Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/230489

Title

The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity

Author(s)

Scrimgeour, Morag I.;  Davis, Tamara;  Blake, Chris;  James, J. Berian;  Poole, Gregory B.;  Staveley-Smith, Lister;  Brough, Sarah;  Colless, Matthew;  Contreras, Carlos;  Couch, Warrick;  Croom, Scott;  Croton, Darren;  Drinkwater, Michael J.;  Forster, Karl;  Gilbank, David;  Gladders, Mike;  Glazebrook, Karl;  Jelliffe, Ben;  Jurek, Russell J.;  Li, I-hui;  Madore, Barry;  Martin, D. Christopher;  Pimbblet, Kevin;  Pracy, Michael;  Sharp, Rob;  Wisnioski, Emily;  Woods, David;  Wyder, Ted K.;  Yee, H. K. C.

Abstract

We have made the largest volume measurement to date of the transition to large-scale homogeneity in the distribution of galaxies. We use the WiggleZ survey, a spectroscopic survey of over 200 000 blue galaxies in a cosmic volume of ∼1 h−3 Gpc3. A new method of defining the ‘homogeneity scale' is presented, which is more robust than methods previously used in the literature, and which can be easily compared between different surveys. Due to the large cosmic depth of WiggleZ (up to z = 1), we are able to make the first measurement of the transition to homogeneity over a range of cosmic epochs. The mean number of galaxies N(< r) in spheres of comoving radius r is proportional to r3 within 1 per cent, or equivalently the fractal dimension of the sample is within 1 per cent of D2 = 3, at radii larger than 71 ± 8 h& 8722;1Mpc at z ∼ 0.2, 70 ± 5 h−1 Mpc at z ∼ 0.4, 81 ± 5 h−1 Mpc at z ∼ 0.6 and 75 ± 4& 8201;h−1 Mpc at z ∼ 0.8. We demonstrate the robustness of our results against selection function effects, using a Λ cold dark matter (ΛCDM) N body simulation and a suite of inhomogeneous fractal distributions. The results are in excellent agreement with both the ΛCDM N-body simulation and an analytical & 0923;CDM prediction. We can exclude a fractal distribution with fractal dimension below D2 = 2.97 on scales from ∼80 h−1 Mpc up to the largest scales probed by our measurement, ∼300 h−1 Mpc, at 99.99 per cent confidence.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 425, no. 1 (Sep 2012), pp. 116-134

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Cosmological observations;  Galaxies;  Large-scale structure of Universe;  Statistics

Publisher

Wiley-Blackwell

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2012.21402.x

Copyright

Copyright © 2012 The Authors. Monthly Notices of the Royal Astronomical Society copyright © 2012 RAS.

Research Projects

The last 8 billion years of cosmic evolution, Australian Research Council grant number DP0772084
The fundamental physics governing the formation of cosmic structure, Australian Research Council grant number DP1093738
The Centre for Allsky ASTROphysics (CAASTRO), Australian Research Council grant number CE11E0090

Peer reviewed