Dips and eclipses in the X-ray binary Swift J1858.6-0814 observed with NICER

Abstract

We present the discovery of eclipses in the X-ray light curves of the X-ray binary Swift J1858.6-0814. From these, we find an orbital period of $P=76841.3_{-1.4}^{+1.3}$ s ($\approx 21.3$ hours) and an eclipse duration of $t_{\mathrm{ec}}=4098_{-18}^{+17}$ s ($\approx 1.14$ hours). We also find several absorption dips during the pre-eclipse phase. From the eclipse duration to orbital period ratio, the inclination of the binary orbit is constrained to $i>70^{\circ }$. The most likely range for the companion mass suggests that the inclination is likely to be closer to this value than $90^{\circ }$. The eclipses are also consistent with earlier data, in which strong variability ('flares') and the long orbital period prevent clear detection of the period or eclipses. We also find that the bright flares occurred preferentially in the post-eclipse phase of the orbit, likely due to increased thickness at the disc-accretion stream interface preventing flares being visible during the pre-eclipse phase. This supports the notion that variable obscuration is responsible for the unusually strong variability in Swift J1858.6-0814.

12 pages, 11 figures, MNRAS accepted

References in corpus (12)

• A Massive Pulsar in a Compact Relativistic Binary
• A Black Hole Nova Obscured by an Inner Disk Torus
• The Soft State of the Black Hole Transient Source MAXI J1820+070: Emission from the Edge of the Plunge Region?
• Eclipse Timings of the Transient Low Mass X-ray Binary EXO0748-676. IV. The Rossi X-Ray Timing Explorer Eclipses
• A NICER View of a Highly-Absorbed Flare in GRS 1915+105
• NuSTAR observations of the Transient Galactic Black Hole Binary Candidate Swift J1858.6-0814: A New Sibling of V404 Cyg and V4641 Sgr?
• The variable radio counterpart of Swift J1858.6-0814
• Probing large-scale wind structures in Vela X-1 using off-states with INTEGRAL
• Puzzling Blue Dips in the Black Hole Candidate Swift J1357.2-0933, from ULTRACAM, SALT, ATCA, Swift and NuSTAR
• Soft X-ray emission lines in the X-ray binary Swift J1858.6-0814 observed with XMM-Newton-RGS: disc atmosphere or wind?
• XRB continuum fitting with sensitive high energy X-ray detectors
• Possible Magnetic Activity in the Low Mass X-ray Binary EXO 0748-676

Cited by in corpus (11)

• Low-Mass X-ray Binaries
• A persistent ultraviolet outflow from an accreting neutron star binary transient
• A shared accretion instability for black holes and neutron stars
• Discovery of optical and infrared accretion disc wind signatures in the black hole candidate MAXI J1348-630
• Long term radio monitoring of the neutron star X-ray binary Swift J1858.6-0814
• The $\text{False Widow}$ Link Between Neutron Star X-ray Binaries and Spider Pulsars
• X-ray Eclipse Mapping Constrains the Binary Inclination and Mass Ratio of Swift J1858.6-0814
• A rapid optical and X-ray timing study of the neutron star X-ray binary Swift J1858.6-0814
• Accretion disc winds in X-ray binaries
• X-ray Iron absorption line in Swift J1858.6-0814
• The complex spectral behavior of the newly discovered neutron star X-ray binary Swift J1858.6-0814