scholarly journals POSSIBLE EVOLUTION OF DIM RADIO-QUIET NEUTRON STAR 1E 1207.4-5209 BASED ON A B-DECAY MODEL

2007 ◽  
Vol 16 (04) ◽  
pp. 619-628 ◽  
Author(s):  
AŞKIN ANKAY ◽  
ARZU MERT ANKAY ◽  
ENISE NIHAL ERCAN
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
Decay Time ◽  
Rotation Period ◽  
Point Sources ◽  
Absorption Lines ◽  
Radio Pulsars ◽  
Characteristic Decay Time ◽  
Decay Model

Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most heavily examined isolated neutron stars. Wide absorption lines were observed in its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These absorption lines can be interpreted as a principal frequency centered at 0.7 keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can be formed by resonant proton cyclotron scattering leading to a magnetic field which is two orders of magnitude larger than the perpendicular component of the surface dipole magnetic field (B) found from the rotation period (P) and the time rate of change in the rotation period [Formula: see text] of 1E 1207.4-5209. Besides, age of the supernova remnant (SNR) G296.5 + 10.0 which is physically connected to 1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age [Formula: see text] of the neutron star. These huge differences between the magnetic field values and the ages can be explained based on a B-decay model. If the decay is assumed to be exponential, the characteristic decay time turns out to be several thousand years which is three orders of magnitude smaller than the characteristic decay time of radio pulsars represented in an earlier work. The lack of detection of radio emission from DRQNSs and the lack of point sources and pulsar wind nebulae in most of the observed SNRs can also be partly explained by such a very rapid exponential decay. The large difference between the characteristic decay times of DRQNSs and radio pulsars must be related to the differences in the magnetic fields, equation of states and masses of these isolated neutron stars.

scholarly journals Estimation of Electrical Conductivity and Magnetization Parameter of Neutron Star Crusts and Applied to the High-Braking-Index Pulsar PSR J1640-4631

Universe ◽  
2020 ◽  
Vol 6 (5) ◽  
pp. 63
Author(s):  
Hui Wang ◽  
Zhi-Fu Gao ◽  
Huan-Yu Jia ◽  
Na Wang ◽  
Xiang-Dong Li
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
General Expression ◽  
Equations Of State ◽  
Rotation Period ◽  
Ohmic Dissipation ◽  
Hartree Fock ◽  
Induction Equation ◽  
The Magnetic Field

Young pulsars are thought to be highly magnetized neutron stars (NSs). The crustal magnetic field of a NS usually decays at different timescales in the forms of Hall drift and Ohmic dissipation. The magnetization parameter ω B τ is defined as the ratio of the Ohmic timescale τ O h m to the Hall drift timescale τ H a l l . During the first several million years, the inner temperature of the newly born neutron star cools from T = 10 9 K to T = 1.0 × 10 8 K, and the crustal conductivity increases by three orders of magnitude. In this work, we adopt a unified equations of state for cold non-accreting neutron stars with the Hartree–Fock–Bogoliubov method, developed by Pearson et al. (2018), and choose two fiducial dipole magnetic fields of B = 1.0 × 10 13 G and B = 1.0 × 10 14 G, four different temperatures, T, and two different impurity concentration parameters, Q, and then calculate the conductivity of the inner crust of NSs and give a general expression of magnetization parameter for young pulsars: ω B τ ≃ ( 1 − 50 ) B 0 / ( 10 13 G) by using numerical simulations. It was found when B ≤ 10 15 G, due to the quantum effects, the conductivity increases slightly with the increase in the magnetic field, the enhanced magnetic field has a small effect on the matter in the low-density regions of the crust, and almost has no influence the matter in the high-density regions. Then, we apply the general expression of the magnetization parameter to the high braking-index pulsar PSR J1640-4631. By combining the observed arrival time parameters of PSR J1640-4631 with the magnetic induction equation, we estimated the initial rotation period P 0 , the initial dipole magnetic field B 0 , the Ohm dissipation timescale τ O h m and Hall drift timescale τ H a l l . We model the magnetic field evolution and the braking-index evolution of the pulsar and compare the results with its observations. It is expected that the results of this paper can be applied to more young pulsars.

scholarly journals Polarization of Thermal Radiation from Neutron Stars

2000 ◽  
Vol 177 ◽  
pp. 625-626
Author(s):  
V. E. Zavlin ◽  
G. G. Pavlov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Thermal Radiation ◽  
Surface Temperature ◽  
Neutron Stars ◽  
Photon Energy ◽  
Energy Surface ◽  
Rotation Period ◽  
Degree Of Polarization ◽  
Star Rotation

AbstractThe degree of polarization of thermal radiation from a neutron star depends on photon energy, surface temperature and magnetic field, and it oscillates with the star rotation period. Observations of this polarization provide a new tool for investigating properties of these objects.

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

2000 ◽  
Vol 177 ◽  
pp. 699-702 ◽  
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.

scholarly journals Spin Evolution of the Progenitors of Binary and Millisecond Pulsars

1996 ◽  
Vol 165 ◽  
pp. 57-64
Author(s):  
Pranab Ghosh
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Binary System ◽  
Neutron Stars ◽  
High Magnetic Field ◽  
Evolutionary History ◽  
Millisecond Pulsars ◽  
History Of ◽  
Low Magnetic Field ◽  
Fast Rotating

In this symposium, I have been given the task of summarizing our current understanding of the evolutionary history of spin periods of the neutron stars that we now see as binary and millisecond pulsars, i.e., recycled pulsars. We believe that a newborn, fast-spinning neutron star (with a rather high magnetic field ∼1011–1013 G) in a binary system first operates as a spin-powered pulsar, subsequently as an accretion-powered pulsar when accretion begins after the pulsar has been spun down adequately, and finally as a spin-powered pulsar for the second time after having been recycled to become a very fast-rotating neutron star (with a rather low magnetic field ∼108–1011 G) (see Ghosh 1994a, b, hereafter G94a, b).

scholarly journals Onset of superconductivity and retention of magnetic fields in cooling neutron stars

2017 ◽  
Vol 13 (S337) ◽  
pp. 213-216
Author(s):  
Wynn C. G. Ho ◽  
Nils Andersson ◽  
Vanessa Graber
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Minimum Energy ◽  
Meissner Effect ◽  
Energy Conditions ◽  
Field Diffusion ◽  
Neutron Star Cooling ◽  
Proton Pairing

AbstractA superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest that magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core retains or is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 106 − 107yr. We estimate the size of flux free regions at 107yr to be ≲ 100m for a magnetic field of 1011G and possibly smaller for stronger field strengths.

scholarly journals Detecting UV Radiation from Nearby Pulsars with the Hubble Space Telescope

1992 ◽  
Vol 128 ◽  
pp. 220-221
Author(s):  
George G. Pavlov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Thermal Radiation ◽  
Neutron Stars ◽  
Hubble Space Telescope ◽  
Thermal Evolution ◽  
The Sun ◽  
Space Telescope ◽  
Additional Constraints ◽  
Relativistic Particles

AbstractEven old (106 to 107 yr) pulsars within a few hundred parsecs of the Sun should give UV and optical fluxes via thermal radiation or radiation from relativistic particles. The surface temperature of a neutron star depends on its mass, radius, magnetic field, and internal composition (existence of pion condensate, superfluidity of nucléons, etc.). If the temperature exceeds ~2x104 K, the thermal radiation can be detected by the Hubble Space Telescope. An analysis of the results will allow one to study the thermal evolution and inner structure of neutron stars in order to obtain additional constraints on pulsar models.

The magnetic field of an isolated neutron star from X-ray cyclotron absorption lines

Nature ◽  
2003 ◽  
Vol 423 (6941) ◽  
pp. 725-727 ◽  
Author(s):  
G. F. Bignami ◽  
P. A. Caraveo ◽  
A. De Luca ◽  
S. Mereghetti
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Absorption Lines ◽  
X Ray ◽  
Cyclotron Absorption ◽  
The Magnetic Field

scholarly journals Pulsars & Magnetars

2008 ◽  
Vol 4 (S259) ◽  
pp. 485-492 ◽  
Author(s):  
Michael Kramer
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Evolutionary Sequence ◽  
Radio Pulsars ◽  
Observable Universe ◽  
Spin Evolution ◽  
Field Strengths

AbstractThe largest magnetic field encountered in the observable Universe can be found in neutron stars, in particular in radio pulsars and magnetars. While recent discoveries have slowly started to blur the distinction between these two classes of highly magnetized neutron stars, it is possible that both types of sources are linked via an evolutionary sequence. Indications for this to be the case are obtained from observations of the spin-evolution of pulsars. It is found that most young pulsars are heading across the top of the main distribution of radio pulsars in the P–Ṗ-diagram, suggesting that at least a sub-class of young pulsars may evolve into objects with magnetar-like magnetic field strengths. Part of this evolutionary sequence could be represented by RRATs which appear to share at least in parts properties with both pulsars and magnetars.

PULSAR DISTRIBUTIONS IN THE MAGNETIC AND SPIN PERIOD DIAGRAM

2013 ◽  
Vol 23 ◽  
pp. 165-169
Author(s):  
CHENGMIN ZHANG ◽  
YUANYUE PAN ◽  
ALI TAANI
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Stellar Evolution ◽  
Distribution Characteristics ◽  
Radio Pulsars ◽  
X Ray ◽  
Spin Period

The various types of pulsars are classified in the magnetic and spin period (B-P) diagram, by which one can recognize their properties there. We also investigate the relation of radio pulsars and X-ray neutron stars, and their distribution characteristics, implying their evolution links. B-P diagram is divided by the special lines, e.g. spin-up line and "death line", which indicate the evolution information of pulsars. Like Hertzsprung-Russell (H-R) diagram of showing the stellar evolution or "lives of stars", we try to develop B-P diagram as a function of representing the evolution track of neutron star.

scholarly journals Partially ionized layers of accreted envelopes of weakly and strongly magnetized neutron stars

2000 ◽  
Vol 177 ◽  
pp. 619-620 ◽  
Author(s):  
Alexander Potekhin ◽  
Gilles Chabrier ◽  
Yuri Shibanov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Strong Field ◽  
Ionization Degree ◽  
Occupation Numbers ◽  
Partially Ionized

AbstractWe study equilibrium properties of partially ionized hydrogen atmospheres and subphotospheric layers of weakly (with magnetic fieldB≪ 109G) and strongly (B≫ 1010G) magnetized neutron stars. In both weak- and strong-field cases, the ionization degree, atomic occupation numbers, and equation of state are calculated. These results are used to calculate opacities of neutron-star atmospheres.

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