Back to Search Start Over

Drop in the Hard Pulsed Fraction and a Candidate Cyclotron Line in IGR J16320–4751 Seen by NuSTAR.

Drop in the Hard Pulsed Fraction and a Candidate Cyclotron Line in IGR J16320–4751 Seen by NuSTAR.

Authors :
Bodaghee, A.
Chiu, J.-L.
Tomsick, J. A.
Bhalerao, V.
Bottacini, E.
Clavel, M.
Cox, C.
Fürst, F.
Middleton, M. J.
Rahoui, F.
Rodriguez, J.
Romano, P.
Wilms, J.
Source :
Astrophysical Journal. 7/1/2023, Vol. 951 Issue 1, p1-11. 11p.
Publication Year :
2023

Abstract

We report on a timing and spectral analysis of a 50 ks NuSTAR observation of IGR J16320−4751 (= AX J1631.9−4752), a high-mass X-ray binary hosting a slowly rotating neutron star. In this observation from 2015, the spin period was 1308.8 ± 0.4 s giving a period derivative P ̇ ∼ 2 × 10 − 8 s s−1 when compared with the period measured in 2004. In addition, the pulsed fraction decreased as a function of energy, as opposed to the constant trend that was seen previously. This suggests a change in the accretion geometry of the system during the intervening 11 yr. The phase-averaged spectra were fit with the typical model for accreting pulsars: a power law with an exponential cutoff. This left positive residuals at 6.4 keV attributable to the known iron K α line, as well as negative residuals around 14 keV from a candidate cyclotron line detected at a significance of 5 σ. We found no significant differences in the spectral parameters across the spin period, other than the expected changes in flux and component normalizations. A flare lasting around 5 ks was captured during the first half of the observation, where the X-ray emission hardened and the local column density decreased. Finally, the binary orbital period was refined to 8.9912 ± 0.0078 days thanks to Swift/BAT monitoring data from 2005–2022. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0004637X
Volume :
951
Issue :
1
Database :
Academic Search Index
Journal :
Astrophysical Journal
Publication Type :
Academic Journal
Accession number :
164708115
Full Text :
https://doi.org/10.3847/1538-4357/acd541