Science News内容：

　　题目：NASA's Bennu Asteroid Sample Contains Carbon, Water

　　摘要：An ancient relic of our solar system’s early days, asteroid Bennu has seen more than 4.5 billion years of history. Bennu likely broke off from a much larger carbon-rich asteroid about 700 million to 2 billion years ago. It likely formed in the main asteroid belt between Mars and Jupiter, and has drifted much closer to Earth since then. Bennu was the target of NASA's first asteroid sample return mission, OSIRIS-REx. The spacecraft dropped off a sample of Bennu on Sept. 24, 2023. Initial studies of the 4.5-billion-year-old asteroid Bennu sample collected in space and brought to Earth by NASA show evidence of high-carbon content and water, which together could indicate the building blocks of life on Earth may be found in the rock.

　　报告人：黄海涛（紫台研究生）

Journal club内容：

　　题目：Endothermic self-interacting dark matter in Milky Way-like dark matter haloes

　　摘要：Self-interacting dark matter (SIDM) offers the potential to mitigate some of the discrepancies between simulated cold dark matter (CDM) and observed galactic properties.We introduce a physically motivated SIDM model to understand the effects of self interactions on the properties of Milky Way and dwarf galaxy sized haloes.This model consists of dark matter with a nearly degenerate excited state, which allows for both elastic and inelastic scattering. In particular,the model includes a significant probability for particles to up-scatter from the ground state to the excited state. We simulate a suite of zoom-in Milky Way-sized N-body haloes with six models with different scattering cross sections to study the effects of up-scattering in SIDM models. We find that the up-scattering reaction greatly increases the central densities of the main halo through the loss of kinetic energy. However, the physical model still results in significant coring due to the presence of elastic scattering and down-scattering. These effects are not as apparent in the subhalo population compared to the main halo, but the number of subhaloes is reduced compared to CDM.

　　报告人：段欣辰（紫台研究生）

　　时间：2023年11月7日星期二12:15

　　地点：紫台3-302

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