bluuebunny/crossref_metadata_2025 huggingface dataset:
Inclination Dependent Luminosity Function of Spiral Galaxies
Authors: Shao Zhengyi
Published: April 2007

We study the inclination dependent luminosity function (LF) of spiral galaxies of the Sloan Digital Sky Survey (SDSS). Up to 60000 sample galaxies are selected from the 2nd data release of SDSS by fracdeVr < 0.5. Magnitudes and other related photometric parameters are taken from NYU-VAGC(Blanton et al.2005). The apparent axis ratio (b/a)is used as an observational inclination indicator to define sub-samples. LFs of all 5 SDSS bands (u, g, r, i, z) are drawn for different sub-samples. Significant correlation is found between characteristic magnitudes (M*) of sub-samples and their inclinations, which can be fairly explained by dust extinction. A linear fit of the relation between M* and log(b/a) measures the M*(0) (for expected face-on spirals, with 0.2 ~ 0.3 mag brighter than that of LF of whole sample) and the intensity of dust extinction γ, for each band (Figure 1(a)). Additionally, since γ ∝ τ (optical depth), the wavelength dependent γ describes the extinction curve. Figure 1(b) shows a good linear fit that implies the extinction curve obeys the power law very well, with τλ = τV(λ/5500Å)−0.97±0.07. The power index n ~ 1 is shallower than that of the MW, LMC and SMC (n=1.1~1.5), but significantly steeper than the value of Charlot et al. (2000) (n=0.7), which under the assumption of a patchy distribution of dust in spiral galaxies. So our result implies that dust distributed in spirals, on average, are not as patchy as Charlot et al. assumed.
Compact and Fossil Groups
Authors: de Oliveira Claudia Mendes , Amram Philippe
Published: April 2007

We present a short review on poor groups of galaxies focusing on the evolution of compact groups and formation of fossil groups. Fossil groups are systems with one dominant luminous elliptical galaxy surrounded by faint companions, in an extended X-ray halo. We will briefly discuss the possibility of fossil groups being the end-products of the merging of compact groups.
The ORELSE Survey
Authors: Gal Roy , Lubin L. M. , Squires G. K.
Published: April 2007

The ORELSE Survey (Observations of Redshift Evolution in Large Scale Environments) is a multi-wavelength program to study the large-scale structure around a sample of 20z>0.6 clusters, with the goal of understanding transformative processes affecting galaxies in a broad range of environments. The survey includes (1) deep optical imaging to map structure around the clusters; (2) optical spectroscopy to confirm redshifts, map the galaxy distribution, obtain cluster masses via dynamical estimates, and measure spectral properties; (3) ground-based K-band imaging, to better constrain galaxy stellar masses and improve photometric redshift estimates; (4) near-IR spectroscopy to study post-starburst galaxies and AGN; (5) HST imaging to obtain galaxy morphologies; (6) Spitzer IRAC and MIPS imaging to separate starburst and AGN populations, and examine dusty galaxies; and (7) Chandra and VLA mapping to find X-ray and radio-loud AGN that are not evident from optical data. We discuss here the motivation and some early results.
Formation and Evolution of Nucleated Galaxies
Authors: Bekki Kenji
Published: April 2007

We discuss how stellar galactic nuclei (SGN) form and evolve during galaxy formation and evolution based on chemodynamical simulations on the central regions (1-1000 pc) of galaxies. Our simulations demonstrate that dissipative formation of SGN through rapid transfer of gas into the central 10 pc of galaxies is more consistent with recent observations of SGN than dissipationless formation of SGN through merging of globular clusters (GCs). Nuclear structures in the remnants of major galaxy mergers between low-mass, nucleated spirals are found to depend strongly on the mass-ratio of massive black holes (MBHs) to SGN in spirals in the sense that the remnants have more distinct SGN in the mergers with the smaller MBH-to-SGN-mass-ratios. During the destruction of low-mass, nucleated galaxies by strong tidal fields of giant galaxies, SGN can remain intact. The stripped SGN can be observed as bright GCs around the giant galaxies. The color-magnitude relation of metal-poor GCs (referred to as “the blue tilt”) recently discovered for bright galaxies is similar to that of SGN, which suggests that the origin of the blue tilt is closely associated with the formation processes of SGN of gas-rich, low-mass dwarfs in the high redshift universe.
Infrared Properties of Nearby Interacting Galaxies: from Spirals to ULIRGs
Authors: Charmandaris Vassilis
Published: April 2007

I present a brief review of some of the mid-infrared properties of interacting galaxies as these were revealed using observations from the Infrared Space Observatory and Spitzer Space Telescope over the last decade. The variation of the infrared spectral energy distribution in interacting galaxies can be used as an extinction free tracer not only of the location of the star formation activity but also of the physical mechanism dominating their energy production.‡.
Secular Evolution and the Morphological Transformation of Cluster and Field Galaxies
Authors: Zhang Xiaolei , Buta Ronald J.
Published: April 2007

Deep surveys conducted during the past decades have shown that galaxies in the distant universe are generally of more irregular shapes, and are disky in appearance and in their star formation rate, compared to galaxies in similar environments in the nearby universe. Given that the merger rate between z= 2 and the local universe is far from adequate to account for this observed morphological transformation rate, an internal mechanism for the morphological transformation of galaxies is to be sought, whose operation can be further aided by environmental factors. The secular evolution mechanism, especially with the discovery of a collisionless dissipation mechanism for stars within the secular evolution paradigm, has provided just such a framework for understanding the morphological evolution of galaxies across the Hubble time. In this paper we will summarize the past theoretical results on the dynamical mechanisms for secular evolution, and highlight new results in the analysis of the observational data, which confirmed that density waves in physical galaxies possess the kind of characteristics which could produce theáobserved rates of morphological transformation for both cluster and field galaxies.
Enviromental Effects on Internal Color Gradients of Early-Type Galaxies
Authors: La Barbera F. , de Carvalho R.R. , Gal R.R. , Busarello G. , Haines C.P. , Mercurio A. , Merluzzi P. , Capaccioli M. , Djorgovski S.G.
Published: April 2007

We use g and r band imaging from the Palomar Abell Cluster Survey (Gal et al. 2000, AJ 120, 540) in order to estimate internal color gradients, measured as the logarithmic slope of galaxy radial color profiles, for a sample of 4000 early-type galaxies in N = 162 Abell clusters, spanning a wide richness range, from poor groups to rich clusters, and a redshift range of z=0.05 to z=0.25. Color gradients are estimated from the galaxy structural parameters (namely, the effective radius, re, and the Sersic index, n) in the g and r bands. These parameters are derived by fitting galaxy images with 2D PSF convolved Sersic models (La Barbera et al. 2002, ApJ, 571, 790). We select as early-type cluster galaxies those objects with Sersic index n>2, that lie on the color magnitude relation of each cluster. Only objects with S/N ratio high enough to derive reliable structural parameters are included in the analysis (La Barbera et al. 2005, ApJL, 626, 19). Field contamination amounts to ~10%; in our sample and is corrected for by using 32 blank fields observed with the same setup and analyzed in the same way as the cluster images. We find that color gradients follow two distinct redshift trends, with color gradients being less steep for richer rather than poor clusters (La Barbera et al. 2005, ApJL, 626, 19). Fig. 1 plots the mean internal color gradient of galaxies as a function of local galaxy density, which is estimated by using the Voronoi tessellation method. We find that color gradients are strongly dependent on local environment, with color gradients being less steep in higher rather than in lower density regions. However, this environmental trend only holds for poor clusters, with galaxies in rich clusters not showing any significant trend. These results support a picture whereby some interaction mechanism, such as galaxy-galaxy merging, flattens the internal color gradient of galaxies, producing the observed correlation with local density in low richness clusters. If rich clusters form through the merging of groups of galaxies, this process would wash out any correlation between local density and the past merging history of galaxies.
Extended HI Rotation Curve of M31 using deep DRAO observations
Authors: Carignan C. , Chemin L. , Foster T.
Published: April 2007

Carignan et al. (C06, 2006, ApJ, 641, L109) recently presented an extended HI rotation curve (RC) of M31, using single dish observations from the 100m Effelsberg and Green Bank telescopes. These data were obtained along the semi-major axis of the approaching half of the M31 HI disk and showed a flat RC at large radius, which extends up to ~35 kpc (using D = 780 kpc). The kinematical analysis of M31 is pursued here and new deep 21cm observations obtained at the Dominion Radio Astrophysical Observatory (DRAO) are presented. A tilted-ring model is fitted to a new HI velocity field, allowing the derivation of the position angle P.A. and inclination i as a function of radius. We concentrate on the approaching half of the disk in order to compare our new results with those from C06. It is shown that the disk warping of M31 does not severely contaminate the kinematics of the neutral gas. As a consequence, the RC from C06 is in very good agreement with the new derived RC.
The Strong Transformation of Spiral Galaxies Infalling into Massive Clusters at z~ 0.2
Authors: Cortese L. , Marcillac D. , Richard J. , Bravo-Alfaro H. , Kneib J.-P. , Rieke G. , Covone G. , Egami E. , Rigby J. , Czoske O. , Davies J.
Published: April 2007

We report the discovery of two peculiar galaxies infalling into the lensing clusters of galaxies Abell 1689 (z~ 0.18) and 2667 (z~ 0.23). Hubble Space Telescope images show extraordinary trails composed by blue bright knots and stellar streams associated with both these systems, an ~L* and ~0.1L* galaxy. Under the combined action of tidal interaction with the cluster potential and of ram pressure by the intra-cluster medium the morphologies and star formation histories of these two galaxies are strongly perturbed. While in the massive system tidal interactions are the dominant effect and are able to produce a sinking of gas towards the galaxy center triggering a strong burst of star formation and changing galaxy's morphology, in the smaller galaxy the effects of gravitation are reduced by ram pressure stripping which blows away the neutral hydrogen from the galactic disk, quenching the star formation activity and transforming a gas rich late type spiral into quiescent disk dominated early type system. This result is a new additional evidence that galaxy mass represents the main driver of galaxy evolution, even during their dive into the harsh cluster environment and can give additional insights on the origin of S0s and dwarf cluster galaxies.
The Size-Luminosity Relation of Disk Galaxies in EDisCS Clusters
Authors: Gogarten Stephanie M. , Dalcanton Julianne J. , Simard Luc , Rudnick Gregory , Desai Vandana ,   the EDisCS Collaboration
Published: April 2007

We present the size-luminosity relation (SLR) for disk galaxies observed in eight clusters from the ESO Distant Cluster Survey (EDisCS). These clusters, at redshifts 0.4 < z < 0.8, were observed with the Hubble Space Telescope's Advanced Camera for Surveys. While we observe a change in the SLR with redshift, namely that there is an absence of low surface brightness galaxies at high redshift, we demonstrate that this could be a product of selection effects and thus is not a confirmation of evolution. We also compare the SLR for cluster and field galaxies in each redshift bin and see no significant effects of environment on the SLR.
The Evolution of Groups and Group Galaxies to Intermediate Redshifts
Authors: Jeltema Tesla E. , Mulchaey John S. , Lubin Lori M. , Fassnacht Christopher D.
Published: April 2007

We have undertaken a multiwavelength project to study the properties of X-ray selected groups at intermediate redshifts (0.2 < z < 0.6). Mulchaey et al. (2006) presented the spectroscopic confirmation of nine groups. Jeltema et al. (2006) presented the X-ray properties of these groups based on observations taken with XMM-Newton. These observations confirm that these systems contain luminous, diffuse gas with luminosities and temperatures consistent with the correlations seen among groups and clusters at low redshift. We find indications of excess entropy in these systems over self-similar predictions out to large radii. We have obtained deeper spectroscopic follow-up of seven groups with the Keck and Gemini telescopes. Along with the HST imaging, we study the galaxy populations in these groups, and our main results are summarized below.
The Sunyaev-Zel'dovich Effect of Nearby Clusters in the 3-Year WMAP Data
Authors: Hu Jian , Nie Jianyin , Zhang Shuangnan
Published: April 2007

We explore the thermal Sunyaev-Zel'dovich (SZ) effect of a sample of 31 clusters in the three-year data of the Wilkinson Microwave Anisotropy Probe (WMAP), and detect strong SZ signal at the ~10 σ level. By comparing the co-added SZ profile of the sample clusters with the prediction based on the X-ray observations of ROSAT and XMM-Newton, we find the SZ profiles are consistent with the isothermal β-model of intracluster medium (ICM), but the central region (<0°.2) may be contaminated by the central radio sources in the clusters. We derive a mean outer radius of the ICM distribution at ~1.2 ± 0.4rvir (68% CL). The existence of the ICM outer edge could be the first evidence of ICM accretion shock, which is important for understanding the formation and evolution of clusters. We also estimate the mean gas mass fraction of the ICM from the overall amplitude of the SZ signals as fgas = 0.10 ± 0.05, which is consistent with the X-ray observation and lower than the cosmic average baryon fraction.
Planetary Nebulae as a Probe of the Local Group Galaxies Evolution
Authors: Kniazev A. Y. , Pustilnik S. A. , Grebel E. K. , Zucker D. B. , Vaisanen P.
Published: April 2007

We present the latest results from our study of PNe and HII regions in two Local Group dwarf irregular galaxies IC 10 and NGC 6822.
Luminosity Function of Galaxies in Substructures of Galaxy Clusters
Authors: Krywult Janusz
Published: April 2007

The analysis of the R-band luminosity function of galaxies in substructures of 21 Abell clusters shows that the characteristic magnitude M* for dominant substructure is brighter than in the second substructure and the magnitude gap between two brightest galaxies in dominant substructure is larger than in the second one.
Catalog of Positions and Spectroscopic Properties of Galaxies in the A1367 Cluster
Authors: Lipovka N. M. , Morales J. C. Saucedo , Lipovka A. A. , Boldycheva A. V. , Maslennikov K. L.
Published: April 2007

In the present work the results of an optical spectroscopy study of 8 galaxies projected in the central part of the A1367 cluster are reported. The observations were made using the 2.2 m. Guillermo Haro Telescope in Cananea (Mexico), and the Boller and Chivens spectrograph. A catalog of the optical positions of more than 100 galaxies in the cluster is presented. The redshifts of 7 galaxies were determined from their absorption systems, while for the remaining galaxy was obtained from its strong emission lines of H-alpha, S II, O III and H-beta. For one of the galaxies the emission redshift is z= 0.015, not showing absorptions lines at the cluster redshifts (z = 0.026), which argues that it is located between the observer and the A1367 cluster.
Intragroup Gas in Differently Evolved Compact Groups of Galaxies
Authors: Verdes-Montenegro L. , Rasmussen J. , Ponman T. , Yun M. S. , Borthakur S.
Published: April 2007

Compact groups are highly isolated, dense galaxy systems, and therefore tidal interactions are expected to be continuous and dynamically important. For this reason they represent unique laboratories for studying interactions in extreme environments and tidally induced star formation as well as morphological and dynamical evolution of galaxies in general. This study is part of a broader investigation of the evolutionary status of HCGs. In order to explain the HI deficiency found in compact groups of galaxies we have proposed a broad evolutionary scenario in which the amount of HI decreases with the secular evolutionary state of a group. The fate of this gas is however not clear. In order to investigate the physical mechanisms responsible for these changes in the gas content of galaxies we have started a study to look for an intragroup medium (IGM). We have considered this IGM to be neutral (see e.g. reports of HI clouds within Virgo cluster (Oosterloo & Van Gorkom 2005), or hot gas (a higher X-ray detection rate of HI deficient groups is found relative to groups with a normal HI content, Verdes-Montenegro et al. 2001). Enhanced star formation activity might also be contributing to exhausting the gas supply. We have observed 25 HCGs with diverse HI content and distribution with the Green Bank radiotelescope, and performed VLA-HI as well as X-ray (XMM or Chandra) observations of the most HI deficient groups HCG 7, 15, 30, 37, 40, 44 and 97. We have also analysed FIR data from Verdes-Montenegro et al. (1998).

Our results are: (a) HI deficient groups show a larger amount of diffuse neutral and X-ray gas when compared to non-deficient ones, consistent with our evolutionary picture; (b) Most groups are still deficient after including diffuse gas. (c) A hot IGM is not detected in most of these systems, but the detection rate is higher for the high velocity dispersion groups, and in these cases ram pressure stripping could potentially cause the observed HI-deficiency. (d) In several of these groups we detect intragroup radio continuum emission, which is surprising since similar features were seen previously only in massive clusters (known as “relic” sources). (e) Star formation activity traced by FIR luminosity is not enhanced, contrary to the general expectation of tidally interacting systems.

Hence neither the presence of a hot or cold IGM nor star formation activity seem to be able to uniquely explain the HI deficiency found in compact groups of galaxies. We plan to explore the possibility that earlier starbursts could have contributed to the present HI deficiency.
3-D Voronoi's Tessellation as a Tool for Identifying Galaxy Groups
Authors: Melnyk Olga V. , Elyiv Andrii A. , Vavilova Iryna B.
Published: April 2007

3-D Voronoi's tessellation method has been applied for identifying groups of galaxies in the structure of the Local Supercluster and evaluation of its properties.
Multiresolution Analysis of Tidal Debris Structures in Groups of Galaxies
Authors: Pereira D. N. Epitácio , De Mello A. B. , Rabaça C. R.
Published: April 2007

Galaxies in groups and clusters often experience strong tidal forces from its neighbors, expelling a significant amount of matter (stars and gas) to the surrounding environment, giving rise to ‘tidal debris’ features. We present the first experiments in a program of identification of substructures of extragalactic tidal debris elements in images from the HST archive, using wavelet-based multiresolution analysis. Tidal structures in two compact groups of galaxies, HCG 79 (Seyfert's Sextet) and HCG 92 (Stephan's Quintet) have been analyzed so far.
Spitzer IRAC Observations of Interacting Galaxies from 0 < z < 3.01
Authors: Smith et al. Howard A.
Published: April 2007

We have observed over 100 interacting galaxies (IGs) with Spitzer IRAC as part of a detailed study of the their properties (see also Zezas, et al. in this volume). The majority of sources are nearby. Precise IRAC imaging photometry of these galaxies finds a wide range of colors in these systems, and correlative spectroscopic data suggests the colors are reflected by composition that is in turn reflective of age; orientation also plays a role. We have also observed a distant pair of interacting galaxies at z=3.01, a HyLIG, EGS20 J1418+5236 (Huagg et al. 2006), and find that, like the nearby systems, it has similar processes at work albeit in a hyperactive way.

To overcome limitations of some previous studies of IGs, we observed two complementary nearby samples, one selected on the basis of galaxy separation, and the other selected on a morphological basis. Figure 1 below is a summary IRAC [3.6um]-[4.5um] versus [5.8um]-[8.0um] color-color plot of these IGs. Five generic regions emerge: ellipticals near (0,-0.1), early-stage IGS around (1.5, -0.1), Seyfert 1s around (1.3, 0.5), Seyfert 2s around (1.5, 1.2), and LINERS/HII galaxies centered at 2.2, 0.2). These systems are each characterized by spectral dust features in the IRAC bands that are strong enough to influence and]or mirror the underlying stellar continuum colors. The arrows suggest possible evolutionary development.
WINGS: WIde-field Nearby Galaxy-cluster Survey
Authors: Varela Jesús ,   the WINGS collaboration
Published: April 2007

The WIde-field Nearby Galaxy-cluster Survey (WINGS) is a long term project whose main goal is to establish the zero point and variance of properties of nearby clusters, and galaxies in them, to be used as a local reference in evolutionary studies.

To achieve such objective, wide-field multiwavelenght photometry and optical spectroscopy has been gathered and analysed for a sample of 77 X-ray emitting nearby galaxy clusters.

This contribution shows the current status of the project.

Complete poster contents is reproduced in “On-line Section” and PDF copy is available in http://web.oapd.inaf.it/wings/Docs/IAU2006_Varela.pdf.
XMM Observation of the Galaxy Cluster Abell 514
Authors: Weratschnig J. , Schindler S. , Gitti M.
Published: April 2007

We present XMM-Newton observations of the galaxy cluster Abell 514. This cluster shows a very complex X-ray morphology. Radio observations show that there are six radio sources located inside the cluster. This makes it possible to determine the magnetic field strength using the Faraday rotation method. This cluster is an example for the hierarchical growth of structure and a very interesting object for studying the correlation between magnetic field strength and X-ray properties.
Star Formation Through Cosmic Time
Authors: Dopita Michael A.
Published: April 2007

This paper reviews the star formation history of the Universe, from the first stars to the current day, with emphasis on the critical analysis of the techniques that have been used to determine it, especially considering the role of dust. We consider the first population of stars, the Population III stars, were formed at redshifts ranging as high asz~ 60, the formation of the Globular Clusters, the main epoch of galaxy formation. In the sub-mm galaxies and high-redshift radio galaxies the collapse of massive galaxies was surprisingly rapid, and that the growth of super-massive black holes at their centers provides the energy input to eject the galactic interstellar medium while at the same time precipitating a final burst of star formation and the ejection of their ISM so that the subsequent evolution of these galaxies is passive.
Extended UV Disk (XUV-disk) Galaxies
Authors: Bianchi Luciana , Thilker David , de Paz Armando Gil , Madore Barry ,   GALEX Science Team
Published: April 2007

Motivated by the GALEX discovery of recent star formation in outermost regions of M83 and NGC4625, we have investigated the nature of the XUV disks with follow-up high resolution imaging and spectroscopy, and attempted to detect them at other wavelengths (IR, Hα). We searched for additional XUV-disk galaxies in the local universe, in order to quantify the incidence of the XUV-disk phenomenon, infer the causes of such extended star formation (SF), and place these systems in the context of disk galaxy evolution.
Starburst and Poststarburst Galaxies from the Sloan Digital Sky Survey
Authors: Blomqvist Anna , Bergvall Nils
Published: April 2007

We have used the SDSS DR 4 to study links between starburst and poststarburst galaxies in the redshift range z=0-0.25. Starburst counterparts to the most luminous postbursts seem to be lacking, probably due to an increasing contribution from dust and AGNs. Starburst lifetimes were derived from spectral evolutionary models and space densities and were found to vary with luminosity, from a few times 107 to the order of Gyr at the low luminosity end.
Star Formation in Nearby Early-Type Galaxies: Mapping in UV, Optical and CO
Authors: Bureau M. , Bacon R. , Cappellari M. , Combes F. , Davies R. L. , de Zeeuw P. T. , Emsellem E. , Falcón-Barroso J. , Jeong H. , Krajnović D. , Kuntschner H. , McDermid R. M. , Peletier R. F. , Sarzi M. , Shapiro K. L. , van de Ven G. , Yi S. K. , Young L. M.
Published: April 2007

The SAURON integral-field survey reveals that small (~0.1,Re) kinematically decoupled cores (KDCs) in early-type galaxies are increasingly young toward the center and are typically found in fast-rotating galaxies, while large KDCs (~0.5 Re) have homogeneously old stars and are present in non-rotating galaxies (McDermid et al. 2006). GALEX UV imaging further allows the direct identification of regions of recent star formation (≤0.5 Gyr). In NGC 2974 for example, young stars are identified in the center and an outer ring Jeong et al. 2006). Nuclear and inner ionised-gas rings (Sarzi et al. 2006) then suggest that current star formation is bar-driven. The CO detection rate of SAURON early-type galaxies is ≈40% (Combes et al. in prep.). Synthesis imaging reveals that it is generally contained in a well-ordered central disk, both in galaxies with a (young) central stellar disk (e.g. NGC 4459, NGC 4526) or a (young) KDC (e.g. NGC 3032, NGC 4150) (Young et al. in prep.). CO also traces well the young stellar populations and ionised gas distribution and kinematics, but in KDCs not always the stellar kinematics Emsellem et al. 2004; Sarzi et al. 2006; Kuntschner et al. 2006).
Insights About Induced SFR in the Shell Systems of Early-Type Galaxies from UV (GALEX)
Authors: Buson L. M. , Bettoni D. , Marino A. , Chiosi C. , Galletta G. , Rampazzo R. , Tantalo R. , Rich R. M.
Published: April 2007

We present UV data of a small sample of shell galaxies. For the majority of them (namely, NGC 2865 and NGC 7135), the NUV matches the optical emission, while the FUV is present in the innermost regions alone.
A New Chemo-Dynamical Tool to Study The Evolution of Galaxies in the Local Universe
Authors: Champavert Nicolas , Wozniak Hervé
Published: April 2007

Figure 1.

Schematic presentation of our new chemo-dynamical tool. See Champavert & Wozniak (2007a) for full details and references.
The Chemical Enrichment and Mass Assembly Histories of SDSS Galaxies
Authors: Fernandes R. Cid , Asari N. V. , Torres-Papaqui J. P. , Schoenell W. , Sodré L. , Mateus A. , Stasińska G.
Published: April 2007

We explore the mass-assembly and chemical enrichment histories of star forming galaxies by applying a population synthesis method to a sample of nearly 70k galaxies culled from over 500k galaxies from the Sloan Digital Sky Survey Data Release 5. Our method decomposes the entire observed spectrum in terms of a sum of simple stellar populations spanning a wide range of ages and metallicities, thus allowing the reconstruction of galaxy histories. A comparative study of galaxy evolution is presented, where galaxies are grouped onto bins of nebular abundances or mass. We find that galaxies whose warm interstellar medium is poor in heavy elements are slow in forming stars. Their stellar metallicities also rise slowly with time, reaching their current values (Z⋆ ~ 1/4Z⊙) in the last ~100 Myr of evolution. Systems with metal rich nebulae, on the other hand, assembled most of their mass and completed their chemical evolution long ago, reaching Z⋆ ~ Z⊙ already at lookback times of a few Gyr. These same trends, which are ultimately a consequence of galaxy downsizing, appear when galaxies are grouped according to their stellar mass. The reconstruction of galaxy histories to this level of detail out of integrated spectra offers promising prospects in the field of galaxy evolution theories.
High Resolution CO(3-2) and HCO+(4-3) Imaging of the Luminous Infrared Galaxy NGC 6240
Authors: Iono D. , Wilson C. , Yun M. , Takakuwa S. , Peck A. , Petitpas G. , Ho P. , Wang Z. , Pihlstrom Y.
Published: April 2007

We present interferometric CO(3-2), HCO+(4-3) and 870 micron continuum images of the luminous infrared galaxy NGC 6240 obtained at the Submillimeter Array (SMA). Our spatially resolved CO (3–2) and HCO+(4–3) emission peaks between the two nuclear components that are known to both harbor AGNs. The kinematical information provided by the CO (3–2) emission shows a rotating disk centered around the northern AGN and a possible face-on disk around the southern AGN, but the kinematics of gas between the two nuclei is extremely turbulent.
The Near-IR [SIII] Lines in a Sample of Star-Forming Galaxies: Chemical Abundances
Authors: Kehrig C. , Vílchez J. M. , Telles E. , Cuisinier F. , Pérez-Montero E.
Published: April 2007

We present a detailed spectroscopic study of a sample of 34 star-forming dwarf galaxies, ranging from the blue to near-infrared (λ3700Å-1μm) (Kehrig et al. 2006). The metal enrichment in this kind of objects has been operating typically at low metallicity enviroments. The spectra were observed with the 1.52m telescope at La Silla/ESO. We derive fundamental parameters for HII regions and ionizing sources in our star-forming galaxies, as well as gaseous metal abundances. All the spectra include the nebular[SIII]λλ9069,9532Å lines, that are of crucial importance in the derivation of the S/H abundances, and relevant ionization diagnostics. We study the relative hardness of their ionizing sources using the η' parameter (Vílchez & Pagel 1988), and exploring the roles played by metallicity and age. The ionic and total O/H was also derived using direct determinations of the te[OIII]. The mean S/O ratio derived in this work is constant and slightly below the solar (S/O)⊙ value (see fig 1). The data presented here are consistent with the conclusion that S/O remains constant as O/H varies among the sample of HII galaxies. Variations in S/O along the whole O/H abundance range may be present, but the scatter in S/O (due mainly to observational errors) is still large to constrain them. The assumption that the S/O ratio remains constant for all abundances is still an open question and should be explored further (Pérez-Montero et al. 2006).
Methods to Calibrate Oxygen Abundances of Star-Forming Galaxies and the Recent Results from the Large Sample of SDSS Galaxies Galaxies
Authors: Liang Y. C. , Yin S. Y. , Hammer F.
Published: April 2007

Using a large sample of ~40,000 star-forming galaxies selected from the SDSS, we derive oxygen abundance calibrations from strong-line ratios, such as [N II]/Hα, [O III]/[N II], [N II]/[O II], [N II]/[S II], [S II]/Hα, and [O III]/Hβ. The derived analytic calibrations cover a quite wide range of metallicity, from 12+log(O/H)= 7.1 to 9.3. These calibrations can be used as calibration references for the future studies about metallicities of star-forming galaxies.
Planetary Nebulae: A Probe of the Galaxies Evolution up to the Hubble Time
Authors: Kholtygin A. F. , Milanova Yu. V.
Published: April 2007

Chemical evolution of the galactic and extragalactic planetary nebulae (PNe) system beginning from the early age of the Galaxy is investigated. We determine the radial and vertical abundance gradients for C, N, O, Ne, Ar, Cl and S in a dependence on mass and age of the progenitor stars of the nebula. In the Table 1 we compare the galactic abundance gradients for O and Ne for our and neigbour galaxies.
Oxygen Abundance and Stellar Populations in the Three Most Metal-Deficient Emission-Line Galaxies Known in the Local Universe: SBS 0335-052,E, SBS 0335-052 W and I Zw 18
Authors: Papaderos P. , Yakobchuk T. , Izotov Y. I. , Guseva N. G. , Fricke K. J.
Published: April 2007

We present new spectroscopic observations of the system of the two blue compact dwarf (BCD) galaxies SBS 0335-052 W and SBS 0335-052 E with the 3.6m ESO telescope. The oxygen abundance in SBS 0335-052 W was determined to be 12 + log(O/H) = 7.13±0.08, confirming that this galaxy is the most metal-deficient emission-line galaxy known. We find that the oxygen abundance in SBS 0335-052 E varies from region to region in the range from 7.20 to 7.31, suggesting the presence of an abundance gradient over a spatial scale of ~1 kpc. Signatures of early carbon-type Wolf-Rayet stars are detected in cluster #3 of SBS 0335-052 E, corresponding to the emission of 20 to 130 WC4 stars, depending on the adopted luminosity of a single WC4 star in the Civ λ4658 emission line (Papaderos et al. 2006).
Spitzer Observations of M33 & M83 and the Hot Star, Hii Region Connection
Authors: Rubin R. , Simpson J. , Colgan S. , Dufour R. , Citron R. , Ray K. , Erickson E. , Haas M. , Pauldrach A.
Published: April 2007

Emission-line observations made with the Spitzer Space Telescope are used to test the predicted ionizing spectral energy distributions of various stellar atmosphere models.
An Infrared Study of Lyman Break Galaxies in the Spitzer First Look Survey Field
Authors: Shim Hyunjin , Im Myungshin
Published: April 2007

We investigate the properties of Lyman Break Galaxies at z ~ 3 in the Spitzer First Look Survey field. The effective area coverage of the study is ~2.63 deg2, the largest among similar studies of R ~ 24 mag u-dropouts. Photometric redshifts, ages, dust extinctions and stellar masses of the LBGs have been derived through SED fitting. More than 70% of IRAC-detected LBGs have stellar masses of order of ~1011 M⊙, comparable with L* galaxies. The MIR luminosity, which represents the rest-frame NIR, is found to be a good tracer of the stellar mass. As the red (optical−MIR) colors of the massive LBGs suggest, IRAC LBGs are older (〈t〉 ~ 0.9 Gyr) and dustier (〈E(B − V)〉 ~ 0.33) than typical LBGs. The age and the amount of dust indicate that the IRAC LBGs are intermediate population between blue LBG population and red DRG population. The number density of LBGs more massive than 1011 M⊙ is Φ = (1.05 ± 0.15) × 10−5 Mpc−3. This value exceeds the predictions of hierarchicl galaxy formation models.
Formation of dwarf galaxies and small-scale problems of CDM
Authors: Gnedin Oleg Y.
Published: April 2007

The concordance cosmological model based on cold dark matter makes definitive predictions for the growth of galaxies in the Universe, which are being actively studied using numerical simulations. These predictions appear to contradict the observations of dwarf galaxies. Dwarf dark matter halos are more numerous and have steeper central density profiles than the observed galaxies. The first of these small-scale problems, the “missing satellites problem”, can be resolved by accounting for the low efficiency of gas cooling and star formation in dwarf halos. A newly-discovered class of HyperVelocity Stars will soon allow us to test another generic prediction of CDM models, the triaxial shapes of dark matter halos. Measuring the proper motions of HVS will probe the gravitational potential out to 100 kpc and will constrain the axis ratios and the orientation of the Galactic halo.
“Downsizing” from the fossil record: Ages and metallicities of red galaxies and their dependence on mass and on environment
Authors: Hudson Michael J. , Smith Russell J. , Nelan Jenica E. , Lucey John R. , Wegner Gary. A.
Published: April 2007

Red-sequence galaxies are known to obey well-defined scaling relations, such as the Fundamental Plane and the colour-magnitude relation, yet their star formation histories, which in part drive these relations, remain poorly understood. In this contribution, we summarize recent results from the NOAO Fundamental Plane Survey (NFPS). These results appear in more detail in Smith et al. (2006) and Nelan et al. (2005).
Measuring the Star Formation Rate of the Universe at z ~ 1 from Hα with Multi-Object Near-Infrared Spectroscopy
Authors: Bunker Andrew , Doherty Michelle , Sharp Rob , Parry Ian , Dalton Gavin , Lewis Ian
Published: April 2007

We have demonstrated the first near-infrared multi-object spectrograph, CIRPASS, on the 4.2-m William Herschel Telescope (WHT) and the 3.9-m Anglo-Australian Telescope. We have conducted an Hα survey of 38 0.77 < z < 1 galaxies over ~100 arcmin2 of the Hubble Deep Field North and Flanking Fields, to determine star formation rates (SFRs) using CIRPASS on the WHT. This represents the first successful application of this technique to observing high redshift galaxies (Doherty et al. 2004). Stacking the spectra in the rest-frame, we find a lower limit (uncorrected for dust reddening) on the star formation rate density at redshift z = 1 of 0.04 M⊙ yr−1 Mpc−3 (Doherty et al. 2006). This implies rapid evolution in the star formation rate density from z = 0 to z = 1 which is proportional to (1 + z)3.1. We intend to extend our work with FMOS on Subaru as the evolSMURF project (the Evolution of Star-formation and Metallicity in the Universe at high Redshift with FMOS). This will represent nearly two orders-of-magnitude improvement on previous work, and for the first time will provide a sample of sufficient size to measure accurately the Hα luminosity function, and so determine the global star formation rate using the same indicator as used in local surveys. Using [O II]3727 Å, Hβ, [O III] 5007 Å and Hα redshifted into the z, J & H bands, we can chart the star formation history over 70% of the age of the Universe, affording complete coverage up to z = 1.6 with the same well-understood diagnostics. The line ratios will also allow the extinction and metallicity to be measured at z>1. This will resolve one of the long-standing puzzles in extragalactic astrophysics – the true evolution of the Madau-Lilly diagram of star formation density.
The Life Cycle of Massive Red Galaxies
Authors: Doherty M. , Bunker A. J. , Ellis R. S. , McCarthy P. J.
Published: April 2007

Samples of Extremely Red Galaxies (ERGs) have generally been seen to comprise a mix of actively star-forming galaxies with significant dust reddening and evolved, passive galaxies, at redshifts about z ≈ 1 − 2. Initial results from deep Keck spectroscopy of ERGs (Doherty et al. 2005) revealed dominant old stellar populations in 75% of our spectroscopic sample, but only 28% have spectra with no evidence of recent star formation activity, such as would be expected for a strictly passively-evolving population. This study suggests that the bulk of the ERGs are luminous, spheroidal, evolved galaxies, but undergoing intermittent activity consistent with continued growth.

Through a detailed investigation of individual galaxies in our sample we aim to address various outstanding questions. What fraction of their mass is produced in ongoing star formation? Is there a characteristic mass at which star formation is abruptly truncated? What mechanism provokes a secondary burst of star formation in evolved galaxies?

We fit Bruzual & Charlot (2003; BC03) simple stellar population models to the broad band SEDs over a wide baseline, using a reduced χ2 minimisation, to investigate ages, stellar masses and star formation histories. The fits for the early types agree well with information in the spectra and return ages of 2–3 Gyr and masses in the range 1011–1012M⊙. The objects with recent star formation episodes are more complex. Some are fit well by continuous star formation models, accounting for the effects of dust. We are now in the process of exploring multi-population fits to investigate the effects of episodic bursts.

Previous morphological studies of ERGs have revealed a diverse mix of galaxies – a combination of pure bulges, disks and a small fraction of irregular or interacting systems. We are curious to determine whether a morphological analysis produces results consistent with the spectroscopic properties of our sample. We are investigating a sub-sample of our galaxies which have HST imaging publically available. Initial results from a quantitative analysis using bulge/disk decomposition with GALFIT and GIM2D indicate that most galaxies with Early type spectra are bulge dominated. In contrast, a significant fraction of the galaxies showing spectroscopic signatures of on-going star formation on top of underlying old stellar populations appear to have a well-established classical spiral morphology, wih knots of star formation located in spiral arms around a central bulge. There is tenuous evidence (under further investigation) that at least half of the post-starbursts in our sample are barred spirals, lending support to theories relating post-starbursts to recent mergers.
What Can We Learn From Dynamics Of Nearby Galaxies To Study Distant Galaxies?
Authors: Epinat B. , Amram P. , Balkowski C.
Published: April 2007

This is an ongoing project.

During last few years, new instruments like GIRAFFE (Flores, H., Hammer, F., Puech, M., et al., 2006, A&A 455,107) or SINFONI (Förster Schreiber, N.M., Genzel, R., Lehnert, M.D., et al., 2006, ApJ 645,1062) have began investigations on 3D kinematics of high redshift galaxies. This is just the head of the iceberg as Extremely Large Telescope will allow this kind of study on a larger sample. By now, it is important to be able to recover the actual kinematic parameters, and overall to disentangle evolutionnary effects from distance effects.
HCN Observations of Submillimeter Galaxies and QSOs at High Redshift
Authors: Gao Yu , Carilli C.L. , Solomon P.M. , Vanden Bout P.A.
Published: April 2007

We have conducted sensitive HCN(1-0) line observations of four high redshift submillimeter (sub-mm) galaxies and QSOs with the VLA. Although none is significantly detected in either line or continuum emission, thanks to the gravitational lens, sub-mm galaxy SMM J16359+6612 is marginally (at the 3-4σ level) detected once the three lensed components are stacked up. The HCN source appears to be double with a separation of ~1.5'', consistent with what has been implied from other observations. This first possible HCN detection of a submm galaxy, and three stringent HCN upper limits, combined with previous HCN detections and upper limits strongly constrain the HCN/CO ratios at high-z to be comparable to that of local ULIRGs.
Finding Hidden Quasars with UKIDSS and AAOmega
Authors: Maddox Natasha , Hewett P. C. , Warren S. J. , Croom S. M.
Published: April 2007

The debate regarding the number of dust-reddened quasars has been ongoing for several years. Selecting quasars based on a UV excess will exclude any quasar that has an SED that departs from the standard power-law or is experiencing obscuration from dust. As longer wavelengths are less affected by dust attenuation, it is advantageous to select quasar candidates in the NIR, but until now, there did not exist a dataset of sufficient depth and coverage suitable for undertaking such an experiment.
The Evolution of Moderately Ionized Gas in the Universe
Authors: Monier Eric , Nestor Dan , Rao Sandhya , Turnshek David , Daino Michael , Quider Anna
Published: April 2007

We present results on the properties and evolution of moderately ionized gas in the Universe based on intervening CIV absorption-line systems. We have compiled a database of CIV systems from the SDSS, and we find evidence for evolution in the incidence of CIV absorbers.
Star Formation Rates of a z~1 DEEP2 Galaxy Sample from LIRIS Multi-slit Hα Spectroscopy
Authors: Rodríguez-Eugenio Nayra , Noeske Kai G. , Acosta-Pulido Jose , Prada Francisco , Manchado Arturo ,   AEGIS Teams
Published: April 2007

We present preliminary results of Hα near-infrared (NIR) spectroscopy of 16 galaxies with redshifts in the range 0.8 ≤ z ≤ 1.0 drawn from the DEEP2 Galaxy Redshift Survey. The spectra were taken using the multi-slit mode of LIRIS (Long-slit Intermediate Resolution Infrared Spectrograph), installed at the 4.2-m WHT. Twelve out of 16 spectra yield robust (>5σ) Hα detections. We compare star formation rates (SFRs) from Hα luminosities to those derived from DEEP2 rest-frame UV measurements. This study is part of a larger program to obtain accurate Hα luminosities of about 50 star-forming galaxies at z ~ 1 in the Extended Groth Strip. Our scientific goals are the measurement of SFRs from Hα, and the comparison and calibration of Hα and other SFR tracers at z ~ 1. The study will be complemented with galaxy stellar masses, reddening estimates, galaxy morphologies and metallicities.
Clustering of galaxies in the overdense regions of radio galaxies at z>0.6
Authors: Popescu Nedelia A.
Published: April 2007

Photometric redshifts technique and red sequence technique are used in order to analyze the clustering of galaxies in the environments of 4 radio galaxies with redshifts z>0.6.
High-z radio starbursts host X-ray AGN
Authors: Richards Anita M. S. , Beswick R. , Garrington S. T. , Muxlow T. W. B. , Thrall H. , Garrett M. A. , Kettenis M. , van Langevelde H. J. , Gonzalez-Solarez E. , Walton N. A. , Allen M. G.
Published: April 2007

We use Virtual Observatory methods to investigate the association between radio and X-ray emission at high redshifts. Fifty-five of the 92 HDF(N) sources resolved by combining MERLIN+VLA data were detected by Chandra, of which 18 are hard enough and bright enough to be obscured AGN. The high-z population of μJy radio sources is dominated by starbursts an order of magnitude more active and more extended than any found at z < 1 and at least a quarter of these simultaneously host highly X-ray-luminous obscured AGN.
Observations of turbulence in the diffuse interstellar medium
Authors: Dickey John M.
Published: April 2007

The warm neutral medium, warm ionized medium, and cool neutral medium all show strong evidence for turbulence as a process dominating their structure and motions on a wide range of scales. The spatial power spectra of density fluctuations in all three phases are consistent with a Kolmogorov slope. Turbulence in the magnetic field in the diffuse medium can also be measured through the structure function of the Faraday rotation measure. With new surveys, new analysis techniques, and new telescopes, in the next few years it will be possible to measure the structure function of the magnetic field over a similarly wide range of scales. This will give a complete picture of the turbulence as a magneto-acoustic process.
Turbulence in high latitude molecular clouds
Authors: Shore S. N. , LaRosa T. N. , Magnani L. , Chastain R. J. , Costagliola F.
Published: April 2007

We summarize a continuing investigation of turbulence in high-latitude translucent molecular clouds. These low mass (~50–100 M), nearby (~100 pc), non-star forming clouds appear to be condensing out of the atomic cirrus. Unlike star-forming clouds the velocity fields in the clouds must be driven by external processes. Our detailed mapping of the clouds MBM 3,16 and 40 indicates that the dynamics in these clouds result from the combination of shear-flow and thermal instabilities, not shocks. These clouds also show coherent structures, non-Gaussian PDFs but no clear velocity-size relation. Lastly, the energetics of these clouds indicate that radiative loss may terminate the cascade before local heating takes place.
Towards resolving the evolution of multi-supernova superbubbles
Authors: Oey M. S.
Published: April 2007

Interstellar superbubbles generated by multiple supernova explosions are common in star-forming galaxies. They are the most obvious manifestation of mechanical feedback, and are largely responsible for transferring both thermal and kinetic energy to the interstellar medium from the massive star population. However, the details of this energy transfer remain surprisingly murky when individual objects are studied. I will summarize what we currently know about candidate dominant processes on these scales.