Stromlo-APM Redshift Survey Research Articles

Two-point Correlation Function and Power Spectrum at Very Large Scales

Subsamples of galaxies with different morphological types have been sorted out from Stromlo-APM redshift survey. Two-point correlation function for each subsample has been calculated. The two-point correlation functions for all subsamples show very large scale fluctuation. We show that the two-point correlation function with fluctuation could be fitted by a modified power spectrum with power excess at wave number comparable to the scale of the fluctuation.

Galaxy luminosity function: a new analytic expression

We propose a new analytic approximation for the luminosity function of galaxies. The suggested expression behaves like the Schechter function at the faint end (f ~ La) but departs considerably at the bright end (L >> L*). We argue here that such a behavior may provide a better fit for the current observational data than does the Schechter function. Its practical interest is stressed by considering roughly the data set provided by the Stromlo-APM redshift survey. Implications on the estimates of the matter density parameter from mass-to-light ratio are also briefly discussed.

UBR charge-coupled device photometry of Stromlo-APM galaxies

We present charge-coupled device (CCD) photometry in the Johnson-Kron-Cousins UBR bands for a sample of 320 galaxies selected from the Stromlo-APM Redshift Survey. We use these CCD data to estimate the galaxy luminosity function in the U, B, R and b J bands, finding consistent results with earlier work. Fainter galaxies serendipitously observed on our CCD frames allow a check of the photometric calibration of the APM Galaxy Survey. We find no evidence of any significant scale error in the APM magnitudes.

The K-band luminosity function of nearby field galaxies

We present a measurement of the K-band luminosity function (LF) of field galaxies obtained from near-infrared imaging of a sample of 345 galaxies selected from the Stromlo-APM Redshift Survey. The LF is reasonably well fitted over the 10-mag range −26⩽MK⩽−16 by a Schechter function with parameters α = −1.16±0.19, M* = −23.58±0.42 and φ* = 0.012±0.008 Mpc−3, assuming a Hubble constant of H0 = 100 km s−1 Mpc−1. We have also estimated the LF for two subsets of galaxies subdivided by the equivalent width of the Hα emission line at EW(Hα) = 10 Å. There is no significant difference in LF shape between the two samples, although there is a hint (∼1σ significance) that emission-line galaxies (ELGs) have M* roughly 1 mag fainter than non-ELGs. Contrary to the optical LF, there is no difference in faint-end slope α between the two samples.

Approaching a homogeneous galaxy distribution: results from the Stromlo-APM redshift survey

Recent results from a number of redshift surveys suggest that the Universe is well described by an inhomogeneous, fractal distribution on the largest scales probed. This distribution has been found to have fractal dimension, D, approximately equal to 2.1, in contrast to a homogeneous distribution in which the dimension should approach the value 3 as the scale is increased. In this paper we demonstrate that estimates of D, based on the conditional density of galaxies, are prone to bias from several sources. These biases generally result in a smaller measured fractal dimension than the true dimension of the sample. We illustrate this behaviour in application to the Stromlo-APM redshift survey, showing that this dataset in fact provides evidence for fractal dimension increasing with survey depth. On the largest scale probed, r approximately 60 h^{-1}Mpc, we find evidence for a distribution with dimension D = 2.76 +/- 0.10. A comparison between this sample and mock Stromlo-APM catalogues taken from Nbody simulations (which assume a CDM cosmology) reveals a striking similarity in the behaviour of the fractal dimension. Thus we find no evidence for inhomogeneity in excess of that expected from conventional cosmological theory. We consider biases affecting future large surveys and demonstrate, using mock SDSS catalogues, that this survey will be able to measure the fractal dimension on scales at which we expect to see full turn-over to homogeneity, in an accurate and unbiased way.

Optical and Near-IR Field Luminosity Functions

AbstractWe present preliminary measurements of the bJ and K-band luminosity functions (LFs) of field galaxies obtained from optical and K-band imaging of a sample of galaxies selected from the Stromlo-APM Redshift Survey. The bJ LF is consistent with that previously published from photographic data. The K-band LF has been estimated over a range of 12 magnitudes and is reasonably well fit by a Schechter function with faint-end slope α = −1.2.

The Local Space Density of Dwarf Galaxies

We estimate the luminosity function of field galaxies over a range of 10 mag (-22<MBJ<-12 for H0 = 100 km s-1 Mpc-1) by counting the number of faint APM galaxies around Stromlo-APM redshift survey galaxies at known distance. The faint end of the luminosity function rises steeply at MBJ ≈ -15, implying that the space density of dwarf galaxies is at least 2 times larger than predicted by a Schechter function with flat faint-end slope. Such a high abundance of dwarf galaxies at low redshift can help explain the observed number counts and redshift distributions of faint galaxies without invoking exotic models for galaxy evolution.

The Stromlo-APM Redshift Survey. IV. The Redshift Catalog

The Stromlo-APM Redshift Survey consists of 1797 galaxies with {ital b}{sub {ital J}}{le}17.15 selected randomly, at a rate of 1 in 20 from automated plate measurement (APM) scans. The survey covers a solid angle of 1.3 sr (4300 deg{sup 2}) in the south Galactic cap. Redshifts have been measured for 1790 (99.6{percent}) of the galaxies. The median galaxy recession velocity is 15,300 km s{sup {minus}1}, and so the volume probed is {ital V}{approx_equal}1.38{times}10{sup 6} h{sup {minus}3} Mpc{sup 3}. In this paper we describe the construction of the redshift catalog and present the survey data. {copyright} {ital 1996 The American Astronomical Society.}

Power spectrum analysis of the Stromlo—APM redshift survey

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 some evidence for a rise in the amplitude of $P(k)$. By comparing the redshift space power spectrum of the Stromlo-APM survey with the real space power spectrum determined from the parent APM Galaxy Survey, we attempt to measure the distortion in the shape of $P(k)$ caused by galaxy peculiar motions. We find some evidence for an effect, but the errors are large and do not exclude a value of $\beta = \Omega^{0.6}/b = 1$, where $\Omega$ is the cosmological density parameter and $b$ is the linear biasing parameter relating galaxy fluctuations to those in the mass, $\left(\delta \rho/\rho\right)_{gal} = b \left(\delta \rho/\rho\right)_{m}$. The shape of the Stromlo-APM power spectrum is consistent with that determined from the CfA-2 survey, but has a slightly higher amplitude by a factor of about 1.4 than the power spectrum of IRAS galaxies.

Is the Luminosity Distribution of Field Galaxies Really Flat?

Recent observations of the galaxy population within rich clusters have found a characteristic luminosity distribution described by a flat (α = - 1.0) Schechter function which exhibits an upturn at faint absolute magnitudes (M_B_ ~ -18). Here we discuss whether such a form for the field luminosity distribution is ruled out by local and/or faint magnitude-limited redshift surveys (MLRSs). Our conclusions are that existing redshift surveys provide few constraints on the volume-density distribution of field galaxies faintward of M_B_ = - 18. The local MLRSs suffer from poor statistics over inhomogeneous volumes, while the faint MLRSs are ambiguous because of the unknown nature of the "faint blue excess" and the "normalization" problem. Adopting a functional form similar to that seen in rich clusters we find that the maximum allowable faint end slope, based on the Mount Stromlo-APM redshift survey, is α ~ -1.8 faintward of M_B_ = - 18.0(H_0_ = 50 km s^-1^ Mpc^-3^).

The Stromlo-APM Redshift Survey. III. Redshift Space Distortions, Omega, and Bias

Galaxy redshift surveys provide a distorted picture of the universe due to the non-Hubble component of galaxy motions. By measuring such distortions in the linear regime one can constrain the quantity s = O0.6/b where O is the cosmological density parameter and b is the (linear) bias factor for optically selected galaxies. In this paper we apply two techniques for estimating s from the Stromlo-APM redshift survey: (1) measuring the anisotropy of the redshift space correlation function in spherical harmonics, and (2) comparing the amplitude of the direction-averaged redshift space correlation function to the real space correlation function. We test the validity of these techniques, particularly whether the assumption of linear theory is justified, using two sets of large N-body simulations. We find that the first technique is affected by nonlinearities on scales up to ~30 h-1 Mpc. The second technique is less sensitive to nonlinear effects and so is more useful for existing redshift surveys. The Stromlo-APM survey data favours a low value for s, with s ?, 0.6. A bias parameter b ? 2 is thus required if O = 1. However, higher-order correlations measured from the APM galaxy survey indicate a low value for the bias parameter b ? 1, requiring that O ?, 0.5. We also measure the relative bias for samples of galaxies of various luminosity and morphological type and find that low-luminosity galaxies are roughly three times less biased than L* galaxies. For the galaxy population as a whole, we measure a real space variance of galaxy counts in 8 h-1 Mpc spheres of (s82)g = 0.89 ± 0.05. © 1996. The American Astronomical Society. All rights reserved.

Counts-in-cells comparisons of redshift surveys

A statistical technique is presented for comparing galaxy counts in cells in redshift surveys sampling the same volume of space. The technique can be used to recover the variances and covariances in the cell counts. It can be used to derive the relative amplitude of the clustering pattern traced by galaxies of different types, for example optical and infrared-selected galaxies, early- and late-type galaxies, or luminous and faint galaxies. The statistics can also be used to test for systematic errors in galaxy catalogues. We illustrate the technique with two applications. We compare the cell count statistics of the 1.2-Jy and QDOT redshift surveys of IRAS galaxies, and show that, although there are large differences in the variances measured in cells of size ℓ = 30 and 40 h− 1 Mpc,1 the two surveys are compatible with the hypothesis that they sample the same underlying density field. We show that the variances measured from the QDOT survey are extremely sensitive to a small number of galaxies in the region of the Hercules supercluster. We also compare the clustering of optically luminous and faint galaxies in the Stromlo–APM redshift survey and show, within large errors, that there is no firm evidence for any differences in the clustering properties of galaxies with different luminosities on scales ℓ ≳ 10 h− 1 Mpc.

The Stromlo-APM redshift survey. 2: Variation of galaxy clustering with morphology and luminosity

We present clustering measurements for samples of galaxies selected by morphological type and luminosity from the recently completed Stromlo-APM Redshift Survey. Early type galaxies are clustered more strongly by a factor 3.5--5.5, than late type galaxies. Low-luminosity galaxies are clustered more weakly by a factor of $\sim 2$ than $L^*$ and brighter galaxies on scales $\simgt 1\hMpc$. Also the slope of the correlation function is steeper for low-luminosity galaxies, so that the amplitude is a factor 4 lower at $ 10 \hMpc$. No difference, however, is seen between the clustering of $L^*$ and more luminous galaxies, an observation which may be hard to reconcile with some theories of biased galaxy formation. Both redshift-space and real-space clustering estimates show a similar dependence on luminosity.

Large-scale structure in the universe - Results from the Stromlo-APM redshift survey

view Abstract Citations (133) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Large-Scale Structure in the Universe: Results from the Stromlo-APM Redshift Survey Loveday, J. ; Efstathiou, G. ; Peterson, B. A. ; Maddox, S. J. Abstract We present results on the clustering of galaxies in the Stromlo-APM redshift survey, which consists of 1787 galaxies sampled at a rate of 1 in 20 at random from the APM Galaxy Survey to a magnitude limit of b_J_ = 17.15. An analysis of counts in cells, and a direct estimate of the two-point correlation function, indicate more large-scale structure than expected in a biased, scale-invariant, {OMEGA} = 1, cold dark matter (CDM) model. Unbiased {OMEGA} = 1 CDM models (which are compatible with the COBE microwave background anisotropy measurements) are allowed by our observations because peculiar motions enhance the amplitude of the clustering pattern measured in redshift space on large scales. However, consistency between the redshift survey results and the angular two-point correlation function determined from the APM Galaxy Survey favors biased, or low-density, models with enhanced clustering in real space compared with standard CDM. Publication: The Astrophysical Journal Pub Date: December 1992 DOI: 10.1086/186645 Bibcode: 1992ApJ...400L..43L Keywords: Cosmology; Galaxies; Red Shift; Sky Surveys (Astronomy); Universe; Computational Astrophysics; Correlation; Dark Matter; Galactic Clusters; Relic Radiation; Spatial Distribution; Statistical Analysis; Astrophysics; COSMOLOGY: DISTANCE SCALE; COSMOLOGY: OBSERVATIONS; GALAXIES: CLUSTERING; SURVEYS full text sources ADS |