Where Are All the Fallback Disks? Constraints on Propeller Systems

Ekşi, K. Yavuz; Hernquist, Lars; Narayan, Ramesh

doi:10.1086/429915

Cited by 50 publications

(55 citation statements)

References 45 publications

(40 reference statements)

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“…As the authors of the latter hypothesis pointed out, abundant oxygen may be accreted from SN debris. Accretion from a fallback disk of SN debris in the propeller regime has been considered for CCOs by several authors [35,5,36,28,37,38]. We propose that this may be the first phase in the life of those neutron stars born rotating slowly with weak magnetic fields.…”

Section: Accreting And/or Coolingmentioning

confidence: 92%

CCO Pulsars as Anti-Magnetars: Evidence of Neutron Stars Weakly Magnetized at Birth

Gotthelf¹,

Halpern

2008

AIP Conference Proceedings

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Abstract. Our new study of the two central compact object pulsars, PSR J1210−5226 (P = 424 ms) and PSR J1852+0040 (P = 105 ms), leads us to conclude that a weak natal magnetic field shaped their unique observational properties. In the dipole spin-down formalism, the 2-sigma upper limits on their period derivatives, < 2 × 10 −16 for both pulsars, implies surface magnetic field strengths of B s < 3 × 10 11 G and spin periods at birth equal to their present periods to three significant digits. Their X-ray luminosities exceed their respective spin-down luminosities, implying that their thermal spectra are derived from residual cooling and perhaps partly from accretion of supernova debris. For sufficiently weak magnetic fields an accretion disk can penetrate the light cylinder and interact with the magnetosphere while resulting torques on the neutron star remain within the observed limits. We propose the following as the origin of radio-quiet CCOs: the magnetic field, derived from a turbulent dynamo, is weaker if the NS is formed spinning slowly, which enables it to accrete SN debris. Accretion excludes neutron stars born with both B s < 10 11 G and P > 0.1 s from radio pulsar surveys, where such weak fields are not encountered except among very old (> 40 Myr) or recycled pulsars. We predict that these birth properties are common, and may be attributes of the youngest detected neutron star, the CCO in Cassiopeia A, as well as an undetected infant neutron star in the SN 1987A remnant. In view of the far-infrared light echo discovered around Cas A and attributed to an SGR-like outburst, it is especially important to determine via timing whether Cas A hosts a magnetar or not. If not a magnetar, the Cas A NS may instead have undergone a one-time phase transition (corequake) that powered the light echo.

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Section: Accreting And/or Coolingmentioning

confidence: 92%

CCO Pulsars as Anti-Magnetars: Evidence of Neutron Stars Weakly Magnetized at Birth

Gotthelf¹,

Halpern

2008

AIP Conference Proceedings

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“…Different aspects of the propeller regime have been investigated analytically (Davies et al 1979;Li & Wickramasinghe 1997;Lovelace et al 1999;Ikhsanov 2002;Rappaport et al 2004;Ekşi et al 2005) and studied with computer simulations (Wang & Robertson 1985;Romanova et al 2003.…”

mentioning

confidence: 99%

Propeller-driven Outflows and Disk Oscillations

Romanova

Ustyugova

Koldoba

et al. 2005

ApJ

115

193

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We report the discovery of propeller-driven outflows in axisymmetric magnetohydrodynamic simulations of disk accretion to rapidly rotating magnetized stars. Matter outflows in a wide cone and is centrifugally ejected from the inner regions of the disk. Closer to the axis there is a strong, collimated, magnetically dominated outflow of energy and angular momentum carried by the open magnetic field lines from the star. The "efficiency" of the propeller may be very high in the respect that most of the incoming disk matter is expelled from the system in winds. The star spins down rapidly due to the magnetic interaction with the disk through closed field lines and with the corona through open field lines. Diffusive and viscous interaction between the magnetosphere and the disk are important: no outflows were observed for very small values of the diffusivity and viscosity. These simulation results are applicable to the early stages of evolution of classical T Tauri stars (CTTSs) and to different stages of evolution of cataclysmic variables and neutron stars in binary systems. As an example, we show that young rapidly rotating magnetized CTTSs spin down to their present slow rotation in less than 10 6 yr.

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“…whereṀ the mass inflow rate within the disk, K (R m ) is the Keplerian angular velocity at R m , γ is a parameter reflecting the various mechanisms and efficiencies for the propeller effect with its value ranging from −1 to 2 Mori and Ruderman 2003;Eksi and Alpar 2003;Eksi et al 2005;Ertan et al 2006). Note that in (3)Ṁ changes with time.…”

Section: The Modelmentioning

confidence: 99%