Expanding the boundaries of dark matter halo

Session

Observational measurements

May 28, 2025, 9:00 AM

C204, Student Center (Shanghai Jiao Tong University)

Conveners

Observational measurements

• Eduardo Rozo (University of Arizona)

Observational measurements

• Eduardo Rozo (University of Arizona)

53. Splashback radius in observations: Challenges and opportunities

Surhud More (IUCAA)

5/28/25, 9:00 AM

Talk

The detection of the boundary of a dark matter halo (splashback radius) combined with the measure of its halo mass allows a direct access to its mass accretion history. Given the importance of mass accretion rates to cosmology and to the formation and evolution of galaxies within the halo, accurate detection of splashback radius is important. I will present the challenges in the detection of...

31. Splashback radius from lensing and correlation function in KiDS

Dr Giorgio Francesco Lesci (University of Bologna)

5/28/25, 9:30 AM

Detections and measurements

Talk

The splashback radius is a physically motivated boundary of galaxy clusters, offering a unique window into the cluster's mass accretion rate and the interplay between dark matter and baryonic processes. Consequently, accurate measurements of the splashback radius are crucial for testing cosmological models and advancing our understanding of structure formation. With the advent of large-scale...

11. The Measurement of the Splash-back Radius of Dark Matter Halos

Dr Weiwei Xu (National Astronomical Observatories, Chinese Academy of Sciences)

5/28/25, 10:35 AM

Detections and measurements

Talk

To avoid the pseudo-evolution problem of the traditionally defined halo mass and radius, we measure the splash-back radius (Rsp), a physically defined halo radius for many halos, using the shear catalog of the DECaLS DR8. The dark matter halos cover the mass of 10^13 - 3 × 10^15Msun and the redshift of 0.08–0.65. Our finding reveals a trend wherein massive halos demonstrate a larger Rsp, and...

43. Indefinitely large galactic dark matter halos from a new weak-lensing method and applications to galaxy clusters

Tobias Mistele (Case Western Reserve University)

5/28/25, 10:55 AM

Detections and measurements

Talk

Weak gravitational lensing is a crucial tool to measure the mass profiles of dark matter halos. I will discuss a recent weak-lensing analysis of isolated galaxies in KiDS DR4 that finds flat circular velocities out to very large galactocentric radii (at least 300kpc), suggesting that the dark matter halos of galaxies are more extended than expected. Futhermore, these dark matter profiles...

47. Detection of a non-evolving ''splashback'' radius of cosmic filaments across 0 < z < 1.2

Qiaoyang Hao (南京大学)

5/28/25, 11:15 AM

Detections and measurements

Talk

Cosmic filaments represent the sites where the majority of galaxies in the universe form. However, the structure of filaments themselves, and the link between physical properties of galaxies and their spatial distribution within the filaments remain unclear. Here based on deep multi-wavelength data in the COSMOS and SDSS surveys, we characterize projected radial profiles (2-dimension) of...

24. Galaxy Cluster Properties using Weak Gravitational Lensing

Carlo Giocoli (INAF - OAS Bologna)

Detections and measurements

Talk

I will present a comprehensive analysis of weak gravitational lensing data to assess mass biases in galaxy clusters and characterize their splashback radius, with implications for precision cluster cosmology.
Systematic assessments using state-of-the-art hydrodynamical simulations reveal that weak lensing mass biases depend on cluster mass, redshift, and orientation, with biases as high as...