Galactic winds are a prime suspect for the metal enrichment of the intergalactic medium and may have a strong influence on the chemical evolution of galaxies and the nature of QSO absorption line systems. We use a sample of 1406 galaxy spectra at z ∼ 1.4 from the DEEP2 redshift survey to show that blueshifted Mg II λ λ 2796, 2803Å absorption is ubiquitous in starforming galaxies at this epoch. This is the first detection of frequent outflowing galactic winds at z ∼ 1. The presence and depth of absorption are independent of AGN spectral signatures or galaxy morphology; major mergers are not a prerequisite for driving a galactic wind from massive galaxies. Outflows are found in coadded spectra of galaxies spanning a range of 30× in stellar mass and 10× in star formation rate (SFR), calibrated from K-band and from MIPS IR fluxes. The outflows have column densities of order N H ∼ 10 20 cm −2 and characteristic velocities of ∼ 300 − 500 km/sec, with absorption seen out to 1000 km/sec in the most massive, highest SFR galaxies. The velocities suggest that the outflowing gas can escape into the IGM and that massive galaxies can produce cosmologically and chemically significant outflows. Both the Mg II equivalent width and the outflow velocity are larger for galaxies of higher stellar mass and SFR, with V wind ∼ SFR 0.3 , similar to the scaling in low redshift IR-luminous galaxies. The high frequency of outflows in the star-forming galaxy population at z ∼ 1 indicates that galactic winds occur in the progenitors of massive spirals as well as those of ellipticals. The increase of outflow velocity with mass and SFR constrains theoretical models of galaxy evolution that include feedback from galactic winds, and may favor momentum-driven models for the wind physics.

We present a detailed study of rotational asymmetry in galaxies for both morphological and physical diagnostic purposes. An unambiguous method for computing asymmetry is developed, robust for both distant and nearby galaxies. By degrading real galaxy images, we test the reliability of this asymmetry measure over a range of observational conditions, e.g. spatial resolution and signal-to-noise (S/N). Compared to previous methods, this new algorithm avoids the ambiguity associated with choosing a center by using a minimization method, and successfully corrects for variations in S/N. There is, however, a strong relationship between the rotational asymmetry and physical resolution (distance at fixed spatial resolution); objects become more symmetric when less well-resolved.We further investigate asymmetry as a function of galactic radius and rotation. We find the asymmetry index has a strong radial dependence that differs vastly between Hubble types. As a result, a meaningful asymmetry index must be specified within a well-defined radius representative of the physical galaxy scale. We enumerate several viable alternatives, which excludes the use of isophotes. Asymmetry as a function of angle (A φ ) is also a useful indicator of ellipticity and higher-order azimuthal structure. In general, we show the power of asymmetry as a morphological parameter lies in the strong correlation with (B − V ) color for galaxies undergoing normal star formation, spanning all Hubble types from ellipticals to irregular galaxies. Interacting galaxies do not fall on this asymmetry-color "fiducial sequence," as these galaxies are too asymmetric for their color. We propose to use this fact to distinguish between 'normal' galaxies and galaxies undergoing an interaction or merger at high redshift.1994; Jangren et al. 1999). A different method -applicable for spirals -has been suggested by Elmegreen & Elmegreen (1982): measures of spiral arm morphology, particularly their patchiness, can be used for classification. Related attempts to classify galaxies have included the use of principle component analysis of photometric structures (Whitmore 1984;Watanabe et al. 1985;Han 1995). These systems revealed correlations of physical and morphological features of galaxies, but have not been generally adopted for practical use, and the basic Hubble (1926) system still lives on.A key element missing from recent work listed above is the connection made by Morgan between image structure and stellar content (i.e. between light concentration, or central surface-brightness, and spectral type). Ironically, in parallel to the above efforts to quantify image structure, there has been considerable effort to develop quantitative methods of spectral classification based on broad-band colors (Bershady 1995) and spectra (Connolly et al. 1995, Folkes et al. 1996, Bromley et al. 1998, Ronen et al. 1999. What is needed, then, is to go full circle to where Morgan left off, by tying together the spectral types with the quantitative classification based image structure. Here,...

This Special Issue of the Astrophysical Journal Letters is dedicated to presenting initial results from the Great Observatories Origins Deep Survey (GOODS) that are primarily, but not exclusively, based on multi-band imaging data obtained with the Hubble Space Telescope (HST) and the Advanced Camera for Surveys (ACS). The survey covers roughly 320 square arcminutes in the ACS F435W, F606W, F814W, and F850LP bands, divided into two well-studied fields. Existing deep observations from the Chandra X-ray Observatory (CXO) and groundbased facilities are supplemented with new, deep imaging in the optical and

We analyse the physical properties of a large, homogeneously selected sample of ALMA-located sub-millimetre galaxies (SMGs) detected in the SCUBA-2 Cosmology Legacy Survey 850-µm map of the UKIDSS/UDS field. This survey, AS2UDS, identified 707 SMGs across the ∼ 1 deg 2 field, including ∼17 per cent which are undetected in the optical/near-infrared to K 25.7 mag. We interpret the UV-to-radio data of these systems using a physically motivated model, magphys and determine a median photometric redshift of z = 2.61±0.08, with a 68 th percentile range of z = 1.8-3.4, with just ∼ 6 per cent at z > 4. The redshift distribution is well fit by a model combining evolution of the gas fraction in halos with the growth of halo mass past a critical threshold of ∼4×10 12 M , thus SMGs may represent the highly efficient collapse of gasrich massive halos. Our survey provides a sample of the most massive, dusty galaxies at z 1, with median dust and stellar masses of M d = (6.8±0.3) × 10 8 M (thus, gas masses of ∼ 10 11 M ) and M * = (1.26±0.05) × 10 11 M . These galaxies have gas fractions of f gas = 0.41±0.02 with depletion timescales of ∼ 150 Myr. The gas mass function evolution of our sample at high masses is consistent with constraints at lower masses from blind CO-surveys, with an increase to z ∼ 2-3 and then a decline at higher redshifts. The space density and masses of SMGs suggests that almost all galaxies with M * 2 × 10 11 M have passed through an SMG-like phase. We find no evolution in dust temperature at a constant far-infrared luminosity across z ∼ 1.5-4. We exploit dust continuum sizes to show that SMGs appear to behave as simple homologous systems in the far-infrared, having properties consistent with a centrally illuminated starburst. Our study provides strong support for an evolutionary link between the active, gas-rich SMG population at z > 1 and the formation of massive, bulge-dominated galaxies across the history of the Universe.