Natal kicks received by stellar-mass black holes

The formation of stellar mass black-holes (BHs) is still very uncertain. Two main uncertainties are the amount of mass ejected in the supernova event (if any) and the magnitude of the natal kick the black hole receives at birth (if any). Repetto et al. 2012, studying the position of Galactic X-ray binaries containing black holes, found evidence for black holes receiving high natal kicks at birth. In this work, we extend that previous study, taking into account the binary evolution of the sources as well. We study the observed Galactic sample of short-period black-hole low-mass X-ray binaries in order to put constraints on the natal kick and mass ejected at BH formation. Short-period BH-LMXBs are compact binaries consisting of a low-mass star orbiting a black hole in a period less than 1 day. We trace their binary evolution backwards in time, from the current state of mass-transfer to the moment the BH was formed, and we add the extra information on the kinematics of the binaries.

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