bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Early-Type Dwarf Galaxy Population of the Fornax Cluster
Authors: Mieske Steffen 
Published: April 2007

AbstractAIMS: We analyse the photometric properties of the early-type Fornax cluster dwarf galaxy population (MV> − 17 mag), based on a wide field imaging study of the central cluster area in V and I bandpasses. We used the instrument/telescope combination IMACS/Magellan at Las Campanas Observatory, providing much larger light collecting area and better image resolution than previous wide field imaging surveys.METHODS: We create a fiducial sample of Fornax cluster dwarf ellipticals (dEs) in the following three steps: (1) To verify cluster membership, we measured I-band surface brightness fluctuations (SBF) distances to candidate dEs known from previous surveys; (2) We re-assessed morphological classifications for those candidate dEs that are too faint for SBF detection; and (3) We searched for new candidate dEs in the size-luminosity regime close to the resolution limit of previous surveys.RESULTS: (1) We confirm cluster membership for 28 candidate dEs in the range −16.6 < MV < −10.1 mag by means of SBF measurement. We find no SBF background galaxy. (2) Of 51 further candidate dEs in the range −13.2 < MV < −8.6 mag, 2/3 are confirmed as probable cluster members by morphological re-assessment, while 1/3 are re-classified as probable background objects. (3) We find 12 new dE candidates in the range −12.3 < MV < −8.8 mag, two of which are directly confirmed via SBF measurement. The resulting fiducial dE sample follows a well-defined surface brightness – magnitude relation, showing that Fornax dEs are about 40% larger than Local Group dEs. The sample also defines a colour-magnitude relation that appears slightly shallower than that of Local Group dEs. The early-type dwarf galaxy luminosity function in Fornax has a very flat faint end slope α ≃ −1.1 ± 0.1. We discuss these findings in the context of structure formation theories.CONCLUSIONS: The SBF method is a very powerful tool to help constrain the faint end of the galaxy luminosity function in nearby galaxy clusters. For the Fornax cluster, morphological cluster memberships – if performed at sufficient resolution – are very reliable.This contribution is based on Mieske et al. (2006).
The Arecibo Galaxy Environments Survey–Description of the Survey and Early Results
Authors: Minchin R. F. , Auld R. , Davies J. I. , Catinella B. , Cortese L. , Linder S. , Momjian E. , Muller E. , O'Neil K. , Rosenberg J. , Sabatini S. , Schneider S. E. , Stage M. , van Driel W. ,   the AGES team
Published: April 2007

AbstractThe Arecibo Galaxy Environments Survey (AGES) is a 2000-hour neutral hydrogen (H I) survey using the new Arecibo L-band Feed Array (ALFA) multibeam instrument at Arecibo Observatory. It will cover 200 square degrees of sky, sampling a range of environments from the Local Void through to the Virgo Cluster with higher sensitivity, spatial resolution and velocity resolution than previous neutral hydrogen surveys.
Poor Groups Around Strong Gravitational Lenses
Authors: Momcheva Ivelina , Williams Kurtis , Zabludoff Ann , Keeton Charles 
Published: April 2007

AbstractPoor groups are common and interactive environments for galaxies, and thus are important laboratories for studying galaxy evolution. Unfortunately, little is known about groups at z ≥ 0.1, because of the difficulty in identifying them in the first place. Here we present results from our ongoing survey of the environments of strong gravitational lenses, in which we have so far discovered six distant (z ≥ 0.5) groups of galaxies. As in the local Universe, the highest velocity dispersion groups contain a brightest member spatially coincident with the group centroid, whereas lower-dispersion groups tend to have an offset brightest group galaxy. This suggests that higher-dispersion groups are more dynamically relaxed than lower-dispersion groups and that at least some evolved groups exist by z ~ 0.5. We also compare the galaxy and hot gas kinematics with those of similarly distant clusters and of nearby groups.
Multi-passband search for galaxy clusters in CFHTLS D1
Authors: Olsen L. F. , Benoist C. , Mazure A. , Adami C. 
Published: April 2007

AbstractWe compare the results of applying different cluster detection methods to photometric data obtained for the Deep-1 field of the Canada-France-Hawaii Telescope Legacy Survey. The poster can be downloaded at http://www.dark-cosmology.dk/~lisbeth/cfhtls_clusters.pdf
The Baryonic Matter at Supercluster Scales: The Case of Corona Borealis Supercluster
Authors: Padilla-Torres Carmen P. , Rebolo Rafael , Gutiérrez Carlos M. , Watson Robert , Génova-Santos Ricardo , Juncosa Robert 
Published: April 2007

AbstractSuperclusters of galaxies are the largest gravitationally bound structures of the Universe. Numerical simulations indicate that a significant fraction of baryonic matter could be located in supercluster (SC) scales in the form of a warm/hot plasma. The sensitivity and resolution of the VSA interferometer at Teide observatory allow us to search for evidence of the Sunyaev-Zeldovich effect (SZE). We have published evidence for such a plasma towards the center of the Corona Borealis Supercluster (CrB-SC), Génova-Santos et al. (2005). Two large decrements in the intensity of the signal measured by VSA at 33 GHz (CrB-B and H) subtending an angle of about 25' could be indicative of a concentration of baryonic matter comparable to thousands of galaxies. This matter could be in the form of a plasma of temperature ~105 − 107 K where no clusters of galaxies have been identified. No other similar spots have been found in the VSA fields observed to measure the CMB primordial power spectrum of fluctuations, Rubiño-Martin et al. (2003), and suggests that this is indeed a very particular feature of the CrB-SC of galaxies. Additional data obtained with the MITO telescope of CrB-H also support this VSA finding Battistelli et al. (2006), and could be related to warm/hot plasma in the SC. We would expect a galaxy population to be associated with such a plasma, as it is well known to occur in clusters of galaxies where the SZE has been measured, Lancaster et al. (2005). However, the absence of X-ray emission in the ROSAT images in the CrB-SC SZ spots suggests that if there is a galaxy population linked to the plasma it may have a peculiar spatial distribution. We obtained photometry of CrB-SC region using the data base from SDSS DR4, covering a total of 15o2 in the CrB-SC area. We built a catogue with 121251 galaxies down a selection criterion based on galaxies colours 0.2 ≤ r − i ≤ 0.6 and δ(g, r, i) ≤ |0.2| errors. In order to study the behaviour of differents regions in the CrB-SC, four regions were measured that belongs it, two regions not associated with overdensity, A2065, and CrB-H with 30' radius for each ones. The completeness magnitude is R ≤ 21. A photometric study produced colour-magnitude diagrams where we can detect evidence that many of these galaxies belong to the same system. The excess in the number density of galaxies appears to be larger in CrB-H where the strongest CMB temperature decrement was found. The number of galaxies in it is a factor ~1.5 lower than A2065 and ~2.5 highest that the SC background field. This resembles the typical number of galaxies in clusters of galaxies. However, it appears these galaxies are more broadly distributed than in the well known clusters of this SC. It is possible that the hot plasma causing the SZ spot is indeed associated with a new large concentration of galaxies unidentified in the SC.
Interactions in Barred Galaxies: Effects of a Companion on the Bar Pattern Speed
Authors: Puerari Ivânio , Pfenniger Daniel 
Published: April 2007

AbstractWe study the effects of a companion in a parabolic co-planar orbit on the bar pattern speed. Unlike previous simulations, we use fully self-consistent 3D N-body simulations with live haloes, which are known to be important for bar evolution.
Near Infrared Photometry of Southern Pairs and Triplets of Galaxies
Authors: Puerari Ivânio , Valdez-Gutiérrez Margarita , Gurovich Sebastian , Freeman Kenneth F. , Hernández-Toledo Héctor 
Published: April 2007

AbstractWe present near infrared photometry of select pairs and triplets of galaxies observed with the CASPIR camera attached to the 2.3m Advanced Technology Telescope at Siding Spring Observatory, Australia. The preliminary results show that galaxies in pairs or triplets present near infrared colors that are redder than normal galaxies. We also performed a morphological analysis using bi-dimensional Fourier Transform techniques, as well as classical bulge + disk fits. Compared to isolated galaxies, the light distribution of galaxies in pairs and triplets often needs a larger number of Fourier coefficients to be well represented. Also, light profiles usually show deviations from the exponential disk (disk distortions, strong bars, etc.). In the future we intend to define some method to quantify the strength of the interactions by using the Fourier coefficients and/or the magnitude of the deviations from the classical Sersic + exponential laws.
Retarded Evolution of Low-Mass Galaxies in Voids?
Authors: Pustilnik S. A. , Kniazev A. Y. 
Published: April 2007

AbstractWe analyze possible differences in the global environments of very metal-poor BCGs with that of typical metallicity BCGs, basing on the parameter DNN – distance to the nearest “luminous” galaxy. We find very significant difference suggesting that a higher fraction of unevolved dwarfs reside in ‘voids’.
Caught in the Act: Witnessing a~Transforming Spiral in a Galaxy Group
Authors: Rasmussen J. , Ponman T. J. , Mulchaey J. S. 
Published: April 2007

AbstractRam pressure stripping of galaxies is believed to be inefficient in galaxy groups, but Chandra X-ray observations of the starburst spiral NGC 2276, a member of a small galaxy group, shows that this galaxy is being stripped of its gas at a rate of ~5 M⊙ yr−1 due to its motion through hot intragroup gas. This provides direct evidence that mechanisms associated with ram pressure can strip galaxies of their gas in systems much smaller than galaxy clusters.
The Formation of Young Clusters in Three Ongoing Galaxy Mergers
Authors: Rothberg B. , Whitmore B. , Schweizer F. , Chandar R. , van der Marel R. , Rossa J. , Blair W. , Mengel S. , Rieke M. 
Published: April 2007

AbstractHigh-resolution, multi-wavelength (UV through NIR) imaging from the Hubble Space Telescope has been obtained for three mergers in the Toomre Sequence, NGC 520, NGC 2623, & NGC 3256, to identify and measure the properties of young Globular Cluster (GC) candidates. Unlike previous merger studies, this work focuses on objects that lie in the middle of the Toomre Sequence. This age range represents a critical dynamical transition in the merging sequence between ongoing mergers and advanced remnants with properties more akin to elliptical galaxies. The early results of our investigation include luminosity functions and age-dating of the GC candidates. These results also address the impact of the dynamical state of the merger on the current young cluster population as compared with earlier studies that have dealt with the very oldest and very youngest mergers in the Toomre Sequence.
Galaxy properties from voids to clusters in the SDSS-DR4
Authors: Sorrentino G. , Rifatto A. , Antonuccio-Delogu V. 
Published: April 2007

AbstractWe investigate the environmental dependence of galaxy populations properties in the SDSS-DR4. Our aim is to search for systematic variations in the properties of galaxies with the local galaxy density in order to find hints that can be related to the presence of a void galaxy population. We find that galaxies in underdense regions (voids) are fainte and bluer than cluster galaxies. Moreover, the transition from underdense to overdense regions is smooth, as well as the percentage of late-type galaxies decreases while the percentage of early-type galaxies increases smoothly from underdense to dense environments.
Results From VLA Observations of Five Spiral Galaxies In The Virgo Cluster Region
Authors: Toribio M. C. , Solanes J. M. 
Published: April 2007

AbstractNew HI synthesis observations have been made for the five spiral galaxies NGC 4307, NGC 4356, NGC 4411a/b and NGC 4492, located in the Virgo Cluster Region, with the Very Large Array in its CS configuration. All these objects, but NGC 4411a, belong to a sample of spirals identified in previous single-dish studies of the HI distribution within the Virgo Cluster and its outskirts. The thirteen members of that sample were selected for showing neutral gas deficiencies as strong as those of the inner galaxies of Virgo and other rich clusters, but apparently lying on the infall region.The goal of the present observations is to progress further on the identification of the external mechanisms that may be responsible for the reduction of the interstellar gas in spiral galaxies and thus contribute to the study of the evolution of galaxies in high-density environments. In particular, the results of this work are relevant for the ongoing debate on the pre-processing of galaxies prior to entering the cluster environment.
Galaxy Population in the Infall Regions of Intermediate Redshift Clusters
Authors: Verdugo Miguel , Ziegler Bodo L. 
Published: April 2007

AbstractWe investigate the galaxy populations in 6 clusters of different x-ray luminosities at intermediate redshifts (z ≈ 0.25) concentrating on their star formation activity. Our ~500 Calar Alto MOSCA spectra come from targets covering large fields out to 2–4 cluster virial radii. To probe this so-called infall region is important since here newly arriving galaxies from the surrounding field encounter the special environment of clusters for the first time. We selected 3 fields containing 2 clusters each from the X-ray Dark Cluster Survey (Gilbank et al. 2004). Results for one field were already published by Gerken et al. 2004.We find evidence that the process(es) that suppresses or truncates the star formation activity in cluster galaxies, sets in already at rather large distances from the cluster cores corresponding to low projected local galaxy densities. This changes the fraction of star forming galaxies rather quickly.
Chandra and XMM Observations of Galaxy Groups: The Influence of Central AGN at the Low End of the Cluster Mass Scale
Authors: Vrtilek J. M. , O'Sullivan E. J. , David L. P. 
Published: April 2007

AbstractChandra and XMM, offering between them high angular resolution, substantial collecting area, and spatially-resolved spectroscopy at good spectral resolution, have given us the means to discover hitherto unanticipated phenomena, in groups as in clusters, and to explore a new set of issues that bring us closer to understanding the formation and evolution of groups and their constituent galaxies: the distribution of heavy elements, the presence of X-ray cavities and their relation to radio observations, the nature of cooling cores, and X-ray signatures of recent galaxy interactions. We here show Chandra and XMM data selected to illustrate recent results regarding some of these themes.
The Faint-End of the Galaxy Luminosity Function in the Hydra I Cluster
Authors: Yamanoi H. , Tanaka M. ,   Suprime-Cam Group
Published: April 2007

AbstractWe examine the galaxy luminosity functions (LFs) in the Hydra I cluster (Abell 1060) at z = 0.0126, for which very faint galaxies (down to M ~ −10) have not been surveyed yet. We conclude that the total LF has a slightly steep slope (α ~ −1.6) at −20 < M < −10 in the B- and RC-bands. The numbers of galaxies at the faint end (M ≳ −14) differ in between the cluster center and the outskirts slightly. We divide the Hydra member galaxies into red/blue galaxies and find that the shape of LFs in the faint magnitude range is determined by red dwarf galaxies.
Simulations of Cosmic Chemical Enrichment
Authors: Kobayashi Chiaki 
Published: April 2007

AbstractWe simulate cosmic chemical enrichment with a hydrodynamical model including supernova and hypernova feedback. We find that the majority of stars in present-day massive galaxies formed in much smaller galaxies at high redshifts, despite their late assembly times. The hypernova feedback drives galactic outflows efficiently in low mass galaxies, and these winds eject heavy elements into the intergalactic medium. The ejected baryon fraction is larger for less massive galaxies, correlates well with stellar metallicity. The observed mass-metallicity relation is well reproduced as a result of the mass-dependent galactic winds.
Neutral Gas and Metals From z = 4 to z = 0.5
Authors: Péroux Céline 
Published: April 2007

AbstractA complementary method to the emission selection of high-redshift galaxies consists in the observation of absorbers along the line of sight toward a background quasar. This selection technique has a constant sensitivity at all redshifts up to z = 6 (i.e. no redshift desert) and allow to select all types of galaxies regardless of their luminosity or star formation rate. The highest column density absorbers, the Damped Lyman-α (DLAs) systems, in particular, can be used to determine the cosmic evolution of HI gas in the Universe, ΩHI, and the global metallicity in the gas phase. Since stars are known to form from HI gas, ΩHI provides an indirect tracer of the history of star formation. Recent results from several parallel VLT programmes aiming at determining the cosmological evolution of the metallicity in the neutral gas phase are presented.
Downsizing in HII galaxies
Authors: Terlevich R. , López J. , Terlevich E. 
Published: April 2007

AbstractIn this work we estimated the statistical age of a set of HII galaxies obtained from the Sloan Digital Sky Survey Data Release Three (SDSS DR3). Applying an inversion method to the observed distribution of an age sensitive parameter such as the equivalent width of (Hα), we estimate the age of the galaxies. We find strong dependence of the age with stellar luminosity, mass and metallicity with the youngest HII galaxies being those with the lowest mass and metallicity. These dependences found among HII galaxies indicate that “downsizing” extends to the low end of the mass distribution of galaxies.
The Rest-Frame Near-Infrared Colors and M/L of Early-Type Galaxies at z = 1
Authors: van der Wel Arjen 
Published: April 2007

AbstractWe present the results of a study of the evolution of the optical and near-IR colors and mass-to-light ratios (M/L) of early-type galaxies from z~ 1 to the present. This exercise is relevant for studies that use photometry of galaxies to infer properties such as stellar masses and star formation histories through comparison with stellar population models. We have dynamical M/L for a sample of 20 early types at z~ 1 with velocity dispersions from deep optical spectroscopy and structural parameters (size and surface brightness) from high-resolution HST imaging. We compare those with 23 early-type galaxies in the Coma Cluster at z=0.02. For both samples rest-frame optical/near-IR photometry is available, from HST and Spitzer in the case of the z~ 1 sample. We find that the M/L evolves faster in the near-IR than expected from most stellar population models, and also that predictions from different models can differ significantly in the near-IR. As a consequence, there is a systematic uncertainty of a factor of two in stellar mass estimates from near-IR photometry for evolved, high-z galaxies. Optical colors provide a less biased indicator of the M/L. Agreement among the models is required before near-IR photometry can be used as a robust tool to estimate galaxy masses without systematic uncertainties.
Gaseous Haloes: Linking Galaxies to the IGM
Authors: Fraternali Filippo 
Published: April 2007

AbstractRecent observations show that spiral galaxies are surrounded by massive and extended haloes of both neutral and ionized gas. These gaseous haloes have peculiar kinematics with respect to their discs: they rotate more slowly and they show an overall inflow motion. Theoretical models of the formation of these gaseous haloes show that they cannot originate solely from a galactic fountain (supernova outflows from the disk); substantial accretion of material from the Intergalactic Medium should play an important role.
The Structure of the Stellar Hosts in Blue Compact Dwarf Galaxies
Authors: Amorín R.O. , Aguerri J.A.L. , Cairós L.M. , Caon N. , Muñoz-Tuñón C. 
Published: April 2007

AbstractBlue compact dwarf (BCD) galaxies are gas-rich, low-luminosity (Mb≳-18 mag) and compact systems, currently undergoing violent star-formation burst (Sargent & Searle 1970). While it was initially hypothesized that they were very young galaxies (e.g. Sargent & Searle 1970, et al. 1988), the subsecuent detection of an extended, redder stellar host galaxy showed that the vast majority of them are old systems (e.g. Gil de Paz et al. 2003,2005). BCDs play an important role for understanding the process of galaxy formation and evolution.The structural properties of the low surface brightness stellar host in BCDs are often studied by fitting r1/n models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task.We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host Amorín et al. 2006, submitted). A set of ideal simulations are presented in order to test the reliability of the method and to determine its robustness and flexibility. We present the different steps of the method discussing its advantages and weaknesses. We compare the results for a sample of eight objects with those already obtained using a one-dimensional technique (Caon et al. 2005).We fit a PSF convolved Sérsic model to the BVR images with the GALFIT publicly software (Peng et al. 2002). We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. Consistency checks are performed to assess the reliability and accuracy of the derived structural parameters.We obtain robust fits for all the sample galaxies, all of which, except one, show low Sérsic indices n—very close to 1—with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles. Since the Sérsic index n of host galaxies is important in the context of the possible structural and evolutionary connections among the different types of dwarf galaxies, we are currently extending the study to a larger sample of objects. This kind of studies will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.
Star Formation and Threshold in Nearby Galaxies Observed with GALEX
Authors: Boissier Samuel ,   the GALEX team
Published: April 2007

AbstractStar formation on galactic scales is the process driving the evolution of galaxies. It is important to understand its various aspects in the nearby universe to properly interpret high redshift observations, and to construct correct models of the evolution of galaxies. Combining UV (GALEX) and infrared (IRAS) data for 43 nearby spatially resolved galaxies with corollary data (HI,CO), we study the star formation law (“Schmidt” law). The absence of a “threshold radius” in the UV supports the idea that star formation proceed at low gas densities and that the usual threshold observed in H-alpha profiles is a small-number statistic effect.