Age Of Galaxy Research Articles

The stellar populations of early-type galaxies - II. The effects of environment and mass

The degree of influence that environment and mass have on the stellar populations of early-type galaxies is uncertain. In this paper we present the results of a spectroscopic analysis of the stellar populations of early-type galaxies aimed at addressing this question. The sample of galaxies is drawn from four clusters, with <z>=0.04, and their surrounding structure extending to ~10R_{vir}. We find that the distributions of the absorption-line strengths and the stellar population parameters age, metallicity and alpha-element abundance ratio do not differ significantly between the clusters and their outskirts, but the tight correlations found between these quantities and velocity dispersion within the clusters are weaker in their outskirts. All three stellar population parameters of cluster galaxies are positively correlated with velocity dispersion. Galaxies in clusters form a homogeneous class of objects that have similar distributions of line-strengths and stellar population parameters, and follow similar scaling relations regardless of cluster richness or morphology. We estimate the intrinsic scatter of the Gaussian distribution of metallicities to be 0.3 dex, while that of the alpha-element abundance ratio is 0.07 dex. The e-folding time of the exponential distribution of galaxy ages is estimated to be 900 Myr. The intrinsic scatters of the metallicity and alpha-element abundance ratio distributions can almost entirely be accounted for by the correlations with velocity dispersion and the intrinsic scatter about these relations. This implies that a galaxies mass plays the major role in determining its stellar population.

Estimation of absorption line indices of early-type galaxies using colours

Context. Absorption line indices are widely used to determine the stellar population parameters such as age and metallicity of galaxies, but it is not easy to obtain the line indices of some distant galaxies that have colours available.

The Starburst – AGN Connection: a Critical Review

AbstractNuclear activity and star formation processes represent two key elements in the evolution of galaxies across the cosmic ages. In spite of very different physical backgrounds, several arguments suggest that they should be closely connected. On the basis of simple theoretical considerations, the transport of appreciable amounts of fuel to the AGN scale is very likely to trigger star formation in the gas. Young stellar populations, in their turn, are expected to affect the properties of the interstellar medium, leading to a complex balance of interactions among nuclear activity and star formation. This scenario is also supported by the observation of super-massive black holes and host galaxy properties, which strongly suggest a common evolutionary track. However, despite several years of extensive investigation, the relationship among the two processes still has to be properly explained. Here we provide a review of some of the most important observations, which are relevant to the issue of the connection among AGN and starburst events. Based on a wide sample of observations, we present an analysis of the spectral signatures connected with AGN and star formation activity. Expanding the concept of the distinction among star forming galaxies and the true active nuclei, we provide systematic evidence for a role of recent starburst events in the circum-nuclear regions of active galaxies and discuss the possibility of its influence onto the AGN environment. We also analyze the age, mass and metallicity properties of star-forming and active galaxies, illustrating that they are arranged in a sequence that is consistent with the identified relation.

The nature of assembly bias - I. Clues from a ΛCDM cosmology

We present a new proxy for the overdensity peak height for which the large-scale clustering of haloes of a given mass does not vary significantly with the assembly history. The peak height, usually taken to be well represented by the virial mass, can instead be approximated by the mass inside spheres of different radii, which in some cases can be larger than the virial radius and therefore include mass outside the individual host halo. The sphere radii are defined as r = $a$ delta_t + $b$ log_10(M_vir/M_nl), where delta_t is the age relative to the typical age of galaxies hosted by haloes with virial mass M_vir, M_nl is the non-linear mass, and $a$=0.2 and $b$=-0.02 are the free parameters adjusted to trace the assembly bias effect. Note that $r$ depends on both halo mass and age. In this new approach, some of the objects which were initially considered low-mass peaks belong to regions with higher overdensities. At large scales, i.e. in the two-halo regime, this model properly recovers the simple prescription where the bias responds to the height of the mass peak alone, in contrast to the usual definition (virial mass) that shows a strong dependence on additional halo properties such as formation time. The dependence on the age in the one-halo term is also remarkably reduced. The population of galaxies whose "peak height" changes with this new definition consists mainly of old stellar populations and are preferentially hosted by low-mass haloes located near more massive objects. The latter is in agreement with recent results which indicate that old, low-mass haloes would suffer truncation of mass accretion by nearby larger haloes or simply due to the high density of their surroundings, thus showing an assembly bias effect. The change in mass is small enough that the Sheth et al. (2001) mass function is still a good fit to the resulting distribution of new masses.

WINGS-SPE II: A catalog of stellar ages and star formation histories, stellar masses and dust extinction values for local clusters galaxies

The WIde-field Nearby Galaxy clusters Survey (WINGS) is a project whose primary goal is to study the galaxy populations in clusters in the local universe (z<0.07) and of the influence of environment on their stellar populations. This survey has provided the astronomical community with a high quality set of photometric and spectroscopic data for 77 and 48 nearby galaxy clusters, respectively. In this paper we present the catalog containing the properties of galaxies observed by the WINGS SPEctroscopic (WINGS-SPE) survey, which were derived using stellar populations synthesis modelling approach. We also check the consistency of our results with other data in the literature. Using a spectrophotometric model that reproduces the main features of observed spectra by summing the theoretical spectra of simple stellar populations of different ages, we derive the stellar masses, star formation histories, average age and dust attenuation of galaxies in our sample. ~5300 spectra were analyzed with spectrophotometric techniques, and this allowed us to derive the star formation history, stellar masses and ages, and extinction for the WINGS spectroscopic sample that we present in this paper. The comparison with the total mass values of the same galaxies derived by other authors based on SDSS data, confirms the reliability of the adopted methods and data.

HerMES: Lyman Break Galaxies Individually Detected at 0.7 ≤ z ≤ 2.0 in GOODS-N with Herschel/SPIRE

AbstractAs part of the Herschel Multi-tiered Extragalactic Survey we have investigated the rest-frame far-infrared (FIR) properties of a sample of more than 4800 Lyman Break Galaxies (LBGs) in the Great Observatories Origins Deep Survey North field. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 &lt; z &lt; 1.6 and one object at z = 2.0. The LBGs have been selected using color-color diagrams; the ones detected by Herschel SPIRE have redder colors than the others, while the undetected ones have colors consistent with average LBGs at z &gt; 2.5. The spectral energy distributions of the objects detected in the rest-frame FIR are investigated using the code cigale to estimate physical parameters. We include far-UV (FUV) data from GALEX. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. It appears that LBGs are located in a triangle-shaped region in the AFUV vs. LogLFUV = 0 diagram limited by AFUV = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. This upper envelop can be used as upper limits for the UV dust attenuation as a function of LFUV. The limits of this region are well explained using a closed-box model, where the chemical evolution of galaxies produces metals, which in turn lead to higher dust attenuation when the galaxies age.

Probing the course of cosmic expansion with a combination of observational data

We study the cosmic expansion history by reconstructing thedeceleration parameter q(z) from the SDSS-II type Ia supernovasample (SNIa) with two different light curve fits (MLCS2k2 andSALT-II), the baryon acoustic oscillation (BAO) distance ratio, thecosmic microwave background (CMB) shift parameter, and the lookbacktime-redshift (LT) from the age of old passive galaxies. Threeparametrization forms for the equation of state of dark energy (CPL,JBP, and UIS) are considered. Our results show that, for the CPL andthe UIS forms, MLCS2k2 SDSS-II SNIa+BAO+CMB and MLCS2k2 SDSS-IISNIa+BAO+CMB+LT favor a currently slowing-down cosmic acceleration,but this does not occur for all other cases, where an increasingcosmic acceleration is still favored. Thus, the reconstructedevolutionary behaviors of dark energy and the course of the cosmicacceleration are highly dependent both on the light curve fittingmethod for the SNIa and the parametrization form for the equation ofstate of dark energy.

Cosmological data analysis of f(R) gravity models

A class of well-behaved modified gravity models with long enough matter domination epoch and a late-time accelerated expansion is confronted with SNIa, CMB, SDSS, BAO and H(z) galaxy ages data, as well as current measurements of the linear growth of structure. We show that the combination of geometrical probes and growth data exploited here allows to rule out f(R) gravity models, in particular, the logarithmic of curvature model. We also apply solar system tests to the models in agreement with the cosmological data. We find that the exponential of the inverse of the curvature model satisfies all the observational tests considered and we derive the allowed range of parameters. Current data still allows for small deviations of Einstein gravity. Future, high precision growth data, in combination with expansion history data, will be able to distinguish tiny modifications of standard gravity from the ΛCDM model.

Cosmological constraints on the Undulant Universe

We use the redshift Hubble parameter H(z) data derived from relative galaxy ages, distant type Ia supernovae (SNe Ia), the Baryonic Acoustic Oscillation (BAO) peak, and the Cosmic Microwave Background (CMB) shift parameter data, to constrain cosmological parameters in the Undulant Universe. We marginalize the likelihood functions over h by integrating the probability density P ∝ e−χ2/2 By using a Markov Chain Monte Carlo (MCMC) technique, we obtain the best fitting results and give the confidence regions in the b − Ωm0 plane. Then we compare their constraints. Our results show that the H(z) data play a similar role with the SNe Ia data in cosmological study. By presenting the independent and joint constraints, we find that the BAO and CMB data play very important roles in breaking the degeneracy compared with the H(z) and SNe Ia data alone. Combined with the BAO or CMB data, one can remarkably improve the constraints. The SNe Ia data sets constrain Ωm0 much tighter than the H(z) data sets, but the H(z) data sets constrain b much tighter than the SNe Ia data sets. All these results show that the Undulant Universe approaches the ΛCDM model. We expect more H(z) data to constrain cosmological parameters in the future.

STELLAR POPULATIONS OF ELLIPTICAL GALAXIES IN THE LOCAL UNIVERSE

We study the stellar populations of 1,923 elliptical galaxies at z<0.05 selected from the Sloan Digital Sky Survey as a function of velocity dispersion, sigma, and environment. We construct average, high signal-to-noise spectra and find the following: (1) lower-sigma galaxies have a bluer optical continuum and stronger (but still weak) emission lines; (2) at fixed sigma, field ellipticals have a slightly bluer stellar continuum, especially at wavelengths \lesssim 4000 \AA, and have stronger (but still weak) emission lines compared to their group counterparts, although this environmental dependence is strongest for low-sigma ellipticals. Based on Lick indices measured from both the individual and average spectra, we find that: (1) at a given sigma, elliptical galaxies in groups have systematically weaker Balmer absorption than their field counterparts, although this environmental dependence is most pronounced at low sigma; (2) there is no clear environmental dependence of <Fe>, while the alpha-element absorption indices such as Mgb are only slightly stronger in galaxies belonging to rich groups. An analysis based on simple stellar populations (SSPs) reveals that more massive elliptical galaxies are older, more metal-rich and more strongly alpha-enhanced. We also find that: (1) the SSP-equivalent ages of galaxies in rich groups are, on average, ~1 Gyr older than in the field, although once again this effect is strongest at low sigma; (2) galaxies in rich groups have slightly lower [Fe/H] and are marginally more strongly alpha-enhanced; and (3) there is no significant environmental dependence of total metallicity, [Z/H]. Our results are generally consistent with stronger low-level recent star formation in field ellipticals at low sigma, similar to recent results based on ultraviolet and infrared observations. (Abridged)

THE SIZE AND ORIGIN OF METAL-ENRICHED REGIONS IN THE INTERGALACTIC MEDIUM FROM SPECTRA OF BINARY QUASARS

We present tomography of the circum-galactic metal distribution at redshift 1.7 to 4.5 derived from echellete spectroscopy of binary quasars. We find CIV systems at similar redshifts in paired sightlines more often than expected for sightline-independent redshifts. As the separation of the sightlines increases from 36 kpc to 907 kpc, the amplitude of this clustering decreases. At the largest separations, the CIV systems cluster similar to Lyman-break galaxies (Adelberger et al. 2005a). The CIV systems are significantly less correlated than these galaxies, however, at separations less than R_1 ~ 0.42 +/- 0.15 h-1 comoving Mpc. Measured in real space, i.e., transverse to the sightlines, this length scale is significantly smaller than the break scale estimated from the line-of-sight correlation function in redshift space (Scannapieco et al. 2006a). Using a simple model, we interpret the new real-space measurement as an indication of the typical physical size of enriched regions. We adopt this size for enriched regions and fit the redshift-space distortion in the line-of-sight correlation function. The fitted velocity kick is consistent with the peculiar velocity of galaxies as determined by the underlying mass distribution and places an upper limit on the outflow (or inflow) speed of metals. The implied time scale for dispersing metals is larger than the typical stellar ages of Lyman-break galaxies (Shapley et al. 2001), and we argue that enrichment by galaxies at z > 4.3 played a greater role in dispersing metals. To further constrain the growth of enriched regions, we discuss empirical constraints on the evolution of the CIV correlation function with cosmic time. This study demonstrates the potential of tomography for measuring the metal enrichment history of the circum-galactic medium.

Ages and metallicities of central and satellite galaxies: implications for galaxy formation and evolution

Using the stellar ages and metallicities of galaxies in the Sloan Digital Sky Survey (SDSS) obtained by Gallazzi et al. and the SDSS galaxy group catalogue of Yang et al., we study how the stellar ages and metallicities of central and satellite galaxies depend on stellar mass, M*, and halo mass, Mh. We find that satellites are older and metal richer than centrals of the same stellar mass, and this difference increases with decreasing M*. In addition, the slopes of the age–stellar mass and metallicity–stellar mass relations are found to become shallower in denser environments (more massive haloes). This is due to the fact that the average age and metallicity of low-mass satellite galaxies (M*≲ 1010h−2 M⊙) increase with the mass of the halo in which they reside. In order to gain understanding of the physical origin of these trends, we compare our results with the semi-analytical model of Wang et al. The model, which predicts stellar mass functions and two-point correlation functions in good overall agreement with observations, also reproduces the fact that satellites are older than centrals of the same stellar mass and that the age difference increases with the halo mass of the satellite. This is a consequence of the fact that satellites are stripped of their hot gas reservoir shortly after they are accreted by their host haloes (strangulation). The ensuing quenching of star formation leaves the stellar populations of satellites to evolve passively, while the prolonged star formation activity of centrals keeps their average ages younger. The resulting age offset is larger in more massive environments because their satellites were accreted earlier. The model does not reproduce he halo mass dependence of the metallicities of low-mass satellites, yields metallicity–stellar mass and age–stellar mass relations that are too shallow and predicts that satellite galaxies have the same metallicities as centrals of the same stellar mass, in disagreement with the data. We argue that these discrepancies are likely to indicate the need to (i) modify the recipes of both supernova feedback and active galactic nucleus feedback, (ii) use a more realistic description of strangulation and (iii) include a proper treatment of the tidal stripping, heating and destruction of satellite galaxies.

Cosmic constraint to DGP brane model: Geometrical and dynamical perspectives

In this paper, the Dvali-Gabadadze-Porrati (DGP) brane model is confronted by current cosmic observational data sets from geometrical and dynamical perspectives. On the geometrical side, the recently released Union2 557 of type Ia supernovae (SN Ia), the baryon acoustic oscillation from the Sloan Digital Sky Survey and the Two Degree Galaxy Redshift Survey (transverse and radial to line-of-sight data points), the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations [shift parameters $R$, ${l}_{a}({z}_{*})$ and redshift at the last scatter surface ${z}_{*}$], ages of high redshifts galaxies, i.e., the lookback time and the high redshift gamma ray bursts are used. On the dynamical side, data points about the growth function of matter linear perturbations are used. Using the same data set combination, we also constrain the flat $\ensuremath{\Lambda}\mathrm{CDM}$ model as a comparison. The results show that current geometrical and dynamical observational data sets much favor the flat $\ensuremath{\Lambda}\mathrm{CDM}$ model and the departure from it is above $4\ensuremath{\sigma}(6\ensuremath{\sigma})$ for the spatially flat DGP model with (without) SN systematic errors. The consistence of growth function data points is checked in terms of a relative departure of redshift-distance relation.

THE AGE SPREAD OF QUIESCENT GALAXIES WITH THE NEWFIRM MEDIUM-BAND SURVEY: IDENTIFICATION OF THE OLDEST GALAXIES OUT TOz∼ 2

With a complete, mass-selected sample of quiescent galaxies from the NEWFIRM Medium-Band Survey, we study the stellar populations of the oldest and most massive galaxies (>1011 M☉) to high redshift. The sample includes 570 quiescent galaxies selected based on their extinction-corrected U − V colors out to z = 2.2, with accurate photometric redshifts, σz/(1 + z) ∼ 2%, and rest-frame colors, σU−V ∼ 0.06 mag. We measure an increase in the intrinsic scatter of the rest-frame U − V colors of quiescent galaxies with redshift. This scatter in color arises from the spread in ages of the quiescent galaxies, where we see both relatively quiescent red, old galaxies and quiescent blue, younger galaxies toward higher redshift. The trends between color and age are consistent with the observed composite rest-frame spectral energy distributions (SEDs) of these galaxies. The composite SEDs of the reddest and bluest quiescent galaxies are fundamentally different, with remarkably well-defined 4000 Å and Balmer breaks, respectively. Some of the quiescent galaxies may be up to four times older than the average age and up to the age of the universe, if the assumption of solar metallicity is correct. By matching the scatter predicted by models that include growth of the red sequence by the transformation of blue galaxies to the observed intrinsic scatter, the data indicate that most early-type galaxies formed their stars at high redshift with a burst of star formation prior to migrating to the red sequence. The observed U − V color evolution with redshift is weaker than passive evolution predicts; possible mechanisms to slow the color evolution include increasing amounts of dust in quiescent galaxies toward higher redshift, red mergers at z ≲ 1, and a frosting of relatively young stars from star formation at later times.

MOIRCS DEEP SURVEY. VI. NEAR-INFRARED SPECTROSCOPY OFK-SELECTED STAR-FORMING GALAXIES ATz∼ 2

We present near-infrared (NIR) spectroscopy for 37 BzK-color-selected star-forming galaxies with MOIRCS on Subaru. The sample is drawn from the Ks-band selected catalog of the MOIRCS Deep Survey (MODS) in the GOODS-N region. About half of our samples are selected from the MIPS 24um-source catalog. Ha emission lines are detected from 23 galaxies, of which the median redshift is 2.12. We derived the star formation rates (SFRs) from extinction-corrected Ha luminosities. The extinction correction is estimated from the SED fitting of multi-band photometric data covering UV to NIR wavelengths. The Balmer decrement of the stacked emission lines shows that the amount of extinction for the ionized gas is larger than that for the stellar continuum. From a comparison of the extinction corrected Ha luminosity and other SFR indicators we found that the relation between the dust properties of stellar continuum and ionized gas is different depending on the intrinsic SFR. The comparison between the Ha SFR and stellar mass estimated from SED fitting shows no correlation between them. Some galaxies with stellar mass smaller than ~10^10 Msun show SFRs higher than ~100 Msun/yr. The specific SFRs (SSFRs) of these galaxies are remarkably high. The average stellar-population age of these high-SSFR galaxies is younger than 100 Myr, which is consistent with the implied high SSFR. The large SFR implies the possibility that the high SSFR galaxies significantly contribute to the cosmic SFR density of the universe at z~2. The total SFR density estimated from the Ha emission line galaxies is 0.089-0.136 Msun/yr/Mpc^3, which is consistent with the total SFR densities in the literature. The metallicity of the high-SSFR galaxies is larger than that expected from the mass-metallicity relation of UV-selected galaxies at z~2 by Erb et al. (2006a). [Abridged]

EVOLVING STARBURST MODELING OF FAR-INFRARED/SUBMILLIMETER/MILLIMETER LINE EMISSION. III. APPLICATION TO NEARBY LUMINOUS INFRARED GALAXIES

In a previous work, we showed that the observed FIR/sub-mm/mm line spectra of a starburst galaxy (M 82) can be successfully modeled in terms of the evolutionary scheme of an ensemble of giant molecular clouds (GMCs) and shells, and such studies can usefully constrain the age(s) or star formation history of a starburst galaxy. In this paper we present a preliminary study of using the template of an ensemble of evolving GMCs/shells we developed for M 82. we apply the model to represent various stages of starburst evolution in a well known sample of nearby luminous infrared galaxies (LIRGs). In this way, we attempt to interpret the relationship between the degree of molecular excitation and ratio of far-infrared (FIR) to $^{12}$CO (or simply CO) luminosity to possibly reflect different stages of the evolution of star-forming activity within their nuclear regions.

Redshift evolution of correlations between gas fraction and stellar population properties of galaxies

The gas fraction is important for understanding the formation and evolution of galaxies. It is found that there are linear correlations between the atomic-gas-to-stellar mass ratio (G/S) and stellar population properties (age, metallicity and stellar mass) of galaxies. However, only a nearby galaxy sample was used. This work investigates how the correlations change with the redshift limit of galaxies, using three volume limited galaxy samples selected from Sloan Digital Sky Survey (SDSS). It shows that there are linear correlations between the G/S and logarithmic values of stellar age, metallicity and mass, for all galaxy samples. It also shows that the linear correlation between G/S and stellar age is much better than others and possibly can be used in future studies. In addition, the scatters of the fitted correlations are found to increase with upper redshift limit of sample galaxies.

Soft bandX/Kluminosity ratios for gas-poor early-type galaxies

<i>Aims. <i/> We aim to place upper limits on the combined X-ray emission from the population of steady nuclear-burning white dwarfs in galaxies. In the framework of the single-degenerate scenario, these systems, known as supersoft sources, are believed to be likely progenitors of Type Ia supernovae. <i>Methods. <i/> From the <i>Chandra<i/> archive, we selected normal early-type galaxies with the point source detection sensitivity better than 10<sup>37<sup/> erg s<sup>-1<sup/> in order to minimize the contribution of unresolved low-mass X-ray binaries. The galaxies, contaminated by emission from ionized ISM, were identified based on the analysis of radial surface brightness profiles and energy spectra. The sample was complemented by the bulge of M 31 and the data for the solar neighborhood. To cover a broad range of ages, we also included NGC 3377 and NGC 3585 which represent the young end of the age distribution for elliptical galaxies. Our final sample includes eight gas-poor galaxies for which we determine <i>L<sub>X<sub/><i/>/<i>L<sub>K<sub/><i/> ratios in the 0.3-0.7 keV energy band. This choice of the energy band was optimized to detect soft emission from thermonuclear-burning on the surface of an accreting white dwarf. In computing the <i>L<sub>X<sub/><i/> we included both unresolved emission and soft resolved sources with the color temperature of <i>kT<i/><sub>bb<sub/> <i>≤<i/> 200 eV.<i>Results. <i/>We find that the <i>X<i/>/<i>K<i/> luminosity ratios are in a rather narrow range of (1.7-3.2) × 10<sup>27<sup/> erg s<sup>-1<sup/> . The data show no obvious trends with mass, age, or metallicity of the host galaxy, although a weak anti-correlation with the Galactic NH appears to exist. It is much flatter than predicted for a blackbody emission spectrum with temperature of ~ 50-75 eV, suggesting that sources with such soft spectra contribute significantly less than a half to the observed <i>X<i/>/<i>K<i/> ratios. However, the correlation of the <i>X<i/>/<i>K<i/> ratios with NH has a significant scatter and in the strict statistical sense cannot be adequately described by a superposition of a power law and a blackbody components with reasonable parameters, thus precluding quantitative constraints on the contribution from soft sources.

New Beryllium results in halo stars from Keck/HIRES spectra

AbstractWe have obtained high-resolution, high signal-to-noise Keck spectra to determine Be abundances in over 100 stars in the Galactic halo. The stellar metallicities range from [Fe/H] = −0.50 to −3.50. Using this large sample, we have examined the trends of Be with Fe and Be with O. We find a real dispersion in Be at a given [O/H] that indicates that Be may not be a good cosmochronometer. Our results indicate that the dominant production mechanism for Be changes as the Galaxy ages. In the early eras of the Galaxy, when massive stars become supernovae, Be is produced from the acceleration of energetic CNO atoms which bombard protons in the vicinity of supernovae. Later spallation reactions occur as high energy protons bombard CNO atoms in the interstellar gas. The change occurs near [Fe/H] = −2.2. We have found that Be is deficient in Li-deficient halo stars, which favors the blue straggler analog hypothesis.

Galaxy morphology, kinematics and clustering in a hydrodynamic simulation of a �� cold dark matter universe

We explore galaxy properties and their link with environment and clustering using a population of ∼1000 galaxies formed in a high-resolution hydrodynamic simulation of the Λ cold dark matter cosmology. At the redshift we concentrate on, z= 1, the spatial resolution is 1.4 proper h−1 kpc and the mass resolution is such that Milky Way sized disc galaxies contain ∼105 particles within their virial radii. The simulations include supermassive black hole accretion and feedback as well as a multiphase model for star formation. Overall, we find that a number of familiar qualitative relationships hold approximately between galaxy properties, for example we observe galaxies as lying between two broad extremes of type, where ‘late’ types tend to be smaller in size, have lower circular velocities, younger stars, higher star formation rates, larger disc to bulge ratios and lower Sersic indices than ‘early types’. We find that as in previous studies of small numbers of resimulated galaxies the stellar component of disc galaxies is not as rotationally supported as in observations. Bulges contain too much of the stellar mass, although exponential discs do have scalelengths compatible with observations, and the stellar mass Tully–Fisher relation at z= 1 is reproduced. The addition of black hole physics to the simulations does not appear to have made a large impact on the angular momentum results compared to these other studies, nor do we find that running an identical simulation with significantly lower mass resolution affects this aspect (although we are unable to test higher mass resolution, which other authors have shown can alleviate the problem). Despite this, we can profitably use the rank order of either disc-to-total ratio, Sersic index, or galaxy age to separate galaxies into morphological classes and examine the density–morphology relation and morphology dependence of clustering. We find that while at redshift z= 0 the well-known preponderance of early types in dense environments is seen, at z= 1 the density–morphology relation becomes flatter and late-type galaxies are even seen to have a higher clustering amplitude than early types.