bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Galaxies and AGNs
Authors: Walter Fabian 
Published: April 2007

AbstractI will discuss the search for galaxies and QSOs at the highest redshifts, out to the Epoch of Reionization. Observations in the submillimeter play a fundamental role in such searches, in particular once ALMA will become operational. I will focus on the properties of the molecular gas (the phase of the ISM out of which stars form) in the earliest systems as derived through observations in the millimetre and radio regime. These observations allow us to measure the reservoir of molecular gas and to constrain the physical properties and excitation of the gas. Resolved imaging of the host galaxies also allows us to derive first dynamical masses for these objects. Such mass determinations are critical to determine whether there is a possible evolution of the famous MBH–σbulgerelation with redshift or not. Recent measurements in the QSO redshift record holder J1148+5251 (z= 6.42) provide evidence that the black hole in this system assembled before the stellar bulge.
Luminosity Dependent Evolution of Lyman Break Galaxies from redshift 5 to 3
Authors: Iwata I , Ohta K. , Tamura N. , Akiyama M. , Aoki K. , Ando M. , Kiuchi G. , Sawicki M. 
Published: April 2007

AbstractThe development of large ground-based telescopes and sensitive large format detectors, as well as the develepment of various techniques for the selection of high-z galaxies enabled us to construct large samples of galaxies in the early universe, as reported in the many contributions in this proceedings. The next major step for the comprehensive understanding of the galaxy evolution would be to explore the relationship of galaxies selected with different criteria at different epochs and find links between them. In this contribution we present the properties of Lyman break galaxies (LBGs) at z ~ 5 obtained by deep and wide blank field surveys, and through the comparison with samples at lower redshift ranges we discuss the evolution of star-forming galaxies in the early universe.
Massive and Evolved Galaxies at z ≥ 5
Authors: Wiklind T. , Mobasher B. , Dickinson M. , Ferguson H. , Giavalisco M. , Grogin N. , Panagia N. 
Published: April 2007

AbstractWe search for massive and evolved galaxies at z ≥ 5 in the Great Observatories Origins Deep Survey (GOODS) southern field. Combining HST ACS, VLT ISAAC and Spitzer IRAC broad–band photometric data, we develop a color selection technique to identify candidates for being evolved galaxies at high redshifts. The color selection is primarily based on locating the Balmer–break using the K- and 3.6 μm bands. Stellar population synthesis models are fitted to the SEDs of these galaxies to identify the final sample. We find 11 candidates with photometric redshifts in the range 4.9 < z < 5.6, dominated by an old stellar population, with ages 0.2-1.0 Gyr, and stellar masses in the range (0.7 − 5) × 1011 M⊙. Most of the candidates have modest amounts of internal dust extinction. The majority of the stars in these galaxies were formed at z>9 and the current star formation activity is a few percent of the inferred initial star formation rate.
Clumpy Galaxies in the Early Universe
Authors: Elmegreen Debra Meloy 
Published: April 2007

AbstractClumpy galaxies are prominent in the early Universe. We present morphological and photometric properties of a wide range of galaxy types and their star-forming clumps in the Hubble Ultra Deep Field. Sizes, scale lengths, and scale heights suggest that galaxies grow by a factor of 2 fromz= 4 to the present, and that thick disks are present in the early Universe. The largest clumps of star formation are 107–109M⊙in different galaxies, much more massive than large star-forming complexes in local galaxies. Dissolved clumps may account for both the exponential disks and the early thick disks of spirals and proto-spiral galaxies.
Galaxy Mergers and Interactions at High Redshift
Authors: Conselice Christopher J. 
Published: April 2007

AbstractIn this review we discuss the evidence for galaxy interactions and mergers in the distant universe and the role of mergers in forming galaxies. Observations show that the fraction of massive (M>M*) galaxies involved in major mergers is roughly 5–10% at z ~ 1. The merger fraction however increases steeply for the most massive galaxies up to z ~ 3, where the merger fraction is 50± 20%. Using N-body models of the galaxy merger process at a variety of merger conditions, merger mass ratios, and viewing angles this merger fraction can be converted into a merger rate, and mass accretion rate due to mergers. A simple integration of the merger rate shows that a typical massive galaxy at z ~ 3 will undergo 4–5 major mergers between z ~ 3 and z ~ 0, with most of this activity, and resulting mass assembly, occurring at z>1.5.
The Evolution of Disk Galaxy Scaling Relations Since Redshift z = 1
Authors: Böhm Asmus , Ziegler Bodo L. 
Published: April 2007

AbstractBased on VLT/FORS spectroscopy and HST/ACS imaging, we have constructed a sample of 125 field spiral galaxies that cover redshifts up to z = 1. By deriving the galaxies' luminosities, disk sizes, maximum rotation velocities, stellar masses, total masses, gas-phase metallicities etc., we are able to study the evolution of fundamental scaling relations like the Tully–Fisher relation as a function of cosmic time. While the evolution of most of the galaxies' fundamental parameters is in compliance with a hierarchical structure growth, the results from stellar population modelling favour a down-sizing scenario in the sense that the average stellar ages in high-mass spirals are older than in low-mass spirals.
Are strong z ≃ 0.5 MgII absorbers the signature of super-winds?
Authors: Bouché N. , Murphy M. , Péroux C. , Csabai I. , Wild V. 
Published: April 2007

AbstractBACKGROUND: In the process of galaxy formation, super-nova driven feedback from low-mass galaxies is the process that most readily account for the galaxy mass-metallicity relation and for the shallower galaxy luminosity function (LF) compared to the halo mass function. Absorption-selected galaxies are prime candidates for the sites of starburst activity as (1) they probe the gaseous halos of galaxies up to ~50 kpc (Steidel 1995), and (2) galaxies on the faint end of the LF are likely dominating the statistics. Galaxies selected via their MgII λ2796/2803 doublet absorption against background QSOs are especially well suited as Mg is produced by type II supernova.GOAL: Our project was to constrain the physical models of the gaseous halos by measuring the dark matter halo-mass (Mh) of the MgII host-galaxies statistically, i.e. without identifying spectroscopically the host-galaxy.METHOD: We have used the cross-correlation w(rθ) (over co-moving scales rθ:0.05–13h−1Mpc) between our sample of 1800 z ≃ 0.5 MgII absorbers with equivalent w width W2796r−0.3 Å, and 250,000 Luminous Red Galaxies (LRGs), both selected from SDSS/DR3. The cross-correlation relies on the LRG photometric redshifts, but is not affected from contaminants such as stars or foreground and background galaxies as shown theoretically in Bouché et al. 2005 and empirically in Bouché et al. 2006.RESULTS: From the cross-correlation analysis, we found (Bouché et al. 2006) (i) that the absorber host-halo mean mass is 〈 log Mh (M⊙)〉 = 11.94 ±0.31(stat)+0.24−0.25(sys), i.e. about 1/2 L*, and (ii) an anti-correlation between halo mass Mh and equivalent width W2796r.INTERPRETATION: One SDSS MgII absorber (system) is made of several sub-components or clouds and the stronger the equivalent with of the absorber, the more clouds per system spread over a larger velocity range (Δv). This follows since each sub-component has a velocity width of ~ 5 kms s−1 (Churchill 1997). As result, the equivalent width W2796r is a measure of velocity width (Δv) as demonstrated by Ellison 2006. Together with our SDSS results, these relations imply a mass–velocity Mh–Δv anti-correlation. If the clouds in the host-halos were virialized, velocity and mass would have been correlated.CONCLUSION: Therefore, our Mh–Δv anti-correlation shows that the clouds are not virialized in the gaseous halos of the hosts. This conclusion is best understood in the context of starburst driven outflows where the velocity Δv is related to bulk motion. This opens the possibility to study M82-analogs up to z ~ 2.0 using the MgII selection.
Evolution of the Mass-to-light Ratio of Galaxies to z~ 0.25
Authors: Catinella B. , Haynes M. P. , Gardner J. P. , Connolly A. J. , Giovanelli R. 
Published: April 2007

AbstractWe present the first results of a targeted survey carried out with the 305m Arecibo radiotelescope to detect HI-line emission from disk galaxies at redshift z > 0.16. We are using this sample to study the evolution of the zero point of the Tully-Fisher relation (TFR) for galaxies at intermediate redshifts. Compared to optical widths, HI measurements sample a larger fraction of the disks, where the rotation curves are typically flat, and are not affected by slit smearing and misalignment or by aperture effects. Thus, in contrast to studies based on optical spectroscopy, this dataset allows for a direct comparison with the local TFR that is technique independent.
The role of the gas in the bar instability. A cosmological approach
Authors: Curir Anna , Mazzei Paola , Murante Giuseppe 
Published: April 2007

AbstractThe growth and the evolution of the bar instability in stellar-gaseous disks embedded in a dark matter halo evolving in a cosmological framework is explored. We point out the impact of different gas fractions on the bar formation, inside disks of different disk-to-halo mass ratio.
The Nature of Near Ultraviolet Sources in the GOODS Fields
Authors: de Mello D. F. , Dahlen T. , Gardner Jonathan P. 
Published: April 2007

AbstractWe present the latest results of the survey searching for the nature of UV-selected galaxies in the Great Observatories Origins Deep Survey fields. By searching for UV-bright galaxies at intermediate redshifts (z ~ 1) we aim at understanding the nature of star-forming galaxies and their counterparts at higher-z, the so-called Lyman Break Galaxies.
The VIMOS VLT Deep Survey: A census of active and passive galaxies to redshift 1.3
Authors: Vergani D. 
Published: April 2007

AbstractWe are studying how stellar masses assemble through cosmic time since the Universe had only 30% of its present age. We are conducting a census of galaxies which covers the end of the most active star-forming phase, using a mass-limited sample of approximately 5,000 objects selected from the VIMOS VLT Deep Survey (VVDS) in the redshift range 0.45 < z < 1.3. With a criterion based on the direct spectral measurement of the 4000Å Balmer break, Dn(4000), we have classified our sample in spectroscopically early and late-type galaxies. The trends existing between stellar mass, spectroscopic classification, and star formation activity are clearly shown in our analysis.
Cosmic Evolution of Quasar Host Galaxies
Authors: Floyd D. , Kukula M. , Dunlop J. , McLure R. , O'Dea C. , Baum S. 
Published: April 2007

AbstractUsing HST WFPC2 and NICMOS observations, and our 2D image weighting and modelling technique (Floyd et al. 2004), we have reliably disentangled host from nucleus for nine optically matched radio-loud quasars (RLQ) and nine radio-quiet quasars (RQQ) at z = 1&2, in two bands spanning the 4000Å break. The resulting galaxy colours provide the first unbiased estimates of galaxy mass for a statistical sample of quasars at high redshift, and indicates a difference in the evolution of radio-loud and radio-quiet objects.
Morphology of z ~ 1 galaxies from deep K-band AO imaging
Authors: Huertas-Company Marc , Rouan Daniel , Soucail Geneviève , Le Fèvre Olivier , Tasca Lidia 
Published: April 2007

AbstractWe present the results of observations of distant galaxies (z ~ 0.8) at high spatial resolution (~0.1"). We observed 7 fields of 1' × 1' with the NACO Adaptive Optics system (VLT) in Ks (2.2μm) band with typical V ~ 14 guide stars and 3h integration time per field. Observed fields are selected within the COSMOS survey area. We analyze the morphologies by means of B/D (Bulge/Disk) decomposition with GIM2D and CAS (Concentration-Asymmetry) estimators for 79 galaxies with magnitudes between Ks = 17 − 23 and classify them in three main morphological types (Late Type, Early Type and Irregulars). We obtain for the first time an estimate of the distribution of galaxy types at redshift z ~ 1 as measured from the near infrared at high spatial resolution.
Photometry and Spectroscopy of i-drop Galaxies: Possible Detection of A Proto-cluster at z=6
Authors: Ota Kazuaki 
Published: April 2007

AbstractWe discovered 30 candidate galaxies are clustering in a small ~200 Mpc2 region at z = 6 with 5σ local density excess in a wide 876 arcmin2 field. Four of them were spectroscopically identified as z = 5.9–6.0 Lyα emitters (~34 Mpc in line-of-sight). This structure is comparable to z = 4.8 and 5.7 galaxy proto-clusters previously found. Since the other candidates are likely to be real galaxies due to low sample contamination, the overdensity can be a z~6 proto-cluster.
The evolution of the mass-metallicity relation up to z≈0.9 from the VIMOS/VLT Deep Survey
Authors: Lamareille F. , Contini T. , Charlot S. , Brinchmann J. ,   the VVDS team
Published: April 2007

AbstractWe present the first results derived from the spectrophotometric properties of the Vimos VLT Deep Survey (VVDS) first epoch data. We have measured the spectral features (emission/absorption lines, 4000Å break) of a sample a ≈8000 galaxies taken from the VVDS deep 02h and CDFS fields using the platefit VVDS pipeline. We first selected a sub-sample of star-forming galaxies, which were distinguished from narrow-line AGNs by standard and blue diagnostic diagrams. Then the gas-phase oxygen abundances have been derived by fitting all available emission lines towards photo-ionization models. Finally the masses have been derived by fitting all photometric points together with significant spectral features to a library of stellar population models with complex star formation histories. The mass-metallicity relation that we find at low redshifts is in good agreement with previsous studies performed in the local Universe. We find moreover a significant evolution of the mass-metallicity relation with the redshift, the galaxies having on average less metals at a given mass when the redshift increases. We also find a flattening of the mass-metallicity relation up to z ~ 1.
The primordial CH molecule as a possible probe for the first structures formation epoch
Authors: Campos J.C. , Saucedo Morales J.C. , Lipovka A.A. , Nunes-Lopez R. 
Published: April 2007

AbstractThe role of primordial CH molecules in the first structures formation epoch is considered. We discuss the plausibility of observing protostructures in the Dark Age epoch of the Universe by studying the rotational structure of the CH molecule. It is stressed that considerable abundances of this molecule could be formed for different Inhomogeneous BBN models, which could lead to observable spectral-spatial fluctuations in the CMBR spectrum. The calculation is carried out for the Lambda-CDM cosmology and for typical first structures physical conditions. The chemical evolution of the structures is followed numerically, and the optical depth for the most important ground rotational transitions of the CH molecule are proposed. It is shown that under reasonable conditions the primordial CH molecule can be observed with mm-telescopes under construction.
The stellar mass-metallicity relations of galaxies from high-z to the local
Authors: Liang Y. C. , Hammer F. , Deng L. C. 
Published: April 2007

AbstractThe stellar mass-metallicity relations of star-forming galaxies at intermediate-z (0.4<z<1) and high-z (z≥2) are compared with the local SDSS galaxies. It shows obvious evolutionary effect, i.e., at a given stellar mass, the intermediate-z galaxies show about 0.3 dex lower metallicity, and the high-z galaxies show about 0.56 dex more metal-deficient than the local ones. These distant galaxies will produce these important parts of their metals during the consequent evolutionary process. A close-box model can explain this evolutionary process generally.
COMBO-17+4: An Optical-NIR Survey for Galaxies out to z=2
Authors: Nicol M-H. , Meisenheimer K. , Tapken C. , Wolf C. 
Published: April 2007

AbstractClassifying Object by Medium-Band Observations in 17 filters (COMBO-17) has already produced a very accurate picture of galaxy evolution since z~1 based on 25000 galaxies in 17 medium optical bands. We now extend the range of reliable multi-color redshifts with COMBO-17+4, a deep optical-NIR survey which will combine the existing optical data set of COMBO-17 with near infrared observation in three medium bands: Y(λ/Δλ = 1040/80nm), J1(1190/130nm) and J2(1320/130nm) and one broad band H(1650/300nm). The NIR bands extend the photometric redshift range to z~2.1. COMBO 17+4 will provide the first large sample of galaxies (>5000) at 1<z<2 with a redshifts accuracy of Δz<0.03(1+z). Three fields are observed: Abell 901, Abell 226 and the COMBO 11h-field, for a total coverage of 0.77□2 of the sky. Each COMBO 17+4 field measures 31 × 30 sqarcmin. The NIR bands are observed with the Omega2000 camera at Calar Alto Observatory in Spain.The scientific goals for this study are multiple. COMBO-17+4 will enable us to establish the luminosity function for the red sequence and blue galaxies in the redshift range 1<z<2. Also it will be possible to determine the formation history at z=2 by analyzing the width of the red sequence galaxies. Moreover this survey will provide several thousand of individual galaxy masses (with an accuracy <30%) obtained with Spectral Energy Distribution (SED) template fitting. Once the masses are obtained the mass function will provide a useful tool to test the hierarchical model of evolution of galaxies by checking whether the massive red sequence galaxies (logM>10.5) are already in place at z>1.5 (9Gyr).We present first results from the full 21 bands photometry in half of the Abell 901 field. It allows us to study not only z>1 galaxies but also the stellar content of several hundred cluster galaxies.
Elliptical Galaxies Since z ~ 1.5: The Evolution of The Fundamental Planes
Authors: Oñorbe J. , Domínguez-Tenreiro R. , Artal H. , Serna A. 
Published: April 2007

AbstractWe use a set of hydrodynamical, self consistent simulations operating in the context of a concordance cosmological model where relaxed elliptical-like objects (ELOs) were identified at different redshifts. ELOs at different redshift are well described by the Sérsic (1968) function. We also obtain a good comparison with observational scaling relations. These results indicate that ELOs conform a homogeneous population at any redshift, except that high z ELOs tend to be more compact that their lower z counterparts. Also, scaling relations point to the rupture of the structural homology.
Detecting Low-Order CO Emission from z ≳ 4 Quasar Host Galaxies
Authors: Riechers D. A. , Walter F. , Carilli C. L. , Knudsen K. K. , Lo K.Y. , Benford D. J. , Staguhn J. G. , Hunter T. R. , Bertoldi F. , Henkel C. , Menten K. M. , Weiss A. , Yun M. S. , Scoville N. Z. 
Published: April 2007

AbstractMolecular gas has now been detected in 15 z>2 QSOs. These detections are commonly obtained by observing high–J CO transitions due to their relatively high peak fluxes and observing frequencies in the millimeter atmospheric windows. However, only observations of the CO ground-state transition, CO(1–0), have the potential to trace the molecular gas at lower excitations, which may give a better estimate of the total molecular gas mass of high–z QSOs. Here we present first z>4 CO(1–0) observations obtained with the NRAO Green Bank Telescope and the MPIfR Effelsberg telescope (Riechers et al. 2006). With these two 100m telescopes, we detect the CO(1–0) transition in the high–redshift QSOs BR 1202-0725 (z = 4.7), PSS J2322+1944 (z = 4.1), and APM 08279+5255 (z = 3.9). We find that the CO/FIR luminosity ratios of these high-z sources follow the same trend as seen for low-z galaxies. Utilizing large velocity gradient (LVG) models based on previous results for higher–J CO transitions, we derive that all CO emission can be described by a single gas component and that all molecular gas appears to be concentrated in a compact nuclear region. We thus find no evidence for luminous, extended CO(1–0) components in the molecular gas reservoirs around our target quasars.
Dense Molecular Gas at High Redshift: First Detection of Emission from HCO+
Authors: Riechers D.A. , Walter F. , Carilli C.L. , Weiss A. , Bertoldi F. , Menten K.M. , Knudsen K.K. , Cox P. 
Published: April 2007

AbstractUsing the Very Large Array (VLA), we have detected the HCO+(1–0) emission line towards the Cloverleaf quasar (z = 2.56; Riechers et al. 2006). This is the first detection of ionized molecular gas emission at high redshift (z>2). HCO+ emission is a star formation indicator similar to HCN, tracing dense molecular hydrogen gas within star-forming molecular clouds. We find a HCO+/CO luminosity ratio of 0.08 and a HCO+/HCN luminosity ratio of 0.8 for the Cloverleaf. These ratios fall within the scatter of the same relationships found for low–z star–forming galaxies. However, a HCO+/HCN luminosity ratio close to unity would not be expected for the Cloverleaf if the recently suggested relation between this ratio and the far–infrared luminosity (Graciá–Carpio et al. 2006) were to hold. We conclude that a ratio between HCO+ and HCN luminosity close to 1 is likely due to the fact that the emission from both lines is optically thick and thermalized and emerges from dense regions of similar volumes. We conclude that HCO+ is potentially a good tracer for dense molecular gas at high redshift.
News from z ~ 6 − 10 galaxy candidates found behind gravitational lensing clusters
Authors: Schaerer D. , Hempel A. , Pello R. , Egami E. , Richard J. , Kneib J.-P. , Wise M. 
Published: April 2007

AbstractFollowing up on the detailed results from our searches for z~ 6–10 galaxies using gravitional lensing clusters descrived in Richard et al. (2006), we have obtained new observations, which are presented here. For a general overview of the project see Schaerer et al. (2006). First, deep HST/ACS observations in the z-band confirm 17 out of 18 high redshift candidates as optical drop-out objects; the remaining object appears faint and star-like. Second, Spitzer/IRAC images at 3.6, 4.5, 5.8 and 8.0 μm have been obtained. 11 out of 18 candidates are in “free”, uncominated regions. These 11 high-z candidates are undetected, with upper limits which are compatible with their SED if these objects are blue star-forming galaxies at high redshift (see Fig. 1). In conclusion, our new observations corroborate so far the high-z nature of the majority of the candidates.
Distribution and evolution of high-z galaxies in the Subaru/XMM-Newton Deep Survey Field (SXDF)
Authors: Sekiguchi K. , Ouchi M. 
Published: April 2007

AbstractWe present results from our on-going study of the distribution and evolution of high-z galaxies. We exploited the large area coverage (~1.3 deg2) of the Subaru / XMM-Newton Deep Survey field (SXDF) to search for Lyman-break galaxies (LBGs) and Lyα Emitters (LAEs) at 3 <z< 7. We have found filamentary large scale structures, which are made of LAEs, with ~10 to 40 Mpc (in commoving units) scale voids as early as at z = 5.7. Galaxies at this redshift show clustering of ~1 Mpc in diameter (in physical unit). The inferred star formation rate density of these clustering is ~130 times the mean of the whole area, indicates burst of star formation activities. Combined with the UKIDSS/UDS photometry, the optical+near-IR SED fitting provides the estimate of masses for some of these high-z galaxies. Preliminary results indicate a number of galaxies at z >5 have already grown up to ~1011 solar mass.