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Here the invisible dark matter is seen rendered in pink on top of the visible-light image. Credit: Kilo-Degree Survey Collaboration/A. Tudorica & C. Heymans/ESO

Here the invisible dark matter is seen rendered in pink on top of the visible-light image.
Credit: Kilo-Degree Survey Collaboration/A. Tudorica & C. Heymans/ESO

It’s been almost 50 years since Dark Matter was confirmed as the most plausible scenario for flat rotation curves, high cluster and group velocity dispersions, and as the seeds for the growth of large scale structure. A key goal of experiments such as the Large Hadron Collider, Belle II and numerous underground experiments, is to identify the dark matter particle candidate and in particular its mass and interaction properties (decay rates, interaction cross-section etc). Within Astrophysics little progress has been made in narrowing down the search space, or in providing additional constraints to assist in these searches, yet astrophysics arguably offers the best experimental environment in which to determine constraints. In this project we will look to pursue a number of pathways to attempt to constrain the properties of dark-matter focussing on both macro and micro properties.

  • Redshift surveys: Redshift surveys are one of our core activity areas within ICRAR and can be used to construct group catalogues from which we derive the dark matter halo mass function. This has been measured over several orders of magnitude and we are now extending this both in accuracy, redshift, and to lower halo masses all of which can be compared to analytic and numerical predictions of Cold and Warm DarkMatter models.
  • Energy budgets: If Dark Matter decays or annihilates it will provide a detectable energy signature at some wavelength. By probing deep sight-lines through the Universe we can determine measurements of the integrated light from galaxies (at any wavelength) and compare to constraints on the diffuse light. The comparison of these two cab provide constraints on unknown energy sources such as that arising from Dark Matter decay or hidden populations or unknown physical processes.
  • Intra-halo light: Large Cold Dark Matter halos (clusters and groups) are likely to undergo an historically greater level of interactions than if the dark matter is hot or warm, resulting in a greater proportion of stripped stellar mass, ergo the fraction of stripped mass in cluster and group halos may provide an interesting constraint on the dark matter particle mass and the temperature (mass) of the dark matter particle.
  • Lyman-alpha forest: The Lyman-alpha forest probes the intervening medium to distant QSO sight-lines and can be used in multiple ways to test the dark matter scenario: the flux power-spectrum can provide information of the faint-end of the halo mass function, while individual instances of very narrow Lyman alpha lines can provide allowability constraints on the dark matter particle mass.

Within this broad project range we hope to assemble a team of PhD and Postdoctoral researchers specifically tasked to pursue all avenues able to inform on the dark matter question, including those listed above and more. The key overriding aim tis to feed Dark Matter constraints from a multitude of astrophysical experiments through to terrestrial ground searches led by particle physics groups.

This experimental project is extremely well suited to gifted students able to work across a range of astrophysics sectors in a responsive, independent and intuitive mode but also with a broad team environment.

Skills gained will be a deep understanding of cosmology, galaxy groups, galaxies and astrophysical constraints on dark matter from an empirical experimental perspective.