A New Class of High-Mass X-Ray Binaries: Implications for Core Collapse and Neutron Star Recoil

By E. Pfahl, S. Rappaport, P. Podsiadlowski, H. Spruit. 2001

167 citations recorded by the source corpus.

We investigate an interesting new class of high-mass X-ray binaries (HMXBs) with long orbital periods (Porb > 30 days) and low eccentricities (e ≲ 0.2). The orbital parameters suggest that the neutron stars in these systems did not receive a large impulse, or "kick," at the time of formation. After considering the statistical significance of these new binaries, we develop a self-consistent phenomenological picture wherein the neutron stars born in the observed wide HMXBs receive only a small kick (≲50 km s-1), while neutron stars born in isolation, in the majority of low-mass X-ray binaries, and in many of the well-known HMXBs with Porb ≲ 30 days receive the conventional large kicks, with a mean speed of ~300 km s-1. Assuming that this basic scenario is correct, we discuss a physical process that lends support to our hypothesis, whereby the magnitude of the natal kick to a neutron star born in a binary system depends on the rotation rate of its immediate progenitor following mass transfer—the core of the initially more massive star in the binary. Specifically, the model predicts that rapidly rotating precollapse cores produce neutron stars (NSs) with relatively small kicks, and vice versa for slowly rotating cores. If the envelope of the NS progenitor is removed before it has become deeply convective, then the exposed core is likely to be a rapid rotator. However, if the progenitor becomes highly evolved prior to mass transfer, then a strong magnetic torque, generated by differential rotation between the core and the convective envelope, may cause the core to spin down to the very slow rotation rate of the envelope. Our model has important implications for the dynamics of stellar core collapse, the retention of neutron stars in globular clusters, and the formation of double neutron star systems in the Galaxy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/dcbb5a498341ddb54dca6684fcf7249b6e6216bb

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Citations in the corpus

On the formation and evolution of black hole binaries (2002, background): “Yet, relatively little is understood about the physical origin of these kicks or the conditions under which kicks are developed (see e.g. Janka & Müller 1994; Fryer, Burrows & Benz 1997; Spruit & Phinney 1998; Fryer & Heger 2000; Lai, Chernoff & Cordes 2001; Pfahl et al. 2002).”
A Deep Chandra Survey of the Globular Cluster 47 Tucanae: Catalog of Point Sources (2005, unknown): “This estimate significantly alleviates the long-standing problem of neutron star retention in globular clusters (Pfahl et al. 2002a), especially when combined with our current understanding of neutron star kick distributions (Arzoumanian et al. 2002; Pfahl et al. 2002b).”
Compact Object Modeling with the StarTrack Population Synthesis Code (2005, background): “A number of faint point X-ray sources were discovered in the Galactic center with deep exposures (Wang et al. 2002;Muno et al. 2003), some of which may be explained in terms of wind-fed close binaries (Pfahl et al. 2002a; Bleach 2002; Willems & Kolb 2003; Belczynski & Taam 2004b).”
On the formation history of Galactic double neutron stars (2018, result): “A bimodal SN natal kick distribution is consistent with the findings of other population synthesis studies [see Belczynski et al. (2002) and Pfahl et al. (2002b) as well as with comparison to observations from Schwab et al. (2010), Beniamini & Piran (2016), and Verbunt et al. (2017)], although…”
The effect of the metallicity-specific star formation history on double compact object mergers (2019, background): “If the progenitor either experiences an electron capture supernova or is ultrastripped by an NS companion, we lower the 1D root mean square kick to 30 km s−1 (Pfahl et al. 2002; Podsiadlowski et al. 2004; Tauris et al. 2015, 2017; VignaGómez et al. 2018).”
Formation of Double Neutron Star Systems (2017, methodology): “A similar method is applied when investigating the formation and evolution of Be-HMXBs (Sections 3.2 and 3.4) following the first SN, see e.g. Pfahl et al. (2002) and Knigge et al. (2011).”
Massive runaway and walkaway stars (2018, background): “…(or oxygen-neon-magnesium) cores produces small natal kicks, possibly resulting in a bi-modal kick distribution (Katz 1975; Arzoumanian et al. 2002; Pfahl et al. 2002; Podsiadlowski et al. 2004; Knigge et al. 2011; Beniamini & Piran 2016; Tauris et al. 2017; Verbunt & Cator 2017; Verbunt et al.…”
High-mass X-ray binaries in the Milky Way (2013, background): “2) orbits, suggesting small natal kick (Pfahl et al., 2002), and by thermal excesses with a temperature of about kT ≃ 1 keV for a small emission region (R < 0.”
THE FIRST FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS (2009, background): “Population syntheses (Pfahl et al. 2002) suggest that several percent of the young pulsars are born while retained in massive star binary systems.”
Short-hard gamma-ray bursts (2007, background): “Several works show that this fraction of surviving binaries is unlikely to exceed 2% (e.g., Pfahl et al. , 2002; Lipunov, Postnov & Prokhorov, 1997).”
The Effects of Binary Evolution on the Dynamics of Core Collapse and Neutron Star Kicks (2003, background): “The common-envelope phase was treated in the same way as in Pfahl et al. (2002c).”
A Study of Compact Object Mergers as Short Gamma-Ray Burst Progenitors (2006, background): “…binary populations dominated by roughly equal-mass binaries as suggested by Pinsonneault & Stanek (2006) and low natal kicks proposed by Pfahl et al. (2002) on progenitors of double neutron star systems, and their relevance for both short GRB and gravitational-wave observations…”
The progenitors of compact-object binaries: impact of metallicity, common envelope and natal kicks (2018, background): “Moreover, Pfahl et al. (2002) study a new class of high-mass X-ray binaries with small eccentricities and long orbital periods, which imply a low natal kick velocity (.”
Be/X-ray binaries (2011, background): “Their low eccentricity requires that the neutron star received a much lower kick velocity at birth than previously assumed by current evolutionary models (Pfahl et al. 2002).”
Double neutron stars: merger rates revisited (2017, background): “For instance, Pfahl et al. (2002b) find that the orbital parameters of a certain class of the high-mass X-ray binaries distinguished by relatively long orbital periods (in excess of 30 days) and small eccentricities (e. 0.2) suggest that neutron stars in these systems must have formed with birth…”
Gravitational N-Body Simulations (2003, background): “…required for globular clusters [Hurley, 2000; ‖ A new class of high-mass X-ray binaries has recently been proposed in which masstransferring systems produce rapidly rotating cores, with smaller asymmetrical recoils of the neutron stars [Pfahl, Rappaport & Podsiadlowski, 2002; Pfahl et al., 2002].”
Ultra-stripped supernovae: progenitors and fate (2015, background): “…study to investigate how the final pre-SN cores in ultra-stripped progenitors differ from those of single star of comparable initial mass to confirm whether low-kick NSs preferentially occur in close binaries, as seems to be indicated by observations (Pfahl et al. 2002; Podsiadlowski et al. 2004).”