Kavli Affiliate: Kohei Inayoshi | Summary:Recent observations have revealed a unique class of active galactic nuclei (AGNs), termed little red dots (LRDs). These objects are hypothesized to be powered by massive black holes rapidly accreting in dense gaseous environments. Theoretical studies suggest that the circum-nuclear gas can form an optically thick black hole envelope (BHE), […]
Kavli Affiliate: Feng Long| Summary: Low-rank adaptation (LoRA) has emerged as a powerful tool for parameter-efficient fine-tuning of large language models (LLMs). This paper studies LoRA under a federated learning setting, enabling collaborative fine-tuning across clients while preserving parameter efficiency. We focus on a highly heterogeneous regime in which clients share only partial structure and […]
Kavli Affiliate: Feng Long| Summary: We develop an adaptive jump test for discretely observed high-frequency semimartingales by combining the A"it-Sahalia–Jacod ratio statistic (A"it-Sahalia and Jacod, 2009) and the Lee–Mykland extreme-return statistic (Lee and Mykland, 2008) with the Cauchy combination rule. Allowing stochastic It^o drift, volatility, and leverage, we show asymptotic independence under the continuous-path null […]
Kavli Affiliate: Feng Long| Summary: We develop an adaptive jump test for discretely observed high-frequency semimartingales by combining the A"it-Sahalia–Jacod ratio statistic (A"it-Sahalia and Jacod, 2009) and the Lee–Mykland extreme-return statistic (Lee and Mykland, 2008) with the Cauchy combination rule. Allowing stochastic It^o drift, volatility, and leverage, we show asymptotic independence under the continuous-path null […]
Kavli Affiliate: Huawei Zhang | Summary:Metal-poor stars are crucially important for understanding the early Galaxy, first stars, and the Universe. In this series of papers, we present a homogeneous non-local thermodynamic equilibrium (NLTE) abundances analysis of 12 elements for 103 very/extremely metal-poor (VMP/EMP) stars with metallicity down to $-4.3$ dex. The sample was selected from […]
Kavli Affiliate: Huawei Zhang | Summary:Metal-poor stars are crucially important for understanding the early Galaxy, first stars, and the Universe. In this series of papers, we present a homogeneous non-local thermodynamic equilibrium (NLTE) abundances analysis of 12 elements for 103 very/extremely metal-poor (VMP/EMP) stars with metallicity down to $-4.3$ dex. The sample was selected from […]
Kavli Affiliate: Claudio Ricci | Summary:Red quasars (rQSOs) have been recognized as a short-lived, early stage in the evolutionary cycle of Active Galactic Nuclei (AGN), with fundamental differences in their intrinsic properties compared to blue quasars (bQSOs). In this work, we present the first large X-ray sample of 380 rQSOs, selected from the eROSITA/SDSS-V collaboration, […]
Kavli Affiliate: Claudio Ricci | Summary:The origin of high-energy astrophysical neutrinos remains a key open question in multimessenger astrophysics. A correlation between unabsorbed hard X-ray emission and high-energy neutrino luminosity has been reported in a sample of six active galactic nuclei with the highest individual IceCube significances, linking neutrino production to compact, photon-rich environments near […]
Kavli Affiliate: Claudio Ricci | Summary:The origin of high-energy astrophysical neutrinos remains a key open question in multimessenger astrophysics. A correlation between unabsorbed hard X-ray and high-energy neutrino luminosity has been reported in six active galactic nuclei with the highest individual IceCube significances, linking neutrino production to compact, photon-rich environments near supermassive black holes. We […]
Kavli Affiliate: Claudio Ricci | Summary:A tight correlation between nuclear millimeter (mm) and X-ray emission has recently been found in nearby ($z < 0.01$) and low-Eddington ratio ($rm λ_Edd < 0.1$) radio-quiet (RQ) Active Galactic Nuclei (AGN), suggesting a common origin in the hot X-ray corona. We test this relation in nine more distant RQ […]