In 2002 the International Virtual Observatory Alliance (IVOA) has been created in order to gather efforts on data standardization and dissemination. Since then, the virtual Observatory allowed to spread validated data all over the world and to use data from everywhere from earth. From the standards definitions to development of tools, developers have set up a technical infrastructure used by astronomers to easily search for data and make science with all available products, more tools and more confidence on the quality of data. The goal of this review is to present the state of the art of the VO data, standards and tools. This review focuses on basic astronomer's questions : what kind of data are accessible, how to deal with these data and how to use them.

Luminous infrared galaxies (LIRGs) are galaxies with LIR > 1011 L⊙. For a star-forming galaxy to emit at a LIRG level, it must have a very high star formation rate (SFR). In the local Universe, the star formation (SF) is primarily triggered by interactions. However, at intermediate redshift, a large fraction of LIRGs are disk galaxies with little sign of recent merger activity. The question arises whether the intermediate redshift LIRGs are “triggered” or experiencing “normal”, if elevated, SF. Understanding these SF processes is important since this type of systems may have contributed to 20% or more of the cosmic SFR in the early Universe. In order to address this issue we study similar systems in the Local Universe, that is isolated late-type galaxies displaying LIRG activity. We use different observational techniques in order to trace the star-forming history of these systems. Here we present preliminary results.

It has been known since many decades that galaxy interactions can induce star formation (hereafter SF) enhancements and that one of the driving mechanisms of this enhancement is related to gas inflows into the central galaxy regions, induced by asymmetries in the stellar component, like bars. In the last years many evidences have been accumulating, showing that interacting pairs have central gas-phase metallicities lower than those of field galaxies, by ~0.2–0.3 dex on average. These diluted ISM metallicities have been explained as the result of inflows of metal-poor gas from the outer disk to the galaxy central regions. A number of questions arises: What's the timing and the duration of this dilution? How and when does the SF induced by the gas inflow enrich the circum-nuclear gas with re-processed material? Is there any correlation between the timing and strength of the dilution and the timing and intensity of the SF? By means of Tree-SPH simulations of galaxy major interactions, we have studied the effect that gas inflows have on the ISM dilution, and the effect that the induced SF has, subsequently, in re-enriching the nuclear gas. In this contribution, we present the main results of this study.

Numerical simulations have shown that strong gravitational torque by non-axisymmetric components induce evolutionary processes such as redistribution of mass and angular momentum in the galactic disks and consequent change of chemical abundance profiles. If we hope to understand chemical evolution gradients and their evolution we must understand the secular processes and re-arrangement of material by non-axisymmetric components and vice-versa. The most obvious of these aforementioned non-axisymmetric components are bars - at least 2/3 of spiral galaxies host a bar, and possibly all disk galaxies have hosted a bar at some point in their evolution. While observationally it has been found that barred galaxies have shallower gas-phase metallicity gradients than non-barred galaxies, a complementary analysis of the stellar abundance profiles has not yet been undertaken. This is unfortunate because the study of both gas and stars is important in providing a complete picture, as the two components undergo (and suffer from) very different evolutionary process. We present here a pilot study of the gas and stellar metallicity and age distributions in a sample of barred and non-barred galaxies using 2D spectroscopic observations. We found that the majority of the stellar mass in our sample is composed of old (~10 Gyr) stars. This is true in the bulge and the disc region, even beyond two disc scalelengths. In the disc region, a larger fraction of young stars is present in the external parts of the disc compared with the inner disc. The disc growth is, therefore, compatible with a moderate inside-out formation scenario, where the luminosity-weighted age changes from ~10 Gyrs in the centre, to ~4 Gyrs at two disc scalelengths, depending upon the galaxy. However, the presence of substructure, like star forming rings, can produce stellar population trends that are not directly related with the growing of the disc but to the bar potential. In the disc region, the metallicity gradient always decrease with the radius. In the bulge region this is not always true and we find inverse metallicity gradients in several galaxies.

Selection effects in the submillimeter/far-infrared inhibit detailed analysis of extreme starbursts in the early Universe. Submillimeter Galaxy (SMG) detection and characterization biases against warm temperature SEDs Tdust ~50 K, against the highest redshift ULIRGs z > 3, and has so far been limited to a small sample of ~100 sources that have reliably identified optical or radio counterparts and spectroscopic redshifts. Recent observations by Herschel ⋅ ⋅ ⋅ ⋅ and ⋅ ⋅ ⋅⋅ ⋅ in the ~70–500 μm wavelength range provide a more complete census of high-z ULIRG activity than previous SMG surveys. However, source confusion and lack of spectroscopic identification of reliable counterparts limit the analysis of extreme ULIRGs to the most basic calculations, frought with a priori assumptions (e.g. Tdust/(1+z) degeneracy, far-IR/radio relation, confusion boosting factors, etc). Herein I address the biases on conclusions of SMG work and I demonstrate the need for thorough, spectroscopic follow-up of high-z ULIRGs in order to infer their physical conditions.

Scaling relations are salient ingredients of galaxy evolution and formation models. I summarize results from the IMAGES survey, which combines spatially-resolved kinematics from FLAMES/GIRAFFE with imaging from HST/ACS and other facilities. Specifically, I will focus on the evolution of the stellar mass and baryonic Tully-Fisher Relations (TFR) from z = 0.6 down to z = 0. We found a significant evolution in zero point and scatter of the stellar mass TFR compared to the local Universe. Combined with gas fractions derived by inverting the Schmidt-Kennicutt relation, we derived for the first time a baryonic TFR at high redshift. Conversely to the stellar mass TFR, the baryonic relation does not appear to evolve in zero point, which suggests that most of the reservoir of gas converted into stars over the past 6 Gyr was already gravitationally bound to galaxies at z = 0.6.

Herschel opens a large field of investigations on the hidden star formation in galaxies. Combining UV and far-IR rest-frame data allows us to measure all the star formation in galaxies and to estimate the net dust attenuation. The analysis can be performed from the local universe using far-IR and GALEX surveys to high z (up to z < 2) by combining deep U data with the Herschel observations of the HerMES project.

The calibration of dust attenuation, and then star formation rate, is reinvestigated. We present the results of the first analyses performed with Herschel data obtained in the Lockman and COSMOS fields as part of the HerMES project and discuss the reliability of dust attenuation corrections.

I review the major surveys of high redshift galaxies observed using integral field spectroscopy techniques in the visible and in the infrared. The comparison of various samples has to be done with care since they have different properties linked to their parent samples, their selection criteria and the methods used to study them. I present the various kinematic types of galaxies that are identified within these samples (rotators, mergers, etc.) and summarize the discussions on the mass assembly processes at various redshifts deduced from these classifications: at intermediate redshift (z ~ 0.6) merger may be the main mass assembly process whereas the role of cold gas accretion along cosmic web filaments may increase with redshift. The baryonic Tully-Fisher relation is also discussed. This relation seems to be already in place 3 Gyr after the Big-Bang and is then evolving until the present day. This evolution is interpreted as an increase of the stellar mass content of dark matter haloes of a given mass. The discovery of positive abundance gradients in MASSIV and LSD/AMAZE samples is highlighted. At z ~ 3 this discovery might be linked to cold gas accretion along cosmic filaments toward the centre whereas at lower redshift (z ~ 1.3), this may be mainly due to accretion of gas from outer reservoirs toward the centre via tidal tails due to interactions.

This summary is from the perspective of a person who is interested in galaxy assembly and works from an observational low redshift perspective, using evidence from the components of our Galaxy: the thin and thick disks, the bulge and the halo.

We have conducted all disk imaging of M33 in 12CO(1-0) using the 45-m telescope at Nobeyama Radio Observatory. We present preliminary results of this project. The spatial resolution of ~ 80 pc is comparable to the size of GMCs. The identified GMCs show wide variety in star forming activity. The variety can be regarded as the difference of their evolutionary stage. We found that Kennicutt-Schmidt law breaks in GMC scale (~ 80 pc), although it is still valid in 1 kpc scale. The correlation between molecular gas fraction, fmol = Σ(H2)/Σ(HI+H2) and gas surface density shows two distinct sequences and shows that fmol tends to be higher near the center. We also made partial mapping 12CO(3-2) with ASTE telescope. These data show that the variation of physical properties of molecular gas are correlated with the GMC evolution and mass. That is, GMCs with more active star formation and more mass tend to have higher fraction of dense gas.

Galaxy-galaxy interactions and large scale galaxy bars are usually considered as the two main mechanisms for driving gas to the centres of galaxies. By using large samples of galaxy pairs and visually classified bars from the Sloan Digital Sky Survey (SDSS), we compare the relative efficiency of gas inflows from these two processes. We use two indicators of gas inflow: star formation rate (SFR) and gas phase metallicity, which are both measured relative to control samples. Whereas the metallicity of galaxy pairs is suppressed relative to its control sample of isolated galaxies, galaxies with bars are metal-rich for their stellar mass by 0.06 dex over all stellar masses. The SFRs of both the close galaxy pairs and the barred galaxies are enhanced by ~60%, but in the bars the enhancement is only seen at stellar masses M∗ > 1010 M⊙. Taking into account the relative frequency of bars and pairs, we estimate that at least three times more central star formation is triggered by bars than by interactions.

Warps are a basic feature of disk galaxies. Usually they occur at radii where the optical disk fades and become most pronounced in the outermost gaseous disks.

As such, warps present a massive reservoir to replenish star forming material in the inner, star forming disks. Furthermore, some possible excitation mechanisms for warps connect their formation to the accretion of extragalctic material. Interactions or mergers with gas-rich companions or the direct accretion of the ambient intergalactic medium might lead to the formation of warps, at the same time supplementing fuel to maintain star formation in galactic disks.

Employing a number of H i studies of warped galaxies, including ultra-deep observations of the prototype warped galaxies NGC 5907 and NGC 4013, I discuss whether the observed kinematics may show evidence for a connection of warps and accretion from the ambient medium.

We present early results from the ongoing Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) Survey, which is being performed with the Westerbork Synthesis Radio Telescope (WSRT). The HALOGAS Survey aims to detect and characterize the cold gas accretion process in nearby spirals, through sensitive observations of neutral hydrogen (Hi) 21-cm line emission. In this contribution, we present an overview of ongoing analyses of several HALOGAS targets.

We performed a deep Hi and Hα mapping of M31 and M33 in order to get accurate kinematical data of those two galaxies and also to make a comparison between the Hi and Hα kinematics. The Hi data were obtained with the DRAO interferometer and the Hα data with the Fabry-Perot system of the Observatoire du mont Mégantic using an EMCCD as a detector. These data will give us the best possible datasets to derive accurate rotation curves and mass models for those two Local Group spirals and provide some new data for the Hii regions studies of these galaxies. While the Hi observations are of low resolution (~1 arcmin), the high resolution of the Hα data (~1 arcsec) should allow us to get much more details in the central regions, allowing at the same time a much better determination of the kinematical parameters. Hence, the inner part of the rotation curve, so inportant to constraint properly the mass models, will be determined more accurately.

The formation and evolution of galaxies is strongly influenced by environment, particularly in clusters, where galaxy luminosity functions vary in shape with the dynamical state of the cluster (relaxed or in various stages of merging), with the photometric band considered and with the position in the cluster. We present here results concerning the optical GLFs in several relaxed and merging clusters.

We have mapped the nearby face-on spiral galaxy M 33 in the 1.1 mm dust continuum using AzTEC on Atacama Submillimeter Telescope Experiment (ASTE). The preliminary results are presented here. The observed dust has a characteristic temperature of ~ 21 K in the central kpc, radially declining down to ~ 13 K at the edge of the star forming disk. We compare the dust temperatures with KS band flux and star formation tracers. Our results imply that cold dust heating may be driven by long-lived stars even nearby star forming regions.

The Galactic neutron star X-ray binary Her X-1 shows a 35-day photometric modulation. Detected across a broad energy range, the modulation is prevalent in X-rays, cycling between low and high states. Since the discovery of the 35-day cycle of Her X-1, the X-ray source has entered and returned from an extended anomalous low state on at least seven occasions. Employing Rossi X-ray Timing Explorer All-Sky Monitor observations, prior predictions that Her X-1 would return from the 2003 - 2004 anomalous low state with a new precession period and accretion luminosity are verified. However, the precession has not been as coherent over recent years as predicted. Potentially there have been more minor anomalous low states between 2004 and the present day.

Two of the dominant channels for galaxy mass assembly are cold flows (cold gas supplied via the filaments of the cosmic web) and mergers. How these processes combine in a cosmological setting, at both low and high redshift, to produce the whole zoo of galaxies we observe is largely unknown. Indeed there is still much to understand about the detailed physics of each process in isolation. While these formation channels have been studied using hydrodynamical simulations, here we study their impact on gas properties and star formation (SF) with some of the first from simulations that capture the multiphase, cloudy nature of the interstellar medium (ISM), by virtue of their high spatial resolution (and corresponding low temperature threshold). In this regime, we examine the competition between cold flows and a supernovae(SNe)-driven outflow in a very high-redshift galaxy (z ≈ 9) and study the evolution of equal-mass galaxy mergers at low and high redshift, focusing on the induced SF. We find that SNe-driven outflows cannot reduce the cold accretion at z ≈ 9 and that SF is actually enhanced due to the ensuing metal enrichment. We demonstrate how several recent observational results on galaxy populations (e.g. enhanced HCN/CO ratios in ULIRGs, a separate Kennicutt Schmidt (KS) sequence for starbursts and the population of compact early type galaxies (ETGs) at high redshift) can be explained with mechanisms captured in galaxy merger simulations, provided that the multiphase nature of the ISM is resolved.

The utilization of integral-field spectroscopy has led us to a new understanding of the physical conditions in galaxies within the first few billion years after the Big Bang. In this proceedings, we analyze observations of ~50 massive galaxies as seen as they were 10 Gyrs ago using SINFONI from the ESO-VLT. We show that the large line width they exhibit can be explained by the intense mechanical energy output from the young stars. We also study the influence of cold gas accretion upon these galaxies: We show that an unrealistic amount of shocked gas would be needed in order to explain the Hα emission from these galaxies through shocks from gas accretion with velocity about the Hα line widths of these galaxies. We also use DEEP2 photometric measurements for a sub-sample of 10 of these galaxies to evaluate their ratio of Hα to FUV flux as a function of their Hα and R-band luminosity surface brightnesses. Our data suggests that perhaps their initial mass function (IMF) is flatter than Salpeter at the high mass end, as has been suggested recently for some local galaxies. It may be that high turbulence is responsible for skewing the IMF towards more massive stars as suggested by some theories of star-formation. Much work is however needed to accredit this hypothesis.

We investigate the age distributions of GC systems in 14 E/S0 galaxies by carrying out a differential comparison of the (g–z) vs. (g–K) two-colour diagrams for different GC systems. No significant distinction is detected in the mean ages of GCs among elliptical galaxies. S0 galaxies on the other hand, show evidence for younger GCs. Surprisingly, this appears to be driven by the more metal-poor clusters. This is suggestive of E type galaxies having assembled most of their GCs in a shorter and earlier period than lenticular galaxies. The latter galaxy type, seems to have a more extended period of GC formation/assembly.