This paper investigates the statistical properties of the Tully-Fisher relations for a volume limited complete sample of spiral galaxies in the nearby Ursa Major cluster. The merits of B, R, I and K ′ surface photometry and the availability of detailed kinematic information from HI synthesis imaging have been exploited. In addition to the corrected HI global profile widths W i R,I , the available HI rotation curves allow direct measurements of the observed maximum rotational velocities V max and the amplitudes V flat of the outer flat parts. The dynamical state of the gas disks could also be determined in detail from the radio observations. The four luminosity and three kinematic measures allowed the construction of twelve correlations for various subsamples. For large galaxy samples, the M b,i R −Log(W i R,I ) correlation in conjunction with strict selection criteria is preferred for distance determinations with a 7% accuracy. Galaxies with rotation curves that are still rising at the last measured point, lie systematically on the low velocity side of the TF-relation. Galaxies with a partly declining rotation curve (V max > V flat ) tend to lie systematically on the high velocity side of the relation when using W i R,I or V max . However, systematic offsets are eliminated when V flat is used. Residuals of the M b,i B −Log(2V flat ) relation correlate consistently with global galaxy properties along the Hubble sequence like morphological type, color, surface brightness and gas mass fraction. These correlations are absent for the near-infrared M b,i K ′ −Log(2V flat ) residuals. The tightest correlation (χ 2 red =1.1) is found for the M b,i K ′ -Log(2V flat ) relation which has a slope of −11.3±0.5 and a total observed scatter of 0.26 magnitudes with a most likely intrinsic scatter of zero. The tightness of the near-infrared correlation is preserved when converting it into a baryonic TF-relation which has a slope of −10.0 in case (M gas /L K ′ )=1.6 while a zero intrinsic scatter remains most likely. Based on the tightness of the near-infrared and baryonic correlations, it is concluded that the Tully-Fisher relation reflects a fundamental correlation between the mass of the dark matter halo, measured through its induced maximum rotational velocity V flat , and the total baryonic mass M bar of a galaxy where M bar ∝V 4 flat . Although the actual distribution of the baryonic matter inside halos of similar mass can vary significantly, it does not affect this relation.

In this data paper we present the results of an extensive 21 cm-line synthesis imaging survey of 43 spiral galaxies in the nearby Ursa Major cluster using the Westerbork Synthesis Radio Telescope. Detailed kinematic information in the form of position-velocity diagrams and rotation curves is presented in an atlas together with HI channel maps, 21 cm continuum maps, global HI profiles, radial HI surface density profiles, integrated HI column density maps, and HI velocity fields. The relation between the corrected global HI linewidth and the rotational velocities Vmax and V flat as derived from the rotation curves is investigated. Inclination angles obtained from the optical axis ratios are compared to those derived from the inclined HI disks and the HI velocity fields. The galaxies were not selected on the basis of their HI content but solely on the basis of their cluster membership and inclination which should be suitable for a kinematic analysis. The observed galaxies provide a well-defined, volume limited and equidistant sample, useful to investigate in detail the statistical properties of the Tully-Fisher relation and the dark matter halos around them.

Magnitude-limited samples of spiral galaxies drawn from the Ursa Major and Pisces clusters are used to determine their extinction properties as a function of inclination. Imaging photometry is available for 87 spirals in B,R,I and K' bands. Extinction causes systematic scatter in color-magnitude plots. A strong luminosity dependence is found. Relative edge-on to face-on extinction of up to 1.7 mag is found at B for the most luminous galaxies but is unmeasurably small for faint galaxies. At R the differential absorption with inclination reaches 1.3 mag, at I it reaches 1.0 mag, and at K' the differential absorption can in the extreme be as great as 0.3 mag. The luminosity dependence of reddening can be translated into a dependence on rotation rate which is a distance-independent observable. Hence, corrections can be made that are useful for distance measurements. The strong dependence of the corrections on luminosity act to steepen luminosity-linewidth correlations. The effect is greatest toward the blue, with the consequence that luminosity-linewidth slope dependencies are now only weakly a function of color.Comment: 23 pages, 5 figure

A comprehensive analysis of 355 high‐quality Westerbork Synthesis Radio Telescope (WSRT) H i 21‐cm line maps of nearby galaxies shows that the properties and incident rate of damped Lyman α absorption systems (DLAs) observed in the spectra of high‐redshift QSOs are in good agreement with DLAs originating in gas discs of galaxies like those in the z≈ 0 population. Comparison of low‐z DLA statistics with the H i incidence rate and column density distribution f(NH i) for the local galaxy sample shows no evidence for evolution in the integral ‘cross‐section density’〈nσ〉=l−1 (l= mean free path between absorbers) below z≈ 1.5, implying that there is no need for a hidden population of galaxies or H i clouds to contribute significantly to the DLA cross‐section. Compared with z≈ 4, our data indicate evolution of a factor of 2 in the comoving density along a line of sight. We find that dN/dz(z= 0) = 0.045 ± 0.006. The idea that the local galaxy population can explain the DLAs is further strengthened by comparing the properties of DLAs and DLA galaxies with the expectations based on our analysis of local galaxies. The distribution of luminosities of DLA host galaxies, and of impact parameters between QSOs and the centres of DLA galaxies, is in good agreement with what is expected from local galaxies. Approximately 87 per cent of low‐z DLA galaxies are expected to be fainter than L*, and 37 per cent have impact parameters less than 1 arcsec at z= 0.5. The analysis shows that some host galaxies with very low impact parameters and low luminosities are expected to be missed in optical follow‐up surveys. The well‐known metallicity–luminosity relation in galaxies, in combination with metallicity gradients in galaxy discs, causes the expected median metallicity of low‐z DLAs to be low (∼1/7 solar), which is also in good agreement with observations of low‐z DLAs. We find that f(NH i) can be fitted satisfactorily with a gamma distribution, a single power law is not a good fit at the highest column densities NH i > 1021 cm−2. The vast majority (≈81 per cent) of the H i gas in the local Universe resides in column densities above the classical DLA limit (NH i > 2 × 1020 cm−2), with NH i∼ 1021 cm−2 dominating the cosmic H i mass density.

The Ursa Major Cluster has received remarkably little attention, although it is as near as the Virgo Cluster and contains a comparable number of HI-rich galaxies. In this paper, criteria for group membership are discussed and data are presented for 79 galaxies identified with the group. Of these, all 79 have been imaged at B, R, I bands with CCDs, 70 have been imaged at K ′ with a HgCdTe array detector, and 70 have been detected in the HI 21 cm line. A complete sample of 62 galaxies brighter than M B = −16.5 is identified. Images and gradients in surface brightness and color are presented at a common linear scale. As has been seen previously, the galaxies with the reddest global colors are reddest at the centers and get bluer at large radii. However, curiously, among the galaxies with the bluest global colors there are systems with very blue cores that get redder at large radii.

We investigate the effect of ram-pressure from the intracluster medium on the stripping of HI gas in galaxies in a massive, relaxed, X-ray bright, galaxy cluster at z = 0.2 from the Blind Ultra Deep HI Environmental Survey (BUDHIES). We use cosmological simulations, and velocity vs. position phase-space diagrams to infer the orbital histories of the cluster galaxies. In particular, we embed a simple analytical description of ram-pressure stripping in the simulations to identify the regions in phase-space where galaxies are more likely to have been sufficiently stripped of their HI gas to fall below the detection limit of our survey. We find a striking agreement between the model predictions and the observed location of HI-detected and non-detected blue (late-type) galaxies in phase-space, strongly implying that ram-pressure plays a key role in the gas removal from galaxies, and that this can happen during their first infall into the cluster. However, we also find a significant number of gas-poor, red (early-type) galaxies in the infall region of the cluster that cannot easily be explained with our model of ram-pressure stripping alone. We discuss different possible additional mechanisms that could be at play, including the pre-processing of galaxies in their previous environment. Our results are strengthened by the distribution of galaxy colours (optical and UV) in phase-space, that suggests that after a (gas-rich) field galaxy falls into the cluster, it will lose its gas via ram-pressure stripping, and as it settles into the cluster, its star formation will decay until it is completely quenched. Finally, this work demonstrates the utility of phase-space diagrams to analyze the physical processes driving the evolution of cluster galaxies, in particular HI gas stripping.

We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45 and 79.2 and with a redshift 0.005 < z < 0.03. The mother sample contains 939 objects, 600 of which will be observed in the course of the CALIFA survey. The selection of targets for observations is based solely on visibility and thus keeps the statistical properties of the mother sample. By comparison with a large set of SDSS galaxies, we find that the CALIFA sample is representative of galaxies over a luminosity range of −19 > M r > −23.1 and over a stellar mass range between 10 9.7 and 10 11.4 M . In particular, within these ranges, the diameter selection does not lead to any significant bias against -or in favour of -intrinsically large or small galaxies. Only below luminosities of M r = −19 (or stellar masses <10 9.7 M ) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form <10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies, finding that the sample covers environmental conditions from the field to genuine clusters. We finally consider the expected incidence of active galactic nuclei among CALIFA galaxies given the existing pre-CALIFA data, finding that the final observed CALIFA sample will contain approximately 30 Sey2 galaxies.

We present dynamically-determined rotation-curve mass decompositions of 30 spiral galaxies, which were carried out to test the maximum-disk hypothesis and to quantify properties of their dark-matter halos. We used measured vertical velocity dispersions of the disk stars to calculate dynamical mass surface densities (Σ dyn ). By subtracting our observed atomic and inferred molecular gas mass surface densities from Σ dyn , we derived the stellar mass surface densities (Σ * ), and thus have absolute measurements of all dominant baryonic components of the galaxies. Using K-band surface brightness profiles (I K ), we calculated the K-band mass-to-light ratio of the stellar disks (Υ * = Σ * /I K ) and adopted the radial mean (Υ * ) for each galaxy to extrapolate Σ * beyond the outermost kinematic measurement. The derived Υ * of individual galaxies are consistent with all galaxies in the sample having equal Υ * . We find a sample average and scatter of Υ * = 0.31 ± 0.07. Rotation curves of the baryonic components were calculated from their deprojected mass surface densities. These were used with circular-speed measurements to derive the structural parameters of the dark-matter halos, modeled as either a pseudo-isothermal sphere (pISO) or a Navarro-Frenk-White (NFW) halo. In addition to our dynamically determined mass decompositions, we also performed alternative rotation-curve decompositions by adopting the traditional maximumdisk hypothesis. However, the galaxies in our sample are submaximal, such that at 2.2 disk scale lengths (h R ) the ratios between the baryonic and total rotation curves (F 2.2h R b ) are less than 0.75. We find this ratio to be nearly constant between 1-6h R within individual galaxies. We find a sample average and scatter of F 2.2h R b = 0.57 ± 0.07, with trends of larger F 2.2h R b for more luminous and higher-surface-brightness galaxies. To enforce these being maximal, we need to scale Υ * by a factor 3.6 on average. In general, the dark-matter rotation curves are marginally better fit by a pISO than by an NFW halo. For the nominal-Υ * (submaximal) case, we find that the derived NFW-halo parameters have values consistent with ΛCDM N-body simulations, suggesting that the baryonic matter in our sample of galaxies has only had a minor effect on the dark-matter distribution. In contrast, maximum-Υ * decompositions yield halo-concentration parameters that are too low compared to the ΛCDM simulations.