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    Eclipses and orbital modulations in binary pulsar PSR J0737-3039
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    The Parkes Multibeam Pulsar Survey is the most successful survey of the Galactic plane ever performed, finding over 600 pulsars in the initial processing. We report on a reprocessing of all 40 000 beams with a number of algorithms, including conventional frequency‐domain searches and an acceleration search for fast binary pulsars. The very large volume of results coupled with the need to distinguish new candidates from known pulsars and their many harmonics, often with multiple detections from different search algorithms, necessitated the development of a new graphical selection tool tightly linked to a web‐based results data base. We discuss and demonstrate the benefits of these software systems, which are specifically designed for large survey projects. The results of this processing have been encouraging. We have discovered 128 new pulsars, including 11 binary and 15 millisecond pulsars; in addition to those previously found in the survey, we have thus far discovered 737 pulsars. In this paper, we discuss the discoveries of PSR J1744−3922 (a 172‐ms mildly recycled pulsar in a 4.6‐h orbit that exhibits nulling behaviour, not previously observed in recycled or binary objects), PSR J1802−2124 (an intermediate mass binary pulsar) and PSR J1801−1417 (a solitary millisecond pulsar).
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    ABSTRACT We present the results of processing an additional 44 per cent of the High Time Resolution Universe South Low Latitude (HTRU-S LowLat) pulsar survey, the most sensitive blind pulsar survey of the southern Galactic plane to date. Our partially coherent segmented acceleration search pipeline is designed to enable the discovery of pulsars in short, highly accelerated orbits, while our 72-min integration lengths will allow us to discover pulsars at the lower end of the pulsar luminosity distribution. We report the discovery of 40 pulsars, including three millisecond pulsar-white dwarf binary systems (PSRs J1537−5312, J1547−5709, and J1618−4624), a black-widow binary system (PSR J1745−23) and a candidate black-widow binary system (PSR J1727−2951), a glitching pulsar (PSR J1706−4434), an eclipsing binary pulsar with a 1.5-yr orbital period (PSR J1653−45), and a pair of long spin-period binary pulsars which display either nulling or intermittent behaviour (PSRs J1812−15 and J1831−04). We show that the total population of 100 pulsars discovered in the HTRU-S LowLat survey to date represents both an older and lower luminosity population, and indicates that we have yet to reach the bottom of the luminosity distribution function. We present evaluations of the performance of our search technique and of the overall yield of the survey, considering the 94 per cent of the survey which we have processed to date. We show that our pulsar yield falls below earlier predictions by approximately 25 per cent (especially in the case of millisecond pulsars), and discuss explanations for this discrepancy as well as future adaptations in RFI mitigation and searching techniques which may address these shortfalls.
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    The double pulsar system PSR J0737-3039 offers an unprecedented opportunity for studying General Relativity and neutron-star magnetospheres. This system has a favourable orbital inclination such that the millisecond pulsar, A, is eclipsed when its slower companion, passes in front. High time resolution light curves of the eclipses reveal periodic modulations of the radio flux corresponding to the fundamental and the first harmonic of pulsar spin frequency. Eclipse modelling is highly sensitive to the geometrical configuration of the system and thus provides a unique probe for parameters like the inclination angle of pulsar B spin axis as well as their time evolution due to relativistic effects. We report on detailed fitting of the pulsar A eclipse light curves to a model that includes, for pulsar B, a simple dipolar magnetic field. We find that the eclipses can be reproduced very well, and we obtain precise measurements of pulsar B's orientation in space. We report on a search for secular changes caused by geodetic precession of pulsar B's spin axis.
    Pulsar planet
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    Eclipse
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    Ephemeris
    Orbital inclination
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    We present an investigation of the morphology and arrival times of integrated radio pulses from the binary millisecond pulsar PSR J1022+1001. This pulsar is renowned for its poor timing properties, which have been postulated to originate from variability in its average pulse profile. Although a sub-class of long-period pulsars are known to exhibit mode changes that give rise to very large deviations in their integrated profiles, this was the first millisecond pulsar thought to have an unstable mean profile. As part of a precision timing program at the Parkes radio telescope we observed this pulsar between January 2003 and March 2004 using a coherent de-dispersion system (CPSR2). A study of morphological variability during our brightest observations suggests that the pulse profile varies by at most a few percent, similar to the uncertainty in our calibration. Unlike previous authors, we find that this pulsar times extremely well. In five minute integrations of 64 MHz bands we obtain a weighted RMS residual of just 2.27 microseconds. The reduced chi-squared of our best fit is 1.43, which suggests that this pulsar can be timed to high accuracy with standard cross-correlation techniques. Combining relativistic constraints with the pulsar mass function and consideration of the Chandrasekhar mass limit on the white dwarf companion, we can constrain the inclination angle of the system to lie within the range 37 < i < 56 degrees. For reasonable pulsar masses, this suggests that the white dwarf is at least 0.9 solar masses. We also find evidence for secular evolution of the projected semi-major axis.
    Binary radio pulsar system J0737-3039 provides an exceptional opportunity to study innermost structure of pulsar magnetospheres due to very tight orbit, favorable directions of pulsars' rotation and magnetic axes and extremely fortuitous orientation of the orbit. In this system the millisecond pulsar A is eclipsed once per orbit. During eclipse a clear modulation at the 2.77 s period of pulsar B is seen, pointing unambiguously to magnetospheric origin of eclipses. A simple geometric model, based on the idea that the radio pulses are attenuated by synchrotron absorption on the closed magnetic field lines of pulsar B, can successfully reproduces the eclipse light curves down to intricate details. This detailed agreement confirms the dipolar structure of the neutron star's magnetic field. The model gives clear predictions for temporal evolution of eclipse profile due to geodetic precession of pulsar B. In addition, pulsar B shows orbital modulations of intensity, being especially bright at two short orbital phases. We showed that these modulations are due to distortion of pulsar B magnetosphere by pulsar A wind which produces orbital phase-dependent changes of the direction along which radio waves are emitted. Thus, pulsar B is intrinsically bright at all times but its radiation beam misses the Earth at most orbital phases.
    Pulsar planet
    X-ray pulsar
    Eclipse
    Binary radio pulsar system J0737-3039 provides an exceptional opportunity to study innermost structure of pulsar magnetospheres due to very tight orbit, favorable directions of pulsars' rotation and magnetic axes and extremely fortuitous orientation of the orbit. In this system the millisecond pulsar A is eclipsed once per orbit. During eclipse a clear modulation at the 2.77 s period of pulsar B is seen, pointing unambiguously to magnetospheric origin of eclipses. A simple geometric model, based on the idea that the radio pulses are attenuated by synchrotron absorption on the closed magnetic field lines of pulsar B, can successfully reproduces the eclipse light curves down to intricate details. This detailed agreement confirms the dipolar structure of the neutron star's magnetic field. The model gives clear predictions for temporal evolution of eclipse profile due to geodetic precession of pulsar B. In addition, pulsar B shows orbital modulations of intensity, being especially bright at two short orbital phases. We showed that these modulations are due to distortion of pulsar B magnetosphere by pulsar A wind which produces orbital phase-dependent changes of the direction along which radio waves are emitted. Thus, pulsar B is intrinsically bright at all times but its radiation beam misses the Earth at most orbital phases.
    Pulsar planet
    X-ray pulsar
    Eclipse
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    The essential characteristics of the pulsar spinning and of the time scales,and the relation between them are analysed. The possible application of the millisecond pulsar to the time metrology is discussed. Based on the measurements of the arrival times of the radio pulses emitted from the millisecond pulsar(s),pulsar time and ensemble pulsar time can be established after the necessary time space transformation,correction and parameters fitting are applied to the measurements.It is possible for pulsar time,especially for ensemble pulsar time,to transfer the accuracy of atomic time from one period to another.It is also possible that pulsar time,especially ensemble pulsar time,may contribute to the knowledge of the stability of atomic time,although there is a dependence of pulsar time(and ensemble pulsar time)on atomic time. In addition, a binary pulsar time can be defined based on the orbital phase of a pulsar in a binary system.
    Pulsar planet
    Millisecond
    X-ray pulsar
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    We discuss the high‐energy emission from isolated and binary pulsars. Models of magnetospheric gamma‐ray emission from isolated pulsars will be constrained by CGRO observations of 'COS‐B‐like' sources. In addition to isolated pulsars, CGRO observations will constrain models for the interaction of pulsar winds with their nebular environments. We briefly describe the characteristics of unpulsed X‐ray and gamma‐ray emission expected in binary interacting pulsar systems where a radiative termination shock of the pulsar wind is produced. Two binary pulsar systems are candicate for high energy emission: young pulsars in massive binaries and old millisecond pulsars with low‐mass companion stars in compact binaries.
    X-ray pulsar
    Pulsar planet
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