Past human population dynamics play a key role in integrated models of understanding socio-ecological change over time. However, little analysis on this issue has been carried out for the prehistoric societies in the Lower Danube and Eastern Balkans area. Here, we use summed probability distributions of radiocarbon dates to investigate potential regional and local variation population dynamics. Our study adopts a formal model-testing approach to the fifth millennium BC archaeological radiocarbon record, performing a region-wide, comparative analysis of the demographic trajectories of the area along lower Danube River. We follow the current framework of theoretical models of population growth and perform global and regional significance and spatial permutation tests on the data. Specifically, we investigate whether populations on both sides of the Danube follow a logistic pattern of steady growth, followed by a major decline over time. Finally, our analysis of local-scale growth investigates whether considerable heterogeneity or homogeneity within the region may be observed over the time span considered here. The results show both similarities and differences in the population trends across the area. Our findings are showcased in relation to the cultural characteristics of the region’s 5th millennium BC societies, and future research directions are also suggested.

A major difficulty hampering the accuracy of UV/optical star formation rate tracers is the effect of interstellar dust, absorbing and scattering light produced by both young and old stellar populations (SPs). Although empirically calibrated corrections or energy balance SED fitting are often used for fast de-reddening of galaxy stellar emission, eventually only radiative transfer calculations can provide self-consistent predictions of galaxy model spectra, taking into account important factors such as galaxy inclination, different morphological components, non-local heating of the dust and scattered radiation. In addition, dust radiative transfer can be used to determine the fraction of monochromatic dust emission powered by either young or old SPs. This calculation needs to take into account the different response of the dust grains to the UV and optical radiation field, depending on the grain size and composition. We determined the dust heating fractions, on both global and local scales, for a high-resolution galaxy model by using our 3D ray-tracing dust radiative transfer code “DART-Ray”. We show the results obtained using this method and discuss the consequences for star formation rate indicators.

DART-Ray is a 3D ray-tracing dust radiative transfer (RT) code that can be used to derive stellar and dust emission maps of galaxy models and simulations with arbitrary geometries. In addition to the previously published RT algorithm, we have now included in DART-Ray the possibility of calculating the stocastically heated dust emission from each volume element within a galaxy. To show the capabilities of the code, we performed a high-resolution (26 pc) RT calculation for a galaxy N-body+SPH simulation. The simulated galaxy we considered is characterized by a nuclear disc and a flocculent spiral structure. We analysed the derived galaxy maps for the global and local effects of dust on the galaxy attenuation as well as the contribution of scattered radiation to the predicted observed emission. In addition, by performing an additional RT calculation including only the stellar volume emissivity due to young stellar populations (SPs), we derived the contribution to the total dust emission powered by young and old SPs. Full details of this work will be presented in a forthcoming publication.

We have carried out a detailed modeling of the dust Spectral Energy Distribution (SED) of the nearby, starbursting dwarf galaxy NGC 4214. A key point of our modeling is that we distinguish the emission from (i) HII regions and their associated photodissociation regions (PDRs) and (ii) diffuse dust. For both components we apply templates from the literature calculated with a realistic geometry and including radiation transfer. The large amount of existing data from the ultraviolet (UV) to the radio allows the direct measurement of most of the input parameters of the models. We achieve a good fit for the total dust SED of NGC 4214. In the present contribution we describe the available data, the data reduction and the determination of the model parameters, whereas a description of the general outline of our work is presented in the contribution of Lisenfeld et al. in this volume.

Present and past gas-fuelling of galaxies is expected to depend upon both the properties of the galaxies themselves, as well as their larger-scale environments. In the case of galaxies in groups the environment, i.e the group mass, can be probed by measuring the velocity dispersion of the group members, as done with the GAMA Galaxy Group catalogue (Robotham et al. 2011), probing the halo mass function all the way to small groups. The gas-fuelling rate of normal late-type galaxies can be traced by the SFR under the assumption of a steady state between gas-fuelling and gas-consumption by SF. We present a method to estimate disk opacities from UV/optical photometric characteristics, calibrated using the radiative transfer model of Popescu et al. (2011), applied to UV-Opt-FIR GAMA/H-ATLAS photometry for a subset of GAMA galaxies. We use the method to extract attenuation corrected SFRs for a large sample of late-type GAMA galaxies, which we use in an initial application to constrain the dependency of star formation/gas-fuelling in late-type galaxies on mass of parent DMH, and compactness of galaxy group.

Even though attenuation by dust strongly attenuates and reddens the UV/optical spectral energy distributions of spiral galaxies, quantifying these effects is challenging, particularly when, as is most often the case, infrared measurements of the absorbed energy are not available. We have initiated a study to model the dependence on inclination of the attenuation of light from galaxies measured in the Galaxy and Mass Assembly (GAMA) survey. We present preliminary results using SDSS galaxies in the phase-I GAMA catalogue, comparing observed attenuation-inclination relations with the predictions of the radiation transfer model of Popescu et al. (2011) to derive a statistical measurement of the mean face-on B-band optical depth of disks τfB in a sample of spiral galaxies complete to the SDSS spectroscopic r-band limit of 17.8 mag.

Hierarchical galaxy formation models predict the development of elliptical galaxies through a combination of the mergers and interactions of smaller galaxies. We are carrying out a study of Early-Type Galaxies (ETGs) using GAMA multi-wavelength and Herschel-ATLAS sub-mm data to understand their intrinsic dust properties. The dust in some ETGs may be a relic of past interactions and mergers of galaxies, or may be produced within the galaxies themselves. With this large dataset we will probe the properties of the dust and its relation to host galaxy properties. This paper presents our criteria for selecting ETGs and explores the usefulness of proxies for their morphology, including optical colour, Sérsic index and Concentration index. We find that a combination of criteria including r band Concentration index, ellipticity and apparent sizes is needed to select a robust sample. Optical and sub-mm parameter diagnostics are examined for the selected ETG sample, and the sub-mm data are fitted with modified Planck functions giving initial estimates for the cold dust temperatures and masses.

We present a theoretical study that quantifies the effect of dust on the derived Sérsic indexes of disks and bulges. The changes in the derived parameters from their intrinsic values (as seen in the absence of dust) were obtained by fitting Sérsic distributions on simulated images of disks and bulges produced using radiative transfer calculations and the model of Popescu et al. (2011). We found that dust has the effect of lowering the measured Sérsic index in most cases, with stronger effects for disks and bulges seen through more optically thick lines of sight.

We make predictions for the diffuse far-infrared (FIR) emission from dust in the intracluster medium (ICM) of the Virgo cluster. The dust injection rate from known sources in the cluster is unlikely to give rise to a detectable diffuse FIR IC emission. However, the outer regions of dynamically young clusters have a further potential source of IC grains since they are still accreting freshly infalling spiral galaxies which are presumably contained in an accreting intergalactic medium (IGM). We show that cosmic ray driven winds from the infalling spirals can inject grains into a subvirial IGM that is external to the observed X-ray-emitting ICM. Predictions for the Virgo cluster are generalised to other clusters, and the possibility of detection of dynamically young clusters at cosmological distances is discussed. Although dominated by the discrete source emission from galactic disks, it is possible that diffuse submillimeter dust emission from the ICM could be detected in experiments similar to those designed to map the submillimeter excess due to the Sunyaev-Zeldovich effect in distant clusters. We further discuss the implications of our proposed scenario for the optical extinction in clusters, as well as for the properties and dust content of the IGM. Further implications for the environmental effects on the chemical evolution of spiral galaxies are also considered.