The X-ray pulsar XTE J1858+034 observed with NuSTAR and Fermi/GBM: spectral and timing characterization plus a cyclotron line

Abstract

Accreting X-ray pulsars (XRPs) undergo luminous X-ray outbursts during which the spectral and timing behavior of the neutron star can be studied in detail. We analyze a $NuSTAR$ observation of the XRP XTE J1858+034 during its outburst in 2019. The spectrum is fit with a phenomenological, a semi-empirical and a physical spectral model. A candidate cyclotron line is found at $48$keV, implying a magnetic field of $5.4\times 10^{12}$G at the site of emission. This is also supported by the physical best-fit model. We propose an orbital period of about $81$ days based on the visual inspection of the X-ray outbursts recurrence time. Based on $Fermi$ Gamma-ray Burst Monitor data, the standard disk accretion-torque theory allowed us to infer a distance of $10.9\pm 1.0$kpc. Pulse profiles are single-peaked and show a pulsed fraction that is strongly energy-dependent at least up to $40$ keV.

Accepted for publication in ApJ; 9 pages, 2 tables, 7 figures

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Cited by in corpus (4)

• A catalogue of high-mass X-ray binaries in the Galaxy: from the INTEGRAL to the Gaia era
• X-ray pulsar XTE J1858+034: discovery of the cyclotron line and the revised optical identification
• The unaltered pulsar: GRO J1750-27, a super-critical X-ray neutron star that does not blink an eye
• Monte-Carlo simulations on possible collimation effects of outflows to fan-beamed emission of ultraluminous accreting X-ray pulsars