Cosmic Flows 2025: Probing the Universe with Peculiar Velocities

Session

Session 9

6 Feb 2025, 08:30

Tamborine Mountain Glades (Brisbane, Australia)

Conveners

Session 9: Thursday

• David Parkinson (KASI)

49. CLONES: Digital Twins of the Local Universe based on peculiar velocities

Jenny Sorce

06/02/2025, 08:30

To understand dark matter and dark energy, which make up 95% of the Universe, cosmological surveys must achieve percent-level precision. However, this precision uncovers tensions between observations and the standard cosmological model, potentially arising from systematic biases. CLONES (Constrained LOcal & Nesting Environment Simulations) are digital twins of the local Universe, derived from...

48. Cosmology with peculiar velocities and machine learning

Dr Francisco Villaescusa-Navarro

06/02/2025, 09:00

I will present a new framework to infer the value of cosmological parameters from peculiar velocity surveys. Our approach, which has been tested on thousands of state-of-the-art cosmological hydrodynamic simulations from the CAMELS project, takes a set of galaxies, together with their peculiar velocities, and performs field-level simulation-based inference while marginalizing over baryonic...

14. SNe Ia intrinsic scatter systematic in $f\sigma_8$ measurements

Bastien Carreres

06/02/2025, 09:30

Type Ia supernovae have been widely used to constrain the dark energy density and its equation of state parameter. The statistics and homogeneity expected from new generations of photometric surveys such as ZTF and Rubin-LSST will allow us to use SNe Ia to probe large-scale structures and make new constraints on parameters including the growth rate of structure, $f\sigma_8$. To prepare for...

22. More precise distances for early-type galaxies using machine learning

Matthew Colless (Australian National University), Melissa Campbell (Australian National University)

06/02/2025, 09:50

Galaxy distances measured using the Fundamental Plane have relative errors of 20-30%. Beyond a few tens of Mpc, this means that the errors in galaxy peculiar velocities are generally larger than the peculiar velocities themselves. It is therefore highly desirable to find ways to reduce the uncertainties in Fundamental Plane distance estimates. The intrinsic scatter about the Fundamental Plane...

6. Preparing for WAVES: Evaluating Galaxy Group-Finders with Shark v2 Mock Catalogues

Dr Trystan Scott Lambert (ICRAR-UWA)

06/02/2025, 10:10

The Wide Area Vista Extragalactic Survey (WAVES) is part of a suite of ambitious surveys utilizing the dedicated 4-meter Multi-Object Spectrograph (4MOST) in Chile. WAVES aims to measure the redshifts of 1.7 million galaxies and is scheduled to launch in December 2025. These next-generation redshift surveys are essential for probing the large-scale structure of the universe, offering...