FORMATION OF BLACK WIDOWS AND REDBACKS—TWO DISTINCT POPULATIONS OF ECLIPSING BINARY MILLISECOND PULSARS

Eclipsing binary millisecond pulsars (MSPs; the so-called black widows and redbacks) can provide important information about accretion history, pulsar irradiation of their companion stars, and the evolutionary link between accreting X-ray pulsars and isolated MSPs. However, the formation of such sys...

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Published inThe Astrophysical journal Vol. 775; no. 1; pp. 1 - 6
Main Authors Chen, Hai-Liang, Chen, Xuefei, Tauris, Thomas M, Han, Zhanwen
Format Journal Article
LanguageEnglish
Published United States 20.09.2013
Subjects
Accretion
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
ECLIPSE
Eclipsing binary stars
EFFICIENCY
EVAPORATION
Evolution
Formations
IRRADIATION
M CODES
Millisecond pulsars
Populations
Progenitors (astrophysics)
PULSARS
STAR ACCRETION
STAR EVOLUTION
STELLAR WINDS
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Summary:Eclipsing binary millisecond pulsars (MSPs; the so-called black widows and redbacks) can provide important information about accretion history, pulsar irradiation of their companion stars, and the evolutionary link between accreting X-ray pulsars and isolated MSPs. However, the formation of such systems is not well understood, nor the difference in progenitor evolution between the two populations of black widows and redbacks. Whereas both populations have orbital periods between 0.1 and 1.0 days, their companion masses differ by an order of magnitude. In this paper, we investigate the formation of these systems via the evolution of converging low-mass X-ray binaries by employing the MESA stellar evolution code. Our results confirm that one can explain the formation of most of these eclipsing binary MSPs using this scenario. More notably, we find that the determining factor for producing either black widows or redbacks is the efficiency of the irradiation process, such that the redbacks absorb a larger fraction of the emitted spin-down energy of the radio pulsar (resulting in more efficient mass loss via evaporation) compared to that of the black widow systems. We argue that geometric effects (beaming) are responsible for the strong bimodality of these two populations. Finally, we conclude that redback systems do not evolve into black widow systems with time.
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/775/1/27