Events
Physics Colloquium
On the origin of power law distribution functions
Prof. Ari Laor
Technion
Tue, 16 Jul 2024, 15:15
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: Power law distribution functions of various properties are prevalent in a vast range of systems, from the smallest dust grains between stars to the largest dark matter halos. Power laws describes the frequency of various phenomena, and appears also in biology, economy, sociology, and linguistics. I will show simulations of a very simple system of colliding hard spheres, and use it to explore the general conditions where a power law distribution function appears, and the possible implications for various other systems.
Astrophysics and Cosmology Seminar
Numerical Methods for Gravitational Lensing: A Weak Lensing Analysis Pipeline
Mr. Ron Peled
BGU
Wed, 17 Jul 2024, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Gravitational lensing, the phenomenon in which light gets deflected by astrophysical and cosmological structures, is a great tool for investigating the Universe in a wide range of scales: from detecting exoplanets to measuring its effects on the CMB anisotropies. In this work, we aim to construct a pipeline that exploits the weak-lensing (WL) regime for computing a galaxy cluster's mass distribution. In this regime, only one distorted image is created for a given source. By using shape measurement and statistical analysis, we are able to detect the WL signal that the galaxy cluster induces on background sources, and then, by using Kaizer & Squires (1993) inversion technique, we are able to obtain the cluster's mass distribution. As a test case, we are using the Abell-2744 galaxy cluster, as was captured by the JWST's NIRCam instrument. The JWST is a great tool for this kind of work: with the deeper, sharper, and broader wavelength range of imaging that it allows, we are able to detect more background sources, perform better ellipticity measurements, and therefore enhance our WL signal detection abilities. We are able to show convincing results, which then opens the possibility for using this pipeline for future studies of newly-imaged galaxy clusters.
Biological and soft-matter physics
Tubular morphogenesis in a dish
Dr. Eyal Karzbrun
Dept of Molecular Genetics, Weizmann
Thu, 18 Jul 2024, 12:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: During human embryonic development, two-dimensional sheets of cells undergo complex shape changes to form functional three-dimensional tubular organs such as the brain, gut, and lungs. While we understand many of the biological details, a physical description of tubular morphogenesis remains a challenge. This knowledge gap is primarily due to a lack of quantitative experimental data, as mammalian embryos develop inside a womb, which is difficult to access. To address this challenge, we develop human stem-cell systems that self-organize into three-dimensional tubular tissues, mirroring organ morphogenesis in a dish. We have recently recreated human neural tube morphogenesis, a key event in the formation of the brain and spinal cord. We apply our bottom-up approach to study the physics of organ shape formation, understand human birth defects, and design new synthetic biological shapes.
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