bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resistivity and dissipation in pulsar magnetospheres
Authors: Li Jason , Spitkovsky Anatoly , Tchekhovskoy Alexander 
Published: March 2013

AbstractCurrent models of pulsar magnetospheres typically assume either a complete absence of plasma or abundant ideal plasma filling the magnetosphere in order to compute the field structure. The latter condition is thought to be closer to reality, but we know of a number of pulsars in which the ideal conditions break down, resulting in dissipation and high-energy emission. In this work we formulate a resistive force-free scheme that allows us to consider the effects of resistive plasma and accelerating fields on the magnetospheric structure. We run numerical simulations to construct a family of resistive solutions that smoothly bridges the gap between the vacuum and the force-free magnetosphere solutions. We further provide a self-consistent model for the spin-down of intermittent pulsars, pulsars which appear to transition between radio-loud and radio-quiet states with different spin-down rates. Finally, we present models for high-energy emission from reconnecting current sheets in Gamma-ray pulsars.
Elementary radiation patterns in pulsar profiles
Authors: Dyks Jarosław , Rudak Bronisław 
Published: March 2013

AbstractHighly symmetric double features observed in averaged pulsar profiles can be interpreted as the imprint of microscopic radiation beam characteristic of radiative mechanism operating in pulsar magnetosphere. The data put strong constraints on the possible radiation patterns, excluding entire classes of mechanisms, such as those based on parallel acceleration, or those that have complicated beams. Instead, several properties of double features (such as their symmetry, depth, shape, merging rate, large polarisation degree, and the association with bifurcated emission components) are consistent with the extraordinary-mode part of the curvature radiation beam. This shows that double notches are a clear signature of the curvature radiation process. We show that even with the emission process fixed, detailed modelling of double features remains a rather sophisticated and demanding task.
Pulsar emission at the bottom end of the electromagnetic spectrum
Authors: Kondratiev Vladislav ,   the LOFAR Pulsar Working Group
Published: March 2013

AbstractPulsars are arguably the only astrophysical sources whose emission spans the entire electromagnetic spectrum, from decameter radio wavelengths to TeV energies. The LOw Frequency ARray (LOFAR) offers the unique possibility to study pulsars over a huge fractional bandwidth in the bottom 4 octaves of the radio window, from 15–240 MHz. Here we present a LOFAR study of pulsar single pulses, focussing specifically on the bright nearby pulsar B0809+74. We show that the spectral width of bright low-frequency pulses can be as narrow as 1 MHz and scales with increasing frequency as Δ f/fc ~ 0.15, at least in the case of the PSR B0809+74. This appears to be intrinsic to the pulsar, as opposed to being due to propagation effects. If so, this behavior is consistent with predictions by the strong plasma turbulence model of pulsar radio emission. We also present other observed properties of the single pulses and discuss their relation to other single-pulse phenomena like giant pulses.
Relativistic strange stars with anisotropy and B-parameter in pseudo spheroidal space time
Authors: Chattopadhyay P. K. , Paul B. C. 
Published: March 2013

AbstractA class of compact cold stars in the presence of strange matter is obtained for a pseudo-spheroidal geometry. Considering the strange matter equation of state $p = \frac{1}{3}(\rho-4B)$ with pressure anisotropy described by Vaidya-Tikekar metric, we determine the parameter B both inside and on the surface of the star for different values of anisotropy parameter α. In the anisotropic case, we note that a stable model of a compact star may be realized.
Pulsar time scale and its future application
Authors: Chen Ding , Hobbs George , Coles William , Manchester Richard 
Published: March 2013

AbstractAn Ensemble Pulsar Time Scale (EPT) is derived based on the Pulsar Timing Array. It is interesting to compare the EPT with the TT terrestrial time scale, and get many new realization on the pulsar time scale and the algorithm. Some future interesting applications of the EPT are described and discussed.
Annular gap model for multi-wavelength pulsed emission from young and millisecond pulsars
Authors: Du Yuan Jie , Qiao Guo Jun 
Published: March 2013

AbstractThe multi-wavelength pulsed emission from young pulsars and millisecond pulsars can be well modeled with the single-pole 3-dimension annular gap and core gap model. To distinguish our single magnetic pole model from two-pole models (e.g. outer gap model and two-pole caustic model), the convincing values of the magnetic inclination angle and the viewing angle will play a key role.
Characterizing glitches and timing irregularities in pulsars and magnetars
Authors: Espinoza Cristobal , Antonopoulou Danai , Patruno Alessandro , Stappers Ben , Watts Anna 
Published: March 2013

AbstractAs the quantity and quality of timing data improves, we have reached the point at which the difference between timing noise and small glitches is unclear. As a consequence, the number of events reported as glitches which show unusual properties, quite different to those of giant glitches, has increased. For example, there is now a substantial population of glitches that apparently involve a decrease in spin-down rate rather than an increase. Motivated by the theoretical implications of such a result, we are conducting a detailed review of how glitches are detected and characterised. We have focused on three main questions: the observational biases affecting glitch detection; the methods used to characterise error bars on changes in spin and spin derivatives; and the physical mechanisms that could potentially explain the different populations of timing irregularities, in the light of improved characterisation. While glitches are thought to be a consequence of the internal dynamics of the star, magnetospheric processes may be responsible for other irregularities, as timing noise and peculiar glitch recoveries. We report the first results from this study, using a small sample of radio pulsars that exhibit a wide variety of glitching behaviour.
A survey of nulling pulsars using the Giant Meterwave Radio Telescope
Authors: Gajjar Vishal , Joshi Bhal Chandra , Kramer Michael 
Published: March 2013

AbstractSeveral pulsars show sudden cessation of pulsed emission, which is known as pulsar nulling. In this paper, the nulling behaviour of 15 pulsars is presented. The nulling fraction of these pulsars, along with the degree of reduction in the pulse energy during the null phase are reported for these pulsars. A unique nulling behaviour is re- ported for PSR J1738-2330, which also showed quasi-periodic bursts. The distributions of lengths of the null and burst phases as well as the typical nulling time scales are estimated for eight strong pulsars. A comparison of the nulling time scales of four pulsars with similar nulling fraction suggests that the fraction of null pulses probably does not quantify the nulling behaviour of a pulsar in full detail. Analysis of these distributions also indicate that while the null and the burst pulses occur in groups, the transition from the null to burst phase and vice verse can be modeled by a Poisson point process.
Magnetars are super hot and super cool
Authors: Ho Wynn C. G. , Glampedakis Kostas , Andersson Nils 
Published: March 2013

AbstractWe examine to what extent the inferred surface temperature of magnetars in quiescence can constrain the presence of a superfluid in the neutron star core and the role of magnetic field decay in the core. By performing detailed simulations of neutron star cooling, we show that extremely strong heating from field decay in the core cannot produce the high observed surface temperatures nor delay the onset of neutron superfluidity in the core. We find that it is not possible to conclude that magnetar cores are in a non-superfluid state purely from high surface temperatures. We find that neutron superfluidity in the core occurs less than a few hundred years after neutron star formation for core fields < 1016 G. Thus all known neutron stars, including magnetars, without a core containing exotic particles, should have a core of superfluid neutrons and superconducting protons.
Population synthesis of young neutron stars
Authors: Igoshev Andrei P. , Kholtygin Alexander F. 
Published: March 2013

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.
Distribution of ionized gas density measured by differential VLBI Observations of pulsars
Authors: Kameya Osamu 
Published: March 2013

AbstractDifferential VLBI observations of pulsars in our Galaxy can derive trigonometric parallax of them. Distance to pulsars derived by the parallax are very important to estimate some mean density of ionized gas between pulsars and the earth using rotation measures of them. Some preliminary results of distribution of the ionized gas density in our galaxy by using previous VLBI results are shown. Possibility of VLBI observations of pulsars using VERA and the other VLBI antennas will be described.
Magnetic field evolution in magnetars
Authors: Kojima Yasufumi 
Published: March 2013

AbstractDynamics of magnetic field decay is numerically studied. For neutron stars with strong magnetic fields, the Hall drift timescale in their crust is very short, and therefore the evolution is significantly affected. The nonlinear coupling between poloidal and toroidal components of the magnetic field is studied. It is also found that the polar field at the surface is highly distorted during the Hall drift timescale. For example, polar dipole field-strength temporarily decreases not by dissipation but by advection. This fact suggests that the dipole field-strength is not sufficient to determine the border between pulsars and magnetars.
A data analysis library for gravitational wave detection
Authors: Lassus A. , van Haasteren R. , Mingarelli C. M. F. , Lee K. J. , Vecchio A. 
Published: March 2013

AbstractOne of the main goals of Pulsar Timing Arrays (PTAs) is the direct detection of gravitational waves (GWs). A first detection will be a major leap for astronomy and substantial effort is currently going into timing as many pulsars as possible, with the highest possible accuracy. As part of the individual PTA projects, several groups are developing data analysis methods for the final stage of a gravitational-waves search pipeline: the analysis of the timing residuals. Here we report the progress of on-going work to develop, within a Bayesian framework, a comprehensive and user friendly analysis library to search for gravitational waves in PTA data.
Relativistic Cowling approximation for fluid oscillation modes of color superconducting self-bound stars
Authors: Lugones German , Flores Cesar Vasquez 
Published: March 2013

AbstractThe investigation of the quasi-normal modes of oscillation of compact stars can reveal much information about their equation of state and internal structure mainly through the analysis of the expected emission of gravitational waves. In this work we study non-radial oscillation modes of strange stars consisting of color superconducting quark matter. We focus on the fundamental and pressure oscillation modes within the frame of the Cowling approximation. We discuss the observable features that may allow a differentiation among hadronic stars, strange stars, and strange stars with color superconductivity.
New observations of the Geminga pulsar at low radio frequencies
Authors: Malofeev V. M. , Malov O. I. , Logvinenko S. V. , Teplykh D. A. 
Published: March 2013

AbstractNew evidence for the detection of Geminga at three low frequencies is presented. The observations were carried out on two sensitive transit radio telescopes in the range 42-112 MHz. We used three new digital receivers to detect the pulses and to obtain dynamic spectra. The exact value of the dispersion measure has been calculated.
Magnetic Color-flavor-locked Stars
Authors: Paulucci Laura , Ferrer Efrain J. , de la Incera Vivian , Horvath Jorge E. 
Published: March 2013

AbstractUsing the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of paired quark matter in a magnetic field, and taking into consideration the separation between the longitudinal and transverse pressures due to the field-induced breaking of the spatial rotational symmetry, the equation of state (EoS) of the MCFL phase is self-consistently determined. Implications for stellar models of magnetized (self-bound) strange stars and hybrid (MCFL core) stars are discussed.
Ultra-compact X-ray binaries with high luminosity: a key for a new scenario
Authors: Pavlovskii Konstantin , Ivanova Natalia 
Published: March 2013

AbstractUltra-compact X-ray binaries (UCXBs) are accreting systems with periods less than 1 hour, which qualifies them to contain a degenerate donor-companion. One would expect such systems to have the easiest theoretical explanation, compared to other kinds of X-ray binaries. Nonetheless, current theory fails to explain high mass transfer (MT) rates in three recently well observed long-period UCXBs. We find that this range of MT rates can be maintained if the donor is a remnant of an out-of-thermal-equilibrium naked core of a giant which was revealed in a very recent episode of a common envelope (CE) event.
On the environments and progenitors of supernova remnants associated with highly magnetized neutron stars
Authors: Safi-Harb S. , Kumar H. S. 
Published: March 2013

AbstractThe distinction between the high-magnetic field pulsars (HBPs, thought to be mainly rotation-powered) and magnetars (commonly believed to be powered by their super-strong magnetic fields) has been recently blurred with the discovery of magnetar-like activity from the HBP J1846–0258 in the SNR Kes 75. What determines the spin properties of a neutron star at birth and its manifestation as a magnetar-like or more classical pulsar is still not clear. Furthermore, although a few studies have suggested very massive progenitors for magnetars, there is currently no consensus on the progenitors of these objects. To address these questions, we examine their environments by studying or revisiting their securely associated SNRs. Our approach is to: 1) infer the mass of their progenitor stars through X-ray spectroscopic studies of the thermally emitting supernova ejecta, and 2) investigate the physical properties of their hosting SNRs and ambient conditions. We here highlight our detailed studies of two SNRs: G292.2–0.5, associated with the HBP J1119–6127, and Kes 73, associated with the AXP 1E 1841–045, and summarize the current view of the other (handful) HBP/magnetar-SNR associations.
The new magnetar Swift J1822.3–1606
Authors: Scholz P. , Ng C.-Y. , Livingstone M. A. , Kaspi V. M. , Cumming A. , Archibald R. 
Published: March 2013

AbstractOn 2011 July 14, a transient X-ray source, Swift J1822.3–1606, was detected by Swift BAT via its burst activities. It was subsequently identified as a new magnetar upon the detection of a pulse period of 8.4 s. Using follow-up RXTE, Swift, and Chandra observations, we have determined a spin-down rate of Ṗ ~ 3 × 10−13, implying a dipole magnetic field of ~ 5 × 1013 G, second lowest among known magnetars, although our timing solution is contaminated by timing noise. The post-outburst flux evolution is well modelled by surface cooling resulting from heat injection in the outer crust, although we cannot rule out other models. We measure an absorption column density similar to that of the open cluster M17 at 10′ away, arguing for a comparable distance of ~1.6 kpc. If confirmed, this could be the nearest known magnetar.
Model of radio emission from spherically symmetric pulsar wind nebulae
Authors: Tanaka Shuta J. 
Published: March 2013

AbstractWe study radio emission from pulsar wind nebulae (PWNe) considering the observed spatial structure. We assume spherical symmetry of the PWN, and model the evolution of the magnetic field and the particle energy distribution. We do not consider the synchrotron cooling of particles but consider the adiabatic cooling, because we are mostly interested in the radio emission from PWNe. The model is applied to the Crab Nebula and succeeds to reproduce the observed spatially integrated spectrum in radio with a single power-law injection. In our previous work (a one-zone model), in contrast, the integrated spectrum of the Crab Nebula is reproduced by a broken power-law injection of particles. However, the spatial structure in radio is inconsistent with observations and we need a radial velocity profile which is very different from the model by Kennel & Coroniti. Further studies of the spatial structure of PWNe are important to understand the origin of the radio emission from young PWNe.
The spectral energy distributions of isolated neutron stars in the resonant cyclotron scattering model
Authors: Tong Hao , Xu Renxin 
Published: March 2013

AbstractThe X-ray dim isolated neutron stars (XDINSs) are peculiar pulsar-like objects, characterized by their very well Planck-like spectrum. In studying their spectral energy distributions, the optical/UV excess is a long standing problem. Recently, Kaplan et al. (2011) have measured the optical/UV excess for all seven sources, which is understandable in the resonant cyclotron scattering (RCS) model previously addressed. The RCS model calculations show that the RCS process can account for the observed optical/UV excess for most sources. The flat spectrum of RX J2143.0+0654 may due to contribution from bremsstrahlung emission of the electron system in addition to the RCS process.
Origin of the pulsar pulse fine structure
Authors: Ulyanov O. M. , Seredkina A. A. , Shevtsova A. I. 
Published: March 2013

AbstractWe give a new numerical model of pulsar pulse radiation through the interstellar medium (ISM) considering the propagation effects. It explains the deficit of a scattering measure at the decameter range of frequencies that leads to the possibility of detecting the pulsar pulse fine structure. The results of numerical simulation confirm that the fine structure may be detected at low frequencies and this is qualitatively agreed with the observational data.
Polarization sounding of the pulsar magnetosphere
Authors: Ulyanov O. M. , Shevtsova A. I. , Seredkina A. A. 
Published: March 2013

AbstractThe possibility of a polarization sounding of the pulsar magnetosphere is examined, using intrinsic pulsar emission as a probe signal, for modern radio telescopes operating in the meter and decameter wavelength range. Different models of the pulsar magnetosphere at altitudes higher than a radius of critical polarization are used. The propagation medium besides magnetosphere is described by the stratified model, in which each layer has its own density of free electrons and vector of magnetic induction, as well as the spatial and temporal fluctuation scales of these parameters.The frequency dependence of the polarization parameters of the pulsar radio emission, obtained in the broad band for a selected pulse phase, will enable a sounding deep into the pulsar magnetosphere.
Quadrupole moments of rotating compact stars
Authors: Urbanec Martin , Miller John , Stuchlik Zdenek 
Published: March 2013

AbstractWe present quadrupole moments of rotating neutron and strange stars calculated using standard Hartle Thorne approach. We demonstrate differences between neutron and strange star parameters connected with quadrupole moments and how this parameters could be, in the case of neutron stars, approximated almost independently on neutron star equation of state.
Particle simulation for an axisymmetric pulsar magnetosphere
Authors: Wada Tomohide 
Published: March 2013

AbstractWe developed a new particle simulation code which includes pair creation (magnetic pair creation and photon collision process), propagation of gamma-ray, inertia of particle, interaction of plasma and multi-pole stellar field for steady axisymmetric pulsar magnetosphere. The photon path is solved stochastically by an analytical solution of the mean free path of pair creation processes at the photon position. The superimposed quadrupole magnetic field forms asymmetric electrostatic clouds on tje poloidal plane and the accelerating region is different from the dipole case. Here, we demonstrate some results of a test run for our simulation. We will adopt the code for more complicated cases, such that all above-mentioned effects will be considered together in future work.
Wave propagation in pulsar magnetospheres
Authors: Wang Chen , Lai Dong , Han Jinlin 
Published: March 2013

AbstractWe study the propagation effects of radio waves in a pulsar magnetosphere, composed of relativistic electron-positron pair plasmas streaming along the magnetic field lines and corotating with the pulsar. We critically examine the various physical effects that can potentially influence the observed wave intensity and polarization. We numerically integrate the transfer equations for wave polarization in the rotating magnetosphere, taking account of all the propagation effects in a self-consistent manner. For typical magnetospheric plasma parameters produced by pair cascade, we find that the observed radio intensity and polarization profiles can be strongly modified by the propagation effects. Some applications of our results are discussed.
On the origin of the low-frequency QPO in GRS 1915+105 ρ state
Authors: Yan Shu-Ping , Wang Na , Ding Guo-Qiang 
Published: March 2013

AbstractWe performed a phase-resolved timing analysis of GRS 1915+105 in its ρ state and identify detailed ρ cycle evolution of frequency, amplitude and coherence of the low-frequency quasi-periodic oscillation (LFQPO). We combined our timing results with the spectral study by Neilsen et al. (2011) to do an elaborate contrast analysis. The results are naturally explained by tying the LFQPO to the corona.
Mutual influence of magnetic field decay and thermal evolution of rotational neutron stars
Authors: Zhou Xia , Kang Miao , Wang Na 
Published: March 2013

AbstractThe effect of magnetic field decay on the chemical heating and thermal evolution of neutron stars is discussed. Our main goal is to study how chemical heating mechanisms and thermal evolution are changed by field decay and how magnetic field decay is modified by the thermal evolution. We show that the effect of chemical heating is suppressed by the star spin-down through decaying magnetic field at a later stage; magnetic field decay is delayed significantly relative to stars cooling without heating mechanisms; compared to typical chemical heating, the decay of the magnetic field can even cause the temperature to turn down at a later stage.