We have studied the star-forming and AGN activity of massive galaxies in the redshift range z = 0.4−2, which are detected in a deep survey field using the AKARI and Subaru telescopes toward the North Ecliptic Pole (NEP). The multi-wavelength survey allows us to select Mid-InfraRed (MIR) bright populations as Luminous InfraRed Galaxies (LIRGs) with L(IR) ≃ 1010–11 L⊙, which can be also sub-classified into Balmer Break Galaxies (BBGs) and Infra-Red (IR) Bump Galaxies (IRBGs). AKARI/IRC multiband photometry can distinguish their star-forming/AGN activity for LIRGs with/without the Polycyclic-Aromatic Hydrocarbon (PAH) emission bands at 6.2, 7.7 and 11.3 μm, and estimate the Star Formation Rate (SFR) from their total emitting InfraRed (IR) luminosities for star-formings and the emissions from dusty torus for AGNs. The results are summarised as below: 1) The rest-frame 7.7 μm luminosity is still a good tracer of the total IR (tIR) luminosity, as the PAH emission dominates for star-forming galaxies even up to z ≃ 2, 2) Rest-frame 5μm Luminosities may trace emissions from dusty torus of AGN in the LIRGs, 3) SFR of Starburst-AGN LIRGs (s/a-LIRGs) tends to quench at z < 0.8 more rapidly than that of Starburst dominated LIRGs (sb-LIRGs), 4) Intrinsic Stellar populations in the s/a-LIRGs show redder colours than those in the sb-LIRGs. These results suggest that Super Massive Black Holes (SMBH) could already have grown to ≃ 3 × 108M⊙ in the agn-LIRGs, with ≃ 1011L⊙ at z > 1.2, and the growth of SMBH tends to follow the star-forming activities around z = 1–2.

The exact contribution of the stellar disk to the overall kinematics of a galaxy remains in most studies a free parameter of the mass models. With the help of chemospectrophotometric evolution models, it is now possible to have a coherent picture of the stellar population of a galaxy including its mass-to-luminosity ratio at every radius spanning a wide range of observable wavelengths. We will focus on discussing the consistency of the mass thus inferred in photometric bands ranging from the FUV to the NIR for individual galaxies and compare this to the maximum-disc hypothesis.

Nuclear regions of galaxies generally host a mixture of components with different exitation, composition, and kinematics. Derivation of emission line ratios and kinematics could then be misleading, if due correction is not made for the limited spatial and spectral resolutions of the observations. The aim of this paper is to demonstrate, with application to a long slit spectrum of the Seyfert 2 galaxy NGC 1358, how line intensities and velocities, together with modelling and knowledge of the point spread function, may be used to resolve the differing structures. In the situation outlined, the observed kinematics differs for different spectral lines. From the observed intensity and velocity distributions of a number of spectral lines and with some reasonable assumptions to diminish the number of free parameters, the true line ratios and velocity structures may be deduced. A preliminary solution for the nuclear structure of NGC 1358 is obtained, involving a nuclear point source and an emerging outflow of high excitation with a post shock cloud, as well as a nuclear emission line disk rotating in the potential of a stellar bulge and expressing a radial exitation gradient. The method results in a likely scenario for the nuclear structure of NGC 1358. For definitive results an extrapolation of the method to two dimensions combined with the use of integral field spectroscopy will generally be necessary.

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.

Due to its proximity, size, complex structure and high inclination angle, M31 offers an excellent opportunity for studying galactic structures outside the Milky Way and for drawing implications for their cosmological origin. We have studied the stellar populations of M 31 using the Sloan Digital Sky Survey (SDSS) photometry and the Spitzer far-infrared (FIR) mappings of dust. Combining these data, we have constructed a 3-dimensional model of the galaxy, laying constraints on the intrinsic (dust-free) properties of the galaxy and its stellar populations: their apparent and intrinsic luminosities, luminosity distributions, colours, shapes and sizes. We have interpreted the derived spectral energy distributions with synthetic stellar populations created with the Starburst99 software, in order to constrain the ages and masses of the stellar components.

During the next decade the IAU intends to mobilize talented astronomers, engineers and teachers around the world, in the service of developing countries. I shall review the content of the IAU Strategic Plan 2010 - 2020 “Astronomy for the Developing World” and give you an update on its implementation. Astronomy is a unique tool for stimulating capacity building because it combines cutting-edge technology with fundamental science and has deep cultural roots. The plan envisages a substantial increase in IAU education and development activities during the next decade. These activities will be bottom-up, with a strong regional influence. An integrated approach tailored to the conditions and needs of each country will involve a mix of education at primary, secondary and tertiary levels and public outreach. As a crucial component of the strategy, the IAU together with the South African National Research Foundation will set up a small office to coordinate and plan the various global activities at the SAAO in Cape Town.

A brief analysis is given of the need for more trained people in science and technology versus the declined interest in studying sciences. In highlighting some of the aspects of research in astronomy, arguments are presented why astronomy education is by far the most attractive way to stimulate young people to study sciences later on. The availability of vast sets of scientific data with software instruments for instructional use is emphasized. Attention is also given to the changing world of young people, and to the needs and problems in Africa. Finally, some conclusions are given of how astronomy can contribute to transform education in sciences into an education for young people that attracts them towards science & technology.

Astronomy as a discipline has not been widely established in Uganda. However, some aspects of astronomy, especially, concerning the solar system, are integrated in geography syllabi for secondary and tertiary institutions. The technological spin-off benefits from astronomy to humanity are immense and therefore, efforts should be geared towards establishing astronomy as an autonomous discipline across the entire school system in the Uganda. So far, the urge and efforts made to popularize the discipline in Uganda have started yielding tangible results. This paper presents the achievements and future strategies of establishing astronomy in Uganda's school system.

On the African continent, most of the activities in Astronomy are found in South Africa where full training in Astrophysics is given in a few Universities and where most of the professional astronomers and of the research instruments (from small telescopes to the 11m SALT, in the optical) can be found. In 2007, we started a full program (undergraduate and graduate) in Astrophysics at the Université de Ouagadougou and an Observatory (ODAUO), for teaching purposes, was also built. In October 2009, we put in crates the 1m Marly telescope in La Silla, Chile which will be rebuilt in 2011-12, as a full research telescope, on mount Djaogari in Burkina Faso.

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.

Dwarf galaxies are by far the most abundant of all galaxy types, yet their properties are still poorly understood–especially due to the observational challenge that their intrinsic faintness represents. AVOCADO aims at establishing firm conclusions on their formation and evolution by constructing a homogeneous, multiwavelength dataset for a statistically significant sample of several thousand nearby dwarfs (−18 < Mi < −14). Using public data and Virtual Observatory tools, we have built GALEX+SDSS+2MASS spectral energy distributions that are fitted by a library of single stellar population models. Star formation rates, stellar masses, ages and metallicities are further complemented with structural parameters that can be used to classify them morphologically. This unique dataset, coupled with a detailed characterization of each dwarf's environment, allows for a fully comprehensive investigation of their origins and to track the (potential) evolutionary paths between the different dwarf types.

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 mass assembly of galaxies leaves various imprints on their surroundings, such as shells, streams and tidal tails. The frequency and properties of these fine structures depend on the mechanism driving the mass assembly: e.g. a monolithic collapse, rapid cold-gas accretion followed by violent disk instabilities, minor mergers or major dry/wet mergers. Therefore, by studying the outskirts of galaxies, one can learn about their main formation mechanism. I present here our on-going work to characterize the outskirts of Early-Type Galaxies (ETGs), which are powerful probes at low redshift of the hierarchical mass assembly of galaxies. This work relies on ultra–deep optical images obtained at CFHT with the wide-field of view MegaCam camera of field and cluster ETGs obtained as part of the ATLAS3D and NGVS projects. State of the art numerical simulations are used to interpret the data. The images reveal a wealth of unknown faint structures at levels as faint as 29 mag arcsec−2 in the g-band. Initial results for two galaxies are presented here.

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.

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.

We performed numerical simulations of mergers between gas-rich disc galaxies, which result in the formation of late-type galaxies. Stars formed during the merger end up in a thick disc that is partially supported by velocity dispersion and has high [α/Fe] ratios at all metallicities. Stars formed later end up in a thin, rotationally supported disc which has lower [α/Fe] ratios. While the structural and kinematical properties of the merger remnants depend strongly upon the orbital parameters of the mergers, we find a clear chemical signature of gas-rich mergers.

We investigated a scenario in which M31 could be the remnant of a major merger and at the origin of the LMC. Galaxy merger simulations were run in order to reproduce some M31 properties. We succeeded in reproducing some of the most important M31 large-scale features like the thick disk or the polar ring, and gave a possible explanation for the formation of the Giant Stream. We also found that the LMC could be expelled by this high energetic phenomenon.

We present the results of numerical simulations on the M51-type galaxy pair KPG 302 (NGC 3893/96) taking as boundary conditions for these simulations the results of our observations on the kinematics of this pair. The observations allow us to deduce the different components of each galaxy in the pair (stellar disk and bulge, dark matter halo) as well as the geometry of the encounter at the present time. The numerical simulations were carried out using GADGET2 numerical code including gas. We describe in detail how the numerical simulations are being done. We succeeded to reproduce the actual conditions of the pair, in particular, the grand-design spiral arms of NGC 3893 (the main galaxy of the pair) when the numerical simulations include gas, consider a parabolic direct collision and multiple passages.

Our understanding of the structuring of the Universe from large-scale cosmological structures down to the formation of galaxies now largely benefits from numerical simulations. The RAMSES code, relying on the Adaptive Mesh Refinement technique, is used to perform massively parallel simulations at multiple scales. The interactive, immersive, three-dimensional visualization of such complex simulations is a challenge that is addressed using the SDvision software package. Several rendering techniques are available, including ray-casting and isosurface reconstruction, to explore the simulated volumes at various resolution levels and construct temporal sequences. These techniques are illustrated in the context of different classes of simulations. We first report on the visualization of the HORIZON Galaxy Formation Simulation at MareNostrum, a cosmological simulation with detailed physics at work in the galaxy formation process. We then carry on in the context of an intermediate zoom simulation leading to the formation of a Milky-Way like galaxy. Finally, we present a variety of simulations of interacting galaxies, including a case-study of the Antennae Galaxies interaction.

Understanding how galaxies obtain baryons, their stars and gas, over cosmic time is traditionally approached in two different ways - theoretically and observationally. In general, observational approaches to galaxy formation include measuring basic galaxy properties, such as luminosities, stellar masses, rotation speeds, star formation rates and how these features evolve through time. Theoretically, cosmologically based models collate the physical effects driving galaxy assembly - mergers of galaxies, accretion of gas, star formation, and feedback, amongst others, to form predictions which are matched to galaxy observables. An alternative approach is to examine directly, in an observational way, the processes driving galaxy assembly, including the effects of feedback. This is a new ‘third way’ towards understanding how galaxies are forming from gas accretion and mergers, and directly probes these effects instead of relying on simulations designed to reproduce observations. This empirical approach towards understanding galaxy formation, including the acquisition history of baryons, displays some significant differences with the latest galaxy formation models, in addition to directly demonstrating the mechanisms by which galaxies form most of their baryonic mass.