The Changing-look Optical Wind of the Flaring X-Ray Transient Swift J1858.6-0814

T. Muñoz-Darias ... [et al.].

Serie: Trabajos publicados del IAR ; no. 1558

Resumen: We present the discovery of an optical accretion disk wind in the X-raytransient Swift J1858.6-0814. Our 90-spectrum data set, taken with the10.4 m Gran Telescopio Canarias telescope over eight different epochsand across five months, reveals the presence of conspicuous P-Cygprofiles in He I at 5876 Å and Hα. These features are detectedthroughout the entire campaign, albeit their intensity and mainobservational properties are observed to vary on timescales as short as5 minutes. In particular, we observe significant variations in the windvelocity, between a few hundreds and ∼2400$\mathrm{km}\,{{\rm{s}}}[elevado a la]{-1}$ . In agreement with previous reports, ourobservations are characterized by the presence of frequent flares,although the relation between the continuum flux variability and thepresence/absence of wind features is not evident. The reported highactivity of the system at radio waves indicates that the optical wind ofSwift J1858.6-0814 is contemporaneous with the radio jet, as is the casefor the handful of X-ray binary transients that have shown so faroptical P-Cyg profiles. Finally, we compare our results with those ofother sources showing optical accretion disk winds, with emphasis onV404 Cyg and V4641 Sgr, since they also display strong and variableoptical wind features as well as similar flaring behavior.