Neutrino processes in strong magnetic fields and implications for supernova dynamics

Duan, Huaiyu; Qian, Yong Zhong

doi:10.1103/physrevd.69.123004

Cited by 33 publications

(30 citation statements)

References 21 publications

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“…will be significantly reduced in strong fields B 0 ≥ 10 16 G (Duan & Qian 2004 because of the quantum effects. As a result, the mass loss rate from the stellar surface which is proportional to the absorption rates will decrease as well.…”

Section: Application To Grbsmentioning

confidence: 99%

Hyperaccreting Disks Around Magnetars for Gamma-Ray Bursts: Effects of Strong Magnetic Fields

Zhang

Dai

2010

ApJ

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Hyperaccreting neutron star or magnetar disks cooled via neutrino emission can be a candidate of gamma-ray burst (GRB) central engines. The strong field ≥ 10 15 − 10 16 G of a magnetar can play a significant role in affecting the disk properties and even lead to the funnel accretion process. In this paper we investigate the effects of strong fields on the disks around magnetars, and discuss implications of such accreting magnetar systems for GRBs and GRB-like events. We discuss quantum effects of the strong fields on the disk thermodynamics and microphysics due to modifications of the electron distribution and energy in the strong field environment, and use the magnetohydrodynamical conservation equations to describe the behavior of the disk flow coupled with a large scale field, which is generated by the star-disk interaction. If the disk field is open, the disk properties mainly depend on the ratio between |B φ /B z | and Ω/Ω K with B φ and B z being the azimuthal and vertical components of the disk field, Ω and Ω K being the accretion flow angular velocity and Keplerian velocity respectively. On the other hand, the disk properties also depend on the magnetar spin period if the disk field is closed. In general, stronger fields give higher disk densities, pressures, temperatures and neutrino luminosity. Moreover, strong fields will change the electron fraction and degeneracy state significantly. A magnetized disk is always viscously stable outside the Alfvén radius, but will be thermally unstable near the Alfvén radius where the magnetic field plays a more important role in transferring the angular momentum and heating the disk than the viscous stress. The funnel accretion process will be only important for an extremely strong field, which creates a magnetosphere inside the Alfvén radius and truncates the plane disk. Because of higher temperature and more concentrated neutrino emission of a ringlike belt region on the magnetar surface covered by funnel accretion, the neutrino annihilation rate from the accreting magnetar can be much higher than that from -2an accreting neutron star without fields. Furthermore, the neutrino annihilation mechanism which releases the gravitational energy of the surrounding disk and the magnetically-driven pulsar wind which extracts the stellar rotational energy from the magnetar surface can work together to generate and feed an ultrarelativistic jet along the stellar magnetic poles.

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Section: Application To Grbsmentioning

confidence: 99%

Hyperaccreting Disks Around Magnetars for Gamma-Ray Bursts: Effects of Strong Magnetic Fields

Zhang

Dai

2010

ApJ

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“…Given the uncertainties in neutrino radiation transport (e.g. Fischer et al 2012;Roberts et al 2012;Martínez-Pinedo et al 2012), especially in the essentially unexplored case of very rapid rotation (however, see Thompson et al 2005;Thompson 2007) and given the effects of ultra-strong magnetic fields on the microphysics (Lai & Qian 1998;Duan & Qian 2004), we concentrate on comparing the properties rotating protomagnetar winds to the conventional unmagnetized spherical wind case.…”

Section: Thermodynamic Trajectoriesmentioning

confidence: 99%

Neutrino-heated winds from millisecond protomagnetars as sources of the weak r-process

Vlasov

Metzger

Lippuner

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We explore heavy element nucleosynthesis in neutrino-driven winds from rapidly-rotating, strongly magnetized proto-neutron stars ("millisecond proto-magnetars") for which the magnetic dipole is aligned with the rotation axis, and the field is assumed to be a static force-free configuration. We process the proto-magnetar wind trajectories calculated by Vlasov et al. (2014) through the r-process nuclear reaction network SkyNet using contemporary models for the evolution of the wind electron fraction during the proto-neutron star cooling phase. Although we do not find a successful second or third peak r-process for any rotation period P, we show that proto-magnetars with P ∼ 1 − 5 ms produce heavy element abundance distributions that extend to higher nuclear mass number than from otherwise equivalent spherical winds (with the mass fractions of some elements enhanced by factors of ∼ > 100 − 1000). The heaviest elements are synthesized by outflows emerging along flux tubes which graze the closed zone and pass near the equatorial plane outside the light cylinder. Due to dependence of the nucleosynthesis pattern on the magnetic field strength and rotation rate of the proto-neutron star, natural variations in these quantities between core collapse events could contribute to the observed diversity of the abundances of weak r-process nuclei in metal-poor stars. Further diversity, including possibly even a successful third-peak r-process, could be achieved for misaligned rotators with non-zero magnetic inclination with respect to the rotation axis. If proto-magnetars are central engines for GRBs, their relativistic jets should contain a high mass fraction of heavy nuclei of characteristic mass numberĀ ≈ 100, providing a possible source for ultra-high energy cosmic rays comprised of heavy nuclei with an energy spectrum that extends beyond the nominal GZK cut-off for protons or iron nuclei.

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“…It has been suggested repeatedly in the literature that the anisotropic terms in the neutrino dispersion relations can have effects in several astrophysical environments including pulsars [28] and the dynamics of supernovas [30][31][32]. The resonance condition for neutrino oscillations in a magnetic field depends onk · B, and therefore is satisfied at different depths, corresponding to different densities and temperatures.…”

Section: A Dispersion Relationsmentioning

confidence: 99%

“…Our goal is to determine the corrections to the neutrino dispersion relation for a neutrino that propagates in such magnetized stream systems. Beyond the intrinsic interest, the results are of practical application in astrophysical contexts in which the asymmetric neutrino propagation is believed to produce important effects such as the dynamics of pulsars [28,29] and supernovas [30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Neutrino dispersion relation in a magnetized multi-stream matter background

2018

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We study the propagation of a neutrino in a medium that consists of two or more thermal backgrounds of electrons and nucleons moving with some relative velocity, in the presence of a static and homogeneous electromagnetic field. We calculate the neutrino self-energy and dispersion relation using the linear thermal Schwinger propagator, we give the formulas for the dispersion relation and discuss general features of the results obtained, in particular the effects of the stream contributions. As a specific example we discuss in some detail the case of a magnetized two-stream electron, i.e., two electron backgrounds with a relative velocity v in the presence of a magnetic field. For a neutrino propagating with momentum k, in the presence of the stream the neutrino dispersion relation acquires an anisotropic contribution of the formk · v in addition to the well known termk · B, as well as an additional contribution proportional to B · v. We consider the contribution from a nucleon stream background as an example of other possible stream backgrounds, and comment on possible generalizations to take into account the effects of inhomogeneous fields. We explain why a term of the formk · (v × B) does not appear in the dispersion relation in the constant field case, while a term of similar form can appear in the presence of an inhomogeneous field involving its gradient.

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Neutrino processes in strong magnetic fields and implications for supernova dynamics

Cited by 33 publications

References 21 publications

Hyperaccreting Disks Around Magnetars for Gamma-Ray Bursts: Effects of Strong Magnetic Fields

Hyperaccreting Disks Around Magnetars for Gamma-Ray Bursts: Effects of Strong Magnetic Fields

Neutrino-heated winds from millisecond protomagnetars as sources of the weak r-process

Neutrino dispersion relation in a magnetized multi-stream matter background

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