Durham E-Theses The large-scale Structure and dynamics of the local universe Radburn-Smith, David James How to cite: Radburn-Smith, David James (2007) The large-scale Structure and dynamics of the local universe, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/2416/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk ••~'Durham University The Large-Scale Structure and Dynamics of the Local Universe by David James Radburn -Smith A thesis submitted to Durham University in accordance with the regulations for admittance to the Degree of Doctor of Philosophy. Department of Physics Durham University September 2007 The copyright of this thesis rests with the author or the university to which it was submitted. No quotation from it, or information derived from it may be published without the prior written consent of the author or university, and any information derived from it should be acknowledged. 1 5 MAY 2008 The Large-Scale Structure and Dynamics of the Local Universe by David James Radburn-Smith PhD Thesis, September 2007 Abstract This thesis investigates the dynamics of the local Universe with particular reference to discovering the source of the Local Group (LG) motion. A redshift survey of the Great Attractor (GA) region, thought responsible for a significant fraction of the LG motion, is presented. Over 3053 galaxies, located in both clusters and filaments, were targeted using the 2dF on the AAT. Velocity distributions and mass estimates for nine clusters are reported. Together with redshifts from the literature, this survey reveals the dominant feature in the core of the GA to be a large filament extending fromAbell S0639 (l= 281°, b=+11°) towards a point at l- 5°, b- -50°, encompassing the Cen-Crux, CIZA Jl324.7-5736, Norma and Pavo 11 clusters. A new model of the local velocity field out to 300h-1 Mpc is derived from the combined REFLEX, BCS and CIZA surveys: the RBC catalogue. This is the first all-sky, X-ray se­ lected galaxy cluster sample. The reconstruction includes an intrinsic correction for the bias of clusters in tracing the total density field. The velocity fields from both this recon­ struction and that of the PSCz survey are compared to the observed peculiar velocities of98local type la supernovae (SNia). The best fits are respectively found for values of 6 fJRBc ( = 0~ / ~Be) = 0.39 ± 0.20 and fJ 1 = 0.55 ± 0.06. These results are found to be robust to culls of the SNia sample by distance, host-galaxy extinction and the reference frame in which the comparison is carried out. As the PSCz preferentially samples late-type galaxies, the derived density field under­ s.amples the contributions from regions of greatest overdensity, precisely the regions traced by the RBC survey. When combined in the ratio 78% PSCz, 22% RBC these two complimentary reconstructions are a better fit to the peculiar velocities of the same SNia sample than either one alone. Compared to galaxy surveys, which only see contributions to the LG motion from struc­ tures within -6oh-1 Mpc, previous cluster surveys have argued that sources at much greater distances (-150h- 1 Mpc) influence local dynamics. However, the RBC recon­ struction presented here shows similar contributions from the same depths as the PSCz, which is partly attributed to the intrinsic bias correction and inclusion of the Virgo clus­ ter in the RBC. The extended GA region, defined as the volume enclosed by 250 < l < 350°, -45 < b < 45° and 2000 <cz< 6000 kms-1, is found to be responsible for 65% of the LG motion, whilst the more distant (-145h- 1 Mpc) SSC only accounts for 12%. Contents 1 Introduction 1 1.1 The Evolution of Structure and Dynamics . 1 1.2 Mapping the Universe: Redshift Surveys . 4 1.2.1 Cosmography . 6 1.3 Distance Indicators: Measuring Peculiar Velocities . 7 1.3.1 Cepheid Variables:;: 20h-1 Mpc . 9 1.3.2 Tully-Fisher Relation:;: 300h-1 Mpc . 9 1.3.3 Fundamental Plane:;: 150h-1 Mpc . 10 1.3.4 Surface Brightness Fluctuations:;: 150h-1 Mpc . 10 1.3.5 Type la Supernovae:;: 1000h-1 Mpc. 11 1.3.6 Malmquist Bias . 12 1.4 Peculiar Velocity Studies: Determining the LG motion 12 1.5 Reconstructing the All-Sky Density and Velocity Fields 16 1.6 Thesis Outline . 17 2 UnveilingTheGA 18 2.1 A Hidden Supercluster . 18 2.2 Observations and Data Reduction . 20 2.2.1 Redshifts . 22 2.3 Large-Scale Structures in the GA/SSC direction . 25 2.3) Review of Large-Scale Structures . 27 2.3.2 Clusters . 29 2.3.3 The Extended Norma Supercluster . 36 2.4 Summary . 40 3 The IRAS Gravity Field 41 Mapping the Local Density and Velocity Fields Mapping the Local Density and Velocity Fields CONTENTS 3.1 Gravitational Instability in the linear Regime . 41 3.2 Application to Galaxy Catalogues . 44 3.3 The PSCz Velocity Field . 46 3.4 The SNia Dataset . 49 3.5 Determining fJ 1 . • . • • . • . • . 50 3.6 Robustness . 52 3. 7 Discussion . 54 3.8 Conclusions . 56 4 TheX-RayGravityField 57 4.1 An Alternate Probe ................................ 57 4.2 The RBC Catalogue . 58 4.2.1 REFLEX . 59 4.2.2 eBCS 60 4.2.3 CIZA 60 4.2.4 Combining the Samples . 61 4.3 Real-Space Reconstruction of the RBC ..................... 62 4.3.1 Weighting the Clusters . 63 4.3.2 Cluster Biasing . 64 4.3.3 Smoothing the Sample . 67 4.3.4 The Iterative Procedure . 67 4.4 Determining fJRBc • • . • . • . · · • • • • • • · • · · · · · · 70 4.5 Robustness . 74 4.6 Conclusions . 77 5 X-Ray and IR View of the Local Universe 78 5.1 The Cluster and Galaxy Dipoles ......................... 78 5.2 Comparison of the RBC and PSCz ....................... 79 Mapping the Local Density and Velocity Fields Mapping the Local Density and Velocity Fields CONTENTS 5.3 The RBC Dipole . 82 5.4 Combining the RBC and PSCz . 86 5.4.1 The Combined Dipole . 89 5.4.2 The GAl SSC Influence . 89 5.5 Conclusions 93 6 Conclusions 95 6.1 Thesis Summary 95 6.2 Future Directions 97 A AppendixA 101 A.1 GA Red shifts . 101 8 Appendix:O 119 B.1 SNia predictions .................................. 119 C Appendix C 122 C.1 Reconstructed RBC cluster positions and velocities . 122 Mapping the Local Density and Velocity Fields [ill) List of Figures 1.1 The present -day galaxy distribution as seen by the 2dFGRS. 2 1.2 The primordial density distribution as seen by WMAP. 2 1.3 A slice through the Coma cluster taken from the extended CfA survey. 4 1.4 The PSCz density and velocity fields plotted in the supergalactic plane. 5 1.5 The 2MRS density and velocity fields. 6 1.6 The components of the LG motion from Aaronson et al. (1986). 13 1. 7 Local peculiar velocity measurements from the STEWS sample (Hudson, 2003). 15 2.1 Fits to the redshift error dispersions measured from repeat observations and comparisons with correlated datasets. 24 2.2 The completeness of targeted galaxies. 25 2.3 The distribution of the measured radial velocities. 26 2.4 Aitoff projections of redshift slices in the GA region, combining the new measurements with those available in the literature. Important large scale features are also indicated. 28 2.5 The radial velocity dispersions and corresponding virial fits for the ob­ served clusters and the velocity distribution of the combined non-cluster fields. 32 2.6 Galactic longitude and latitude of galaxies observed in the Cen-Crux region. 33 2. 7 An Aitoff projection and pieplot of the radial velocities in the Norma su­ percluster as seen below the ZoA. 37 2.8 An Aitoff projection and pieplot of the radial velocities in the Norma su­ percluster as seen through and above the ZoA. 38 3.1 SNia Hubble flow residuals before and after correction with the PSCz pre­ dicted velocity field. 50 3.2 Comparison of SNia and predicted PSCz peculiar velocities in the CMB and LG rest frames. 53 4.1 The sky distribution of sources in the combined RBC catalogue. 59 Mapping the Local Density and Velocity Fields UY) Mapping the Local Density and Velocity Fields LIST OF FIGURES 4.2 The separate, binned luminosity functions of the three recomputed sam­ ples, corrected for completeness. The solid line indicates the best Schechter fit to the combined sample. 62 4.3 The average intrinsic bias applied to the survey as a function of cluster distance . 66 4.4 The RBC velocity and density fields in the Supergalactic plane. 69 4.5 The shot noise in the Supergalactic plane of the RBC reconstruction. 70 4.6 The likelihood and x2 as a function of fJRBc for the default RBC reconstruc- tion. 73 4. 7 Comparison of the observed SNia peculiar motions to the predicted RBC values in the LG and CMB frames.