Extinct radio pulsars as a source of subrelativistic positrons

ABSTRACT Extinct radio pulsars, in which stationary, self-sustaining generation of a relativistic electron–positron plasma becomes impossible when rotation brakes down, can be sources of a subrelativistic flux of positrons and electrons. We assume that the observed excess of positrons in the bulge and the disc of the Galaxy is associated with these old neutron stars. The production of pairs in their magnetospheres occurs due to one-photon absorption of gamma quanta of the Galactic and extragalactic backgrounds. The cascade process of plasma production leads to the flux of positrons escaping from the open magnetosphere ≃3 × 1034 s−1. The total flux of positrons from all old Galactic neutron stars with rotational periods 1.5 < P < 35 s is ≃3 × 1043 s−1. The energy of positrons is less than ≃10 MeV. The estimated characteristics satisfy the requirements for the positron source responsible for the 511-keV Galactic annihilation line.

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Energy Loss of Radio Pulsars

International Astronomical Union Colloquium ◽

10.1017/s0252921100060024 ◽

2000 ◽

Vol 177 ◽

pp. 371-374

Author(s):

V.S. Beskin ◽

R.R. Rafikov

Keyword(s):

Boundary Layer ◽

Energy Loss ◽

Electric Current ◽

Relativistic Electron ◽

Electromagnetic Energy ◽

Radio Pulsars ◽

Electron Positron ◽

Light Surface ◽

Almost All ◽

Two Fluid

AbstractTwo-fluid effects on the radial 2D outflow of relativistic electron–positron plasma are considered. It is shown that when the longitudinal electric current is smaller than the Goldreich–Julian one, almost all electromagnetic energy is transformed into the energy of particles in the narrow boundary layer near the light surface |E| = |B|.

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Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge

Advances in High Energy Physics ◽

10.1155/2014/869425 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 11

Author(s):

J.-R. Cudell ◽

M. Yu. Khlopov ◽

Q. Wallemacq

Keyword(s):

Dark Matter ◽

Positron Annihilation ◽

Cross Section ◽

Ground State ◽

Galactic Bulge ◽

Annihilation Line ◽

Electron Positron ◽

The Galaxy ◽

Stable Particles ◽

Electron Positron Pair

It was recently proposed that stable particles of charge −2,O--, can exist and constitute dark matter after they bind with primordial helium in O-helium (OHe) atoms. We study here in detail the possibility that this model provides an explanation for the excess of gamma radiation in the positron-annihilation line from the galactic bulge observed by INTEGRAL. This explanation assumes that OHe, excited to a 2s state through collisions in the central part of the Galaxy, deexcites to its ground state via anE0transition, emitting an electron-positron pair. The cross-section for OHe collisions with excitation to 2s level is calculated and it is shown that the rate of such excitations in the galactic bulge strongly depends not only on the mass of O-helium, which is determined by the mass ofO--, but also on the density and velocity distribution of dark matter. Given the astrophysical uncertainties on these distributions, this mechanism constrains theO--mass to lie in two possible regions. One of these is reachable in the experimental searches for stable multicharged particles at the LHC.

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Millisecond Pulsar Formation and Evolution

Symposium - International Astronomical Union ◽

10.1017/s0074180900161017 ◽

1987 ◽

Vol 125 ◽

pp. 393-406 ◽

Cited By ~ 1

Author(s):

E.P.J. van den Heuvel

Keyword(s):

Neutron Stars ◽

Millisecond Pulsar ◽

Radio Pulsars ◽

X Ray ◽

Binary Pulsars ◽

The Galaxy ◽

History Of ◽

Low Mass ◽

Formation And Evolution ◽

X Ray Binaries

The evolutionary history of binary radio pulsars, including the two millisecond binary pulsars, is reviewed. There are two groups of binary pulsars, the PSR 1913+16-group, which descended from massive X-ray binaries, and the PSR 1953+29-group, which descended from fairly wide low-mass X-ray binaries. The neutron stars in the second group probably formed by the accretion-induced collapse of a massive white dwarf. The companion stars in both groups of systems are expected to be dead stars, i.e. white dwarfs or neutron stars.The large total number of millisecond binary pulsars in the galaxy (∼ 104), indicates that magnetic fields of neutron stars do not decay below a value of order 109 G. Possible explanations for this phenomenon are discussed.Coalescence with a close degenerate companion provides a viable model for the formation of the single millisecond pulsar.

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Binary Pulsars: Observations and Implications

Symposium - International Astronomical Union ◽

10.1017/s0074180900161005 ◽

1987 ◽

Vol 125 ◽

pp. 383-392

Author(s):

J. H. Taylor

Keyword(s):

Neutron Stars ◽

Binary Systems ◽

Radio Pulsars ◽

X Ray ◽

Orbital Parameters ◽

Binary Pulsars ◽

Essential Parameter ◽

Timing Data ◽

The Galaxy ◽

Pulse Timing

The Galaxy contains a large number of neutron stars in gravitation-ally bound binary systems. Among the most fruitful of these to study have been the binary radio pulsars, of which seven are now known. Unlike the “accretion-powered” neutron stars located in mass-exchanging X-ray binary systems, the “rotation-powered” binary radio pulsars are found in dynamically simple, clean systems in which both stellar components have already completed their nuclear evolution, thereby shedding their atmospheres and most of their mass. In such circumstances the orbital parameters of the system and the rotational parameters of the pulsar can be determined with high precision from analysis of pulse timing data. These measurements constrain the component masses and yield an estimate of the pulsar's magnetic dipole moment, which turns out to be an essential parameter in understanding the evolution of the systems. In this paper I review the known facts concerning binary pulsars, and then briefly discuss some implications for our understanding of the place of neutron stars in stellar evolution.

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Photon Upconversion through a Cascade Process of Two-Photon Absorption in CsPbBr3 and Triplet-Triplet Annihilation in Organic Molecules

10.29363/nanoge.iperop.2019.026 ◽

2018 ◽

Author(s):

Akinori Saeki

Keyword(s):

Organic Molecules ◽

Photon Absorption ◽

Cascade Process ◽

Two Photon Absorption ◽

Two Photon ◽

Triplet Triplet Annihilation

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A New View on Young Pulsars in Supernova Remnants: Slow, Radio-quiet & X-ray Bright

International Astronomical Union Colloquium ◽

10.1017/s0252921100061017 ◽

2000 ◽

Vol 177 ◽

pp. 699-702 ◽

Cited By ~ 2

Author(s):

E. V. Gotthelf ◽

G. Vasisht

Keyword(s):

Magnetic Field ◽

Neutron Stars ◽

Supernova Remnants ◽

Simple Explanation ◽

Crab Pulsar ◽

Radio Pulsars ◽

Substantial Fraction ◽

Subsequent Evolution ◽

X Ray ◽

Field Decay

AbstractWe propose a simple explanation for the apparent dearth of radio pulsars associated with young supernova remnants (SNRs). Recent X-ray observations of young remnants have revealed slowly rotating (P∼ 10s) central pulsars with pulsed emission above 2 keV, lacking in detectable radio emission. Some of these objects apparently have enormous magnetic fields, evolving in a manner distinct from the Crab pulsar. We argue that these X-ray pulsars can account for a substantial fraction of the long sought after neutron stars in SNRs and that Crab-like pulsars are perhaps the rarer, but more highly visible example of these stellar embers. Magnetic field decay likely accounts for their high X-ray luminosity, which cannot be explained as rotational energy loss, as for the Crab-like pulsars. We suggest that the natal magnetic field strength of these objects control their subsequent evolution. There are currently almost a dozen slow X-ray pulsars associated with young SNRs. Remarkably, these objects, taken together, represent at least half of the confirmed pulsars in supernova remnants. This being the case, these pulsars must be the progenitors of a vast population of previously unrecognized neutron stars.

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