@booklet {41843,
	title = {Time-resolved UV spectroscopy of the accretion disk and wind in a super-Eddington black-hole X-ray transient},
	year = {2019},
	month = {2019/07/1},
	pages = {15984},
	abstract = {In October 2018, Swift announced the discovery of a new Galactic X-ray transient, Swift J1858. Just before Sun-angle constraints rendered the system unobservable, follow-up observations revealed extreme flaring activity, of a kind that has so far only been seen in the famous black hole X-ray binary (BHXRB) V404 Cyg during its 2015 eruption and in V4641 Sgr. The peculiar behaviour of these sources is thought to be a consequence of super-Eddington accretion regime. <P />After several months of unusual strong and rapid flaring in its high-luminosity state, Swift J1858 is currently exhibiting impressive optical P-Cygni profiles, suggesting the pres- ence of a dense and cool wind from the outer accretion disk. The dominant spectroscopic signatures of such winds are actually expected to lie in the far-ultraviolet region, but they are usually inaccessible in black-hole X-ray binaries, due to interstellar reddening. Given its low extinction, Swift J1858 provides us with a rare chance to study the accretion disk wind in the crucial ultraviolet band - an opportunity that was missed in the other two systems. <P />Building on an ongoing multi-wavelength campaign (X-rays: NICER; optical: GTC; radio: VLA \& AMI), we therefore request far- and near-UV time-resolved spectroscopic observations of this system with HST/STIS+COS in order to (a) study its extreme accretion disk wind; (b) test proposed wind driving mechanisms; (c) characterize its UV variability properties and determine the origin of these variations; (d) construct the broad-band SED of the outer accretion disk that dominates the UV flux; and (e) determine the extinction towards the system in order to constrain the mass accretion rate.},
	url = {https://ui.adsabs.harvard.edu/abs/2019hst..prop15984C},
	author = {Castro Segura, Noel and Knigge, Christian and Long, Knox S. and Altamirano, Diego and Armas Padilla, Montserrat and Casares, Jorges and Charles, Philip A. and Degenaar, Nathalie and Fender, Rob and Gandhi, Poshak and Hernandez Santisteban, Juan Venancio and Higginbottom, Nick and Jimenez-Ibarra, Felipe and Matthews, James and Mendez, Mariano and Middleton, Matthew and Munoz Darias, Teo and Ozbey Arabaci, Mehtap and Pahari, Mayukh and Paice, John and Perez-Torres, Miguel and Rhodes, Lauren and Russell, Tom and Scaringi, Simone and Vasilopoulos, Georgios and Vicentelli, Federico and Williams, David Richard Alexander and van den Eijnden, Jakob}
}
