenticular system with an effective radius of 6 kpc. Beyond this, the LSB disk has an effective radius of similar to 38 kpc and an extrapolated central surface brightness of similar to 26 mag arcsec(-2). Both components have a combined stellar mass of similar to 8 x 10(10) M-circle dot, and are embedded in a massive (10(10) M-circle dot) low-density (<3 M-circle dot pc(-2)) HI disk with a radius of 110 kpc, making this one of the largest isolated disk galaxies known. The system resides in a massive dark matter halo of at least 2 x 10(12) M-circle dot. Although possibly part of a small group, its low-density environment likely plays a role in the formation and retention of the giant LSB and HI disks. We model the spectral energy distributions and find that the LSB disk is likely older than the lenticular component. UGC. 1382 has UV-optical colors typical of galaxies transitioning through the green valley. Within the LSB disk are spiral arms forming stars at extremely low efficiencies. The gas depletion timescale of similar to 10(11) years suggests that UGC. 1382 may be a very-long-term resident of the green valley. We find that the formation and evolution of the LSB disk in UGC. 1382 is best explained by the accretion of gas-rich LSB dwarf galaxies.

We present CO(1-0) observations of objects within the Shocked POststarburst Galaxy Survey taken with the Institut de Radioastronomie Millimetrique 30 m single dish and the Combined Array for Research for Millimeter Astronomy interferometer. Shocked poststarburst galaxies (SPOGs) represent a transitioning population of galaxies, with deep Balmer absorption (EWH delta > 5 angstrom), consistent with an intermediate-age (A-star) stellar population, and ionized gas line ratios inconsistent with pure star formation. The CO(1-0) subsample was selected from SPOGs detected by the Wide-field Infrared Survey Explorer with 22 mu m flux detected at a signal-to-noise ratio. (S/N) > 3. Of the 52 objects observed in CO(1-0), 47 are detected with S/N > 3. A large fraction (37%-46% +/- 7%) of our CO-SPOG sample were visually classified as morphologically disrupted. The H-2 masses detected were between 10(8.7-10.8) M-circle dot, consistent with the gas masses found in normal galaxies, though approximately an order of magnitude larger than the range seen in poststarburst galaxies. When comparing the 22 mu m and CO(1-0) fluxes, SPOGs diverge from the normal star-forming relation, having 22 mu m fluxes in excess of the relation by a factor of = 4.91(-0.39)(+0.42), suggestive of the presence of active galactic nuclei (AGNs). The Na I D characteristics of CO-SPOGs show that it is likely that many of these objects host interstellar winds. Objects with. large Na I D enhancements also tend to emit in the radio, suggesting possible AGN. driving of neutral winds.

We present LZIFU (LaZy-IFU), an IDL toolkit for fitting multiple emission lines simultaneously in integral field spectroscopy (IFS) data. LZIFU is useful for the investigation of the dynamical, physical and chemical properties of gas in galaxies. LZIFU has already been applied to many world-class IFS instruments and large IFS surveys, including the Wide Field Spectrograph, the new Multi Unit Spectroscopic Explorer (MUSE), the Calar Alto Legacy Integral Field Area (CALIFA) survey, the Sydney-Australian-astronomical-observatory Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. Here we describe in detail the structure of the toolkit, and how the line fluxes and flux uncertainties are determined, including the possibility of having multiple distinct kinematic components. We quantify the performance of LZIFU, demonstrating its accuracy and robustness. We also show examples of applying LZIFU to CALIFA and SAMI data to construct emission line and kinematic maps, and investigate complex, skewed line profiles presented in IFS data. The code is made available to the astronomy community through github. LZIFU will be further developed over time to other IFS instruments, and to provide even more accurate line and uncertainty estimates.