1640006

We request Target of Opportunity (ToO) observations to study a (new or known) Black Hole (BH) transient in two distinct spectral states (200 ks each or a minimum of a full orbit) simultaneously with two XMM-Newton observations (10 ks each) and multi-wavelength campaigns. BH transients sporadically appear and display complex spectra and fast time-variability properties. Our goal is to witness their evolutions and connections to radio/Opt./NIR properties to understand the accretion/ejection processes. Using INTEGRAL simultaneously with XMM-Newton and ground-based facilities we aim to measure in detail the spectral variations (curvature and breaks of the Compton medium) and correlate them with disc and jet evolutions. With an unprecedented high-energy sensitivity in any sky region INTEGRAL allows us to i) disentangle the different contributions to the broadband continuum emission (strength of the reflection hump test of thermal Comptonization vs hybrid models) ii) shed light on the nature of the additional parameter to the accretion rate suspected to drive state changes and iii) reveal the relationship between the hard X/soft gamma-ray emission jets and their evolution with time. The different physical components (star accretion disc winds hot inner flow compact object corona relativistic jet) emit and absorb radiations at different frequencies and are influenced by the others. Such multiwavelength observations are the most fruitful way forward to constrain distinct models as we have showing during many such observational campaign the last was performed on the exceptional June 2015 outburst of V404 Cygni. [truncated! Please see actual data for full text]