scholarly journals Rotating neutron stars, pulsars, and cosmic X-ray sources

1970 ◽  
Vol 37 ◽  
pp. 202-207
Author(s):  
Wallace H. Tucker
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Mass Loss ◽  
Magnetic Energy ◽  
Crab Nebula ◽  
Mass Loss Rate ◽  
Angular Diameter ◽  
Relativistic Electrons ◽  
X Ray ◽  
Extended Sources

The purpose of this paper is to discuss the relationship between rotating neutron stars, pulsars, and cosmic X-ray sources. The latter may be divided into at least two classes: the sources with large angular diameters, such as the Crab Nebula, and those with small angular diameter, such as Sco X-1. I submit that a basic model, consisting of a rotating neutron star losing mass in the presence of a large magnetic field, can account for both types of X-ray source. The extended sources represent the case where the energy in the ‘neutron-star wind’ is greater than the magnetic energy. The streaming protons and electrons deposit their energy far out into the nebula in a shock transition region. The relativistic electrons responsible for the extended sources of radio, optical and X-ray emission are produced in the transfer of energy between the protons and electrons in the shock wave, and by magnetic pumping in hydromagnetic waves which are generated by fluctuations in the mass loss rate. The compact sources, such as Sco X-1, represent the other extreme where the magnetic energy dominates, so that no mass loss occurs. The particles are then accelerated and radiate in radiation belts around the neutron star, resulting in a source with a small angular diameter.

scholarly journals Physical Processes and Parameters in the Magnetosphere of NP 0532

1971 ◽  
Vol 46 ◽  
pp. 394-406
Author(s):  
F. Pacini
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Supernova Remnants ◽  
Crab Nebula ◽  
General Relation ◽  
Energy Generation ◽  
Main Pulse ◽  
Physical Processes ◽  
X Ray ◽  
The Crab Nebula

The Crab Nebula pulsar conforms to the model of a rotating magnetised neutron star in the rate of energy generation and the exponent of the rotation law.It is suggested that the main pulse is due to electrons and the precursor to protons. Both must radiate in coherent bunches. Optical and X-ray radiation is by the synchrotron process.The wisps observed in the Nebula may represent the release of an instability storing about 1043 erg and 1047–48 particles.Finally, some considerations are made about the general relation between supernova remnants and rotating neutron stars.

scholarly journals Superfluidity in Neutron Stars

1974 ◽  
Vol 53 ◽  
pp. 151-165
Author(s):  
George Greenstein
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Crab Nebula ◽  
Crab Pulsar ◽  
X Ray ◽  
Effects Of Rotation ◽  
The Crab Nebula

We present a short Cook's tour of the possible effects of rotation coupled with superfluid properties of neutron star interiors. A suggestion is made to take advantage of forthcoming lunar occultations of the Crab Nebula in order to search for blackbody X-ray emission from the Crab pulsar.

Do neutron stars produce jets?

1986 ◽  
Vol 64 (4) ◽  
pp. 474-478 ◽  
Author(s):  
Eric D. Feigelson
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Supernova Remnants ◽  
Binary Systems ◽  
Crab Nebula ◽  
Compact Object ◽  
Radio Pulsars ◽  
X Ray ◽  
The Crab Nebula ◽  
X Ray Binaries

The evidence for jets emanating from neutron stars is reviewed. Isolated radio pulsars do not appear to produce collimated outflows. A few supernova remnants, notably the Crab nebula, exhibit jetlike protrusions at their outer boundaries. These are probably "blowouts" of the plasma in the remnant rather than true jets from a neutron star. However, several cases of degenerate stars in X-ray binary systems do make jets. SS433 has twin precessing jets moving outward at v ~ 0.26c, and Sco X-1 has radio lobes with v ~ 0.0001c. Cyg X-3 appears to eject synchrotron plasmoids at high velocities. Other X-ray binaries associated with variable radio sources are discussed; some are interesting candidates for collimated outflow. G109.1-1.0 is an X-ray binary in a supernova remnant that may have radio or X-ray jets. It is not clear in all these cases, however, that the compact object is a neutron star and not a black hole or white dwarf.A tentative conclusion is reached that isolated neutron stars do not produce jets, but degenerate stars in accreting binary systems can. This suggests that the presence of an accretion disk, rather than the characteristics of an isolated pulsar's dipole magnetosphere, is critical in making collimated outflows.

scholarly journals Super-Eddington accretion discs with advection and outflows around magnetized neutron stars

2019 ◽  
Vol 626 ◽  
pp. A18 ◽  
Author(s):  
Anna Chashkina ◽  
Galina Lipunova ◽  
Pavel Abolmasov ◽  
Juri Poutanen
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Mass Loss ◽  
Accretion Rate ◽  
Accretion Disc ◽  
Accretion Discs ◽  
X Ray ◽  
Radial Profiles ◽  
X Ray Binaries ◽  
Eddington Limit

We present a model for a super-Eddington accretion disc around a magnetized neutron star taking into account advection of heat and the mass loss by the wind. The model is semi-analytical and predicts radial profiles of all the basic physical characteristics of the accretion disc. The magnetospheric radius is found as an eigenvalue of the problem. When the inner disc is in radiation-pressure-dominated regime but does not reach its local Eddington limit, advection is mild, and the radius of the magnetosphere depends weakly on the accretion rate. Once it approaches the local Eddington limit the disc becomes advection-dominated, and the scaling for the magnetospheric radius with the mass accretion rate is similar to the classical Alfvén relation. Allowing for the mass loss in a wind leads to an increase in the magnetospheric radius. Our model can be applied to a wide variety of magnetized neutron stars accreting close to or above their Eddington limits: ultra-luminous X-ray pulsars, Be/X-ray binaries in outbursts, and other systems. In the context of our model we discuss the observational properties of NGC 5907 X-1, the brightest ultra-luminous pulsar currently known, and NGC 300 ULX1, which is apparently a Be/X-ray binary experiencing a very bright super-Eddington outburst.

scholarly journals Neutron Star Powered Accelerators

2000 ◽  
Vol 195 ◽  
pp. 463-471
Author(s):  
M. Ruderman
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gamma Ray ◽  
Crab Nebula ◽  
Surrounding Medium ◽  
Radio Pulsars ◽  
X Ray ◽  
Energetic Radiation ◽  
Γ Ray ◽  
Star Binary

Neutron stars can be the underlying source of energetic particle acceleration in several ways. The huge gravitational-collapse energy released in their birth, or the violent fusion at the end of the life of a neutron-star binary, is the energy source for an accelerator in the surrounding medium far from the star. This would be the case for: (a) cosmic rays from supernova explosions with neutron-star remnants; (b) energetic radiation from “plerions” around young neutron stars (e.g., the Crab Nebula, see Pacini 2000); and (c) “afterglow” and γ-rays of cosmic Gamma-Ray Burst (GRB) sources with possible neutron-star central engines. Particles can also be energetically accelerated if a neutron star's gravitational pull sustains an accretion disk fed by a companion. Examples are accretion-powered X-ray pulsars and low-mass X-ray binaries. A third family of “neutron-star powered” accelerators consists of those which do not depend on the surrounding environment. These are the accelerators which must exist in the magnetospheres of many solitary, spinning-down, magnetized neutron stars (“spinsters”) when they are observed as radio pulsars or γ-ray pulsars. (There are probably ~ 103 dead radio pulsars for each one in our Galaxy that is still active; the ratio for γ-ray pulsars may well exceed 105.)

DO YOUNG NEUTRON STARS WHICH SHOW THEMSELVES AS AXPs AND SGRs ACCRETE?

2003 ◽  
Vol 12 (05) ◽  
pp. 825-831 ◽  
Author(s):  
S. O. TAGIEVA ◽  
E. YAZGAN ◽  
A. ANKAY
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Supernova Explosion ◽  
X Ray ◽  
X Ray Binaries

We examined the fall-back disk models, and in general accretion, proposed to explain the properties of AXPs and SGRs. We checked the possibility of some gas remaining around the neutron star after a supernova explosion. We also compared AXPs and SGRs with the X-ray pulsars in X-ray binaries. We conclude that the existing models of accretion from a fall-back disk are insufficient to explain the nature of AXPs and SGRs.

scholarly journals Radio Supernovae as Direct Evidence of Stellar Evolution in Real Time

1998 ◽  
Vol 11 (1) ◽  
pp. 367-367
Author(s):  
S.D. Van Dyk ◽  
M.J. Montes ◽  
K.W. Weiler ◽  
R.A. Sramek ◽  
N. Panagia
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Loss Rate ◽  
Direct Evidence ◽  
Mass Loss Rate ◽  
X Ray ◽  
Stringent Constraint ◽  
Clear Change ◽  
Late Stages ◽  
Circumstellar Environment

The radio emission from supernovae provides a direct probe of a supernova’s circumstellar environment, which presumably was established by mass-loss episodes in the late stages of the progenitor’s presupernova evolution. The observed synchrotron emission is generated by the SN shock interacting with the relatively high-density circumstellar medium which has been fully ionized and heated by the initial UV/X-ray flash. The study of radio supernovae therefore provides many clues to and constraints on stellar evolution. We will present the recent results on several cases, including SN 1980K, whose recent abrupt decline provides us with a stringent constraint on the progenitor’s initial mass; SN 1993J, for which the profile of the wind matter supports the picture of the progenitor’s evolution in an interacting binary system; and SN 1979C, where a clear change in presupernova mass-loss rate occurred about 104 years before explosion. Other examples, such as SNe 19941 and 1996cb, will also be discussed.

scholarly journals On the Nature of the Emission of the Crab Nebula

1958 ◽  
Vol 8 ◽  
pp. 1047-1047
Author(s):  
I. S. Shklovsky
Keyword(s):  
Field Strength ◽  
Magnetic Energy ◽  
Crab Nebula ◽  
Central Star ◽  
Emission Sources ◽  
Relativistic Electrons ◽  
Internal Motions ◽  
The Crab Nebula ◽  
Lines Of Force

The emission of the Crab Nebula is perhaps connected with the internal motions of the gas. As shown by the observations, the power of the emission sources differs by some hundred times in different points of the amorphous mass (“wisps” and other details). Oort and Walraven believe the “wisps” to be condensations of relativistic electrons ejected from the central star. However, there are some other variable details elsewhere in the nebula (as described by Lampland, and Oort and Walraven).Oort and Walraven's hypothesis met some important difficulties: (a) the direction of the magnetic lines in this region of the nebula is perpendicular to the wisp's velocity; (b) the dimension of the wisp is about three light months, while it appears during a month and faster, so that the relativistic electrons moving along the lines of force have no time to spread along the wisp; and (c) if the strength is not changing, the energy of the relativistic electrons in the wisp must be some hundred times greater than the density of the magnetic energy, consequently the field strength must grow in the wisp to keep the electrons in the volume.

scholarly journals Transfer of Energy to the Crab Nebula Following the Spin-Up of the Pulsar

1971 ◽  
Vol 46 ◽  
pp. 296-307 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Energy Flux ◽  
Central Region ◽  
Crab Nebula ◽  
Point Of View ◽  
Relativistic Electrons ◽  
Synchrotron Emission ◽  
X Ray ◽  
Enhanced Activity ◽  
The Crab Nebula

Observed enhanced activity in the central region of the Crab Nebula following the spin-up of the pulsar is discussed from the point of view of the transfer of energy to relativistic electrons. It is argued that a rapid deposition of energy associated with the spin-up of the pulsar causes a radial energy flux which becomes a flux in hydromagnetic activity at about the regions where enhanced synchrotron emission is observed. It is shown that such hydromagnetic activity is rapidly damped by the relativistic electrons with energy being transferred to the relativistic electrons. This acceleration can account for the short synchrotron halflifetimes observed. The model predicts highly enhanced X-ray emission from the central region of the Nebula following a spin-up.

35. Stellar Constitution (Constitution Des Étoiles)

1988 ◽  
Vol 20 (01) ◽  
pp. 473-492
Author(s):  
D. Sugimoto ◽  
A. Maeder ◽  
P.H. Bodenheimer ◽  
C.S. Chiosi ◽  
A.N. Cox ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Mass Loss ◽  
Structure Stability ◽  
X Ray ◽  
Entire Field ◽  
Physical Mechanisms ◽  
Stellar Formation ◽  
Great Progress

This report of Commission 35, as in past reports, consists of some details of only a few selected topics. This is necessary because a survey of the entire field of stellar formation, structure, stability, evolution, explosion, and nucleosynthesis for the three year period from mid-1984 to mid-1987 would be excessively long. Our topics here, in order from early to late evolutionary pahses are: Convective Overshooting (N.H. Baker), Mass Loss (I. Appenzeller), Novae (M. Livio), Presupernova Models and SN1987A (K. Nomoto), and Structure of X-Ray Bursting Neutron Stars (M.Y. Fujimoto and D. Sugimoto). In addition, Asteroseismology (H. Shibahashi) is reported briefly as one of the new disciplines now being developed. About two decades ago, Professor Martin Schwarzschild suggested convection, mass loss, and calculation of models through supernova stage as ones of the most important problems to attack. Though great progress has been achieved in these topics, we still have some fundamental questions concerning physical mechanisms involved. This is the reason why these topics are selected for this report.

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