We have conducted interferometric observations with the Combined Array for Research in Millimeter Astronomy (CARMA) and an on-the-fly mapping with the 45 m telescope at Nobeyama Radio Observatory (NRO45) in the CO (J = 1-0) emission line of the nearby spiral galaxy NGC 3521. Using the new combined CARMA + NRO45 data of NGC 3521, together with similar data for NGC 5194 (M51a) and archival SINGS Hα, 24 μm THINGS H i, and Galaxy Evolution Explorer/Far-UV (FUV) data for these two galaxies, we investigate the empirical scaling law that connects the surface density of star formation rate (SFR) and cold gas (known as the Schmidt-Kennicutt law or S-K law) on a spatially resolved basis and find a super-linear slope for the S-K law when carefully subtracting the background emissions in the SFR image. We argue that plausibly deriving SFR maps of nearby galaxies requires the diffuse stellar and dust background emission to be subtracted carefully (especially in the mid-infrared and to a lesser extent in the FUV). Applying this approach, we perform a pixel-by-pixel analysis on both galaxies and quantitatively show that the controversial result whether the molecular S-K law (expressed as) is super-linear or basically linear is a result of removing or preserving the local background. In both galaxies, the power index of the molecular S-K law is super-linear (γ H 2 1.5) at the highest available resolution (∼230 pc) and decreases monotonically for decreasing resolution. We also find in both galaxies that the scatter of the molecular S-K law (σ H 2 ) monotonically increases as the resolution becomes higher, indicating a trend for which the S-K law breaks down below some scale. Both γ H 2 and σ H 2 are systematically larger in M51a than in NGC 3521, but when plotted against the de-projected scale (δ dp ), both quantities become highly consistent for the two galaxies, tentatively suggesting that the sub-kpc molecular S-K law in spiral galaxies depends only on the scale being considered, without varying among spiral galaxies. A logarithmic function γ H 2 = −1.1 log[δ dp /kpc] + 1.4 and a linear relation σ H 2 = −0.2[δ dp /kpc] + 0.7 are obtained through fitting to the M51a data, which describes both galaxies impressively well on sub-kpc scales. A larger sample of galaxies with better sensitivity, resolution, and broader field of view are required to test the general applicability of these relations.

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Quasar feedback is suspected to play a key role in the evolution of massive galaxies, by removing or reheating gas in quasar host galaxies and thus limiting the amount of star formation. In this paper we continue our investigation of quasar-driven winds on galaxy-wide scales. We conduct Gemini Integral Field Unit spectroscopy of a sample of luminous unobscured (type 1) quasars, to determine the morphology and kinematics of ionized gas around these objects, predominantly via observations of the [O iii]λ5007Å emission line. We find that ionized gas nebulae extend out to ∼13 kpc from the quasar, that they are smooth and round, and that their kinematics are inconsistent with gas in dynamical equilibrium with the host galaxy. The observed morphological and kinematic properties are strikingly similar to those of ionized gas around obscured (type 2) quasars with matched [O iii] luminosity, with marginal evidence that nebulae around unobscured quasars are slightly more compact. Therefore in samples of obscured and unobscured quasars carefully matched in [O iii] luminosity we find support for the standard geometry-based unification model of active galactic nuclei, in that the intrinsic properties of the quasars, of their hosts and of their ionized gas appear to be very similar. Given the apparent ubiquity of extended ionized regions, we are forced to conclude that either the quasar is at least partially illuminating pre-existing gas or that both samples of quasars are seen during advanced stages of quasar feedback. In the latter case, we may be biased by our [O iii]-based selection against quasars in the early "blow-out" phase, for example due to dust obscuration.

The most robust way for determining the distance of quasar absorption outflows is the use of troughs from ionic excited states. The column density ratio between the excited and resonance states yields the outflow number density. Combined with a knowledge of the outflow's ionization parameter, a distance from the central source (R) can be determined. Here we report results from two surveys targeting outflows that show troughs from S iv. One survey includes 1091 SDSS and BOSS quasar spectra, and the other includes higher-quality spectra of 13 quasars observed with the Very Large Telescope. Our S iv samples include 38 broad absorption line (BAL) outflows, and four mini-BAL outflows. The S iv is formed in the same physical region of the outflow as the canonical outflow-identifying species C iv. Our results show that S iv absorption is only detected in 25% of C iv BAL outflows. The smaller detection fraction is due to the higher total column density (N H ) needed to detect S iv absorption. Since R empirically anti-correlates with N H the results of these surveys can be extrapolated to C iv quasar outflows with lower N H as well. We find that at least 50% of quasar outflows are at distances larger than 100 pc from the central source, and at least 12% are at distances larger than 1000 pc. These results have profound implications to the study of the origin and acceleration mechanism of quasar outflows and their effects on the host galaxy.

We report high resolution 12 CO(J = 2-1), 13 CO(J = 2-1), and 12 CO(J = 3-2) imaging of the Seyfert 1/starburst ring galaxy NGC 1097 with the Submillimeter Array to study the physical and kinematic properties of the 1-kpc circumnuclear starburst ring. Individual star clusters as detected in the HST map of Paα line emission have been used to determine the star formation rate, and are compared with the properties of the molecular gas. The molecular ring has been resolved into individual clumps at GMA-scale of 200-300 pc in all three CO lines. The intersection between the dust lanes and the starburst ring, which is associated with orbit-crowding region, is resolved into two physically/kinematically distinct features in the 1. ′′ 5×1. ′′ 0 (105×70 pc) 12 CO(J = 2-1) map. The clumps associated with the dust lanes have broader line width, higher surface gas density, and lower star formation rate, while the narrow line clumps associated with the starburst ring have opposite characteristics. Toomre-Q value under unity at the radius of the ring suggests that the molecular ring is gravitationally unstable to fragment at the scale of the GMA. The line widths and surface density of gas mass of the clumps show an azimuthal variation related to the large scale dynamics. The star formation rate, on the other hand, is not significantly affected by the dynamics, but has a correlation with the intensity ratio of 12 CO (J = 3-2) and 12 CO(J = 2-1), which traces the denser gas associated with star formation. Our resolved CO map, especially in the orbit-crowding region, for the first time demonstrates observationally that the physical/kinematic properties of the GMAs are affected by the large scale bar-potential dynamics in NGC 1097.