Star-Forming Galaxies at z~2: An Emerging Picture of Galaxy Dynamics and Assembly

In these proceedings, we summarize recent results from our "SINS" VLT/SINFONI integral-field survey, focusing on the 52 detected UV/optically-selected star-forming galaxies at z~2. Our H-alpha emission-line imaging and kinematic data of these systems illustrates that a substantial fraction (> 1/3) of these galaxies are large, rotating disks and that these disks are clumpy, thick, and forming stars rapidly. We compare these systems to local disk scaling relations and find that the backbones of these relations are already in place at z~2. Detailed analysis of the large disks in our sample provides strong evidence that this population cannot result from a merger-dominated formation history and instead must be assembled by the smooth but rapid inflow of gas along filaments. These systems will then secularly evolve from clump-dominated disks to bulge-dominated disks on short timescales, a phenomenon that is observed in our SINS observations and is consistent with predictions from numerical simulations. These results provide new and exciting insights into the formation of bulge-dominated galaxies in the local Universe.Comment: 7 pages, to appear in the proceedings of "Galaxy Evolution: Emerging Insights and Future Challenges," Austin, TX, 11-14 Nov 200

A Massive Galaxy in its Core Formation Phase Three Billion Years After the Big Bang

Most massive galaxies are thought to have formed their dense stellar cores at early cosmic epochs. However, cores in their formation phase have not yet been observed. Previous studies have found galaxies with high gas velocity dispersions or small apparent sizes but so far no objects have been identified with both the stellar structure and the gas dynamics of a forming core. Here we present a candidate core in formation 11 billion years ago, at z=2.3. GOODS-N-774 has a stellar mass of 1.0x10^11 Msun, a half-light radius of 1.0 kpc, and a star formation rate of 90[+45-20]Msun/yr. The star forming gas has a velocity dispersion 317+-30 km/s, amongst the highest ever measured. It is similar to the stellar velocity dispersions of the putative descendants of GOODS-N-774, compact quiescent galaxies at z~2 and giant elliptical galaxies in the nearby Universe. Galaxies such as GOODS-N-774 appear to be rare; however, from the star formation rate and size of the galaxy we infer that many star forming cores may be heavily obscured, and could be missed in optical and near-infrared surveys.Comment: To appear in Natur

Mergers and Mass Accretion Rates in Galaxy Assembly: The Millennium Simulation Compared to Observations of z~2 Galaxies

Recent observations of UV-/optically selected, massive star forming galaxies at z~2 indicate that the baryonic mass assembly and star formation history is dominated by continuous rapid accretion of gas and internal secular evolution, rather than by major mergers. We use the Millennium Simulation to build new halo merger trees, and extract halo merger fractions and mass accretion rates. We find that even for halos not undergoing major mergers the mass accretion rates are plausibly sufficient to account for the high star formation rates observed in z~2 disks. On the other hand, the fraction of major mergers in the Millennium Simulation is sufficient to account for the number counts of submillimeter galaxies (SMGs), in support of observational evidence that these are major mergers. When following the fate of these two populations in the Millennium Simulation to z=0, we find that subsequent mergers are not frequent enough to convert all z~2 turbulent disks into elliptical galaxies at z=0. Similarly, mergers cannot transform the compact SMGs/red sequence galaxies at z~2 into observed massive cluster ellipticals at z=0. We argue therefore, that secular and internal evolution must play an important role in the evolution of a significant fraction of z~2 UV-/optically and submillimeter selected galaxy populations.Comment: 5 pages, 4 figures, Accepted for publication in Ap

A Genome Assembly of the Barley 'Transformation Reference' Cultivar Golden Promise

Barley (Hordeum vulgare) is one of the most important crops worldwide and is also considered a research model for the large-genome small grain temperate cereals. Despite genomic resources improving all the time, they are limited for the cv. Golden Promise, the most efficient genotype for genetic transformation. We have developed a barley cv. Golden Promise reference assembly integrating Illumina paired-end reads, long mate-pair reads, Dovetail Chicago in vitro proximity ligation libraries and chromosome conformation capture sequencing (Hi-C) libraries into a contiguous reference assembly. The assembled genome of 7 chromosomes and 4.13Gb in size, has a super-scaffold N50 after Chicago libraries of 4.14Mb and contains only 2.2% gaps. Using BUSCO (benchmarking universal single copy orthologous genes) as evaluation the genome assembly contains 95.2% of complete and single copy genes from the plant database. A high-quality Golden Promise reference assembly will be useful and utilized by the whole barley research community but will prove particularly useful for CRISPR-Cas9 experiments

The SINS/zC-SINF survey of z~2 galaxy kinematics: Outflow properties

Based on SINFONI Ha, [NII] and [SII] AO data of 30 z \sim 2 star-forming galaxies (SFGs) from the SINS and zcSINF surveys, we find a strong correlation of the Ha broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 Msun yr^-1 kpc^-2. Above this threshold, we find that SFGs with logm_\ast>10 have similar or perhaps greater wind mass loading factors (eta = Mdotout/SFR) and faster outflow velocities than lower mass SFGs. This trend suggests that the majority of outflowing gas at z \sim 2 may derive from high-mass SFGs, and that the z \sim 2 mass-metallicity relation is driven more by dilution of enriched gas in the galaxy gas reservoir than by the efficiency of outflows. The mass loading factor is also correlated with the SFR and inclination, such that more star-forming and face-on galaxies launch more powerful outflows. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to at least the half-light radius (\sim a few kpc). We propose that the observed threshold for strong outflows and the observed mass loading of these winds can be explained by a simple model wherein break-out of winds is governed by pressure balance in the disk. Using the ratio of the [SII] doublet in a broad and narrow component, we find that outflowing gas has a density of \sim10-100 cm^-3, significantly less than that of the star forming gas (600 cm^-3).Comment: 7 pages, 3 figures, accepted by Ap

The SINS Survey: Broad Emission Lines in High-Redshift Star-Forming Galaxies

High signal-to-noise, representative spectra of star-forming galaxies at z~2, obtained via stacking, reveal a high-velocity component underneath the narrow H-alpha and [NII] emission lines. When modeled as a single Gaussian, this broad component has FWHM > 1500 km/s; when modeled as broad wings on the H-alpha and [NII] features, it has FWHM > 500 km/s. This feature is preferentially found in the more massive and more rapidly star-forming systems, which also tend to be older and larger galaxies. We interpret this emission as evidence of either powerful starburst-driven galactic winds or active supermassive black holes. If galactic winds are responsible for the broad emission, the observed luminosity and velocity of this gas imply mass outflow rates comparable to the star formation rate. On the other hand, if the broad line regions of active black holes account for the broad feature, the corresponding black holes masses are estimated to be an order of magnitude lower than those predicted by local scaling relations, suggesting a delayed assembly of supermassive black holes with respect to their host bulges.Comment: 11 pages, 5 figures. Accepted version, incorporating referee comments, including changes to title, abstract, figures, and discussion sectio

Assessing competency to stand trial. A case study of technology diffusion in four states

During the 1970's, in the wake of major court decisions affirming the due process rights of criminal defendants suspected of incompetency to stand trial, state criminal justice and forensic mental health systems instigated changes both in the organization of systems through which alleged incompetents were processed and in the specific format and objectives of the competency examination itself. The early part of this period coincided with the latter phases of a project sponsored by the National Institute of Mental Health to develop reliable instruments that would translate the essentially legal criteria for competency into terms capable of being assessed by the mental health professionals now charged with competency evaluations in most states. l The hope was that these instruments, properly used, would provide a more reliable and consistent basis for competency determination than the unelaborated legal criteria by themselves. Dr. A. Louis McGarry, director of the NIMH project and the man whose name is most frequendy associated with the instruments, developed them at the Harvard Laboratory for Community Psychiatry and employed them for a time, with some success, at Bridgewater and Boston State Hospitals in Massachusetts. As other states showed interest, Dr. McGarry also made visits to demonstrate the instruments or to give depositions concerning aspects of the competency determination process. This paper reports the findings of a project designed to explore the factors influencing four states to use or not use the results of the NIMH-supported research directed by Dr. McGarry. The states are Tennessee, Ohio, North Carolina, and West Virginia. Since the instruments came on the scene at a time of general ferment in the area of psychiatric diversion from the criminal justice system, and since their adoption or non-adoption (and the modes thereoO are heavily influenced by the structure of state forensic service systems and their relationship to criminal justice systems, it was not possible to study the use of the instruments, or the states' encounter with McGarry's work, in isolation. Instead the project sought to explore these issues in the context of on-going developments in forensic service organization in each state. As will be documented later on, these developments, as much as th

A CANDELS - 3D-HST Synergy: Resolved Star Formation Patterns at 0.7 < z < 1.5

We analyze the resolved stellar populations of 473 massive star-forming galaxies at 0.7 < z < 1.5, with multi-wavelength broad-band imaging from CANDELS and Halpha surface brightness profiles at the same kiloparsec resolution from 3D-HST. Together, this unique data set sheds light on how the assembled stellar mass is distributed within galaxies, and where new stars are being formed. We find the Halpha morphologies to resemble more closely those observed in the ACS I band than in the WFC3 H band, especially for the larger systems. We next derive a novel prescription for Halpha dust corrections, which accounts for extra extinction towards HII regions. The prescription leads to consistent SFR estimates and reproduces the observed relation between the Halpha/UV luminosity ratio and visual extinction, both on a pixel-by-pixel and on a galaxy-integrated level. We find the surface density of star formation to correlate with the surface density of assembled stellar mass for spatially resolved regions within galaxies, akin to the so-called 'main sequence of star formation' established on a galaxy-integrated level. Deviations from this relation towards lower equivalent widths are found in the inner regions of galaxies. Clumps and spiral features, on the other hand, are associated with enhanced Halpha equivalent widths, bluer colors, and higher specific star formation rates compared to the underlying disk. Their Halpha/UV luminosity ratio is lower than that of the underlying disk, suggesting the ACS clump selection preferentially picks up those regions of elevated star formation activity that are the least obscured by dust. Our analysis emphasizes that monochromatic studies of galaxy structure can be severely limited by mass-to-light ratio variations due to dust and spatially inhomogeneous star formation histories.Comment: Accepted by The Astrophysical Journal, 18 pages, 1 table, 10 figure