Understanding Compact Object Formation and Natal Kicks. Ii. The Case of Xte J1118 + 480

Abstract

In recent years, an increasing number of proper motions have been measured for Galactic X-ray binaries. When supplemented with accurate determinations of the component masses, orbital period, and donor effective temperature, these kinematical constraints harbor a wealth of information on the system's past evolution. Here, we consider all this available information to reconstruct the full evolutionary history of the black hole X-ray binary XTE J1118+480, assuming that the system originated in the Galactic disk and the donor has solar metallicity. This analysis accounts for four evolutionary phases: mass transfer through the ongoing X-ray phase, tidal evolution before the onset of Roche-lobe overflow, motion through the Galactic potential after the formation of the black hole, and binary orbital dynamics due to explosive mass loss and possibly a black hole natal kick at the time of core collapse. We find that right after black hole formation, the system consists of a ≃ 6.0 − 10.0 M ⊙ black hole and a ≃ 1.0 − 1.6 M ⊙ main-sequence star. We also find that that an asymmetric natal kick is not only plausible but required for the formation of this system, and derive a lower and upper limit on the black hole natal kick velocity magnitude of 80 km s −1 and 310 km s −1 , respectively.

Estimates of black hole natal kick velocities from observations of low-mass X-ray binaries

“…This calculation for XTE J1118+480, which yields a minimal birth kick of 80 km/s (Fragos et al 2009), provides a firm lower bound on the maximum black hole kick.…”

Probing Electron-Capture Supernovae: X-Ray Binaries in Starbursts

“…We set the maximum NS mass at 2.5 M and draw natal kicks for "standard" ICC-SN events from a single Maxwellian kick distribution with mean of 265 km s −1 (Hobbs et al 2005). Kicks are potentially associated with BH formation as well (see Fragos et al (2009) for the strongest evidence at present for a BH kick). For BHs formed through SNe explosions and subsequent fallback of material, we multiply the normal Maxwellian kick by the fraction of the SN ejecta which is ultimately lost from the system.…”

Displacement of X-ray binaries: constraints on the natal kicks

“…Some systems seem to require no or at most a small natal BH kick (e.g., Cygnus X-1; Nelemans et al 1999;GRS 1915+105;Dhawan et al 2007; and Cygnus X-1; Wong et al 2010); while others prefer a more appreciable one (e.g., GRO J1655-40; Willems et al 2005;and XTE J1118+480;Remillard et al 2000;Mirabel et al 2001;Gualandris et al 2005;Fragos et al 2009). These conclusions are mainly based on detailed evolutionary modeling for the observed individuals.…”