CONNECTION OF ADDITIONAL PULSAR EMISSION COMPONENTS IN THE CRAB WITH THE RESONANCE REFLECTION FROM A NEUTRON STAR

AbstractThe recently discovered pulsar PSR J0537-6910 is the most rapidly rotating young pulsar known. This latest example of a Crab-like pulsar, located in the supernova remnant N157B in the Large Magellanic Cloud, is rotating twice as fast as the Crab pulsar. With a characteristic age of 5000 years, it is also the oldest known example of a Crab-like pulsar and was likely rotating close to the maximum rate for a neutron star when it was born. Here we report preliminary results from an intensive monitoring campaign of X-ray observations acquired with the Rossi X-ray Timing Explorer that began in January 1999. These observation have revealed a large glitch event in the pulse timing during the first six month of our campaign, consistent with those suggested by sparse observations dating back to 1993. The current evolution of the rotation rate of PSR J0537-6910 provides a unique probe of the internal structure of neutron stars and constraints on possible pulsar emission mechanisms.

Download Full-text

Probing X-ray emission in different modes of PSR J1023+0038 with a radio pulsar scenario

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936312 ◽

2019 ◽

Vol 629 ◽

pp. L8 ◽

Cited By ~ 3

Author(s):

S. Campana ◽

A. Miraval Zanon ◽

F. Coti Zelati ◽

D. F. Torres ◽

M. C. Baglio ◽

...

Keyword(s):

Neutron Star ◽

Spectral Properties ◽

Source Parameters ◽

High Mode ◽

Radio Pulsar ◽

Emission Model ◽

Emission Mechanism ◽

Pulsar Emission ◽

X Ray ◽

Pulsar Wind

Transitional pulsars provide us with a unique laboratory to study the physics of accretion onto a magnetic neutron star. PSR J1023+0038 (J1023) is the best studied of this class. We investigate the X-ray spectral properties of J1023 in the framework of a working radio pulsar during the active state. We modelled the X-ray spectra in three modes (low, high, and flare) as well as in quiescence, to constrain the emission mechanism and source parameters. The emission model, formed by an assumed pulsar emission (thermal and magnetospheric) plus a shock component, can account for the data only adding a hot dense absorber covering ∼30% of the emitting source in high mode. The covering fraction is similar in flaring mode, thus excluding total enshrouding, and decreases in the low mode despite large uncertainties. This provides support to the recently advanced idea of a mini-pulsar wind nebula (PWN), where X-ray and optical pulsations arise via synchrotron shock emission in a very close (∼100 km, comparable to a light cylinder), PWN-like region that is associated with this hot absorber. In low mode, this region may expand, pulsations become undetectable, and the covering fraction decreases.

Download Full-text

POSSIBLE SIGNATURES OF THE CONVERSION OF A NEUTRON STAR TO A STRANGE STAR

International Journal of Modern Physics D ◽

10.1142/s0218271894000794 ◽

1994 ◽

Vol 03 (03) ◽

pp. 653-664

Author(s):

O.G. BENVENUTO ◽

M.I. KRIVORUCHENKO ◽

B.V. MARTEMYANOV

Keyword(s):

Neutron Star ◽

Neutron Stars ◽

High Recurrence Rate ◽

Massive Quark ◽

Pulsar Emission ◽

Strange Stars ◽

X Ray ◽

Supernova Explosions ◽

Low Mass ◽

Step Mechanism

The problem of the identification of strange stars is discussed. We suggest some characteristic signatures for the search for strange stars: a two-step mechanism for supernova explosions accompanied by the occurrence of strange stars and two neutrino bursts; microstructure analysis in the profile of pulsar emission; and unusual stability in the rotation of millisecond pulsars due to the absence of internal crust in strange stars. The cooling of strange stars is faster than the cooling of ordinary neutron stars, so low surface temperature of pulsars can indicate the existence of massive quark cores in observed pulsars. Low mass strange stars as bursters and/or X-ray sources have peculiar observable features: low luminosity and (for bursters) high recurrence rate, large duration of bursts, low ratio of energy emitted between two bursts and energy emitted during the burst.

Download Full-text

Radio and high-energy emission of pulsars revealed by general relativity

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037979 ◽

2020 ◽

Vol 639 ◽

pp. A75

Author(s):

Q. Giraud ◽

J. Pétri

Keyword(s):

General Relativity ◽

Neutron Star ◽

Thermal Emission ◽

High Energy ◽

Light Curves ◽

Radiation Mechanisms ◽

Pulse Profile ◽

Pulsar Emission ◽

Light Cylinder ◽

General Relativistic

Context. According to current pulsar emission models, photons are produced within their magnetosphere and current sheet, along their separatrix, which is located inside and outside the light cylinder. Radio emission is favoured in the vicinity of the polar caps, whereas the high-energy counterpart is presumably enhanced in regions around the light cylinder, whether this is the magnetosphere and/or the wind. However, the gravitational effect on their light curves and spectral properties has only been sparsely researched. Aims. We present a method for simulating the influence that the gravitational field of the neutron star has on its emission properties according to the solution of a rotating dipole evolving in a slowly rotating neutron star metric described by general relativity. Methods. We numerically computed photon trajectories assuming a background Schwarzschild metric, applying our method to neutron star radiation mechanisms such as thermal emission from hot spots and non-thermal magnetospheric emission by curvature radiation. We detail the general-relativistic effects onto observations made by a distant observer. Results. Sky maps are computed using the vacuum electromagnetic field of a general-relativistic rotating dipole, extending previous works obtained for the Deutsch solution. We compare Newtonian results to their general-relativistic counterpart. For magnetospheric emission, we show that aberration and curvature of photon trajectories as well as Shapiro time delay significantly affect the phase delay between radio and high-energy light curves, although the characteristic pulse profile that defines pulsar emission is kept.

Download Full-text

The Effect of Light Bending and Redshift on Pulsar Beaming: The Case of Shorter Rotation Periods

International Astronomical Union Colloquium ◽

10.1017/s0002731600155209 ◽

1992 ◽

Vol 128 ◽

pp. 225-227

Author(s):

R. C. Kapoor

Keyword(s):

Neutron Star ◽

Kerr Metric ◽

Emission Region ◽

Pulse Profile ◽

Pulsar Emission ◽

Rotation Periods ◽

Light Bending ◽

Inertial Frames ◽

Order Of Magnitude ◽

Effect Of Light

AbstractAn estimate of the effect of light bending and redshift on pulsar beam characteristics has been made using a weak Kerr metric for the case of a 1.4 M⊙ neutron star with a radius in the range 6-10 km and rotation periods of 1.56 ms and 33 ms, respectively. Assuming that the pulsar emission has the form of a narrow conical beam directed away from the surface and is located within two stellar radii, the beam is found to be widened by a factor of ≤ 2 and to suffer a reduction in the intensity (flattening of the profile) by an order of magnitude or less. The effect is largest for the most rapidly rotating the neutron stars. For an emission region located beyond 20 km, the flattening is generally insignificant. The pulse profile is slightly asymmetrical due to dragging of the inertial frames. For millisecond periods, aberration tends to reverse the flattening effect of space-time curvature by narrowing the pulse and can completely overcome it for emission from a location beyond ≃30km. Although the pulse must slightly brighten up, a large redshift factor overcomes this effect to keep the pulse flattened for all neutron star radii considered here.

Download Full-text

K-means Clustering-based Radio Neutron Star Pulsar Emission Mechanism

Recent Advances in Computer Science and Communications ◽

10.2174/2213275912666200129115401 ◽

2020 ◽

Vol 13 ◽

Author(s):

Shubham Shrimali ◽

Amritanshu Pandey ◽

Chiranji Lal Chowdhary

Keyword(s):

Neural Networks ◽

Neutron Star ◽

Decision Tree ◽

Machine Learning Algorithms ◽

Training Data ◽

Emission Mechanism ◽

Decision Tree Classifier ◽

Emission Data ◽

Pulsar Emission ◽

Tree Classifier

: The aim of this paper is to work on K-means clustering-based radio neutron star pulsar emission mechanism. Background: The pulsars are a rare type of neutron star that produces radio rays. Such type of rays are detectable on earth and it attracts scientists because of its concern with space-time, interstellar medium, and states of matter. During the rotation of pulsar rays, it emits the rays in the whole sky and after crossing the threshold value, the pattern of radio emission broadband detected. As rotation speed of pulsar increases then accordingly the types of the pattern produced periodically. Every pulsar emits different patterns which are a little bit different from each other which is fully depends on its rotation. The detected signals are known as a candidate. Its length of observation can determine it and it is average of all rotation of pulsar. Objective: The main objectives of this radio neutron star pulsar emission mechanism are: (a) Decision Tree Classifier (2) K-means Clustering (3) Neural Networks. Method: The Pulsar Emission Data was broken down into two sets of data: Training Data and Testing Data. The Training Data used to train the Decision Tree The algorithm, K-means clustering, and Neural Networks to allow it to identify, which attributes (Training Labels), are useful for identification of Neutron Pulsar Emissions. Results: The analysis is using multiple machine learning algorithms; it concluded that using neural networks is the best possible method to detect pulsar emissions from neutron stars. The best result achieved is 98% using Neural Networks. Conclusion: There are so many benefits of pulsar rays in different technology. Earth can detect pulsar ray from low orbit. Earth can completely absorb X-ray in the atmosphere and from these; we can say that the wavelength is limited to those who do not have an atmosphere like space. The result we got according to that we can say that the algorithm we used successfully used for detecting the pulsar signals.

Download Full-text

Low Frequency Emission Regions in Pulsars

Symposium - International Astronomical Union ◽

10.1017/s0074180900169372 ◽

2002 ◽

Vol 199 ◽

pp. 377-378

Author(s):

Jaroslaw Kijak

Keyword(s):

Neutron Star ◽

Low Frequency ◽

Component Separation ◽

Geometrical Method ◽

Polar Cap ◽

Pulsar Emission ◽

Different Altitudes ◽

Frequency Radiation ◽

Frequency Emission

The systematic increase of component separation and profile widths with decreasing frequency in pulsars suggests that the radiation at different frequencies is emitted from different altitudes above the polar cap. This concept is known as the radius-to-frequency mapping. According to RFM the observed low-frequency radiation should be generated farther from the neutron star than higher-frequency radiation. We discuss radial locations of the pulsar emission regions using a geometrical method for the estimation of emission altitudes. It is argued that the emission altitude at a given frequency is slightly different for young and old pulsars.

Download Full-text