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تسجيل مستخدم جديدThe PSCz Catalogue
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We present the catalogue, mask, redshift data and selection function for the PSCz survey of 15411 IRAS galaxies across 84% of the sky. Most of the IRAS data is taken from the Point Source Catalog, but this has been supplemented and corrected in various ways to improve the completeness and uniformity. We quantify the known imperfections in the catalogue, and we assess the overall uniformity, completeness and data quality. We find that overall the catalogue is complete and uniform to within a few percent at high latitudes and 10% at low latitudes. Ancillary information, access details, guidelines and caveats for using the catalogue are given.
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We compare the measured peculiar velocities of 98 local (<150/h Mpc) type Ia supernovae with predictions derived from the PSCz survey. There is excellent agreement between the two datasets with a best fit beta_I (=Omega_m^0.6/b_I) of 0.55+-0.06. Subs
ets of the supernovae dataset are further analysed and the above result is found to be robust with respect to culls by distance, host-galaxy extinction and to the choice of reference frame in which the analysis is carried out. Alternative methods of determining beta_I including density-density comparisons, dipole measurements and WMAP-based results are also discussed. We conclude that most recent determinations are consistent with a value of beta_I=0.5.
We apply the Delaunay Tessellation Field Estimator (DTFE) to reconstruct and analyze the matter distribution and cosmic velocity flows in the Local Universe on the basis of the PSCz galaxy survey. The prime objective of this study is the production o
f optimal resolution three-dimensional maps fully volume-covering of the volume-weighted velocity and density fields throughout the nearby Universe, out to a distance of 150 Mpc/h. Based on the Voronoi and Delaunay tessellation defined by the spatial galaxy sample, DTFE involves the estimate of density values on the basis of the volume of the related Delaunay tetrahedra and the subsequent use of theDelaunay tessellation as natural multidimensional (linear) interpolation grid for the corresponding density and velocity fields throughout the sample volume. The linearized model of the spatial galaxy distribution and the corresponding peculiar velocities of the PSCz galaxy sample, produced by Brachini et al. (1999), forms the input sample for the DTFE study. The DTFE maps reproduce the high-density supercluster regions in optimal detail, both their internal structure as well as their elongated or flattened shape. The corresponding velocity flows trace the bulk and shear flows marking the region extending from the Pisces-Perseus supercluster, via the Local superclusters, towards the Hydra-Centaurus and the Shapley concentration. The most outstanding and unique feature of the DTFE maps is the sharply defined radial outflow regions in and around underdense voids, marking the dynamical importance of voids in the Local Universe. The maximum expansion rate of voids defines a sharp cutoff in the DTFE velocity divergence pdf. We found that on the basis of this cutoff DTFE manages to consistently reproduce the value of O_m ~ 0.35 underlying the linearized velocity dataset.
The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows testing of the unified scheme for AGN. We present analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN supposedly detected by INTEGRAL
above 20 keV. The data analysed here allow a significant spectral extraction on 148 objects and an optical variability study of 57 AGN. The slopes of the hard X-ray spectra of Seyfert 1 and Seyfert~2 galaxies are found to be consistent within the uncertainties, whereas higher cut-off energies and lower luminosities are measured for the more absorbed / type 2 AGN. The intermediate Seyfert 1.5 objects exhibit hard X-ray spectra consistent with those of Seyfert 1. When applying a Compton reflection model, the underlying continua appear the same in Seyfert 1 and 2 with photon index 2, and the reflection strength is about R = 1, when assuming different inclination angles. A significant correlation is found between the hard X-ray and optical luminosity and the mass of the central black hole in the sense that the more luminous objects appear to be more massive. There is also a general trend toward the absorbed sources and type 2 AGN having lower Eddington ratios. The black holemass appears to form a fundamental plane together with the optical and X-ray luminosity of the form Lv being proportional to Lx^0.6 M^0.2, similar to that found between radio luminosity Lr, Lx, and M. The unified model for Seyfert galaxies seems to hold, showing in hard X-rays that the central engine is the same in Seyfert 1 and 2, but seen under different inclination angles and absorption. (Abridged)
Peculiar velocities arise from gravitational instability, and thus are linked to the surrounding distribution of matter. In order to understand the motion of the Local Group with respect to the Cosmic Microwave Background, a deep all-sky map of the g
alaxy distribution is required. Here we present a new redshift compilation of 69~160 galaxies, dubbed 2M++, to map large-scale structures of the Local Universe over nearly the whole sky, and reaching depths of K <= 12.5, or 200 Mpc/h. The target catalogue is based on the Two-Micron-All-Sky Extended Source Catalog (2MASS-XSC). The primary sources of redshifts are the 2MASS Redshift Survey, the 6dF galaxy redshift survey and the Sloan Digital Sky Survey (DR7). We assess redshift completeness in each region and compute the weights required to correct for redshift incompleteness and apparent magnitude limits, and discuss corrections for incompleteness in the Zone of Avoidance. We present the density field for this survey, and discuss the importance of large-scale structures such as the Shapley Concentration.
We demonstrate the use of the AKARI survey photometric data in the study of galactic star formation. Our aim was to select young stellar objects (YSOs) in the AKARI FIS catalogue. We used AKARI Far-Infrared Surveyor and Wide-field Infrared Survey Exp
lorer data to derive mid- and far-infrared colours of YSOs. Classification schemes based on Quadratic Discriminant Analysis have been given for YSOs. The training catalogue for QDA was the whole sky selection of previously known YSOs (i.e. listed in SIMBAD). A new catalogue of AKARI FIS YSO candidates including 44001 sources has been prepared. Reliability of the classification is over 90% as tested in comparison to known YSOs. As much as 76% of our YSO candidates are from previously uncatalogued type. The vast majority of these sources are Class I and II types according to the Lada classification. The distribution of AKARI FIS YSOs is well correlated with that of the galactic ISM. Local over densities were found on infrared loops and towards the cold clumps detected by Planck.
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