The APM cluster-galaxy cross-correlation function : Constraints on Omega and galaxy bias

(abridged) We estimate the cluster-galaxy cross-correlation function (Xi_cg), from the APM galaxy and galaxy cluster surveys, both in real space from the inversion of projected statistics and in redshift space using the galaxy and cluster redshift samples. The amplitude of Xi_cg is found to be almost independent of cluster richness. At large separations, r >~5 h^-1 Mpc, Xi_cg has a similar shape to the galaxy-galaxy and cluster-cluster autocorrelation functions. Xi_cg in redshift space can be related to the real space Xi_cg by convolution with an appropriate velocity field model. Here we apply a spherical collapse model, which we have tested against N-body simulations, finding that it provides a surprisingly accurate description of the averaged infall velocity of matter into galaxy clusters. We use this model to estimate beta (Omega^{0.6}/b) and find that it tends to overestimate the true result in simulations by only ~10-30%. Application to the APM results yields beta=0.43 with beta < 0.87 at 95% confidence. We also compare the APM Xi_cg and galaxy autocorrelations to results from popular cosmological models and derive two independent estimates of the galaxy biasing expected as a function of scale. Both low and critical density CDM models require anti-biasing by a factor ~2 on scales r <~ 2 h^-1Mpc and an MDM model is consistent with a constant biasing factor on all scales. We use the velocity fields predicted from the different models to distort the APM real space cross-correlation function. Comparison with the APM redshift space Xi_cg yields an estimate of the value of Omega^0.6 needed in each model. Only the low Omega model is fully consistent with observations, with MDM marginally excluded at the ~2 sigma level.Comment: Latex (mn.sty), 17 pages, 16 ps figs, submitted to MNRA

The Power Spectrum of Rich Clusters of Galaxies on Large Spatial Scales

We present an analysis of the redshift-space power spectrum, $P(k)$, of rich clusters of galaxies based on an automated cluster catalogue selected from the APM Galaxy Survey. We find that $P(k)$ can be approximated by a power law, P(k)\proptok^{n}, with $n\approx-1.6$ over the wavenumber range 0.04\hr. Over this range of wavenumbers, the APM cluster power spectrum has the same shape as the power spectra measured for optical and IRAS galaxies. This is consistent with a simple linear bias model in which different tracers have the same power spectrum as that of the mass distribution but shifted in amplitude by a constant biasing factor. On larger scales, the power spectrum of APM clusters flattens and appears to turn over on a scale k \sim 0.03\hmpcrev. We compare the power spectra estimated from simulated APM cluster catalogues to those estimated directly from cubical N-body simulation volumes and find that the APM cluster survey should give reliable estimates of the true power spectrum at wavenumbers k \simgt 0.02\hmpcrev. These results suggest that the observed turn-over in the power spectrum may be a real feature of the cluster distribution and that we have detected the transition to a near scale-invariant power spectrum implied by observations of anisotropies in the cosmic microwave background radiation. The scale of the turn-over in the cluster power spectrum is in good agreement with the scale of the turn-over observed in the power spectrum of APM galaxies.Comment: 9 pages, 7 ps figures, two style files, submitted to MNRAS. Un-xxx-ed version available at http://www-astro.physics.ox.ac.uk/research/preprints/aug97/cluspaper.ps.g

Higher Order Statistics from the Apm Galaxy Survey

We apply a new statistics, the factorial moment correlators, to density maps obtained from the APM survey. The resulting correlators are all proportional to the two point correlation function, substantially amplified, with an amplification nearly exponential with the total rank of the correlators. This confirms the validity of the hierarchical clustering assumption on the dynamic range examined, corresponding to 0.5 \hmpc - 50 \hmpc in three dimensional space. The Kirkwood superposition with loop terms is strongly rejected. The structure coefficients of the hierarchy are also fitted. The high quality of the APM catalog enabled us to disentangle the various contributions from the power spectrum, small scale nonlinear clustering, and combinatorial effects, all of which affect the amplification of the correlators. These effects should appear in correlations of clusters in a similar fashion.Comment: 30 pages text, 3 pages tables, 5 figures, uuencoded tarred postscrip

The APM Galaxy Survey:- V. Catalogues of Galaxy Clusters

We describe the construction of catalogues of galaxy clusters from the APM Galaxy survey using an automated algorithm based on Abell-like selection criteria. We investigate the effects of varying several parameters in our selection algorithm, including the magnitude range, and radius from the cluster centre used to estimate the cluster richnesses. We quantify the accuracy of the photometric distance estimates by comparing with measured redshifts, and we investigate the stability and completeness of the resulting catalogues. We find that the angular correlation functions for different cluster catalogues are in good agreement with one another, and are also consistent with the observed amplitude of the spatial correlation function of rich clusters.Comment: 14 pages, PostScript, including 15 figures, submitted to MNRAS. Also available from ftp://ftp-astro.physics.ox.ac.uk/pub/gbd/papers/apm5.ps.g

The Subaru FMOS galaxy redshift survey (FastSound). V. Intrinsic alignments of emission line galaxies at z∼1.4z\sim 1.4

Intrinsic alignments (IA), the coherent alignment of intrinsic galaxy orientations, can be a source of a systematic error of weak lensing surveys. The redshift evolution of IA also contains information about the physics of galaxy formation and evolution. This paper presents the first measurement of IA at high redshift, $z\sim 1.4$, using the spectroscopic catalog of blue star-forming galaxies of the FastSound redshift survey, with the galaxy shape information from the Canada-Hawaii-France telescope lensing survey. The IA signal is consistent with zero with power-law amplitudes fitted to the projected correlation functions for density-shape and shape-shape correlation components, $A_{\delta+}=-0.0071\pm 0.1340$ and $A_{++}=-0.0505\pm 0.0848$, respectively. These results are consistent with those obtained from blue galaxies at lower redshifts (e.g., $A_{\delta+}=0.0035_{-0.0389}^{+0.0387}$ and $A_{++}=0.0045_{-0.0168}^{+0.0166}$ at $z=0.51$ from the WiggleZ survey). The upper limit of the constrained IA amplitude corresponds to a few percent contamination to the weak-lensing shear power spectrum, resulting in systematic uncertainties on the cosmological parameter estimations by $-0.052<\Delta \sigma_8<0.039$ and $-0.039<\Delta \Omega_m<0.030$.Comment: 11pages, 7 figures, 1 table, accepted for publication in PAS

Constraint on the inflow/outflow rates in star-forming galaxies at z~1.4 from molecular gas observations

We constrain the rate of gas inflow into and outflow from a main-sequence star-forming galaxy at z~1.4 by fitting a simple analytic model for the chemical evolution in a galaxy to the observational data of the stellar mass, metallicity, and molecular gas mass fraction. The molecular gas mass is derived from CO observations with a metallicity-dependent CO-to-H2 conversion factor, and the gas metallicity is derived from the H{\alpha} and [NII]{\lambda} 6584 emission line ratio. Using a stacking analysis of CO integrated intensity maps and the emission lines of H{\alpha} and [NII], the relation between stellar mass, metallicity, and gas mass fraction is derived. We constrain the inflow and outflow rates with least-chi-square fitting of a simple analytic chemical evolution model to the observational data. The best-fit inflow and outflow rates are ~1.7 and ~0.4 in units of star-formation rate, respectively. The inflow rate is roughly comparable to the sum of the star-formation rate and outflow rate, which supports the equilibrium model for galaxy evolution; i.e., all inflow gas is consumed by star formation and outflow.Comment: 5 pages, 2 figures, Accepted for publication in the Ap