Help Privacy Policy Disclaimer
  Advanced SearchBrowse




Journal Article

A rapid optical and X-ray timing study of the neutron star X-ray binary Swift J1858.6-0814


Clark,  C. J.
Observational Relativity and Cosmology, AEI-Hannover, MPI for Gravitational Physics, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)

(Preprint), 5MB

Supplementary Material (public)
There is no public supplementary material available

Shahbaz, T., Paice, J. A., Rajwade, K. M., Veledina, A., Gandhi., P., Dhillon, V. S., et al. (2023). A rapid optical and X-ray timing study of the neutron star X-ray binary Swift J1858.6-0814. Monthly Notices of the Royal Astronomical Society, 520(1), 542-559. doi:10.1093/mnras/stad163.

Cite as: https://hdl.handle.net/21.11116/0000-000C-D233-D
We present a rapid timing analysis of optical (HiPERCAM and ULTRACAM) and
X-ray (NICER) observations of the X-ray transient Swift J1858.6-0814 during
2018 and 2019. The optical light curves show relatively slow, large amplitude
(~1 mags in g$_s$) `blue' flares (i.e. stronger at shorter wavelengths) on
time-scales of ~minutes as well as fast, small amplitude (~0.1 mag in g$_s$)
`red' flares (i.e. stronger at longer wavelengths) on time-scales of ~seconds.
The `blue' and `red' flares are consistent with X-ray reprocessing and
optically thin synchrotron emission, respectively, similar to what is observed
in other X-ray binaries. The simultaneous optical versus soft- and hard-band
X-ray light curves show time- and energy dependent correlations.
The 2019 March 4 and parts of the June data show a nearly symmetric positive
cross correlations (CCFs) at positive lags consistent with simple X-ray disc
reprocessing. The soft- and hard-band CCFs are similar and can be reproduced if
disc reprocessing dominates in the optical and one component (disc or
synchrotron Comptonization) dominates both the soft and hard X-rays. A part of
the 2019 June data shows a very different CCFs. The observed positive
correlation at negative lag in the soft-band can be reproduced if the optical
synchrotron emission is correlated with the hot flow X-ray emission.
The observed timing properties are in qualitative agreement with the hybrid
inner hot accretion flow model, where the relative role of the different X-ray
and optical components that vary during the course of the outburst, as well as
on shorter time-scales, govern the shape of the optical/X-ray CCFs.