Abstract. We present the final data release of observations of λ21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey (LDS: Hartmann & Burton 1997, Atlas of Galactic Neutral Hydrogen) of the sky north of δ = −30• with the Instituto Argentino de Radioastronomía Survey (IAR: Arnal et al. 2000, A&AS, 142, 35; and Bajaja et al. 2005, A&A, 440, 767) of the sky south of δ = −25• . The angular resolution of the combined material is HPBW ∼ 0.• 6. The LSR velocity coverage spans the interval −450 km s −1 to +400 km s −1 , at a resolution of 1.3 km s −1 . The data were corrected for stray radiation at the Institute for Radioastronomy of the University of Bonn, refining the original correction applied to the LDS. The rms brightness-temperature noise of the merged database is 0.07−0.09 K. Residual errors in the profile wings due to defects in the correction for stray radiation are for most of the data below a level of 20−40 mK. It would be necessary to construct a telescope with a main beam efficiency of η MB > ∼ 99% to achieve the same accuracy. The merged and refined material entering the LAB Survey of Galactic H  is intended to be a general resource useful to a wide range of studies of the physical and structural characteristices of the Galactic interstellar environment. The LAB Survey is the most sensitive Milky Way H  survey to date, with the most extensive coverage both spatially and kinematically.

We present the HI data for 5 spiral galaxies that, along with their Halpha rotation curves, are used to derive the distribution of dark matter within these objects. A new method for extracting rotation curves from HI data cubes is presented; this takes into account the existence of a warp and minimises projection effects. The rotation curves obtained are tested by taking them as input to construct model data cubes that are compared to the observed ones: the agreement is excellent. On the contrary, the model data cubes built using rotation curves obtained with standard methods, such as the first-moment analysis, fail the test. The HI rotation curves agree well with the Halpha data, where they coexist. Moreover, the combined Halpha + HI rotation curves are smooth, symmetric and extended to large radii. The rotation curves are decomposed into stellar, gaseous and dark matter contributions and the inferred density distribution is compared to various mass distributions: dark haloes with a central density core, $\Lambda$ Cold Dark Matter ($\Lambda$CDM) haloes (NFW, Moore profiles), HI scaling and MOND. The observations point to haloes with constant density cores of size $r_{core} \sim r_{opt}$ and central densities scaling approximately as $\rho_0 \propto r_{core}^{-2/3}$. $\Lambda$CDM models (which predict a central cusp in the density profile) are in clear conflict with the data. HI scaling and MOND cannot account for the observed kinematics: we find some counter-examples.Comment: 23 pages, 15 figures, MNRAS accepted. Comments welcome. Version with Figs. 1 and 3 at full resolution available at http://www.astro.uni-bonn.de/~ggentile/paper_highres.ps.g

Abstract. We present the first fully and uniformly sampled, spatially complete H  survey of the entire Magellanic System with high velocity resolution (∆v = 1.0 km s −1 ), performed with the Parkes Telescope . Approximately 24 percent of the southern sky was covered by this survey on a ≈5 grid with an angular resolution of HPBW = 14. 1. A fully automated data-reduction scheme was developed for this survey to handle the large number of H  spectra (1.5 × 10 6 ). The individual Hanning smoothed and polarization averaged spectra have an rms brightness temperature noise of σ = 0.12 K. The final data-cubes have an rms noise of σ rms ≈ 0.05 K and an effective angular resolution of ≈16 . In this paper we describe the survey parameters, the datareduction and the general distribution of the H  gas. , if all H  gas is at the same distance of 55 kpc. Approximately two thirds of this H  gas is located close to the Magellanic Clouds (Magellanic Bridge and Interface Region), and 25% of the H  gas is associated with the Magellanic Stream. The Leading Arm has a four times lower H  mass than the Magellanic Stream, corresponding to 6% of the total H  mass of the gaseous features.We have analyzed the velocity field of the Magellanic Clouds and their neighborhood introducing a LMC-standard-of-rest frame. The H  in the Magellanic Bridge shows low velocities relative to the Magellanic Clouds suggesting an almost parallel motion, while the gas in the Interface Region has significantly higher relative velocities indicating that this gas is leaving the Magellanic Bridge building up a new section of the Magellanic Stream. The Leading Arm is connected to the Magellanic Bridge close to an extended arm of the LMC. The clouds in the Magellanic Stream and the Leading Arm show significant differences, both in the column density distribution and in the shapes of the line profiles. The H  gas in the Magellanic Stream is more smoothly distributed than the gas in the Leading Arm. These morphological differences can be explained if the Leading Arm is at considerably lower z-heights and embedded in a higher pressure ambient medium.

Neutral atomic hydrogen (Hi) traces the interstellar medium (ISM) over a broad range of physical conditions. Its 21-cm emission line is a key probe of the structure and dynamics of the Milky Way Galaxy. About 50 years after the first detection of the 21-cm line the exploration of the Hi distribution of the Milky Way has undergone a true renaissance. This was triggered by several large-scale 21-cm surveys that became available within the past decade. New all-sky surveys unravel the shape and volume density distribution of the gaseous disk up to its borders. High-resolution Galactic plane surveys disclose a wealth of shells, filaments, and spurs that bear witness to the recycling of matter between stars and the ISM. All these observational results indicate that the Hi gas traces a dynamical Galactic ISM with structures on all scales, from tens of astronomical units to kiloparsecs. The Galaxy can be considered to be a violent, breathing disk surrounded by highly turbulent extra-planar gas.

The European Space Agency's Planck satellite, dedicated to studying the early Universe and its subsequent evolution, was launched 14 May 2009 and has been scanning the microwave and submillimetre sky continuously since 12 August 2009. In March 2013, ESA and the Planck Collaboration released the initial cosmology products based on the first 15.5 months of Planck data, along with a set of scientific and technical papers and a web-based explanatory supplement. This paper gives an overview of the mission and its performance, the processing, analysis, and characteristics of the data, the scientific results, and the science data products and papers in the release. The science products include maps of the cosmic microwave background (CMB) and diffuse extragalactic foregrounds, a catalogue of compact Galactic and extragalactic sources, and a list of sources detected through the Sunyaev-Zeldovich effect. The likelihood code used to assess cosmological models against the Planck data and a lensing likelihood are described. Scientific results include robust support for the standard six-parameter ΛCDM model of cosmology and improved measurements of its parameters, including a highly significant deviation from scale invariance of the primordial power spectrum. The Planck values for these parameters and others derived from them are significantly different from those previously determined. Several large-scale anomalies in the temperature distribution of the CMB, first detected by WMAP, are confirmed with higher confidence. Planck sets new limits on the number and mass of neutrinos, and has measured gravitational lensing of CMB anisotropies at greater than 25σ. Planck finds no evidence for non-Gaussianity in the CMB. Planck's results agree well with results from the measurements of baryon acoustic oscillations. Planck finds a lower Hubble constant than found in some more local measures. Some tension is also present between the amplitude of matter fluctuations (σ 8 ) derived from CMB data and that derived from Sunyaev-Zeldovich data. The Planck and WMAP power spectra are offset from each other by an average level of about 2% around the first acoustic peak. Analysis of Planck polarization data is not yet mature, therefore polarization results are not released, although the robust detection of E-mode polarization around CMB hot and cold spots is shown graphically.

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Models of the chemical evolution of the Milky Way suggest that the observed abundances of elements heavier than helium ('metals') require a continuous infall of gas with metallicity (metal abundance) about 0.1 times the solar value. An infall rate integrated over the entire disk of the Milky Way of approximately 1 solar mass per year can solve the 'G-dwarf problem'--the observational fact that the metallicities of most long-lived stars near the Sun lie in a relatively narrow range. This infall dilutes the enrichment arising from the production of heavy elements in stars, and thereby prevents the metallicity of the interstellar medium from increasing steadily with time. However, in other spiral galaxies, the low-metallicity gas needed to provide this infall has been observed only in associated dwarf galaxies and in the extreme outer disk of the Milky Way. In the distant Universe, low-metallicity hydrogen clouds (known as 'damped Ly alpha absorbers') are sometimes seen near galaxies. Here we report a metallicity of 0.09 times solar for a massive cloud that is falling into the disk of the Milky Way. The mass flow associated with this cloud represents an infall per unit area of about the theoretically expected rate, and approximately 0.1-0.2 times the amount required for the whole Galaxy.

Context. The determination of the global structure of the planar and extra-planar Milky Way H i disk depends critically on a reliable database but also on reasonable assumptions about the shape of the Milky Way rotation curve.Aims. We derive the 3D H i volume density distribution for the Galactic disk out to R ∼ 60 kpc.Methods. Our analysis is based on parameters for the warp and rotation curve derived previously. The data are taken from the Leiden/Argentine/Bonn all sky 21 cm line survey.Results. The Milky Way H i disk is significantly warped but shows a coherent structure out to R ∼ 35 kpc. The radial surface density distribution, the densities in the middle of the warped plane, and the H i scale heights all follow exponential relations. The radial scale length for the surface density distribution of the H i disk is 3.75 kpc. Gas at the outskirts for 40 < ∼ R < ∼ 60 kpc is described best by a distribution with an exponential radial scale length of 7.5 kpc and a velocity dispersion of 74 km s −1 . Such a highly turbulent medium fits also well with the average shape of the high velocity profile wings observed at high latitudes. The turbulent pressure gradient of such extra-planar gas is on average in balance with the gravitational forces. About 10% of the Milky Way H i gas is in this state. The large scale H i distribution is lopsided; for R > ∼ 15 kpc there is more gas in the south. The H i flaring indicates that this asymmetry is caused by a dark matter wake, located at R ∼ 25 kpc in direction of the Magellanic System. Conclusions.The H i disk is made up of two major components. Most prominent is the normal H i disk which can be traced to R ∼ 35 kpc. This is surrounded by a patchy distribution of highly turbulent gas reaching large scale heights but also large radial distances. At the position of the Sun the exponential scale height in the z direction is 3.9 kpc. This component resembles the anomalous gas discovered previously in some galaxies.