Spinning galaxies within the large scale structure of the Universe

Finding links between the large scale structure of the Universe and galaxy formation presents an important challenge for cosmology. The properties of dark matter halos in N-body simulations, in particular the spin angular momentum, can provide these links. This thesis is an in depth study of the alignments of halo spin direction within filaments in the large scale structure. Filaments in the halo and galaxy distribution of the Millennium simulation were identified using two simple methods and a difference between the spin orientation of low and high mass halos with the axis of filaments was uncovered. The evolution of these alignments and other aspects of halo spin suggested an ongoing process of angular momentum acquisition. This process was found to be largely reliant on the anisotropic infall of satellite halos. The spin of dark matter halos tends to become increasingly parallel to the axis of filaments and this change is driven by major mergers between halos traveling orthogonal to the axis of filaments. This new scenario of the build-up of dark matter halo spin could see significant consequences in theories of galaxy formation. Statement of Originality This thesis describes work carried out in the Sydney Institute for Astronomy, within the School of Physics, University of Sydney, between March 2009 and July 2013. The work presented in this thesis is, to the best of my knowledge and belief, original except as acknowledged in the text. I hereby declare that I have not submitted this material, either in full or in part, for a degree or diploma at this university or any other institution. Holly E. Trowland Date Included Publications Chapter 4 of this thesis contains a reproduction of a paper that has been published in a peer-reviewed journal. The paper consists of research conducted by myself, in consultation with my supervisors Geraint Lewis and Joss Bland-Hawthorn. The original text of the paper is presented in the Appendix. The Cosmic History of the Spin of Dark Matter Halos within the Large-scale Structure Trowland H. E. , Lewis G. F. , Bland-Hawthorn J., 2013, ApJ, 762, 72 Additional Publications The following papers are are listed as forming a small part of my thesis. However, my contributions to them were minor. The SAMI IFU Galaxy Survey Konstantopoulos, I. ; Croom, S. M. ; Lawrence, J. S. ; BlandHawthorn, J.; Bryant, J.; Fogarty, L. ; Richards, S. ; Goodwin, M. ; Farrell, T. ; Miziarski, S. ; Heald, R. ; Jones, D. ; Lee, S. ; Colless, M. ; Brough, S. ; Hopkins, A. M. ; Bauer, A. E. ; Birchall, M. N. ; Ellis, S. C. ; Horton, A. J.; Leon-Saval, S. G. ; Lewis, G. F. ; Lopez-Sanchez, A. R. ; Min, S. ; Trinh, C. ; Trowland, H. & Team, S. , 2013, American Astronomical Society Meeting Abstracts, 221, 215.01 The Sydney-AAO Multi-object Integral field spectrograph Croom, S. M. ; Lawrence, J. S. ; Bland-Hawthorn, J.; Bryant, J. J.; Fogarty, L. ; Richards, S. ; Goodwin, M. ; Farrell, T. ; Miziarski, S. ; Heald, R. ; Jones, D. H. ; Lee, S. ; Colless, M. ; Brough, S. ; Hopkins, A. M. ; Bauer, A. E. ; Birchall, M. N. ; Ellis, S. ; Horton, A. ; Leon-Saval, S. ; Lewis, G. ; LpezSnchez, A. R. ; Min, S. -S. ; Trinh, C. & Trowland, H. , 2012, MNRAS, 421, 872-893 First Science with SAMI: A Serendipitously Discovered Galactic Wind in ESO 185-G031 Fogarty, L. M. R. ; Bland-Hawthorn, J.; Croom, S. M. ; Green, A. W. ; Bryant, J. J.; Lawrence, J. S. ; Richards, S. ; Allen, J. T. ; Bauer, A. E. ; Birchall, M. N. ; Brough, S. ;