KLUN+ peculiar velocity survey

The enhanced Kinematics of the Local Universe (KLUN+) galaxy sample is a collection of galaxies suitable for Tully-Fisher (TF) or Faber-Jackson (FJ) distance estimation. Here we extract a subsample of 6229 KLUN+ galaxies closer than 80 Mpc/h, and calculate their distances and peculiar velocities with the Iterative Normalized Distance method. Within this method we can derive an analytical formula, independent from the density inhomogeneities, for correcting the selection biases. The radial peculiar velocities can then be derived from the redshifts and the corrected distances. The velocities are smoothed, and the smoothed velocity field is used as a correction term at the next derivation of normalized distances. This iterative procedure is repeated until converging values are reached. Here we present the resulting map of the radial peculiar velocity field at the < 80 Mpc/h environment. The infall patterns towards the main galaxy clusters are clearly visible. The color version of the map, other figures, and animations are provided on the project web site

Revisiting the optical depth of spiral galaxies using the Tully-Fisher B relation

Aims. We attempt to determine the optical depth of spiral galaxy disks by a statistical study of new Tully-Fisher data from the ongoing KLUN+ survey, and to clarify the difference between the true and apparent behavior of optical depth. Methods. By utilizing so-called normalized distances, a subsample of the data is identified to be as free from selection effects as possible. For these galaxies, a set of apparent quantities are calculated for face-on positions using the Tully-Fisher diameter and magnitude relations. These values are compared with direct observations to determine the mean value of the parameter C describing the optical depth. Results. The present study suggests that spiral galaxy disks are relatively optically thin tauB = 0.1, at least in the outermost regions, while they appear in general to be optically thick tauB > 1 when the apparent magnitude and average surface brightness are studied statistically.Comment: 9 pages, 13 figures, accepted for publication in Astronomy & Astrophysic

Metapopulation-Level Adaptation of Insect Host plant Preference and Extinction-Colonization Dynamics in Heterogenous Landscapes

Species living in highly fragmented landscapes typically occur as metapopulations with frequent turnover of local populations. The turnover rate depends on population sizes and connectivities, but it may also depend on the phenotypic and genotypic composition of populations. The Glanville fritillary butterfly ("Melitaea cinxia") in Finland uses two host plant species, which show variation in their relative abundances at two spatial scales: locally among individual habitat patches and regionally among networks of patches. Female butterflies in turn exhibit spatial variation in genetically-determined host plant preference within and among patch networks. Emigration, immigration and establishment of new populations have all been shown to be strongly influenced by the match between the host plant composition of otherwise suitable habitat patches and the host plant preference of migrating butterflies. The evolutionary consequences of such biased migration and colonization with respect to butterfly phenotypes might differ depending on spatial configuration and plant species composition of the patches in heterogenous patch networks. Using a spatially realistic individual-based model we show that the model-predicted evolution of host plant preference due to biased migration explains a significant amount of the observed variation in host plant use among metapopulations living in dissimilar networks. This example illustrates how the ecological extinction-colonization dynamics may be linked with the evolutionary dynamics of life history traits in metapopulations

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Peer reviewe

On the quiescence of the Hubble flow in the vicinity of the Local Group

Cepheid distances of local galaxies (<7 Mpc) are used to study the very nearby velocity field, as pioneered by Sandage (Sandage 1986) who also pointed out its remarkable properties: linearity and quietness. The new data show that the velocity dispersion in the distance range as seen from the barycentre of the Local Group 1-8 Mpc is as low as 38 km/sec. The local rate of expansion coincides with the global Hubble constant. Down to 1.5 Mpc we cannot detect a deviation from the linear Hubble flow. This puts an upper limit for the mass of the Local Group, for a wide class of Friedman models, including those with the cosmological constant.Comment: 4 pages, 3 figures. Accepted to Astron. Astrophys. Letter