scholarly journals The Case for no field decay from improved pulsar population studies

1996 ◽  
Vol 160 ◽  
pp. 47-48
Author(s):  
J.W. Hartman ◽  
F. Verbunt ◽  
D. Bhattacharya ◽  
R. Wijers
Keyword(s):  
Population Studies ◽  
Solar Neighborhood ◽  
Radio Pulsar ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Free Electrons ◽  
New Model ◽  
Full Report ◽  
The Galaxy ◽  
Field Decay

We perform radio pulsar population synthesis to study the evolution of the pulsar population. In doing this, we continue our earlier work on this subject (Bhattacharya et al. 1992). We have extended our work by 1) calculating orbits in the whole galaxy (the simulation of the observations however is still limited to the solar neighborhood), 2) using the high birth velocities of radio pulsars from Lyne & Lorimer (1994) and 3) implementing the new model by Taylor & Cordes (1993) of the distribution of free electrons in the galaxy. A full report of this work will be given in Hartman et al. (1996).

scholarly journals The velocity distribution of young radio pulsars: simulating the observations

1996 ◽  
Vol 160 ◽  
pp. 53-54 ◽  
Author(s):  
J.W. Hartman
Keyword(s):  
Magnetic Field ◽  
Velocity Distribution ◽  
Proper Motion ◽  
Transverse Velocity ◽  
Radio Pulsar ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Full Report ◽  
Simulated Sample

Lyne & Lorimer (1994) argue that the velocities of young pulsars are much higher than was previously thought. However, recent radio pulsar population synthesis work by Hartman et al. (1996, these proceedings) shows that simulations that use a birth velocity distribution with more pulsars at low velocities, Phinney’s modification of the Paczyński (1990) distributiondescribes the observed magnetic field, period and luminosity distribution equally well as simulations that use the Lyne & Lorimer distribution.We use this radio pulsar population synthesis model to obtain the proper motion distribution of the simulated sample, and from that we calculate the transverse velocity distribution to compare it with the observed transverse velocity distribution. A full report of this work will be given in Hartman (1996).

scholarly journals Masses of double neutron star mergers

2020 ◽  
Vol 639 ◽  
pp. A123 ◽  
Author(s):  
Matthias U. Kruckow
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Milky Way ◽  
Radio Pulsar ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Wave Observation ◽  
Binary Evolution ◽  
Star Binary

Aims. I aim to explain the mass discrepancy between the observed double neutron-star binary population by radio pulsar observations and gravitational-wave observation. Methods. I performed binary population synthesis calculations and compared their results with the radio and the gravitational-wave observations simultaneously. Results. Simulations of binary evolution were used to link different observations of double neutron star binaries with each other. I investigated the progenitor of GW190425 in more detail. A distribution of masses and merger times of the possible progenitors is presented. Conclusions. A mass discrepancy between the radio pulsars in the Milky Way with another neutron star companion and the inferred masses from gravitational-wave observations of those kind of merging systems is naturally found in binary evolution.

scholarly journals Population synthesis of young neutron stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 411-413
Author(s):  
Andrei P. Igoshev ◽  
Alexander F. Kholtygin
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Supernova Explosion ◽  
Population Synthesis ◽  
Surface Magnetic Field ◽  
The Galaxy ◽  
The Mean ◽  
Field Decay

AbstractWe investigate the fortune of young neutron stars (NS) in the whole volume of the Milky Way with new code for population synthesis. We start our modeling from the birth of massive OB stars and follow their motion in the Galaxy up to the Supernova explosion. Next we integrate the equations of motion of NS in the averaged gravitational potential of the Galaxy. We estimate the mean kick velocities from a comparison the model Z and R-distributions of radio emitting NS with that for galactic NS accordingly ATNF pulsar catalog. We follow the history of the rotational velocity and the surface magnetic field of NS taking into account the significant magnetic field decay during the first million year of a neutron star's life. The derived value for the mean time of ohmic decay is 2.3ċ105 years. We model the subsample of galactic radio pulsars which can be detected with available radio telescopes, using a radio beaming model with inhomogeneous distribution of the radio emission in the cone. The distributions functions of the pulsar periods P, period derivatives Ṗ and surface magnetic fields B appear to be in a close agreement with those obtained from an ensemble of neutron stars in the ATNF catalogue.

scholarly journals Markov Chain Monte Carlo population synthesis of single radio pulsars in the Galaxy

2020 ◽  
Vol 492 (3) ◽  
pp. 4043-4057 ◽  
Author(s):  
Marek Cieślar ◽  
Tomasz Bulik ◽  
Stefan Osłowski
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Model Parameters ◽  
Population Synthesis ◽  
Radio Luminosity ◽  
Radio Pulsars ◽  
The Galaxy ◽  
Single Radio

ABSTRACT We present a model of evolution of solitary neutron stars, including spin parameters, magnetic field decay, motion in the Galactic potential, and birth inside spiral arms. We use two parametrizations of the radio-luminosity law and model the radio selection effects. Dispersion measure is estimated from the recent model of free electron distribution in the Galaxy (YMW16). Model parameters are optimized using the Markov Chain Monte Carlo technique. The preferred model has a short decay scale of the magnetic field of $4.27^{+0.4}_{-0.38}$ Myr. However, it has non-negligible correlation with parameters describing the pulsar radio luminosity. Based on the best-fitting model, we predict that the Square Kilometre Array surveys will increase the population of known single radio pulsars by between 23 and 137 per cent. The indri code used for simulations is publicly available to facilitate future population synthesis efforts.

scholarly journals The radio pulsar population of the Small Magellanic Cloud

2020 ◽  
Vol 494 (1) ◽  
pp. 500-510
Author(s):  
N Titus ◽  
S Toonen ◽  
V A McBride ◽  
B W Stappers ◽  
D A H Buckley ◽  
...  
Keyword(s):  
Magellanic Cloud ◽  
Star Formation History ◽  
Radio Pulsar ◽  
Population Synthesis ◽  
Small Magellanic Cloud ◽  
Radio Pulsars ◽  
Stellar Objects ◽  
Formation History ◽  
Envelope Model ◽  
Selection Of

ABSTRACT We model the present-day, observable, normal radio pulsar population of the Small Magellanic Cloud (SMC). The pulsars are generated with SeBa, a binary population synthesis code that evolves binaries and the constituent stellar objects up to remnant formation and beyond. We define radio pulsars by selecting neutron stars (NSs) that satisfy a selection of criteria defined by Galactic pulsars, and apply the detection thresholds of previous and future SMC pulsar surveys. The number of synthesized and recovered pulsars is exceptionally sensitive to the assumed star formation history and applied radio luminosity model, but is not affected extensively by the assumed common-envelope model, metallicity, and NS kick velocity distribution. We estimate that the SMC formed (1.6 ± 0.3) ×104 normal pulsars during the last 100 Myr. We study which pulsars could have been observed by the Parkes multibeam survey of the SMC, by applying the survey’s specific selection effects, and recover 4.0 ± 0.8 synthetic pulsars. This is in agreement with their five observed pulsars. We also apply a proposed MeerKAT configuration for the upcoming SMC survey, and predict that the MeerKAT survey will detect 17.2 ± 2.5 pulsars.

scholarly journals Abundances in the Gaseous Galactic Halo

1998 ◽  
Vol 11 (1) ◽  
pp. 86-89
Author(s):  
Ulysses J. Sofia
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
High Velocity ◽  
Galactic Halo ◽  
Solar Neighborhood ◽  
Local Interstellar Medium ◽  
The Galaxy ◽  
Metal Abundances ◽  
High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

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 The Galactic Pulsar Population and Neutron Star Birth

1987 ◽  
Vol 125 ◽  
pp. 67-78
Author(s):  
Ramesh Narayan
Keyword(s):  
Angular Momentum ◽  
Neutron Star ◽  
Binary Systems ◽  
Magnetic Coupling ◽  
Scale Height ◽  
High Magnetic Fields ◽  
Radio Pulsars ◽  
X Ray ◽  
The Galaxy ◽  
Low Mass

The radio pulsars in the Galaxy are found predominantly in the disk, with a scale height of several hundred parsecs. After allowing for pulsar velocities, the data are consistent with the hypothesis that single pulsars form from massive stellar progenitors. The number of active single pulsars in the Galaxy is ∼ 1.5 × 105, and their birthrate is 1 per ∼ 60 yrs. There is some evidence that many single pulsars, particularly those with high magnetic fields, are born spinning slowly, with initial periods ∼ 0.5–1s. This could imply an origin through binary “recycling” followed by orbit disruption, or might suggest that the pre-supernova stellar core efficiently loses angular momentum to the envelope through magnetic coupling. The birthrate of binary radio pulsars, particularly of the millisecond variety, seems to be much larger than previous estimates, and might suggest that these systems do not originate in low mass X-ray binary systems.

scholarly journals Relation Between Star Formation and Angular Momentum in Spiral Galaxies

1983 ◽  
Vol 100 ◽  
pp. 135-136
Author(s):  
L. Carrasco ◽  
A. Serrano
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Radial Distribution ◽  
Spiral Galaxies ◽  
Formation Rate ◽  
Inverse Function ◽  
Solar Neighborhood ◽  
Spin Angular Momentum ◽  
Stellar Formation ◽  
The Galaxy

We derive the radial distribution of the specific angular momentum j=J/M, for the gas in M31, M51 and the galaxy, objects for which well observed unsmoothed rotation curves are available in the literature. We find the specific angular momentum to be anti-correlated with the present stellar formation rate, i.e. minima of spin angular momentum correspond to the loci of spiral arms. We find that the stellar formation rate is an inverse function of j. We derive new values of Oort's A constant for the arm and interarm regions in the solar neighborhood.

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