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V404 Cyg, Cyg X-3, V4641 Sgr, and GRS 1915+105 are among the brightest X-raybinaries and display complex behavior in their multiwavelength emission. Apartfrom Cyg X-3, the other three sources have large accretion disks, and there isevidence of a high orbital inclination. Therefore, any large scale geometricalchange in the accretion disk can cause local obscuration events. On the otherhand, Cyg X-3 orbits its Wolf-Rayet companion star inside the heavy stellarwind obscuring the X-ray source. We study here whether the peculiar X-rayspectra observed from all four sources can be explained by local obscurationevents. We fit the source spectra with two physically motivated modelsdescribing either a scenario where all the intrinsic emission is reprocessed inthe surrounding matter or where the emitter is surrounded by a thick torus withvariable opening angle. We show that the X-ray spectra during specific timesare similar in all four sources likely arising from the high-densityenvironments where they are embedded. The fitted models suggest that alow-luminosity phase preceding an intense flaring episode in the 2015 outburstof V404 Cyg is heavily obscured, but intrinsically very bright(super-Eddington) accretion state. Similar spectral evolution to that of V404Cyg is observed from the recent, unusually low-luminosity state of GRS1915+105. The modeling results point to a geometry change in the (outflowing)obscuring matter in V404 Cyg and GRS 1915+105, which is also linked to theradio (jet) evolution. All sources display obscured X-ray emission but withdifferent intrinsic luminosities which points towards different factors causingthe obscuration. This work highlights the importance of taking into account thereprocessing of the X-ray emission in the surrounding medium in the modeling ofthe X-ray spectra that may well take place in other sources as well.

The obscured X-ray binaries V404 Cyg, Cyg X-3, V4641 Sgr, and GRS 1915+105