Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mrao.cam.ac.uk/galevol/abstracts_posters.pdf Дата изменения: Wed Aug 28 19:53:02 2013 Дата индексирования: Fri Feb 28 00:07:58 2014 Кодировка: Поисковые слова: spiral galaxy

Poster presentations
[1] Paola Santini
Title: The evolution of the dust and gas content in galaxies Abstract: I will present recent results obtained with Herschel data on the evolution of dust and gas properties from z2.5 to lo cal galaxies. In order to resolve the degeneracies asso ciated with the Main Sequence relation, dust and gas evolution have been investigated by disentangling the effects of the stellar mass and SFR. I will show how the dust content scales separately with the SFR and with the stellar mass and how it lacks any clear redshift evolution. The gas content is estimated from dust mass measurements by adopting assumptions on the dust-to-gas ratio. The inferred relation between the SFR and the gas mass (integrated Schmidt-Kennicutt relation) for the bulk of the population is in excellent agreement with previous results based on CO measurements, despite the completely different approaches. This confirms the reliability of this metho d, applicable to much larger sample of galaxies and affected by a lower number of uncertainties than CO-based results. All galaxies follow the same S-K law, and the average star formation efficiency decreases by a factor of 4 from z2 to z0. The relation between gas fraction, stellar mass and SFR do es not evolve with redshift, at least out to z2.5, it is an universal relation. Galaxies move across such relation as their gas content evolves across the cosmic epo chs. The pro jection of this 3D fundamental relation onto the Mstar-SFR plane yields the Main Sequence and its evolution with redshift. For Main Sequence galaxies with Mstar 2 в 101 0Msun, the gas fraction increases by a factor of 7 from z0 to z2.5. This evolution is shallower for more massive galaxies, implying that their gas-rich epo ch must o ccur at higher redshifts, in agreement with a downsizing scenario.

[2] Sarah Reeves Title: A search for intervening HI absorption in nearby, gas-rich galaxies Abstract: The 21cm HI absorption-line provides an ideal probe of the gas distribution and kinematics in galaxies well beyond the lo cal universe (z ї 0.3). However, we currently lack the understanding to infer galaxy properties from absorption-line data alone. To address this, we are conducting a search for intervening HI absorption in a sample of 20 nearby, gas-rich galaxies (selected from HIPASS). We investigate how detection-rate varies with distance from the galaxies, and make detailed comparisons of the absorption- and emission-line features to improve our understanding of the interpretation of absorption-line data. We also investigate how the properties of the background source might affect the detection rate. Here I present our results to date, and discuss implications for future absorption-line surveys. [3] Walter Maciel
Email: maciel@astro.iag.usp.br Title: Chemical evolution and abundance gradients in spiral galaxies Abstract: Chemical evolution mo dels of spiral galaxies require observational constraints in order to make accurate predictions concerning interstellar abundances, star formation history, age-metallicity relations, etc. Radial abundance gradients constitute one of the most interesting constraints, due to the fact that several chemical elements can be observed and, apart from the average gradients, spatial and temporal variations are also observed. In other words, gradients are responsible for a series of observational constraints that must be satisfied by any realistic chemical evolution mo del. In this work, we present new radial abundance gradients for the Milky Way disk derived from different samples of galactic planetary nebulae. The ob jects are divided into groups according to the age of the progenitor stars, so that we can obtain an estimate of the time variation of the gradients since the oldest progenitors were born. Several metho ds have been employed to estimate the stellar ages, based either on the nebular abundances or on their kinematic properties. The derived results suggest very small or no variations during the last 3 to 5 1


Gyr, so that no important differences are expected between the derived gradients and those obtained by a younger population such as HII regions and cepheid variables. Recent observational data on these ob jects seem to confirm these predictions. Finally, an attempt is made to apply these results to spiral galaxies in the Lo cal Group.

[4] Rafael Lopez Fernandez
Email: rafael@iaa.es Title: Multi-wavelength study of the stellar populations of galaxies in the integral field mapping CALIFA. Abstract: With the aim of determining the contribution of young stellar populations which contribute to a lesser extent the optical range and determine the star formation history of each spatially resolved galaxy, we combine CALIFA spectroscopic data with photometric data obtained in the ultraviolet range with GALEX. For this goal we use the synthesis co de STARLIGHT. As a first step we fo cus on the integrated spectrum of galaxies. We derive the integrated properties of the stellar populations, obtaining information about age, metallicity and extinction, and computing the SFR. We compare the results that we obtain with and without ultraviolet range.

[5] Lukas Lindroos
Email: lindro os@chalmers.se Title: Searching for distant faint galaxies in the radio and sub-millimetre Abstract: In the study of the high redshift universe large samples of galaxies are becoming increasingly important. By lo oking at large and deep samples we are able to draw conclusions on the large scale trends in galaxy evolution. Current radio/mm/submm high redshift surveys, however, primarily probe starbursts and AGN. A way to probe the submm and mm emission from less luminous galaxies is stacking. Stacking is a statistical approach to measure the average flux for known ob jects that typically are not detected individually. We have investigated stacking in the context of ALMA and JVLA data since interferometry provides some unique challenges for stacking. We will present a uv-based stacking algorithm and show that it present some clear advantages to traditional stacking for interferometric data. We present some stacking of simulated and real data. The stacking has been aplied to the Extended Fields-Deep-Field South (ECDFS) survery at 1.4 GHz. We have obtained stacked radio detections for different classes of high redshift star forming galaxies in this field. The results for the SFR are consistent with the results obtained in other fields. Our co de is currently being prepared to be released in an easy to use format for everyone.

[6] Rebecca Bowler
E-mail: raab@ro e.ac.uk Title: The first constraints on the bright end of the z7 luminosity function Abstract:The first constraints on the bright end of the z7 luminosity function In the last decade, a succession of deep ground and space-based near-IR surveys has led to the discovery of hundreds of galaxies at z > 6, allowing the first detailed studies of the properties of these early galaxies. In a broader context, repro ducing the observed prevalence of galaxies at high redshift, parameterised by the rest-frame UV luminosity function, is a key test for mo dels of galaxy formation. However, there remains a deficit in the number of bright (L >2L*) galaxies known at high redshift due to the rarity of such ob jects over the typically small field of view covered, for example, by Wide Field Camera 3 on the Hubble Space Telescope. Hence the bright end of the luminosity function, where results from lower redshifts indicate that there is an exponential cut-off in the number density, is still highly uncertain. With the combined 1.5 sq. degrees of the UltraVISTA and UDS surveys, we have detected the brightest galaxies known at 2


z 7 and hence can provide the first constraints on the form of the luminosity function out to 10L*. The multi-wavelength data also gives us a glimpse of the properties of these extremely luminous and therefore arguable massive galaxies at a time less than 1 billion years after the Big Bang.

[7] Crystal Martin Email: cmartin@physics.ucsb.edu Title: Galactic Winds: Confronting Prescriptions with Data Abstract: Feedback from star formation is central to cosmological mo dels of galaxy formation and evolution. Tuning the feedback prescription so that simulations repro duce the observed properties of the galaxy population have provided much insight into which galaxies may lose significant amounts of metals and gas via galactic winds. The new challenge comes in testing these recipes against empirical measurements of outflows. My talk/poster will present the demographics of outflow galaxies at z Ў 2 and compare recent estimates of wind mass loading to the values used in theoretical mo dels. [8] Rebecca Williams Email: rw480@mrao.cam.ac.uk Title: Dynamics and metallicity of far-IR selected galaxies Abstract: We present near-IR integral field spectroscopy of 10 Herschel selected galaxies at redshifts between 1.2 and 1.7. From detailed mapping of the Halpha and [NII] emission lines we were able to trace the dynamics, star formation rates, metallicities and also investigate gas fractions for these 10 galaxies. Our analysis of galaxy dynamics shows that minor dynamical disruptions (e.g. minor merging) are not enough to cause a deviation from the established "Main Sequence" relation. Only one galaxy in our sample strongly deviates from the main sequence; this galaxy is in strong interaction with a massive companion. These results suggest that only ma jor interactions between galaxies can push them off the main sequence. Furthermore, most galaxies are found to follow the fundamental metallicity relation, with four of them deviating. The deviation from the fundamental metallicity relation is independent of the galaxy dynamical properties, suggesting no link between metallicity and dynamical status (in contrast with the expectations of some theoretical mo dels). The metallicity maps show that for all but one galaxy there is a regular metallicity gradient with metallicity decreasing from the centre outwards. By inverting the SK-law we could infer the gas distribution and gas fraction in galaxies. We find the gas fraction of the sample to be an order of magnitude higher than that of lo cal galaxies. The inferred distribution of gas fraction and metallicity in individual galaxies can be explained by the presence of central outflows that fall back and cause enriched inflows in to outer regions of the galaxy. [9] Kristen Coppin
Email: k.coppin@herts.ac.uk Title: [O I]63 m in submillimetre galaxies at z1 Abstract: We present Herschel-PACS spectroscopy of the [O I]63 um far-infrared co oling line from a sample of six unlensed and spectroscopically confirmed 870 um selected submm galaxies (SMGs) at 1.1 < z < 1.6 from the LABOCA Extended Chandra Deep Field South (ECDFS) Submm Survey (LESS). This is the first survey of [O I]63 um, one of the main photo disso ciation region (PDR) co oling lines, in SMGs. We find that SMGs do not show a deficit in their [O I]63um-to-far-infrared (FIR) continuum luminosity ratios (with ratios ranging from 0.5 to 1.5 per cent), similar to what was seen previously for the [C II]158um-to-FIR ratios in SMGs. These observed ratios are about an order of magnitude higher than what is seen typically for lo cal ultraluminous infrared galaxies (ULIRGs), which adds to the growing bo dy of evidence that SMGs are not simply 'scaled up' versions of lo cal ULIRGs. Rather, the PDR line-to-LFIR ratios suggest that the star formation mo des of SMGs are likely more 3


akin to that of lo cal normal (lower-luminosity) star-forming galaxies, with the bulk of the star formation o ccurring in extended galaxy-scale (kpc) regions.

[10] Yingjie Peng
Email: yp244@mrao.cam.ac.uk Title: The dependence of the galaxy mass-metallicity relation on environment and the implied metallicity of the inflow Abstract: We explore the dependence of the galaxy mass-metallicity relation on environment, in terms of both over-density and central/satellite dichotomy. We find that at given stellar mass, there is a strong dependence of metallicity on over-density for star-forming satellites, while for star-forming centrals no correlation is found. In particular, the star-forming satellites at different stellar masses make up a tight sequence in the average over-density-metallicity plane, which covers the entire observed range of metallicity and stellar mass. This remarkable result appears to imply that there exists a unique evolutionary path for all star-forming satellites, regardless of their stellar masses. Given that the SFR distribution function at given stellar mass is universal and depends neither on over-density nor on central/satellite dichotomy, the strong correlation between over-density and metallicity for star-forming satellites indicates that the gas inflow of the satellites is getting progressively metal-enriched in dense regions. Employing the gas regulator mo del, we find that the metallicity of the enriched inflow of star-forming satellite galaxies, Z0 , strongly increases with increasing over-density. The derived Z0 - overdensity relation is largely independent of stellar mass and can be well described by a simple power law. If the metallicity of the inflow of star-forming satellites can represent the metallicity of the IGM, then the implied metallicity of the IGM rises from 0.01 Zsun in the void-like environment to 0.3 Zsun in the cluster-like environment, in broad agreement with observations. We show that the observed metallicity difference between star-forming centrals and star-forming satellites becoming smaller towards high stellar masses can be well explained by the mass-independent enriched inflow, without the need to involve any massdependent environmental effect on metallicity. Since satellite galaxies account for at least half of the galaxy population, our findings prompt for a revision of galaxy evolutionary mo dels, which generally assume pristine gas inflows.

[11] Aaron Robotham Email: aaron.robotham@uwa.edu.au Title: Galaxy Dodgems: Halo Scale Galaxy Feedback Abstract: The recently constructed G3C group catalogue, built using GAMA redshift data, contains robust halo masses across the largest dynamic range ever assembled. Here I present published and ongoing work that investigates the complex interplay between galaxy-galaxy interactions, halo mass and galaxy properties (morphology, star formation and colour). Galaxy-galaxy interactions pro duce the most dramatic effects on measurable galaxy properties, and this allows correlated evolution between central and satellite galaxies to be naturally explained. [12] Woong-Seob Jeong
Email: jeongws@kasi.re.kr Title: Observation of Cosmic Near-Infrared Background in Space Abstract: In Korea, the recent developments of astronomical instrument in space are concentrated on the observation of near-infrared background through the small satellite programs. The small infrared space telescope, MIRIS (Multipurpose Infra-Red Imaging System), had been developed to cover wide area of 10 deg. x 10 deg. in I and H bands. After the successful development of MIRIS, the new near-infrared mission, NISS (Near-infrared Imaging Spectrometer for Star formation history) is started 4


for the purpose of near-infrared imaging spectroscopy (R20) to obtain both broad spectral and spatial information of near-infrared sky. In addition to the current space pro ject, we are proposing the nearinfrared instrument (FPC-S, Fo cal Plane Camera - Science) in order to participate the future space pro ject, SPICA. One of main sciences proposed in those instruments is to study the cosmic infrared background. Especially, the detected excess emission feature in the near-infrared is regarded as the signature of integrated photons from first stars. The efficient near-infrared observation can be performed in space by evading the atmospheric emission as well as other thermal noise. The observation of cosmic near-infrared background enables us to reveal the origin of cosmic near-infrared background in early Universe with an indirect way through the measurement of absolute brightness and spatial fluctuation.

[13] Kshitij Thorat
Email: kshitij@rri.res.in Title: Linking Radio Source Morphologies and Their Optical Environments Abstract: The connections between galaxy evolution and the growth and activity of the AGNs are well established. Here we examine one such link between extended radio sources and their optical envionments. The gas environments in which radio sources reside and evolve have an influence on the morphology of the radio sources as shown in previous studies where radio source structures have been compared with the X-ray gas environments. Optical studies have fo cussed mainly on the differences between optical environments of different classes of radio sources.

[14] Doroshkevich Andrey
Email: dorr@asc.rssi.ru Title: Model of the galaxy formation Abstract: The possible applications of the well known analitical mo del to the galaxy formation at large redshifts are discussed. With this mo del we link the mass and redshift of the ob ject formation or completion what allows us to quantify the dependence of the halo formation pro cess with the initial power spectrum.

[15] Steven Phillipps
Email: s.phillipps@bristol.ac.uk Title: Galaxies in Colliding Clusters Abstract: One way to explore the many various influences on galaxy evolution in clusters is to lo ok for extreme cases where one factor may be expected to be unusually strong. We have therefore obtained deep HST imaging of a number of colliding clusters, exemplified by the 'Bullet Cluster'. Since the clusters have suffered interpenetrating high speed collisions, the gas has been 'left behind' as the clusters pass through one another. This means that the galaxies will have suffered much greater ram pressure stripping in the fairly recent past than would be the case for galaxies interacting with the IGM in their own cluster. In fact, we find no significant difference in the luminosity function or colourmagnitude diagram between the colliding clusters and a sample of 'normal' clusters at the same redshifts.

[16] Geraint Harker Email: geraint.harker@colorado.edu Title: Seeing the cosmic dawn from lunar orbit with the sky-averaged 21-cm signal Abstract: The sky-averaged, highly redshifted 21-cm line has emerged as a promising way to study the impact of the first stars and galaxies on the IGM using relatively simple instrumentation. The far side of the Mo on may well be the best lo cation in the inner solar system from which to observe this signal, since it blo cks RFI, avoids the Earth's ionosphere and provides a very stable environment to
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assist instrumental calibration. The Dark Ages Radio Explorer (DARE) is a concept being prepared for submission to NASA's Explorer programme, and would carry a simple but well characterised lowfrequency (40-120 MHz, 10.8ЎzЎ34.5) antenna in a low lunar orbit, to provide a first probe of the end of the cosmic dark ages. Galactic, extragalactic and solar-system foregrounds and instrumental calibration present significant challenges in performing the measurement. Ground-based prototypes currently being operated by the DARE team must, in addition, deal with environmental variation, RFI and the ionosphere, but are esssential for developing the instrument and testing the signal extraction pipeline. I will show how well DARE will be able to distinguish different scenarios for early star and galaxy formation using realistic simulations of the data and the signal extraction pro cess. I will also report on the application of the extraction pipeline to ground-based data, and show how constraints are affected in this case.

[17] Michael Brown Email: Michael.Brown@monash.edu Title: Galaxy Spectra Over Two and a Half Decades Abstract: We present a new library of 120 galaxy template spectra spanning from the ultraviolet to the mid-infrared. The library is principally intended for use in mo delling galaxy colours, determining k-corrections and deriving photometric redshifts. The spectra consist of optical, Akari and Spitzer spectra and MAPHYS mo dels, that have been constrained and verified with matched aperture photometry from GALEX, Swift, SDSS, 2MASS, Spitzer and WISE. Our library contains more galaxies, spans a broader range of colours and has smaller systematic errors than previous libraries of galaxy spectra. We demonstrate that the library pro duces significantly improved k-corrections and photometric redshifts, including for relatively nearby galaxies. [18] Gergo Popping
Email: g.popping@astro.rug.nl Title: Modeling the nature of the ISM in galaxies during the star formation activity peak of the Universe Abstract: At redshift z1-3 the star-formation activity of the Universe reached its peak, after which it dropped towards its current day value. In the near future ALMA will allow us to observe atoms and molecules like [CII], CO and HCN for large groups of star-forming galaxies during this cosmic epo ch. Such species are go o d tracers of the properties of the interstellar medium (ISM) of these galaxies and can possibly give understanding to why the star-formation activity of the Universe decreased at lower redshifts. The most recent versions of cosmological mo dels of galaxy formation explicitly include the detailed tracking of the atomic and molecular hydrogen content of galaxies and a more physicallymotivated H2-based star formation recipe. In this talk I will discuss how such mo dels, in combination with radiative-transfer and line-tracing co des, can provide detailed predictions of the ISM properties for statistical sets of galaxies that can directly be observed with ALMA. We find that normal star-forming galaxies at z1.2 have much higher CO-excitation peaks than their lo cal counterparts, indicative of much denser and warmer star-forming clouds. I will discuss the mo del predictions for the CO, HCN, [CII], [OI] and neutral carbon properties of typical star-forming galaxies at high-redshift, how this shapes our understanding of the gas physics driving the star formation, strategies to observe these predictions and how our mo del can be used for other purposes.

[19] Imogen Whittam
Email: ihw24@mrao.cam.ac.uk Title: The faint source population at 15 GHz Abstract: Over the past few years the Arcminute Microkelvin Imager (AMI) has been conducting 15 6


GHz observations over 30 square degrees and has pro duced the deepest high-frequency survey of the extra-galactic sky to date. We have studied a sample of 296 sources selected from an area of this survey in the Lo ckman Hole (Whittam et al., 2013MNRAS.429.2080W). We have found a significant increase in the proportion of flat spectrum sources below approximately 1 mJy, which is not predicted by the mo dels of de Zotti et al. and the SKA Simlulated Sky by Wilman et al. It is likely that this shift towards a flatter spectrum population is due to the cores of Fanaroff-Riley type I (FRI) sources being more dominant than predicted by the mo dels. Recent results from VLBI observations in the Lo ckman Hole support these conclusions and the wealth of multi-wavelength data available in this field provide further insights into the nature of this faint, flat spectrum population. We have recently extended this study to even fainter flux densities (down to 100 microJy) using new very deep 15 GHz observations from AMI and 610 MHz GMRT observations. We have found that the median spectral index increases again below approximately 400 microJy, suggesting that the nature of the source population is changing and star-forming galaxies are becoming dominant at these flux densities. Our faint, 15 GHz samples are vital in understanding the nature of this po orly understo o d high frequency source population.

[20] Florian Pranger
Email: florian.pranger@uibk.ac.at Title: The galaxy population of the complex cluster system Abell 3921 Abstract: I would like to present a spectrophotometric analysis of the galaxy population in the area of the merging cluster Abell 3921 at z=0.093 that has been carried out with the aim of investigating the impact of the complex cluster environment on galaxy properties such as morphology or star formation rate. Multi-ob ject spectroscopy from the Two Degree Field (2dF) spectrograph has been combined with optical imaging taken with the ESO Wide Field Imager. A redshift analysis has been carried out and cluster velo city dispersions were determined using biweight statistics. Cluster and field galaxies were investigated with respect to [OII] and H equivalent width, star formation rate and morphological descriptors such as concentration index and Gini co efficient. These cluster galaxy properties will be presented as a function of clustercentric distance. Further, the the spatial distribution of various galaxy types will be discussed. The results of a Dressler-Shectman test will be shown: A third component (A3921-C) was found in addition to the two main subclusters (A3921-A and A3921-B) already known. Similar to previous studies of galaxy clusters, it was found that a large fraction of the disk galaxies close to the cluster core show no detectable star formation. These are likely systems that are quenched due to ram pressure stripping. Interestingly, quenched spirals are also found at rather large distances of 3-4 Mpc from the cluster core. The talk will end with a conclusions-section explaining that A3921-C might be a group of galaxies falling onto the main cluster components. Further, the unexpected population of quenched spirals at large clustercentric radii in A3921-A and A3921-B might be an effect of the ongoing cluster merger: sho cks in the ICM might give raise to enhanced ram pressure stripping and at least in part be the cause for the quenching of star formation. These quenched spirals might be an intermediate stage in the morphological transformation of field spirals into cluster S0s.

[21] Didier Fraix-Burnet
Email: didier.fraix-burnet@obs.ujf-grenoble.fr Title: Classification in a multivariate world Abstract: The availabitily of data at several wavelengths raises the question of the statistical clustering of the ob jects in the parameter space that can provide a physically pertinent classification. It is not because an observable is both available and a priori astrophysically informative that it is statistically discriminant enough to partition the sample. In this talk, we present a typical strategy that should be followed in order to cluster the observed ob jects into robust groups. We then illustrate on several results 7


how a multivariate classification can be interpreted in the light of galaxy diversification.

[22] Julie Banfield
Email: Julie.Banfield@csiro.au Title: The Australia Telescope Large Area Survey: Data Release and Early Science Abstract: The Australia Telescope Large Area Survey (ATLAS) is the widest deep radio survey to date, covering 7 square degrees down to 15uJy/beam at 1.4 GHz. ATLAS covers two fields: (1) the Chandra Deep Field South (CDFS); and (2) the European Large Area ISO Survey South 1 (ELAIS S1). We have catalogued over 5000 source components and compliment the current multiwavelength coverage from X-Rays to Radio wavelengths. The primary science goal of ATLAS is to study the formation and evolution of galaxies and I will present the data release and a first lo ok at the science ATLAS will contribute to the broader astronomical community.

[23] Matthew Prescott
Email: matt.x.prescott@gmail.com Title: GAMA: Evolution of the 325 MHz Luminosity Function Abstract: Combining data from the Galaxy And Mass Assembly (GAMA) survey and the Giant Meterwave Radio Telescope (GMRT), using the likeliho o d ratio technique. I will present radio luminosity functions at 325 Mhz showing the evolution of low-luminosity radio sources in the lo cal Universe.

[24] Brigitte Rocca-Volmerange
Email: ro cca@iap.fr Title: Huge starburst, old stars and AGN activity in high-z radio galaxies with the new code PEGASE.3 Abstract: The far-IR and submm domains bring essential clues to understand galaxy evolution in relation with the growth of supermassive black holes. Our preferred targets are hyperluminous radio galaxies, continuously observed with Herschel-SpitzerOptical on a large distance-coverage (1ЎzЎ6) in the HeRGE catalog. The co de PEGASE.3 (Fio c, Ro ccaVolmerange, Dwek, 2013) will be so on proposed to the community via a readme on the pegase site. The analysis (Ro cca-Volmerange et al, 2013) is computed in the observer's frame including k+e corrections relative to lo cal templates with the help of PEGASE.3. Main results are relative masses and ages of starburst and old stellar populations superimposed to the AGN emission. They confirm huge masses at the earliest epo chs,extreme star formation rates and constraints on the SMBH growth, all deserving discussions on galaxy formation theories and simulations.

[25] Andrey Doroshkevich Email: dorr@asc.rs