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arXiv · astro-ph/0610158

A new symbiotic low mass X-ray binary system: 4U 1954+319

F. Mattana·D. Gotz·M. Falanga·F. Senziani·A. De Luca·P. Esposito·P. A. Caraveo
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Abstract

4U 1954+319 was discovered 25 years ago, but only recently has a clear picture of its nature begun to emerge. We present for the first time a broad-band spectrum of the source and a detailed timing study using more than one year of monitoring data. The timing and spectral analysis was done using publicly available Swift, INTEGRAL, BeppoSAX, and RXTE/ASM data in the 0.7-150 keV energy band. The source spectrum is described well by a highly absorbed (N_H~10^23 cm^-2) power law with a high-energy exponential cutoff around 15 keV. An additional black body component is needed below 3 keV to account for a soft excess. The derived ~5 hr periodicity, with a spin-up timescale of ~25 years, could be identified as the neutron star spin period. The spectral and timing characteristics indicate that we are dealing both with the slowest established wind-accreting X-ray pulsar and with the second confirmed member of the emerging class dubbed "symbiotic low mass X-ray binaries" to host a neutron star.

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F. Mattana, D. Gotz, M. Falanga, F. Senziani, A. De Luca, P. Esposito, P. A. Caraveo. 2006-10-05. A new symbiotic low mass X-ray binary system: 4U 1954+319. https://doi.org/10.1051/0004-6361%3A20066154

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