Satellite kinematics – I. A new method to constrain the halo mass–luminosity relation of central galaxies

Satellite kinematics can be used to probe the masses of dark matter haloes of central galaxies. In order to measure the kinematics with sufficient signal-to-noise ratio, one uses the satellite galaxies of a large number of central galaxies stacked according to similar properties (e.g. luminosity). However, in general, the relation between the luminosity of a central galaxy and the mass of its host halo will have non-zero scatter. Consequently, this stacking results in combining the kinematics of satellite galaxies in haloes of different masses, which complicates the interpretation of the data. In this paper, we present an analytical framework to model satellite kinematics, properly accounting for this scatter and for various selection effects. We show that in the presence of scatter in the halo mass–luminosity relation, the commonly used velocity dispersion of satellite galaxies can not be used to infer a unique halo mass–luminosity relation. In particular, we demonstrate that there is a degeneracy between the mean and the scatter of the halo mass–luminosity relation. We present a new technique that can break this degeneracy, and which involves measuring the velocity dispersions using two different weighting schemes: host weighting (each central galaxy gets the same weight) and satellite weighting (each central galaxy gets a weight proportional to its number of satellites). The ratio between the velocity dispersions obtained using these two weighting schemes is sensitive to the scatter in the halo mass–luminosity relation, and can thus be used to infer a unique relation between light and mass from the kinematics of satellite galaxies.     

Modelling galaxy–galaxy weak lensing with Sloan Digital Sky Survey groups

We use galaxy groups selected from the Sloan Digital Sky Survey (SDSS) together with mass models for individual groups to study the galaxy–galaxy lensing signals expected from galaxies of different luminosities and morphological types. We compare our model predictions with the observational results obtained from the SDSS by Mandelbaum et al. for the same samples of galaxies. The observational results are well reproduced in a Λ cold dark matter (ΛCDM) model based on the Wilkinson Microwave Anisotropy Probe ( WMAP ) 3-yr data, but a ΛCDM model with higher σ₈, such as the one based on the WMAP 1-yr data, significantly overpredicts the galaxy–galaxy lensing signal. We model, separately, the contributions to the galaxy–galaxy lensing signals from different galaxies: central versus satellite, early type versus late type and galaxies in haloes of different masses. We also examine how the predicted galaxy–galaxy lensing signal depends on the shape, density profile and the location of the central galaxy with respect to its host halo.     

A photometric study of the southern Blazhko star SS For: unambiguous detection of quintuplet components

We present our analysis of photometric data in the Johnson B and V filter of the southern Blazhko star SS For. In parallel, we analysed the V observations obtained with the All Sky Automated Survey-3 photometry of the star gathered between 2000 and 2008. In the frequency spectra resulting from a Fourier analysis of our data, the triplet structure is detectable up to high order, both in the B and V data. Moreover, we find evidence for quintuplet components. We confirm from our data that the modulation components decrease less steeply than the harmonics of the main frequency. We derived the variations of the Fourier parameters quantifying the light-curve shape over the Blazhko cycle. There is good agreement between the spectroscopic abundance and the metallicity determined from the Fourier parameters of the average light curve. SS For is peculiar as a Blazhko star because of its strong variations around minimum light.     

Potential climate change effects on warm-season livestock production in the Great Plains

Projected production responses were derived for confined swine and beef and for milk-producing dairy cattle based on climate change projections in daily ambient temperature. Milk production from dairy cattle and the number of days to grow swine and beef cattle were simulated. Values were obtained for three central United States transects and three climate scenarios which were based on projected mean daily ambient temperatures associated with a baseline, doubling, and tripling of atmospheric greenhouse gas (CO₂) levels for the period June 1 to October 31. For swine, a slight northwest to southeast gradient is evident. Transect 1 (west side) shows no losses under the doubling scenario and losses up to 22.4% under the tripling scenario. Transect 3 (east side) displays losses of over 70% under the tripling scenario. For beef, positive benefits were simulated in Transect 1 with increasing temperatures, although a northwest to southeast gradient was also evident. For dairy, no positive benefits in milk production were found due to climate effects. Projected production declines ranged from 1% to 7.2%, depending on location. However, ranges in predicted differences were less than those simulated for beef and swine. These simulations suggest regional differences in animal production due to climate change will be apparent. For small changes in climate conditions, animals will likely be able to adapt, while larger changes in climate conditions will likely dictate that management strategies be implemented. Exploration of the effects of climate changes on livestock should allow producers to adjust management strategies to reduce potential impact and economic losses due to environmental changes.     

Energy balance closure for the LITFASS-2003 experiment

In the first part, this paper synthesises the main results from a series of previous studies on the closure of the local energy balance at low-vegetation sites during the LITFASS-2003 experiment. A residual of up to 25% of the available energy has been found which cannot be fully explained either by the measurement uncertainty of the single components of the surface energy balance or by the length of the flux-averaging period. In the second part, secondary circulations due to heterogeneities in the surface characteristics (roughness, thermal and moisture properties) are discussed as a possible cause for the observed energy balance non-closure. This hypothesis seems to be supported from the fluxes derived from area-averaging measurement techniques (scintillometers, aircraft).     

Three centuries of Slovakian drought dynamics

Tree-ring data from Slovakia are used to reconstruct decadal-scale fluctuations of the self-calibrated Palmer Drought Severity Index (scPDSI) over 1744–2006. The ring width chronology correlates at 0.58 (annual) and 0.88 (decadal) with regional-scale (48–50°N and 18–20°E) summer (June–August) scPDSI variations (1901–2002). Driest and wettest years common to the tree-ring and target data are 1947, 1948, 1964, and 1916, 1927, 1938, 1941, respectively. The model indicates decadal-scale drought ~1780–1810, 1850–1870, 1940–1960, and during the late twentieth century. The wettest period occurred ~1745–1775. Instrumental measurements and documentary evidence allow the reconstructed drought extremes to be verified and also provide additional insights on associated synoptic drivers and socioeconomic impacts. Comparison of anomalous dry conditions with European-scale fields of 500 hPa geopotential height retains positive pressure anomalies centered over Central Europe leading to atmospheric stability, subsidence and dry conditions. Negative mid-tropospheric geopotential height anomalies over Western Europe are connected with anomalous wet conditions over Slovakia. Nine existing, annually resolved hydro-climatic reconstructions from Central Europe, which were herein considered for comparison with the Slovakian findings, reveal significant high- to low-frequency coherency among the majority of records. Differences between the Slovakian and the other reconstructions are most evident at the end of the nineteenth century.     

Opportunities provided by geographic information systems and volunteered geographic information for a timely emergency response during flood events in Cologne,Germany

The occurrence of disasters such as extreme flooding in urban environments has severe consequences, not only on the human population but also on critical infrastructures such as the road networks, which are of vital importance for everyday living and particularly for emergency response. In this article, our main goal is to present-conceptually and in praxis-a model that could be used from the emergency responders for timely and efficient emergency management and response in an urban complex environment. For the city of Cologne in Germany, we aim to indicate possible ways to decrease the emergency response time during an extreme flood scenario through the development of an accessibility indicator, which consists of different components. Therefore, we will investigate the opportunities that occur, in a flood risk scenario, from the use of geographic information in different forms such as Volunteered Geographic Information (VGI) and open-source data in an ArcGIS environment, to increase urban resilience through the decreasing emergency response time. We will focus on network analysis for the fire brigades (first acting emergency responders) during a flood scenario to calculate their emergency response ranges and emergency response routes through flooded road networks, for the assistance of the possibly affected hospitals, refugee homes and fire brigades, which can be flooded. At the end of the paper, we suggest that the vulnerable community of the refugees could be taken into consideration as a new source of VGI, as an additional component that would lead to the decrease in the emergency response time. The geo-located information that could be provided by the refugee community can be very useful in emergency situations, such as those examined in this article where timely information can be forwarded to the proper authorities for a more focused and timely emergency response, increasing the resilience of the urban population and their community.

     

Modification of martian slope streaks by eolian processes

Recent images from the High Resolution Imaging Science Experiment (HiRISE) camera have shown that slope streaks have relief on the order of a meter or less. This study presents observations of transverse bedforms and infill deposits within slope streak beds that were not previously identified or were uncommon from earlier analyses of HiRISE images. Transverse bedforms are linear to slightly arcuate features oriented transverse to the slope streak bed which may be analogous to terrestrial splash or coarse-grained ripples based on their morphology, wavelength, and amplitude. In addition to the bedforms, there is also evidence that slope streak beds gradually shallow over time by infilling of material. The presence of ripples within slope streaks implies that saltation-capable material is available on the surface today and/or was available in the recent past. Although airfall dust is not a capable saltation source material, aggregates of electrostatically-bound dust that are possibly later cemented by salts may serve as a source. From the results of this study, we hypothesize a sequence of events in a slope streak formation and modification cycle where grains saltate to form ripples along the bed of a slope streak, airfall dust mantling causes gradual fading of the streak, and infill material buries the ripples, eventually reaching the pre-avalanche surface that removes all traces of relief.