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    4. Dynamical formation of XRBs with black holes

    Low-mass X-ray binaries with black holes (BH LMXBs) are close binaries consisting of a stellar BH and a low-mass companion star (typically a MS star with M < 1 Msun), in which the MS companion fills its Roche Lobe, and transfers mass onto the BH. The ''classical'' formation channel for such systems involves at least one common envelope (CE) phase that is needed to reduce the separation between the components. However, alternative scenarios have also been proposed.

    In Klencki et al. 2017 we test one of such scenarios, one that was proposed by Michaely & Perets (2016). It involved very wide (~ 500 AU) BH-MS systems in the Galactic field that are subject to random dynamical encounteres with fly-by stars. As a result, the orbits of some of such systems may become very eccentric (e > ~0.99), leading to their circularization by the tidal forces at close pericenter passages. We test this scenario by performing a binary population synthesis (StarTrack code) with a numerical treatment of random stellar encounters (FEWBODY code).

    The following data, as well as the four tested models for tidal circularization, are described in details in Klencki et al. 2017.

    We provide two types of data:
    (i) our candidates for the dynamically formed BH LMXBs (wide BH-MS systems that have become very eccentric and are likely to be circularized)
    They are given in two separate packages:
    a) First package contains BH LMXB candidates originating from binaries with the initial orbital periods log(P/day) < 5.5. It consists of four different files named "X_at_circ.dat" where "X" denotes the assumed model for tidal circularization (see Klencki et al. 2017 for details.)
    b) Second package contains BH LMXB candidates originating from systems with the initial orbital periods of 5.5 < log(P/day) < 8.5. The formation of binary systems with massive primary components and orbits this wide is debatable, and it seems like many of such systems could in fact be triples (see Moe & Di Stefano 2017). The package stored four different files named "X_at_circ_ultrawide.dat" where "X" denotes the assumed model for tidal circularization (see Klencki et al. 2017 for details.)
    The data format of all the 8 datafiles in 2 different packages is as follows:

    column no. || description
    *************************
    1. a [Rsun] -- semimajor axis (1e+50 means a disrupted binary)
    2. e -- eccentricity
    3. Ma [Msun] -- mass of the BH
    4. Mb [Msun] -- mass of the MS companion
    5. age [Myr] -- time that has passed from the ZAMS
    6. birth time [Myr] -- time that has passed from the formation of the
    Galactic disc (assumed 10 Gyr ago) to the binary birth (i.e. ZAMS);
    Constant star formation was assumed.
    7. age at ZA BH-MS [Myr] -- age of the binary at the moment of BH formation
    8. Ra [Rsun] -- gravitational radius of the BH
    9. Rb [Rsun] -- radius of the MS companion
    10. Ka [14] -- stallar type of the primary after Hurley et al. 2002 (this will always be 14)
    11. Kb [0,1] -- stallar type of the secondary after Hurley et al. 2002 (this will always be either 0 or 1)
    12. Vr [km/s] -- radial velocity component in cylindrical coordinates
    13. Vphi [km/s] -- azimutal velocity component in cylindrical coordinates
    14. Vz [km/s] -- vertical velocity component in cylindrical coordinates
    15. X [pc] -- binary position in the Galaxy (X component)
    16. Y [pc] -- binary position in the Galaxy (Y component
    17. Z [pc] -- binary position in the Galaxy (Z component, vertical to the disc)

    The second type of data we provide is:
    (ii) our entire population of BH-MS systems (at the moment just after the BH formation).
    Again, it is split into two separate packages:
    a) "normal_ZA_BHMS.dat" are systems originating from binaries with the initial periods log(P/day) < 5.5. The package stores only one datafile.
    b) "ultra_wide_ZA_BHMS.dat" are systems originating from binaries with the initial periods 5.5 < log(P/dat) < 8.5 (see above and Klencki et al. 2017 for the discussion on why such a population of systems is debatable)
    The data format of both datafiles is as follows:

    column no. || description
    *************************
    1. age [Myr] -- that has passed from the ZAMS
    2. Ma [Msun] -- mass of the BH
    3. Mb [Msun] -- mass of the MS companion
    4. a [Rsun] -- semimajor axis (1e+50 means a disrupted binary)
    5. e -- eccentricity
    6. Vcmx [km/s] -- center of mass velocity (X axis), 0.0 in the case of a disrupted binary
    7. Vcmy [km/s] -- center of mass velocity (Y axis), 0.0 in the case of a disrupted binary
    8. Vcmz [km/s] -- center of mass velocity (Z axis), 0.0 in the case of a disrupted binary
    9. Vnk_raw [km/s] -- raw natal kick velocity (before the reduction due to fallback; Vnk_final = Vnk_raw * (1 - fb))
    10. fb [0-1] -- fraction of mass falling back onto the proto-NS during the BH formation in SN (from 0 to 100%)

    XRBs database files