New Frontier on Neutron Star Structure from Theoretical and Observational Points of View

2015 Fiscal Year Final Research Report

• Project/Area Number: 25287066
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Hatsuda Tetsuo 国立研究開発法人理化学研究所, 仁科加速器研究センター, 主任研究員 (20192700)
• Co-Investigator(Kenkyū-buntansha): NAKATSUKASA Takashi 理化学研究所, 仁科加速器研究センター, 准主任研究員 (40333786)
• Co-Investigator(Renkei-kenkyūsha): TAKATSUKA Tatsuyuki 岩手大学, 人文社会科学部, 特任教授 (50043427) ; NAIDON Pascal 理化学研究所, 仁科加速器研究センター, 専任研究員 (70611979) ; TAMAGAWA Toru 理化学研究所, 仁科加速器研究センター, 准主任研究員 (20333312)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 中性子星 / 高密度物質 / 量子色力学

Outline of Final Research Achievements

Bulk properties of hot and cold neutron stars (such as the radius, mass, temperature/density profile, and sound velocity profile) were studied from the point of view of the hadron-quark crossover. A new equation of state "CRover", which can treat the matter from subnuclear densities to 10 times the nuclear matter density, was formulated Using CRover, possible origin of 2 solar mass neutron stars was studied extensively. The radius of the neutron stars are found to be centered around 12.5km for CRover. We have also studied the hot neutron stars on the basis of a finite temperature CRover: Under the isentropic condition, we found that the internal temperature of the massive neutron stars decrease due to the appearance of the strongly interacting quark matter in the core region. Quantitative analysis on the release of the gravitational energy and the spin-up rate during the course of the cooling stage of the neutron stars by the neutrino emission was also carried out.

Free Research Field

ハドロン物理学