TY - JOUR
T1 - NICER Discovery that SRGA J144459.2–604207 Is an Accreting Millisecond X-Ray Pulsar
AU - Ng, Mason
AU - Ray, Paul S.
AU - Sanna, Andrea
AU - Strohmayer, Tod E.
AU - Papitto, Alessandro
AU - Illiano, Giulia
AU - Albayati, Arianna C.
AU - Altamirano, Diego
AU - Boztepe, Tuğba
AU - Güver, Tolga
AU - Chakrabarty, Deepto
AU - Arzoumanian, Zaven
AU - Buisson, D. J. K.
AU - Ferrara, Elizabeth C.
AU - Gendreau, Keith C.
AU - Guillot, Sebastien
AU - Hare, Jeremy
AU - Jaisawal, Gaurava K.
AU - Malacaria, Christian
AU - Wolff, Michael T.
PY - 2024
Y1 - 2024
N2 - 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 4 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 > 0.1 M ⊙. 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 ≈ 0.9 keV and power-law photon index Γ ≈ 1.9. Time-resolved burst spectroscopy confirmed the thermonuclear nature of the burst, where an additional blackbody component reached a maximum temperature of nearly kT ≈ 3 keV at the peak of the burst. We discuss the nature of the companion as well as the type I X-ray burst.
AB - 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 4 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 > 0.1 M ⊙. 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 ≈ 0.9 keV and power-law photon index Γ ≈ 1.9. Time-resolved burst spectroscopy confirmed the thermonuclear nature of the burst, where an additional blackbody component reached a maximum temperature of nearly kT ≈ 3 keV at the peak of the burst. We discuss the nature of the companion as well as the type I X-ray burst.
KW - Neutron stars
KW - X-ray transient sources
KW - Millisecond pulsars
KW - X-ray bursts
KW - Low-mass x-ray binary stars
U2 - 10.3847/2041-8213/ad4edb
DO - 10.3847/2041-8213/ad4edb
M3 - Journal article
SN - 2041-8205
VL - 968
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
M1 - L7
ER -