Galaxy Formation in Modified Gravity Cosmologies

Lead Research Organisation: Durham University
Department Name: Physics


The aim of this project is to extend the GALFORM semi-analytical model of galaxy formation to predict the formation and evolution of galaxies in a modified gravity cosmology. Such models are competitors to the standard model in which gravity is described by general relativity. A change to the law of gravity can potentially change the structure and spin of dark matter halos, the merger history of dark matter halos, the rate at which gas cools, the dynamics of galaxies and the evolution of their stellar populations. The results of the project will be used to make mock galaxy surveys for DESI and Euclid.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/N50404X/1 01/10/2015 31/03/2021
1630387 Studentship ST/N50404X/1 01/10/2015 30/06/2019 Piotr Oleskiewicz
ST/P006744/1 01/10/2017 30/09/2024
1630387 Studentship ST/P006744/1 01/10/2015 30/06/2019 Piotr Oleskiewicz
Title HBT+ merger trees of FoF dark matter haloes from Liminality simulation 
Description I have generated & processed merger trees, starting from Shi+2015 simulation data, to be presented in Oleskiewicz+2019 (in prep.). 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? No  
Impact Merger trees for high resolution GR / f(R) simulation using latest HBT+ merger tree builder are used to compare & contrast growth of large scale structures in GR / f(R) models. 
Title Multiple realisations of GALFORM Lacey+2016 model for sensitivity analysis 
Description Over 2000 different variations of the Lacey+2016 model were created in order to calculate Sobol' sensitivity indices and test model sensitivity to parameter variation. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? No  
Impact Sensitivity analysis of galaxy formation models has only been carried out on individual, Milky-Way-size haloes (see Gomez+2014). This dataset is an exploration of interactions between 7 most critical parameters across the sub-volumes of the P-Millennium N-body simulation. 
Description Secondment 
Organisation Atom Bank
Country United Kingdom 
Sector Private 
PI Contribution I have implemented and analysed the sensitivity of the mortgage pricing model at Atom Bank as a part of my secondment. It was a pilot run of the Durham Centre for Data Intensive Science industrial placement programme.
Collaborator Contribution I have been one of the first students to participate in the industry-academia exchange, and have brought back statistical techniques (sensitivity testing) I now use in my research.
Impact see above.
Start Year 2018
Title Sensitivity Analysis Toolkit 
Description sa == **sa** is a sensitivity analysis toolkit written in C. Requirements ------------ - C99 compiler (tested with clang and gcc) - `gsl` (tested with v2.5) - `gnuplot` for plots - `awk` for rescaling (any, but `mawk` is the best) Tools ----- - `./sa-plot`: gnuplot script plotting a 2D grid of points (expects to be piped to a PNG file) - `./sa-rescale`: awk script for rescaling columns from `[0,1]` interval to any other uniform region - `./sa-sample-random N D`: N points from uniform PRNG, reshaped to N by D matrix - `./sa-sample-sobol N D`: N points from the Sobol' sequence in D dimensions - `./sa-sample-saltelli N D`: N points from the Saltelli sapling in D dimensions (`(N+2)*d` entries); it generates 2 Sobol' sequences, A and B, sub-samples them into AB, and concatenates vertically, as per saltelli2010 - `./sa-sample-halton N D`: N points from D-dimensional Halton sequence - `./sa-sample-niederreiter N D`: N points from D-dimensional Niederreiter sequence - `./sa-sample-recurrent N D`: generates N points from a D-dimensional Kronecker recurrence relation with seed 0.5 and precision 10 (implementation based on Matrin Roberts) 
Type Of Technology Software 
Year Produced 2019 
Open Source License? Yes  
Impact It is being used to compare quasirandom sequence sampling for sensitivity analysis of semi-analytic galaxy formation model GALFORM. 
Title analysis of HBT+ dark matter haloes in Python 
Description Python module with helpers for analysis of dark matter haloes from HBTplus halo finder, used for my work on modified gravity / GR comparison project. 
Type Of Technology Software 
Year Produced 2018 
Impact It is the main repository for my 2019 paper showing differences in halo formation between GR and modified gravity models (in prep.). 
Description Celebrate Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact "Celebrate Science" is a science festival taking place every year for 2 days, with hundreds of visitors.
We presented astrophysics & cosmology demos, featuring:

- gravitational lensing demonstration using Xbox Kinect
- 3d simulation movie in a VR environment
- inflatable planetarium
- live simulation and 3d render of galaxy formation
Year(s) Of Engagement Activity 2015,2016,2017,2018
Description School Visit 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Visit to a local school to organise an outreach event in astrophysics, featuring:

- gravitational lensing demonstration using Xbox Kinect
- diffraction of Sun / fluorescent lightbulb into different wavelengths
- 3d simulation movie
Year(s) Of Engagement Activity 2017,2018