A Chandra X-ray Visionary Project reveals the formation efficiency of high-mass X-ray binaries

X-ray binaries (XRBs) are our main tool for studying the populations of compact objects in galaxies, and the formation and evolution of intermediate and higher mass binary stellar systems. Systematic studies of nearby galaxies have provided initial estimates of the formation rate of XRBs as a function of the star-formation rate (SFR) and stellar mass (M*) of their host galaxies. A strong dependence of the XRB formation rate on age and metallicity has been predicted. The Small Magellanic Cloud (SMC) is the ideal target to study the dependence of the formation efficiency of XRBs on the age of their parent stellar population. In this talk, I will present our measurement of the formation efficiency of the SMC HMXB populations as a function of their age, the most detailed such measurement so far, using data from our deep Chandra X-ray Visionary Project. We find that the HMXB formation efficiency increases as a function of time (following a burst of star formation) up to \textasciitilde 40-60 Myr, and then gradually decreases. The formation efficiency peaks at \textasciitilde 30-40 Myr with average rates of N(HMXB)/SFR$=$339\textasciicircum \textbraceleft $+$78\textbraceright \textunderscore \textbraceleft -83\textbraceright (Mo/yr)\textasciicircum \textbraceleft -1\textbraceright , and N(HMXB)/M*$=$(8.74\textasciicircum \textbraceleft $+$1.0\textbraceright \textunderscore \textbraceleft -0.92\textbraceright )x10\textasciicircum \textbraceleft -6\textbraceright Mo\textasciicircum \textbraceleft -1\textbraceright , in good agreement with previous estimates of the average formation efficiency in the broad \textasciitilde 20-60 Myr age range.