Cosmic Flows 2025: Probing the Universe with Peculiar Velocities

Session

Session 12

7 Feb 2025, 08:30

Tamborine Mountain Glades (Brisbane, Australia)

Conveners

Session 12: Friday

• Jeremy Mould (Swinburne University of Technology)

16. The TRGB-SBF Project: a Pop II path to H0

Dr Brent Tully (University of Hawaii)

07/02/2025, 08:30

The path from Cepheid variables to type Ia supernovae gives a value of the Hubble constant which significantly disagrees with the value determined from observations of conditions in the early universe and a cosmological model. A totally independent measurement of H0 from observed redshifts and distances is needed to evaluate the possibilities of systematic errors. A path is being explored...

10. Analyzing the Large-Scale Bulk Flow using CosmicFlows4: Tension with the Standard Cosmological model

Rick Watkins

07/02/2025, 09:00

We present estimates of the Bulk Flow in volumes of increasing radii using the minimum variance method with data from the CosmicFlows4 catalog. Contrary to expectations, we find that the Bulk Flow amplitude increases with increasing radius, with the Bulk Flow amplitude in a volume of radius $200h^{-1}$Mpc being large enough to have only a 0.003% chance of occurring in the Standard Model. We...

40. Evaluating bulk flow estimators for CosmicFlows-4 measurements

Abbe Whitford

07/02/2025, 09:30

For over a decade there have been contradictory claims in the literature regarding measurements of local bulk flow motions of galaxies, as to whether measurements are consistent or in tension with the currently accepted model of cosmology, Lambda-CDM. A bulk flow measurement can be thought of as an average of galaxy motions sourced by gravity in a volume of space. The robustness of various...

29. Cosmic Flow Challenges

Mike Hudson (Waterloo Centre for Astrophysics)

07/02/2025, 09:50

Cosmic flows are currently undergoing a renaissance with major new peculiar velocity and redshift surveys such as 4HS, DESI and ZTF, as well as new methods like kinetic Sunyaev-Zeldovich effect at high redshifts. I will review the challenges of current data sets that must be overcome to turn Cosmic Flows into competitive cosmological probe, and prospects for the future.

2. Probing the missing baryons with the kinetic Sunyaev-Zeldovich effect

Y Ma

07/02/2025, 10:10

The kinetic Sunyaev-Zeldovich (kSZ) effect represents a secondary anisotropy in the cosmic microwave background (CMB) radiation, caused by the inverse Compton scattering of free electrons in galaxy clusters. Observations from the Planck satellite, as well as the ACT and SPT experiments, have enabled the measurement of this effect, providing insights into the dynamics of large-scale structures....