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Abstract Black hole–neutron star binaries are of interest in many ways: they are intrinsically transient, radiate gravitational waves detectable by LIGO, and may produceγ-ray bursts. Although it has long been assumed that their late-stage orbital evolution is driven entirely by gravitational wave emission, we show here that in certain circumstances, mass transfer from the neutron star onto the black hole can both alter the binary's orbital evolution and significantly reduce the neutron star's mass: when the fraction of its mass transferred per orbit is ≳10−2, the neutron star's mass diminishes by order unity, leading to mergers in which the neutron star mass is exceptionally small. The mass transfer creates a gas disk around the black holebeforemerger that can be comparable in mass to the debris remaining after merger, i.e., ~0.1M⊙. These processes are most important when the initial neutron star–black hole mass ratioqis in the range ≈0.2–0.8, the orbital semimajor axis is 40 ≲ a0/rg ≲ 300 (rg ≡ GMBH/c2), and the eccentricity is large ate0 ≳ 0.8. Systems of this sort may be generated through the dynamical evolution of a triple system, as well as by other means.
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Jump-starting Relativistic Flows and the M87 Jet
Abstract We point out the dominant importance of plasma injection effects of relativistic winds from pulsars and black holes. We demonstrate that outside the light cylinder, the magnetically dominated outflows sliding along the helical magnetic field move nearly radially with very large Lorentz factors,γ0≫ 1, imprinted into the flow during pair production within the gaps. Only at larger distances,r≥γ0(c/Ω), does MHD acceleration Γ ∝rtake over. As a result, Blandford–Znajek (BZ)-driven outflows produce spine-brightened images. The best-resolved case of the jet in M87 shows both edge-brightened features, as well as weaker spine-brightened features. Only the spine-brightened component can be BZ driven/originate from the black hole's magnetosphere.
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- Award ID(s):
- 1903332
- PAR ID:
- 10550113
- Publisher / Repository:
- Astrophysical Journal
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 962
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 18
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/1538-4357/ad0ecc
