NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1

Keek, L ; Arzoumanian, Z ; Bult, P ; Cackett, E M ; Chakrabarty, D ; Chenevez, J ; Fabian, A C ; Gendreau, K C ; Guillot, S ; Güver, T(İstanbul Üniversitesi, İstanbul, Turkey)

关键词: ACCRETION DISKS;    AUGMENTATION;    COMPANION STARS;    CORONAS;    DOPPLER EFFECT;    DRAG;    EMISSION SPECTRA;    HYDROGEN;    IRRADIATION;    NEUTRON STARS;    PHOTOIONIZATION;    RECLAMATION;    SPECTRAL THEORY;    X RAY BINARIES;   

RP-ID  :  GSFC-E-DAA-TN66162

学科分类：天体物理学

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Accretion disks around neutron stars regularly undergo sudden strong irradiation by Type I X-raybursts powered by unstable thermonuclear burning on the stellar surface. We investigate the impacton the disk during one of the first X-ray burst observations with the Neutron Star Interior CompositionExplorer (NICER) on the International Space Station. The burst is seen from Aql X-1 during the hardspectral state. In addition to thermal emission from the neutron star, the burst spectrum exhibits anexcess of soft X-ray photons below 1 keV, where NICER's sensitivity peaks. We interpret the excessas a combination of reprocessing by the strongly photoionized disk and enhancement of the pre-burstpersistent flux, possibly due to Poynting Robertson drag or coronal reprocessing. This is the firstsuch detection for a short sub-Eddington burst. As these bursts are observed frequently, NICER willbe able to study how X-ray bursts affect the disk and corona for a range of accreting neutron starsystems and disk states.