Dr Cullan Howlett
Dr

Cullan Howlett

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0420776717

Background

I am a Senior Research Fellow in Cosmology based in the School of Mathematics and Physics. I work on making maps of the positions and motions of millions of galaxies in our Universe to uncover how it has evolved since the Big Bang. Current observations suggest 95% of our Universe consists of ellusive Dark Matter and Dark Energy; we can detect these by the influence they have on the light from galaxies, stars and that permeates the background Universe itself, but they don't emit light themselves and we have no idea yet what they are. My research seeks to uncover these using the largest galaxy surveys in the world.

I have been involved in planning, carrying out, and analysing a large number of these surveys. I currently working groups in the American-led Dark Energy Spectroscopic Instrument (DESI) project, the WALLABY survey based in Western Australia, and the 4MOST Hemisphere Survey (4HS) which will be carried out from Chile. Combined, these will produce the most detailed maps of galaxy positions and motions ever created --- over 40,000,000 unique galaxies!

My personal research makes use of state-of-the art computing techniques to simulate the distributions of these galaxies, their properties, and how fast they are moving. I then analyse these distributions using different statistical techniques and compare to the real data. The properties of Dark Matter and Dark Energy and all the other things that make up our Universe can then be extracted by modelling these statistics with theoretical models, or looking for discrepancies between the simulations and the data. My hope is that by doing so, we are currently on the cusp of uncovering something fundamental about how the Universe came to be the way it is today, and what will happen to it in the future.

Academic Background

  • Undergraduate: MPhys 1st Class Honours - University of Sussex, 2008-2012
  • Postgraduate: PhD - University of Portmouth, 2012-2016
  • Research Associate - University of Western Australia, 2015-2019
  • Research Fellow in Cosmology - University of Queensland, 2019-

Availability

Dr Cullan Howlett is:
Not available for supervision
Media expert

Fields of research

Astronomical instrumentation Astronomical sciences Cosmology and extragalactic astronomy Galactic astronomy General relativity and gravitational waves Physical Sciences

Qualifications

  • Doctor of Philosophy, University of Portsmouth

Research interests

  • Testing gravity using galaxy positions and motions

    One compelling way to explain dark matter and dark energy is that our current theory of gravity (General Relativity) doesn't work on scales much larger than the Solar system. One of my interests is developing different models and understanding how they can be proven or disproven with galaxy properties.

  • Fast simulations of large scale structure

    Current state of the art simulations are able to simulate the distributions of billions of galaxies, but these are very slow and can take weeks to run on the largest supercomputers. I'm interested in new approximate ways for generating these simulations or cool computational techniques such as machine learning, that can be run in a fraction of the time, or on fewer processors.

  • New statistical methods for analysing distributions of galaxies

    In addition to theoretical developments, I'm interested in looking for new statistical ways to use the galaxy data we have to give us insight into the Universe.

  • Gravitational waves

    Gravitational waves, first detected in 2015 are the new hot topic in physics and offer interesting ways to test cosmology. I'm interested in creating simulated catalogues of gravitational waves and using these to working out what cosmological insights gravitational waves can bring

Research impacts

The nature of dark matter and dark energy is the biggest question in modern science. Are they particles we haven't discovered yet, or perhaps a misunderstanding of our fundamental pillars of physics (Einstein's theory of General Relativity or Quantum Mechanics). We don't know, but the answer is out there, and it's likely profound. It will change everything we know about physics, and with this understanding could come unimagined new ideas and technologies. In the same way that our modern understanding of the atom and electromagnetism has lead to the technologic marvels we have today that would seem wonderous to someone 200 years ago, in 200 years from now who knows where an understanding of the Dark parts of our Universe will take us.

In order to unlock this information, cosmologists including myself have to come up with new techniques for supercomputing, for dealing with big data problems, and for mining every possible piece of data from the surveys we have. The statistics, methods and codes we develop are cutting edge and can often be used in fields outside astronomy (for instance in finance, environmental science, business planning, and even tackling pandemics...)

Search Professor Cullan Howlett’s works on UQ eSpace

85 works between 2012 and 2025
All (85) Journal Article (83) Conference Publication (2)

61 - 80 of 85 works

2021

Journal Article

Cosmic flow measurement and mock sampling algorithm of Cosmicflows-4 Tully−Fisher catalog

Qin, Fei, Parkinson, David, Howlett, Cullan and Said, Khaled (2021). Cosmic flow measurement and mock sampling algorithm of Cosmicflows-4 Tully−Fisher catalog. The Astrophysical Journal, 922 (1) 59, 59. doi: 10.3847/1538-4357/ac249d

Cosmic flow measurement and mock sampling algorithm of Cosmicflows-4 Tully−Fisher catalog

2021

Journal Article

The effect of systematic redshift biases in BAO cosmology

Glanville, Aaron, Howlett, Cullan and Davis, Tamara M. (2021). The effect of systematic redshift biases in BAO cosmology. Monthly Notices of the Royal Astronomical Society, 503 (3), 3510-3521. doi: 10.1093/mnras/stab657

The effect of systematic redshift biases in BAO cosmology

2021

Journal Article

CosmoBit: A GAMBIT module for computing cosmological observables and likelihoods

Renk, Janina J., Stöcker, Patrick, Bloor, Sanjay, Hotinli, Selim, Balázs, Csaba, Bringmann, Torsten, Gonzalo, Tomás E., Handley, Will, Hoof, Sebastian, Howlett, Cullan, Kahlhoefer, Felix, Scott, Pat, Vincent, Aaron C. and White, Martin (2021). CosmoBit: A GAMBIT module for computing cosmological observables and likelihoods. Journal of Cosmology and Astroparticle Physics, 2021 (2) 022, 022-022. doi: 10.1088/1475-7516/2021/02/022

CosmoBit: A GAMBIT module for computing cosmological observables and likelihoods

2020

Journal Article

Constraining the growth rate of structure with phase correlations

Byun, Joyce, Franco, Felipe Oliveira, Howlett, Cullan, Bonvin, Camille and Obreschkow, Danail (2020). Constraining the growth rate of structure with phase correlations. Monthly Notices of the Royal Astronomical Society, 497 (2), 1765-1790. doi: 10.1093/mnras/staa2020

Constraining the growth rate of structure with phase correlations

2020

Journal Article

WALLABY – an SKA Pathfinder H I survey

Koribalski, Bärbel S., Staveley-Smith, L., Westmeier, T., Serra, P., Spekkens, K., Wong, O. I., Lee-Waddell, K., Lagos, C. D.P., Obreschkow, D., Ryan-Weber, E. V., Zwaan, M., Kilborn, V., Bekiaris, G., Bekki, K., Bigiel, F., Boselli, A., Bosma, A., Catinella, B., Chauhan, G., Cluver, M. E., Colless, M., Courtois, H. M., Crain, R. A., de Blok, W. J.G., Dénes, H., Duffy, A. R., Elagali, A., Fluke, C. J., For, B. Q. ... Wolf, C. (2020). WALLABY – an SKA Pathfinder H I survey. Astrophysics and Space Science, 365 (7) 118. doi: 10.1007/s10509-020-03831-4

WALLABY – an SKA Pathfinder H I survey

2020

Journal Article

BARRY and the BAO Model Comparison

Hinton, Samuel R., Howlett, Cullan and Davis, Tamara M. (2020). BARRY and the BAO Model Comparison. Monthly Notices of the Royal Astronomical Society, 493 (3), 4078-4093. doi: 10.1093/mnras/staa361

BARRY and the BAO Model Comparison

2020

Journal Article

Multiwavelength consensus of large-scale linear bias

Pan, Hengxing, Obreschkow, Danail, Howlett, Cullan, Lagos, Claudia del P., Elahi, Pascal J., Baugh, Carlton and Gonzalez-Perez, Violeta (2020). Multiwavelength consensus of large-scale linear bias. Monthly Notices of the Royal Astronomical Society, 493 (1), 747-764. doi: 10.1093/mnras/staa222

Multiwavelength consensus of large-scale linear bias

2019

Journal Article

Can redshift errors bias measurements of the Hubble Constant?

Davis, Tamara M., Hinton, Samuel R., Howlett, Cullan and Calcino, Josh (2019). Can redshift errors bias measurements of the Hubble Constant?. Monthly Notices of the Royal Astronomical Society, 490 (2), 2948-2957. doi: 10.1093/mnras/stz2652

Can redshift errors bias measurements of the Hubble Constant?

2019

Journal Article

The redshift-space momentum power spectrum II: measuring the growth rate from the combined 2MTF and 6dFGSv surveys

Qin, Fei, Howlett, Cullan and Staveley-Smith, Lister (2019). The redshift-space momentum power spectrum II: measuring the growth rate from the combined 2MTF and 6dFGSv surveys. Monthly Notices of the Royal Astronomical Society, 487 (4) stz1576, 5235-5247. doi: 10.1093/mnras/stz1576

The redshift-space momentum power spectrum II: measuring the growth rate from the combined 2MTF and 6dFGSv surveys

2019

Journal Article

The redshift-space momentum power spectrum – I. Optimal estimation from peculiar velocity surveys

Howlett, Cullan (2019). The redshift-space momentum power spectrum – I. Optimal estimation from peculiar velocity surveys. Monthly Notices of the Royal Astronomical Society, 487 (4) stz1403, 5209-5234. doi: 10.1093/mnras/stz1403

The redshift-space momentum power spectrum – I. Optimal estimation from peculiar velocity surveys

2019

Journal Article

2MTF - VII. 2MASS Tully-Fisher survey final data release: distances for 2,062 nearby spiral galaxies

Hong, Tao, Staveley-Smith, Lister, Masters, Karen L, Springob, Christopher M, Macri, Lucas M, Koribalski, Bärbel S, Jones, D Heath, Jarrett, Tom H, Crook, Aidan C, Howlett, Cullan and Qin, Fei (2019). 2MTF - VII. 2MASS Tully-Fisher survey final data release: distances for 2,062 nearby spiral galaxies. Monthly Notices of the Royal Astronomical Society, 487 (2), 2061-2069. doi: 10.1093/mnras/stz1413

2MTF - VII. 2MASS Tully-Fisher survey final data release: distances for 2,062 nearby spiral galaxies

2019

Journal Article

Bulk flow and shear in the local Universe: 2MTF and COSMICFLOWS-3

Qin, Fei, Howlett, Cullan, Staveley-Smith, Lister and Hong, Tao (2019). Bulk flow and shear in the local Universe: 2MTF and COSMICFLOWS-3. Monthly Notices of the Royal Astronomical Society, 482 (2), 1920-1930. doi: 10.1093/mnras/sty2826

Bulk flow and shear in the local Universe: 2MTF and COSMICFLOWS-3

2018

Journal Article

Bulk flow in the combined 2MTF and 6dFGSv surveys

Qin, Fei, Howlett, Cullan, Staveley-Smith, Lister and Hong, Tao (2018). Bulk flow in the combined 2MTF and 6dFGSv surveys. Monthly Notices of the Royal Astronomical Society, 477 (4), 5150-5166. doi: 10.1093/mnras/sty928

Bulk flow in the combined 2MTF and 6dFGSv surveys

2018

Journal Article

Cosmological constraints from fourier phase statistics

Ali, Kamran, Obreschkow, Danail, Howlett, Cullan, Bonvin, Camille, Llinares, Claudio, Oliveira Franco, Felipe and Power, Chris (2018). Cosmological constraints from fourier phase statistics. Monthly Notices of the Royal Astronomical Society, 479 (2), 2743-2753. doi: 10.1093/mnras/sty1696

Cosmological constraints from fourier phase statistics

2018

Journal Article

A short research note on calculating exact distribution functions and random sampling for the 3D NFW profile

Robotham, A. S. G. and Howlett, Cullan (2018). A short research note on calculating exact distribution functions and random sampling for the 3D NFW profile. Research Notes of the AAS, 2 (2), 55. doi: 10.3847/2515-5172/aacc70

A short research note on calculating exact distribution functions and random sampling for the 3D NFW profile

2017

Journal Article

Galaxy two-point covariance matrix estimation for next generation surveys

Howlett, Cullan and Percival, Will J. (2017). Galaxy two-point covariance matrix estimation for next generation surveys. Monthly Notices of the Royal Astronomical Society, 472 (4), 4935-4952. doi: 10.1093/mnras/stx2342

Galaxy two-point covariance matrix estimation for next generation surveys

2017

Journal Article

2MTF-VI. Measuring the velocity power spectrum

Howlett, Cullan, Staveley-Smith, Lister, Elahi, Pascal J., Hong, Tao, Jarrett, Tom H., Jones, D. Heath, Koribalski, Barbel S., Macri, Lucas M., Masters, Karen L. and Springob, Christopher M. (2017). 2MTF-VI. Measuring the velocity power spectrum. Monthly Notices of the Royal Astronomical Society, 471 (3), 3135-3151. doi: 10.1093/mnras/stx1521

2MTF-VI. Measuring the velocity power spectrum

2017

Journal Article

The Taipan Galaxy Survey: Scientific Goals and Observing Strategy

da Cunha, Elisabete, Hopkins, Andrew M., Colless, Matthew, Taylor, Edward N., Blake, Chris, Howlett, Cullan, Magoulas, Christina, Lucey, John R., Lagos, Claudia, Kuehn, Kyler, Gordon, Yjan, Barat, Dilyar, Bian, Fuyan, Wolf, Christian, Cowley, Michael J., White, Marc, Achitouv, Ixandra, Bilicki, Maciej, Bland-Hawthorn, Joss, Bolejko, Krzysztof, Brown, Michael J. I., Brown, Rebecca, Bryant, Julia, Croom, Scott, Davis, Tamara M., Driver, Simon P., Filipovic, Miroslav D., Hinton, Samuel R., Johnston-Hollitt, Melanie ... Watson, Fred (2017). The Taipan Galaxy Survey: Scientific Goals and Observing Strategy. Publications of the Astronomical Society of Australia, 34 e047, 1-28. doi: 10.1017/pasa.2017.41

The Taipan Galaxy Survey: Scientific Goals and Observing Strategy

2016

Journal Article

Cosmology with peculiar velocities: observational effects

Andersen, P., Davis, T. M. and Howlett, C. (2016). Cosmology with peculiar velocities: observational effects. Monthly Notices of the Royal Astronomical Society, 463 (4), 4083-4092. doi: 10.1093/mnras/stw2252

Cosmology with peculiar velocities: observational effects

2015

Journal Article

Cosmological implications of baryon acoustic oscillation measurements

Aubourg, Éric, Bailey, Stephen, Bautista, Julian E., Beutler, Florian, Bhardwaj, Vaishali, Bizyaev, Dmitry, Blanton, Michael, Blomqvist, Michael, Bolton, Adam S., Bovy, Jo, Brewington, Howard, Brinkmann, J., Brownstein, Joel R., Burden, Angela, Busca, Nicolás G., Carithers, William, Chuang, Chia-Hsun, Comparat, Johan, Croft, Rupert A. C., Cuesta, Antonio J., Dawson, Kyle S., Delubac, Timothée, Eisenstein, Daniel J., Font-Ribera, Andreu, Ge, Jian, Le Goff, J. M., Gontcho, Satya Gontcho A., Gott, J. Richard, Gunn, James E. ... Zhao, Gong-Bo (2015). Cosmological implications of baryon acoustic oscillation measurements. Physical Review D - Particles, Fields, Gravitation and Cosmology, 92 (12) 123516. doi: 10.1103/PhysRevD.92.123516

Cosmological implications of baryon acoustic oscillation measurements

Current funding

  • 2025 - 2028
    Cosmic Cartography to Counter Cosmic Conundrums
    ARC Discovery Projects
    Open grant
  • 2022 - 2025
    A Space Odyssey: Exploring the Universe with Gravitational-Wave Sirens
    ARC Discovery Projects
    Open grant

Availability

Dr Cullan Howlett is:
Not available for supervision

Supervision history

Current supervision

  • Doctor Philosophy

    Modelling exotic cosmological models in the era of next generation galaxy surveys

    Principal Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Completing the Puzzle: Unveiling Clues for Gravitational Wave Astrophysics and Cosmology with Simulations

    Principal Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Using the motions of galaxies to probe fundamental physics

    Principal Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Investigating Gravitational Wave Cosmology with Simulated Data

    Principal Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Completing the Puzzle: Unveiling Clues for Gravitational Wave Astrophysics and Cosmology with Simulations

    Principal Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Cosmology with the Dark Energy Survey

    Associate Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Measuring Neutrino Mass with the Dark Energy Spectroscopic Instrument

    Associate Advisor

    Other advisors: Professor Tamara Davis

  • Doctor Philosophy

    Gravitational wave cosmology

    Associate Advisor

    Other advisors: Professor Tamara Davis

Completed supervision

Enquiries

Contact Dr Cullan Howlett directly for media enquiries about:

  • Astronomy
  • Astrophysics
  • Cosmology
  • Dark energy
  • Dark matter

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