학술논문
NICER Discovery that SRGA J144459.2-604207 is an Accreting Millisecond X-ray Pulsar
Document Type
Working Paper
Author
Ng, Mason; Ray, Paul S.; Sanna, Andrea; Strohmayer, Tod E.; Papitto, Alessandro; Illiano, Giulia; Albayati, Arianna C.; Altamirano, Diego; Boztepe, Tuğba; Güver, Tolga; Chakrabarty, Deepto; Arzoumanian, Zaven; Buisson, D. J. K.; Ferrara, Elizabeth C.; Gendreau, Keith C.; Guillot, Sebastien; Hare, Jeremy; Jaisawal, Gaurava K.; Malacaria, Christian; Wolff, Michael T.
Source
Subject
Language
Abstract
We present the discovery, with the Neutron Star Interior Composition Explorer (NICER), that SRGA J144459.2-604207 is a 447.9 Hz accreting millisecond X-ray pulsar (AMXP), which underwent a four-week long outburst starting on 2024 February 15. The AMXP resides in a 5.22 hr binary, orbiting a low-mass companion donor with $M_d>0.1M_\odot$. We report on the temporal and spectral properties from NICER observations during the early days of the outburst, from 2024 February 21 through 2024 February 23, during which NICER also detected a type-I X-ray burst that exhibited a plateau lasting ~6 s. The spectra of the persistent emission were well described by an absorbed thermal blackbody and power-law model, with blackbody temperature $kT\approx0.9{\rm\,keV}$ and power-law photon index $\Gamma\approx1.9$. Time-resolved burst spectroscopy confirmed the thermonuclear nature of the burst, where an additional blackbody component reached a maximum temperature of nearly $kT\approx3{\rm\,keV}$ at the peak of the burst. We discuss the nature of the companion as well as the type-I X-ray burst.
Comment: 11 pages, 4 figures, 3 tables. Accepted by ApJL
Comment: 11 pages, 4 figures, 3 tables. Accepted by ApJL