Recent observations have revealed the existence of a ‘main sequence’ of star-forming galaxies out to high redshift. While the majority of star-forming galaxies are observed to be close to this relation between star formation rate (SFR) and stellar mass, a smaller subset of the population – so-called ‘starbursts’ – displays specific star-formation rates and star-formation efficiencies that exceed those of normal (main-sequence) galaxies by up to an order of magnitude. A large degree of homogeneity and similarity has been observed for the properties of the population of normal galaxies across a broad redshift range, including a narrow correlation between their CO luminosity (hence gas content) and IR luminosity and an almost invariable IR SED getting warmer with redshift, while starburst galaxies display systematically different properties. This can be used to devise a simple description of the evolution of the star-forming galaxy population since z ~ 2 and, with a higher degree of uncertainty, even further back in time, in a scheme that we dub two star formation mode framework (2-SFM). We show how this can successfully reproduce the shape of the IR luminosity function of galaxies as a function of redshifts, and the IR number counts. Furthermore, we can link the cosmic evolution of the sSFR of main-sequence galaxies to the evolution of the molecular fuel reservoir and to derive estimates of the molecular gas mass functions of star-forming galaxies that are based on their empirically measured gas properties rather than simulations or semi-analytical modelling. We also infer the evolution of the cosmic abundance of molecular gas and briefly discuss its expected observational signature by molecular line emission, the CO luminosity function.

MAHALO-Subaru (MApping HAlpha and Lines of Oxygen with Subaru) is our on-going large programme which aims to investigate how the star forming activities in galaxies are propagated as a function of time, mass, and environment. We are targeting 10 clusters and proto-clusters at 0.4<z<2.6, and two general fields (GOODS-N and SXDF-CANDELS) with Suprime-Cam and MOIRCS by utilizing our unique sets of narrow-band filters. The narrow-band imaging can map out star forming galaxies with the redshifted Halpha and/or [OII] emission lines from our targets, and thus providing relatively unbiased views of star forming activities across time and environment. We have almost completed narrow-band imaging of our targets, and found that star forming activity is very high even in the proto-cluster cores (z≳1.5), and that the peak of star formation is shifted outwards with time, indicating the inside-out formation of clusters. Moreover, we have identified many “red” emitters especially in high density regions at z>2, which suggests that the mode of star formation and/or the activation of AGN are dependent on environment, and thus holding the key to the environmental effects at the early stage of cluster galaxies formation and evolution.

Distant radio galaxies, hosted by massive ellipticals, follow the galaxy evolution process on an extremely large (0 ≥ z ≥7) time-scale ≥ 1012Gyrs, up to primeval galaxies. The new evolutionary code Pégase.3 predicts on similar time-scales, the coupled stellar and dust emissions of various galaxy types: starbursts and Hubble sequence types. All z=0 templates are fitted on local observations at ages ≃13 Gyrs (except irregulars at 9 Gyrs). The multi-λ spectral energy distributions (SEDs) of two z=3.8 radiogalaxies, including the most recent Herschel data from the HeRGÉ consortium, are interpreted in the observer's frame by Rocca-Volmerange et al. (2012) with Pégase.3. The apparent SEDs are fitted at best with the sum of a young starburst and an older early-type population, an AGN simple model is taken into account. These results favor massive gas-rich mergers at work in evolved galaxies at z≃4. Massive starbursts would be at the origin of galaxy evolution initiated at the earliest epochs (zfor≥10). The possible relation with super massive black holes is still debated.

We present a result of IRS spectroscopy of 14 Ultra-Luminous Infrared Galaxies (ULIRGs) in the Extended Groth Strip region. These galaxies are massive and have very high star formation rate. Four objects of this sample are detected in the HST/WFC3 near-infrared imaging. They show very diversified rest-frame optical morphologies, including string-like, extended/diffused, and even spiral with a possible bulge, implying different formation processes for these galaxies. We also search for signatures of active galactic nucleus (AGN) in our sample in the X-ray, mid-infrared and radio bands. This sample is dominated by objects with intensive star formation, only 14–29% of them have AGN activities.

MASSIV (Mass Assembly Survey with SINFONI in VVDS) is an ESO large program which consists of 84 star-forming galaxies, spanning a wide range of stellar masses, observed with the IFU SINFONI on the VLT, in the redshift range 1 ≤ z ≤ 2. To be representative of the normal galaxy population, the sample has been selected from a well-defined, complete and representative parent sample. The kinematics of individual galaxies reveals that 58% of the galaxies are slow rotators, which means that a high fraction of these galaxies should probably be formed through major merger processes which might have produced gaseous thick or spheroidal structures supported by velocity dispersion rather than by rotation. Computations on the major merger rate from close pairs indicate that a typical star-forming galaxy underwent ~0.4 major mergers in the last ~9.5 Gyr, showing that merging is a major process driving mass assembly into the red sequence galaxies. These objects are also intriguing due to the fact that more than one galaxy over four is more metal-rich in its outskirts than in its center.

We investigate the evolution of the Hα equivalent width, EW(Hα), with redshift and its dependence on stellar mass, using the first data from the 3D-HST survey, a large spectroscopic Treasury program with the HST-WFC3. Combining our Hα measurements of 854 galaxies at 0.8<z<1.5 with those of ground based surveys at lower and higher redshift, we can consistently determine the evolution of the EW(Hα) distribution from z=0 to z=2.2. We find that at all masses the characteristic EW(Hα) is decreasing towards the present epoch, and that at each redshift the EW(Hα) is lower for high-mass galaxies. We find EW(Hα) ~ (1+z)1.8 with little mass dependence. Qualitatively, this measurement is a model-independent confirmation of the evolution of star forming galaxies with redshift. A quantitative conversion of EW(Hα) to sSFR (specific star-formation rate) is model dependent, because of differential reddening corrections between the continuum and the Balmer lines. The observed EW(Hα) can be reproduced with the characteristic evolutionary history for galaxies, whose star formation rises with cosmic time to z ~ 2.5 and then decreases to z = 0. This implies that EW(Hα) rises to 400 Å at z = 8. The sSFR evolves faster than EW(Hα), as the mass-to-light ratio also evolves with redshift. We find that the sSFR evolves as (1+z)3.2, nearly independent of mass, consistent with previous reddening insensitive estimates. We confirm previous results that the observed slope of the sSFR-z relation is steeper than the one predicted by models, but models and observations agree in finding little mass dependence.

Ultra-luminous infrared galaxies (LIR > 1012 L⊙) are locally rare, but appear to dominate the co-moving energy density at higher redshifts (z>2). Many of these are optically-faint, dust-obscured galaxies that have been identified by the detection of their thermal dust emission at sub-mm wavelengths. Multi-wavelength spectroscopic follow-up observations of these sub-mm galaxies (SMGs) have shown that they are massive (Mstellar ~ 1011 M⊙) objects undergoing intense star-formation (SFRs ~ 102−103 M⊙ yr−1) with a mean redshift of z ~ 2, coinciding with the epoch of peak quasar activity. The large fraction of AGNs in SMGs and the derived SMBH masses (M• < 108 M⊙) in these galaxies suggest that the submm phase may play an important role in the rapid growth of SMBHs. When both AGN and star-formation activity are present, long-slit spectroscopic techniques face difficulties in disentangling their contributions and may result in SFR and mass overestimates. We present an integral field view of the Hα emission in a sample of 3 SMGs at z~1.4–2.4 with the IFU instrument OSIRIS on Keck. Designed to be used with Laser Guide Star Adaptive Optics, OSIRIS allows a spatial resolution of up to 10× higher than what has been possible in previous seeing-limited studies of the ionized gas in these galaxies. Our main results are the following: (1) We detect multiple galactic-scale sub-components: the compact, broad Hα emission (FWHM >1000 km s−1) likely associated with an AGN, the more extended narrow-line Hα emission (FWHM ≲500 km s−1) of star-forming regions; the latter are dominated by multiple 1–2 kpc sized Hα-bright clumps, each contributing 1-25% of the total clump-integrated Hα emission. (2) We derive clump dynamical masses ~1–10×109M⊙, 1–2 orders of magnitude larger than the kpc-scaled stellar clumps uncovered in optically-selected z ~ 2 star-forming galaxies. (3) We determine high star-formation rate surface densities (ΣSFR~1–50 M⊙yr−1 kpc−2, after extinction correction), similar to local starbursts and luminous infrared galaxies. In contrast to these local environments, SMGs undergo such intense activity on significantly larger spatial scales as revealed by extended Hα emission over 4–16 kpc. (4) We find no evidence of ordered global motion as it would be found in a disk, but rather large velocity offsets (~ few × 100 km s−1) between the distinct stellar clumps. The merger interpretation is likely the most accurate scenario for the SMGs in our sample. However, the final test of whether an underlying disk structure is present will come from studies of the cold gas at the high spatial resolutions possible with ALMA.

We refer the reader to Menéndez-Delmestre et al. (2012) for more details.

It is remarkable that the long gamma-ray bursts, as objects connected with the supernovae - i.e. with the end-stages of massive stars, trace the star formation rate. This connection is discussed in this contribution. The presentation is in essence a recapitulation of the article by Mészáros et al. (2006).

Radio and mm observations play an important role in determining the star formation properties of high redshift galaxies. However, most galaxies at high redshift are too faint to be detected individually at these wavelengths. A way to study this population of galaxies is to use stacking. By averaging the emission of a large number of galaxies detected in optical or near infrared surveys, we can achieve statistical detection.

We investigate methods for stacking data from interferometric surveys. Interferometry poses unique challenges in stacking due to the nature of imaging of this data. We have compared directly stacking the uv data with stacking of the imaged data, the latter being the typically used approach. Using simulated data, we find that uv-stacking may provide around 50% less noise and that image based stacking systematically loses around 10% of the flux.

We have combined the semi-analytic galaxy formation model of Guo et al. (2011) with a novel particle-tagging technique to predict galaxy surface brightness profiles in a representative sample of ~1900 massive dark matter haloes (1012–1014 M⊙) from the Millennium II ΛCDM N body simulation. We focus on the outer regions of galaxies and stars accreted in mergers. Our simulations cover scales from the stellar haloes of Milky Way-like galaxies to the ‘cD envelopes’ of groups and clusters, and resolve low surface brightness substructure such as the tidal streams of dwarf galaxies. We find that the spatial distribution of stars in low surface brightness regions is tightly correlated with DM halo mass and that collisionless merging during the hierarchical assembly of galaxies largely determines the structure of spheroidal stellar components. Our ΛCDM model agrees well with the available data.

The evolution of size and shape of massive quiescent galaxies over cosmic history has been challenging to explain within standard models of galaxy assembly. Several mechanisms have been proposed to explain the size growth of these systems, including major mergers, expansion, and late accretion via a series of minor mergers. The central mass density is shown to be an excellent tool for discriminating between different evolutionary scenarios. We present here the analysis performed on a spectroscopic sample of ~500 quiescent systems with stellar masses M*>1010 M⊙ spanning the redshift range 0.2<z<2.7 for which we calculate stellar mass densities within central 1 kpc and show that this quantity evolves linearly with redshift. Our results do not change when only systems at constant number density are considered in order to account for the mass growth during mergers and to relate progenitors to their descendants. Discrepancy between our findings and other recent studies performed on an order of magnitude smaller samples emphasizes the need for larger homogeneous spectroscopic samples to be used in such analysis.

We use the UKIDSS Ultra-Deep Survey, the deepest degree-scale near-infrared survey to date, to investigate the clustering of star-forming and passive galaxies to z ~ 3.5. Our new measurements include the first determination of the clustering for passive galaxies at z > 2, which we achieve using a cross-correlation technique. We find that passive galaxies are the most strongly clustered, typically hosted by massive dark matter halos with Mhalo > 1013 M⊙ irrespective of redshift or stellar mass. Our findings are consistent with models in which a critical halo mass determines the transition from star-forming to passive galaxies.

The connection between the growth of supermassive black holes (SMBHs) and the assembly of their host galaxies is termed ‘co-evolution’. Understanding co-evolution is one of the most fundamental issues in modern astrophysics. In this contribution, we review recent progress in addressing how the growth of SMBHs is linked to the properties of their host galaxies in the context of galaxy evolution, from the observational point of view. Although a coherent picture has not yet emerged, multiple pathways of co-evolution appear to be favored with a probable dependence on AGN luminosity and redshift.

We have conducted deep optical spectroscopic follow up of a sample of radio galaxies with redshifts z < 0.7. The spectra were used to construct robust sub-samples of low excitation and high excitation AGN and perform stellar population analysis via line indices and spectral fitting. While the high excitation objects have lower luminosity-weighted ages and lower metallicities than the low excitation galaxies, this can be explained by the different stellar mass distributions of the samples. When stellar mass is taken into account the age and metallicity distribution of both populations are consistent with the galaxy population as a whole.

We use data from the Sloan Digital Sky Survey (SDSS) and the DEEP2 survey to characterize the distribution of stellar mass and light of galaxies in the low-redshift and z = 1 Universe. We investigate the clustering bias of stellar mass and light by comparing these to projected autocorrelations of dark matter estimated from the Millennium Simulations (MS). All of the autocorrelation and bias functions show systematic trends with spatial scale and waveband, which are impressively similar at the two redshifts. This shows that the well-established environmental dependence of stellar populations in the local Universe is already in place at z = 1. The recent MS-based galaxy formation simulation of Guo et al. (2011) reproduces the scale-dependent clustering of luminosity to an accuracy better than 30% in all bands and at both redshifts, but substantially overpredicts mass autocorrelations at separations below ~ 2 Mpc. Further comparison of the shapes of our stellar mass bias functions with those predicted by the model suggests that both the SDSS and DEEP2 data prefer a fluctuation amplitude of σ8 ~ 0.8 rather than the σ8 = 0.9 assumed by the MS.

The formation and evolution of massive galaxies represent one of the most intriguing open problems in astrophysics. Their underlying stellar populations encode valuable information about their past history. Detailed spectroscopic observations allow us to constrain the star formation histories, revealing a complicated mixture of a strong, early formation process, followed by passive evolution in the cores, along with an extended assembly of the outer regions via minor mergers. In this contributed talk, some recent results are presented from the analysis of samples of massive galaxies both at z ~ 0 and moderate redshift.

We perform a spectroscopic analysis of 492,450 galaxy spectra from the first two years of observations of the Sloan Digital Sky Survey-III/Baryonic Oscillation Spectroscopic Survey (BOSS) collaboration. This data set has been released in the ninth SDSS data release, the first public data release of BOSS spectra. We show that the typical signal-to-noise ratio of BOSS spectra is sufficient to measure stellar velocity dispersion and emission line fluxes for individual objects. The typical velocity dispersion of a BOSS galaxy is 240 km/s, with an accuracy of better than 30 per cent for 93 per cent of BOSS galaxies. The distribution in velocity dispersion is redshift independent between redshifts 0.15 and 0.7, which reflects the survey design targeting massive galaxies with an approximately uniform mass distribution in this redshift interval. The majority of BOSS galaxies lack detectable emission lines. We analyse the emission line properties and present diagnostic diagrams using the emission lines [OII], Hβ, [OIII], Halpha, and [NII] (detected in about 4 per cent of the galaxies). We show that the emission line properties are strongly redshift dependent and that there is a clear correlation between observed frame colours and emission line properties. Within in the low-z sample around 0.15 < z < 0.3, half of the emission-line galaxies have LINER-like emission line ratios, followed by Seyfert-AGN dominated spectra, and only a small fraction of a few per cent are purely star forming galaxies. AGN and LINER-like objects, instead, are less prevalent in the high-z sample around 0.4 < z < 0.7, where more than half of the emission line objects are star forming. This is a pure selection effect caused by the non-detection of weak Hβ emission lines in the BOSS spectra. Finally, we show that star forming, AGN and emission line free galaxies are well separated in the g - r vs r - i target selection diagram.

We develop a new method to estimate galaxy physical parameters, such as stellar masses, or star formation histories. This method is based on principal component analysis (PCA), using the information in rest-frame 3700-5500Å spectral region. The derived physical parameters are then applied to study the evolution of the most massive galaxies from z ~ 0.6 to the local Universe, especially on how radio AGN influence the recent star formation histories of host galaxies.

The Dark Energy Survey (DES) will be the new state-of the-art in large-scale galaxy imaging surveys. With 5,000 deg2, it will cover an area of the sky similar to SDSS-II, but will go over two magnitudes deeper, reaching 24th magnitude in all four optical bands (griz). DES will further provide observations in the redder Y-band and will be complemented with VISTA observations in the near-infrared bands JHK. Hence DES will furnish an unprecedented combination of sky and wavelength coverage and depth, unreached by any of the existing galaxy surveys. The very nature of the DES data set – large volume at intermediate photometric depth – allows us to probe galaxy formation and evolution within a cosmic-time range of ~ 10 Gyr and in different environments. In fact there will be many galaxy clusters available for galaxy evolution studies, given that one of the main aims of DES is to use their abundance to constrain the equation of state of dark energy. The X-ray follow up of these clusters, coupled with the use of gravitational lensing, will provide very precise measures of their masses, enabling us to study in detail the influence of the environment on galaxy formation and evolution processes. DES will leverage the study of these processes by allowing us to perform a detailed investigation of the galaxy luminosity and stellar mass functions and of the relationship between dark and baryonic matter as described by the Halo Occupation Distribution.

Increasingly good statistical data on the galaxy population at high and low redshift enable the development of new phenomenological approaches to galaxy evolution based on application of the simplest continuity equations. This has given new insights into the different ways in which star-formation in galaxies is quenched, the role of merging in the population, and in to the control of star-formation in star-forming galaxies and the links with chemical evolution. The continuity approach provides a self-consistent view of the evolving population and exposes linkages between different aspects of galaxy evolution.