A survey of galaxy redshifts. III - The density field and the induced gravity field

Davis, Marc; Huchra, J.

doi:10.1086/159751

Cited by 235 publications

(211 citation statements)

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“…The error due to large-scale structure fluctuations is (Davis & Huchra 1982), where J 3 is the second moment of the two-point spatial correlation function (Peebles 1980) and V is the appropriate volume. We use J 3 ≈ 10, 000 (h −1 Mpc) 3 (Tucker et al 1997) and record the error from density fluctuations alongside the uncertainty in φ * due to M * and α.…”

Section: Methodsmentioning

confidence: 99%

The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster

Small

Sargent

et al. 1998

ApJ

106

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We measure the field galaxy luminosity function (LF) as a function of color and redshift from z = 0 to z = 0.5 using galaxies from the Norris Survey of the Corona Borealis Supercluster. The data set consists of 603 field galaxies with 0 < z ≤ 0.5 and spans a wide range in apparent magnitude (14.0 m ∼ < r ∼ < 21.5 m ), although our field galaxy LF analysis is limited to 493 galaxies with r ≤ 20.0 m . We use the observed g − r colors of the galaxies to compute accurate corrections to the rest B AB and r bands. We find that our local r-band LF, when normalized to counts in high galactic latitude fields, agrees well with the local LF measured in the Las Campanas Redshift Survey. Our B AB -band local LF, however, does not match the b j -band LF from the Stromlo/APM survey, having a normalization 1.6 times higher. We see compelling evidence that the B AB -band field galaxy LF evolves with redshift. The evolution is strongest for the population of star-forming galaxies with [O II] λ3727 rest-frame equivalent widths greater than 10Å. The population of red, quiescent galaxies shows no sign of evolution to z = 0.5. The evolution of the LF which we observe is consistent with the findings of other faint galaxy redshift surveys. The fraction of galaxies with [O II] emission increases rapidly with redshift, but the fraction of galaxies with strong Hδ absorption, a signature of a burst of star-formation, does not. We thus conclude that the star formation in distant galaxies is primarily long-lived.We also compute the LFs of the Corona Borealis supercluster (z ≈ 0.07, 419 galaxies with 14.1 m ≤ r ≤ 20.0 m ) and the Abell 2069 supercluster (z ≈ 0.11, 1 present address: Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK -2 -318 galaxies with 15.1 m ≤ r ≤ 20.0 m ). The shapes of the two supercluster luminosity functions are broadly similar to the shape of the local luminosity function. However, there are important differences. Both supercluster LFs have an excess of very bright galaxies. In addition, the characteristic magnitude of the Corona Borealis supercluster LF is roughly half a magnitude brighter than that of the local field galaxy LF, and there is a suggestion of an upturn in the LF for galaxies fainter than M(B AB ) ∼ −17 m .

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Section: Methodsmentioning

confidence: 99%

The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster

Small

Sargent

et al. 1998

ApJ

106

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“…Groth & Peebles 1977;Davis & Huchra 1982). The spatial twopoint correlation function is defined as the excess probability, compared with that expected for a random distribution, of finding a pair of galaxies at a separation r 1,2 .…”

Section: Two-point Correlation Functionmentioning

confidence: 99%

The simulated H I sky at low redshift

Popping

Davé

Braun

et al. 2009

A&A

107

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Context. Observations of intergalactic neutral hydrogen can provide a wealth of information about structure and galaxy formation, potentially tracing accretion and feedback processes on Mpc scales. Below a column density of N HI ∼ 10 19 cm −2 , the "edge" or typical observational limit for H i emission from galaxies, simulations predict a cosmic web of extended emission and filamentary structures.Current observations of this regime are limited by telescope sensitivity, which will soon advance substantially. Aims. We study the distribution of neutral hydrogen and its 21-cm emission properties in a cosmological hydrodynamic simulation, to gain more insight into the distribution of H i below N HI ∼ 10 19 cm −2 . Such Lyman limit systems are expected to trace out the cosmic web and are relatively unexplored. Methods. Beginning with a 32 h −1 Mpc simulation, we extract the neutral hydrogen component by determining the neutral fraction, including a post-processed correction for self-shielding based on the thermal pressure. We take molecular hydrogen into account, assuming an average density ratio Ω H 2 /Ω HI = 0.3 at z = 0. The statistical properties of the H i emission are compared with observations, to assess the reliability of the simulation. We then make predictions for upcoming surveys. Results.The simulated H i distribution robustly describes the full column density range between N HI ∼ 10 14 and N HI ∼ 10 21 cm −2 and agrees very well with available measurements from observations. Furthermore there is good correspondence in the statistics when looking at the two-point correlation function and the H i mass function. The reconstructed maps are used to simulate observations of existing and future telescopes by adding noise and accounting for the sensitivity of the telescopes.Conclusions. The general agreement in statistical properties of H i suggests that neutral hydrogen, as modelled in this hydrodynamic simulation, is a fair representation of neutral hydrogen in the Universe. Our method can be applied to other simulations, to compare different models of accretion and feedback. Future H i observations will be able to probe the regions where galaxies connect to the cosmic web.

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“…An additional, much stronger, assumption often adopted is that the space density is a constant, i.e., n(r) = const. This assumption is for instance at the basis of the so-called standard minimum variance estimator (Davis & Huchra 1982;Blanton et al 2003;Loveday 2004). It is clear that we want to avoid making this further assumption because we want to test whether the space density is (or can be approximated by) a simple constant.…”

Section: Appendix C: the Luminosity Functionmentioning

confidence: 99%

Breaking the self-averaging properties of spatial galaxy fluctuations in the Sloan Digital Sky Survey – Data release six

Labini

Vasilyev

Baryshev

2009

A&A

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Statistical analyses of finite sample distributions usually assume that fluctuations are self-averaging, i.e. statistically similar in different regions of the given sample volume. By using the scale-length method, we test whether this assumption is satisfied in several samples of the Sloan Digital Sky Survey Data Release Six. We find that the probability density function (PDF) of conditional fluctuations, if filtered on large enough spatial scales (i.e., r > 30 Mpc/h), shows relevant systematic variations in different subvolumes of the survey. Instead for scales of r < 30 Mpc/h, the PDF is statistically stable, and its first moment presents scaling behavior with a negative exponent around one. Thus while up to 30 Mpc/h galaxy structures have well-defined power-law correlations, on larger scales it is not possible to consider whole sample average quantities as meaningful and useful statistical descriptors. This situation stems from galaxy structures corresponding to density fluctuations that are too large in amplitude and too extended in space to be self-averaging on such large scales inside the sample volumes: galaxy distribution is inhomogeneous up to the largest scales, i.e. r ≈ 100 Mpc/h probed by the SDSS samples. We show that cosmological corrections, such as K-corrections and standard evolutionary corrections, do not qualitatively change the relevant behaviors. We consider in detail the relation between several statistical measurements generally used to quantify galaxy fluctuations and the scale-length analysis by discussing how the breaking of self-averaging properties makes it impossible to have a reliable estimation of average fluctuations amplitude, variance, and correlations for r > 30 Mpc/h. Finally we show that the large-amplitude galaxy fluctuations observed in the SDSS samples are at odds with the predictions of the standard ΛCDM model of structure formation.

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A survey of galaxy redshifts. III - The density field and the induced gravity field

Cited by 235 publications

References 0 publications

The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster

The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster

The simulated H I sky at low redshift

Breaking the self-averaging properties of spatial galaxy fluctuations in the Sloan Digital Sky Survey – Data release six

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