Résumé du preprint Irfu-11-04

Irfu-11-04
Broad components in optical emission lines from the ultra luminous X-Ray source NGC 5408 X-1 (ApJ)
D. Cseh, F. Grise, S. Corbel, P. Kaaret
High-resolution optical spectra of the ultraluminous X-ray source NGC 5408 X-1 show a broad component with a width of ∼750 km/s in the Heii and Hβ lines in addition to the narrow component observed in these lines and [O iii]. Reanalysis of moderate-resolution spectra shows a similar broad component in the Heii line. The broad component likely originates in the ULX system itself, probably in the accretion disk. The central wavelength of the broad Heii line is shifted by 252 47 km/s between the two observations. If this shift represents motion of the compact object, then its mass is less than ∼1800 M⊙.