Title: Binary Neutron Stars: Mergers, kilonovae/merger-novae, and their host galaxies

Speaker: 陆由俊

Institute: 中国科学院国家天文台

Host: 张小霞

Time: 2026.6.25 周四 14:30

Location: 物理楼 552

Abstract:

Binary neutron star mergers are premier multi-messenger laboratories, probing relativistic processes in extreme gravitational fields and nuclear-density regimes. Interpreting current and future observations requires physically consistent models that connect binary formation and evolutionary channels to merger dynamics and the emergent electromagnetic counterparts. In this talk, we will review the observational landscape, from Galactic binary neutron star populations to the multi-messenger detections of GW170817 and GW190425, and then present a comprehensive population synthesis model for the formation and evolution of binary neutron stars in the Galaxy and across cosmic time that links progenitor channels to observable merger properties. We will introduce a phenomenological model for kilonovae/merger-novae that captures the key electromagnetic signatures of observed events. We will then use these frameworks to estimate the cosmic BNS merger rate density, predict kilonova observables, and characterize likely host-galaxy environments. The talk will conclude with prospects for upcoming multi-messenger studies of binary neutron star mergers.

Bio:

Youjun Lu is a professor at the University of Chinese Academy of Sciences and a researcher at tthe National Astronomical Observatories of China. He obtained his BSc in physics in 1992 from Anhui Universityand PhD in astrophysics in 1997 from University of Science and Technology of China. His primary research interests include gravitational wave astrophysics, black hole physics, active galactic nuclei, galaxies and cosmology. Currently, he leads the Gravitational Wave Astrophysics Research Group in the National Astronomical Observatories of China.

Related papers:

Chu, Q., Yu, S., & Lu, Y. 2022, “Formation and Evolution of Binary Neutron Stars: Mergers and Their Host Galaxies”, MNRAS, 509, 1557-1586

Chu, Q., Lu, Y., & Yu, S. 2025. “Spin evolution and mass distribution of the Galactic binary neutron stars”, ApJ, 980, 181

Zhao, C., Lu, Y., Chu, Q., & Zhao, W. 2023, “The luminosity functions of kilonovae from binary neutron star mergers under different equation of states”, MNRAS, 522, 912

Zhao, C., Lu, Y., & Zhao, W. 2025, “Detectability of kilonovae from binary neutron star mergers through electromagnetic survey telescopes”, RAA, 25, Issue 3, id.035018

Chen, Z., Zhang, J., Lu, Y., Liu, J., & Zeng, C. 2025, “Constraining Common Envelope Evolution in Binary Neutron Star Formation with Combined Galactic and Gravitational-Wave Observations”, MNRASL, 544, L89-95

Chen, Z., Lu, Y., Ma, H., & Chu, Q. 2025, “Luminosity Functions and detectability of Binary Neutron Star Merger-nova signals with Various Merger Remnants”, MNRAS, 544, 3883-3899