37
37
Sep 20, 2013
09/13
by
H. Tadros; G. Efstathiou
texts
eye 37
favorite 0
comment 0
We test estimators of the galaxy power spectrum $P(k)$ against simulated galaxy catalogues constructed from N-body simulations and we derive formulae to correct for biases. These estimators are then applied to compute the power spectrum of galaxies in the Stromlo-APM redshift survey. We test whether the amplitude of $P(k)$ depends on galaxy luminosity, but find no significant luminosity dependence except at absolute magnitudes brighter than $M_{\bj} = -20.3$, ($H_{0} = 100 \kms$) where there is...
Source: http://arxiv.org/abs/astro-ph/9603016v1
56
56
Sep 22, 2013
09/13
by
H Tadros; S J Warren; P C Hewett
texts
eye 56
favorite 0
comment 0
We report preliminary results from a first season of photometric monitoring of 600 quasars behind the Virgo galaxy cluster with the aim of detecting microlensing by the cluster dark matter. Our project is sensitive to dark objects of surface mass densities down to ~20 g/cm^2. We are thus capable of detecting diffuse objects, such as cold molecular clouds, unlike all Galactic microlensing surveys whose surface mass density limits are > 10^4 g/cm^2. The average optical depth to microlensing of...
Source: http://arxiv.org/abs/astro-ph/0003422v1
43
43
Sep 18, 2013
09/13
by
W. E. Ballinger; A. N. Taylor; A. F. Heavens; H. Tadros
texts
eye 43
favorite 0
comment 0
We have constrained the redshift-distortion parameter $\beta \equiv \Omega^{0.6}/b$ and the real-space power spectrum of the IRAS PSCz survey using a spherical-harmonic redshift-distortion analysis combined with a data compression method which is designed to deal with correlated parameters. Our latest result, $\beta=0.4 \pm 0.1$, strongly rules out $\beta=1$.
Source: http://arxiv.org/abs/astro-ph/0005094v1
62
62
Sep 17, 2013
09/13
by
A. N. Taylor; W. E. Ballinger; A. F. Heavens; H. Tadros
texts
eye 62
favorite 0
comment 0
We apply a spherical harmonic analysis to the Point Source Redshift Survey (PSCz), to compute the real-space galaxy power spectrum and the degree of redshift distortion caused by peculiar velocities. We employ new parameter eigenvector and hierarchical data compression techniques, allowing a much larger number of harmonic modes to be included, and correspondingly smaller error bars. Using 4644 harmonic modes, compressed to 2278, we find that the IRAS redshift-space distortion parameter is...
Source: http://arxiv.org/abs/astro-ph/0007048v1
44
44
Sep 18, 2013
09/13
by
W. Sutherland; H. Tadros; G. Efstathiou; C. S. Frenk; O. Keeble; S. Maddox; R. G. McMahon; S. Oliver; M. Rowan-Robinson; W. Saunders; S. D. M. White
texts
eye 44
favorite 0
comment 0
We measure the redshift-space power spectrum P(k) for the recently completed IRAS Point Source Catalogue (PSC) redshift survey, which contains 14500 galaxies over 84% of the sky with 60 micron flux >= 0.6 Jansky. Comparison with simulations shows that our estimated errors on P(k) are realistic, and that systematic errors due to the finite survey volume are small for wavenumbers k >~ 0.03 h Mpc^-1. At large scales our power spectrum is intermediate between those of the earlier QDOT and 1.2...
Source: http://arxiv.org/abs/astro-ph/9901189v1
44
44
Sep 18, 2013
09/13
by
I. Schmoldt; E. Branchini; L. Teodoro; G. Efstathiou; C. Frenk; O. Keeble; S. Maddox; S. Oliver; M. Rowan-Robinson; W. Saunders; W. Sutherland; H. Tadros; S. D. M. White
texts
eye 44
favorite 0
comment 0
We compute the acceleration on the Local Group using 11206 IRAS galaxies from the recently completed all-sky PSCz redshift survey. Measuring the acceleration vector in redshift space generates systematic uncertainties due to the redshift space distortions in the density field. We therefore assign galaxies to their real space positions by adopting a non-parametric model for the velocity field that solely relies on the linear gravitational instability and linear biasing hypotheses. Remaining...
Source: http://arxiv.org/abs/astro-ph/9901087v2
52
52
Sep 18, 2013
09/13
by
E. Branchini; L. Teodoro; C. S. Frenk; I. Schmoldt; G. Efstathiou; S. D. M. White; W. Saunders; M. Rowan-Robinson; O. Keeble; H. Tadros; S. Maddox; S. Oliver; W. Sutherland
texts
eye 52
favorite 0
comment 0
We present a self consistent nonparametric model of the local cosmic velocity field based on the density distribution in the PSCz redshift survey of IRAS galaxies. The error analysis, carried out on mock PSCz catalogues constructed from N-body simulations, reveals uncertainties of ~70 km/sec. The denser sampling provided by the PSCz survey compared to previous IRAS galaxy surveys allows us to reconstruct the velocity field out to larger distances. The most striking feature of the model velocity...
Source: http://arxiv.org/abs/astro-ph/9901366v2
71
71
Sep 20, 2013
09/13
by
E. Branchini; C. S. Frenk L. Teodoro; I. Schmoldt; G. Efstathiou; W. Saunders; S. D. M. White; M. Rowan-Robinson; W. Sutherland; H. Tadros; S. Maddox; S. Oliver; O. Keeble
texts
eye 71
favorite 0
comment 0
We present a self-consistent nonparametric model of the cosmic velocity field based on the spatial distribution of IRAS galaxies in the recently completed all-sky PSC$z$ redshift survey. The most streaking feature of the PSCz model velocity field is a coherent large-scale streaming motion along the Perseus Pisces, Local Supercluster, Great Attractor and Shapley Concentration baseline, with no evidence for a backinfall into the Great Attractor region. A likelihood analysis has been performed to...
Source: http://arxiv.org/abs/astro-ph/9810106v1
41
41
Sep 21, 2013
09/13
by
M. D. Seaborne; W. Sutherland; H. Tadros; G. Efstathiou; C. S. Frenk; O. Keeble; S. Maddox; R. G. McMahon; S. Oliver; M. Rowan-Robinson; W. Saunders; S. D. M. White
texts
eye 41
favorite 0
comment 0
We present a direct comparison of the clustering properties of two redshift surveys covering a common volume of space: the recently completed IRAS Point Source Catalogue redshift survey (PSCz) containing 14500 galaxies with a limiting flux of 0.6 Jy at 60 microns, and the optical Stromlo-APM survey containing 1787 galaxies in a region of 4300 deg^2 in the southern Galactic cap. We use three methods to compare the clustering properties: the counts-in-cells comparison of Efstathiou (1995), the...
Source: http://arxiv.org/abs/astro-ph/9905182v1
96
96
Jul 20, 2013
07/13
by
A. Canavezes; V. Springel; S. J. Oliver; M. Rowan-Robinson; O. Keeble; S. D. M. White; W. Saunders; G. Efstathiou; C. Frenk; R. G. McMahon; S. Maddox; W. Sutherland; H. Tadros
texts
eye 96
favorite 0
comment 0
We investigate the topology of the new Point Source Catalogue Redshift Survey (PSCz) of IRAS galaxies by means of the genus statistic. The survey maps the local Universe with approximately 15000 galaxies over 84.1 per cent of the sky and provides an unprecedented number of resolution elements for the topological analysis. For comparison with the PSCz data we also examine the genus of large N-body simulations of four variants of the cold dark matter cosmogony. The simulations are part of the...
Source: http://arxiv.org/abs/astro-ph/9712228v2
56
56
Sep 18, 2013
09/13
by
J. Sharpe; M. Rowan-Robinson; A. Canavezes; W. Saunders; E. Branchini; G. Efstathiou; C. Frenk; O. Keeble; R. G. McMahon; S. Maddox; S. J. Oliver; W. Sutherland; H. Tadros; S. D. M. White; .
texts
eye 56
favorite 0
comment 0
We use the Least Action Principle to predict the peculiar velocities of PSC-z galaxies inside $cz=2000$\km. Linear theory is used to account for tidal effects to $cz=15000$\km, and we iterate galaxy positions to account for redshift distortions. As the Least Action Principle is valid beyond Linear theory, we can predict reliable peculiar velocities even for very nearby galaxies (ie $cz \leq 500$\km). These predicted peculiar velocities are then compared with the observed velocities of 12...
Source: http://arxiv.org/abs/astro-ph/0012027v2
47
47
Sep 18, 2013
09/13
by
P. Monaco; G. Efstathiou; S. J. Maddox; E. Branchini; C. S. Frenk; R. G. McMahon; S. J. Oliver; M. Rowan-Robinson; W. Saunders; W. J. Sutherland; H. Tadros; S. D. M. White
texts
eye 47
favorite 0
comment 0
The algorithm ZTRACE of Monaco & Efstathiou (1999) is applied to the IRAS PSCz catalogue to reconstruct the initial conditions of our local Universe with a resolution down to ~5 Mpc/h. The 1-point PDF of the reconstructed initial conditions is consistent with the assumptions that (i) IRAS galaxies trace mass on scales of ~5 Mpc/h, and (ii) the statistics of primordial density fluctuations is Gaussian. We use simulated PSCz catalogues, constructed from N-body simulations with Gaussian...
Source: http://arxiv.org/abs/astro-ph/0006066v1
53
53
Sep 22, 2013
09/13
by
W. Saunders; W. J. Sutherland; S. J. Maddox; O. Keeble; S. J. Oliver; M. Rowan-Robinson; R. G. McMahon; G. P. Efstathiou; H. Tadros; S. D. M. White; C. S. Frenk; A. Carraminana; M. R. S. Hawkins
texts
eye 53
favorite 0
comment 0
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...
Source: http://arxiv.org/abs/astro-ph/0001117v2
46
46
Jul 20, 2013
07/13
by
Inga M. Schmoldt; Veikko Saar; Prasenjit Saha; E. Branchini; G. P. Efstathiou; C. S. Frenk; O. Keeble; S. Maddox; R. McMahon; S. Oliver; M. Rowan-Robinson; W. Saunders; W. J. Sutherland; H. Tadros; S. D. M. White
texts
eye 46
favorite 0
comment 0
We present a version of the Fourier Bessel method first introduced by Fisher et al (1994) and Zaroubi et al (1994) with two extensions: (a) we amend the formalism to allow a generic galaxy weight which can be constant rather than the more conventional overweighting of galaxies at high distances, and (b) we correct for the masked zones by extrapolation of Fourier Bessel modes rather than by cloning from the galaxy distribution in neighbouring regions. We test the procedure extensively on N-body...
Source: http://arxiv.org/abs/astro-ph/9906035v1
62
62
Sep 18, 2013
09/13
by
H. Tadros; W. E. Ballinger; A. N. Taylor; A. F. Heavens; G. Efstathiou; W. Saunders; C. S. Frenk; O. Keeble; R. McMahon; S. J. Maddox; S. Oliver; M. Rowan-Robinson; W. J. Sutherland S. D. M. White
texts
eye 62
favorite 0
comment 0
We apply the formalism of spherical harmonic decomposition to the galaxy density field of the IRAS PSCz redshift survey. The PSCz redshift survey has almost all-sky coverage and includes IRAS galaxies to a flux limit of 0.6 Jy. Using maximum likelihood methods to examine (to first order) the distortion of the galaxy pattern due to redshift coordinates, we have measured the parameter \beta= \Omega^{0.6}/b. We also simultaneously measure (a) the undistorted amplitude of perturbations in the...
Source: http://arxiv.org/abs/astro-ph/9901351v1
73
73
Sep 19, 2013
09/13
by
M. Rowan-Robinson; J. Sharpe; S. J. Oliver; O. Keeble; A. Canavezes; W. Saunders; A. N. Taylor; H. Valentine; C. S. Frenk; G. P. Efstathiou; R. G. McMahon; S. D. M. White; W. Sutherland; H. Tadros; S. Maddox
texts
eye 73
favorite 0
comment 0
We use the PSCz IRAS galaxy redshift survey to analyze the cosmological galaxy dipole out to a distance 300 h$^{-1}$ Mpc. The masked area is filled in three different ways, firstly by sampling the whole sky at random, secondly by using neighbouring areas to fill a masked region, and thirdly using a spherical harmonic analysis. The method of treatment of the mask is found to have a significant effect on the final calculated dipole. The conversion from redshift space to real space is accomplished...
Source: http://arxiv.org/abs/astro-ph/9912223v1
