超長周期ラジオトランジェントの物理的本質を解明（Researchers Reveal Physical Nature of Ultra-Long-Period Radio Transients）

2025-07-29 中国科学院(CAS)

The death valley of strange dwarf pulsars in the magnetic-field—period diagram (Image bu ZHOU Xia)

＜関連情報＞

• https://english.cas.cn/newsroom/research_news/phys/202508/t20250801_1048948.shtml
• https://iopscience.iop.org/article/10.3847/1538-4357/add268

超長周期ラジオトランジェントの性質：奇妙な矮小パルサーである可能性はあるか？ Nature of Ultralong Period Radio Transients: Could They Be Strange Dwarf Pulsars?

Xia Zhou, Abdusattar Kurban, Wen-Tong Liu, Na Wang, and Ya-Jing Yuan
The Astrophysical Journal  Published: 2025 June 10
DOI:10.3847/1538-4357/add268

Abstract

Ultralong period radio transients (ULPTs), with periods of thousands of seconds, challenge conventional pulsar models. We propose that these isolated sources are strange dwarf (SD) pulsars—compact objects with a strange quark matter core surrounded by a normal matter crust. We develop a theoretical framework for SD pulsars and apply it to four known isolated ULPTs: GLEAM-X J162759.5–523504.3, GPM J1839–10, ASKAP J1832–0911 (DART J1832–0911), and ASKAP J193505.1+214841.0 (ASKAP J1935+2148). Our analysis shows that SD pulsars naturally explain both the ultralong periods and coherent radio emission of these sources, which occupy a distinctive region in the magnetic field–period diagram. We find that these objects have surface magnetic fields ranging from 10⁶ to 10¹⁰ G, with a consistent lower bound near 10⁶ G that suggests a fundamental threshold for pair production in these magnetospheres. Their radio emission efficiencies (η_rad,rot ≈ 10⁻⁴–10⁻²) align with those of normal pulsars despite their extreme periods. ASKAP J1935+2148 represents a boundary case, positioned below the theoretical death line but still radio active, offering crucial insights into emission mechanisms at extreme periods. The observed X-ray properties of ASKAP J1832–0911, including its two-component spectrum and synchronous X-ray/radio variability, strongly support the SD pulsar model. This framework provides a unified explanation for ULPTs and has significant implications for understanding exotic dense matter in compact objects.