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High-precision baseband timing of 15 millisecond pulsars 总被引：1，自引：0，他引：1
A. W. Hotan M. Bailes S. M. Ord 《Monthly notices of the Royal Astronomical Society》2006,369(3):1502-1520
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B. C. Joshi M. A. McLaughlin A. G. Lyne D. A. Ludovici N. A. Pawar A. J. Faulkner D. R. Lorimer M. Kramer M. L. Davies 《Monthly notices of the Royal Astronomical Society》2009,398(2):943-948
We report on the discovery of three new pulsars in the first blind survey of the north Galactic plane (45° < l < 135°; | b | < 1°) with the Giant Meterwave Radio telescope (GMRT) at an intermediate frequency of 610 MHz. The survey covered 106 deg2 with a sensitivity of roughly 1 mJy to long-period pulsars (pulsars with period longer than 1 s). The three new pulsars have periods of 318, 933 and 1056 ms. Their timing parameters and flux densities, obtained in follow-up observations with the Lovell Telescope at Jodrell Bank and the GMRT, are presented. We also report on pulse nulling behaviour in one of the newly discovered pulsars, PSR J2208+5500. 相似文献
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D. R. Lorimer P. C. C. Freire I. H. Stairs M. Kramer M. A. McLaughlin M. Burgay S. E. Thorsett R. J. Dewey A. G. Lyne R. N. Manchester N. D'Amico A. Possenti B. C. Joshi 《Monthly notices of the Royal Astronomical Society》2007,379(3):1217-1221
We investigate the age constraints that can be placed on the double pulsar system using models for the spin-down of the first-born 22.7-ms Pulsar A and the 2.77-s Pulsar B with characteristic ages of 210 and 50 Myr, respectively. Standard models assuming dipolar spin-down of both pulsars suggest that the time since the formation of Pulsar B is ∼50 Myr, that is, close to Pulsar B's characteristic age. However, adopting models which account for the impact of Pulsar A's relativistic wind on Pulsar B's spin-down, we find that the formation of Pulsar B took place either 80 or 180 Myr ago, depending on the interaction mechanism. Formation 80 Myr ago, closer to Pulsar B's characteristic age, would result in the contribution from J0737−3039 to the inferred coalescence rates for double neutron star binaries increasing by 40 per cent. The 180 Myr age is closer to Pulsar A's characteristic age and would be consistent with the most recent estimates of the coalescence rate. The new age constraints do not significantly impact recent estimates of the kick velocity, tilt angle between pre- and post-supernova orbital planes or pre-supernova mass of Pulsar B's progenitor. 相似文献
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Luciano Nicastro & Simon Johnston 《Monthly notices of the Royal Astronomical Society》1998,293(3):L65-L67
We report the discovery of a pulsar with a Galactic longitude of 304° and a dispersion measure (DM) of 875 cm−3 pc. PSR J1302−63 has the second largest DM of any known pulsar. It is also relatively weak, with a flux density of only 0.2 mJy at 1500 MHz. This is the 13th pulsar with a DM greater than 400 cm−3 pc located more than 50° from the Galactic Centre. It provides further evidence for a significant pulsar population and enhanced electron densities within the major spiral arms. 相似文献
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Brad M. S. Hansen & Sterl Phinney 《Monthly notices of the Royal Astronomical Society》1998,294(4):569-581
We use the grid of models described in Paper I to analyse those millisecond pulsar binaries whose secondaries have been studied optically. In particular, we find cooling ages for these binary systems that range from < 1 to ∼ 15 Gyr. Comparison of cooling ages and characteristic spin-down ages allows us to constrain the initial spin periods and spin-up histories for individual systems, showing that at least some millisecond pulsars had sub-Eddington accretion rates and long magnetic field decay times. 相似文献
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D. R. Lorimer M. A. McLaughlin D. J. Champion I. H. Stairs 《Monthly notices of the Royal Astronomical Society》2007,379(1):282-288
We present 3 yr of timing observations for PSR J1453+1902, a 5.79-ms pulsar discovered during a 430-MHz drift-scan survey with the Arecibo telescope. Our observations show that PSR J1453+1902 is solitary and has a proper motion of 8 ± 2 mas yr−1 . At the nominal distance of 1.2 kpc estimated from the pulsar's dispersion measure, this corresponds to a transverse speed of 46 ± 11 km s−1 , typical of the millisecond pulsar population. We analyse the current sample of 55 millisecond pulsars in the Galactic disc and revisit the question of whether the luminosities of isolated millisecond pulsars are different from their binary counterparts. We demonstrate that the apparent differences in the luminosity distributions seen in samples selected from 430-MHz surveys can be explained by small-number statistics and observational selection biases. An examination of the sample from 1400-MHz surveys shows no differences in the distributions. The simplest conclusion from the current data is that the spin, kinematic, spatial and luminosity distributions of isolated and binary millisecond pulsars are consistent with a single homogeneous population. 相似文献
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H. S. Knight 《Monthly notices of the Royal Astronomical Society》2007,378(2):723-729
We report on 685-MHz observations of PSR J1823–3021A using the Parkes radio telescope. A total of 120 giant pulses (GPs) were found by searching for spiky emission at 16-μs time resolution. The energies of these pulses follow a power law that has a very steep exponent of −3.1. This means that the emission mechanism that gives rise to the GPs almost always produces pulses that only have moderate energies. The profile formed by adding all the GPs has components that are narrower and more widely separated than the profile formed from all pulses. Aberration and retardation of emission from a corotating volume mean that components emitted at high altitude will have asymmetric phases compared to those emitted at low altitude. By assuming that the components of the pulse profile form conal pairs, we use this effect to limit the GPs to be emitted no higher than 4 km above ordinary emission. The arrival times of the GPs are well modelled by Poisson statistics at time-scales around 100 s. We report a GP with spikes of emission at the phases of both components. The probability of two independent GPs occurring within a single pulse period is , so an interpretation can be conjectured that the two pulses are not independent. This may mean that the magnetosphere can remain in a state that is susceptible to discrete 'giant' emission events for as long as 2 ms. 相似文献
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D. R. Lorimer K. M. Xilouris A. S. Fruchter I. H. Stairs F. Camilo A. M. Vazquez J. A. Eder M. A. McLaughlin M. S. E. Roberts J. W. T. Hessels S. M. Ransom 《Monthly notices of the Royal Astronomical Society》2005,359(4):1524-1530
We present the results of a 430-MHz survey for pulsars conducted during the upgrade to the 305-m Arecibo radio telescope. Our survey covered a total of 1147 deg2 of sky using a drift-scan technique. We detected 33 pulsars, 10 of which were not known prior to the survey observations. The highlight of the new discoveries is PSR J0407+1607, which has a spin period of 25.7 ms, a characteristic age of 1.5 Gyr and is in a 1.8-yr orbit about a low-mass (>0.2 M⊙ ) companion. The long orbital period and small eccentricity ( e = 0.0009) make the binary system an important new addition to the ensemble of binary pulsars suitable to test for violations of the strong equivalence principle. We also report on our initially unsuccessful attempts to detect optically the companion to J0407+1607, which imply that its absolute visual magnitude is >12.1. If, as expected on evolutionary grounds, the companion is an He white dwarf, our non-detection implies a cooling age of least 1 Gyr. 相似文献
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M. J. Keith M. Kramer A. G. Lyne R. P. Eatough I. H. Stairs A. Possenti F. Camilo R. N. Manchester 《Monthly notices of the Royal Astronomical Society》2009,393(2):623-627
We report the discovery of PSR J1753−2240 in the Parkes Multibeam Pulsar Survey data base. This 95-ms pulsar is in an eccentric binary system with a 13.6-d orbital period. Period derivative measurements imply a characteristic age in excess of 1 Gyr, suggesting that the pulsar has undergone an episode of accretion-induced spin-up. The eccentricity and spin period are indicative of the companion being a second neutron star, so that the system is similar to that of PSR J1811−1736, although other companion types cannot be ruled out at this time. The companion mass is constrained by geometry to lie above 0.48 solar masses, although long-term timing observations will give additional constraints. If the companion is a white dwarf or a main-sequence star, optical observations may yield a direct detection of the companion. If the system is indeed one of the few known double neutron star systems, it would lie significantly far from the recently proposed spin-period/eccentricity relationship. 相似文献
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Bhaswati Bhattacharyya Rajaram Nityananda 《Monthly notices of the Royal Astronomical Society》2008,387(1):273-278
We present a simple method for determination of the orbital parameters of binary pulsars, using data on the pulsar period at multiple observing epochs. This method uses the circular nature of the velocity space orbit of Keplerian motion and produces preliminary values based on two one-dimensional searches. Preliminary orbital parameter values are then refined using a computationally efficient linear least-squares fit. This method works for random and sparse sampling of the binary orbit. We demonstrate the technique on (i) the highly eccentric binary pulsar PSR J0514−4002 (the first known pulsar in the globular cluster NGC 1851) and (ii) 47 Tuc T, a binary pulsar with a nearly circular orbit. 相似文献
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M. Serylak B. W. Stappers P. Weltevrede M. Kramer A. Jessner A. G. Lyne C. A. Jordan K. Lazaridis J. A. Zensus 《Monthly notices of the Royal Astronomical Society》2009,394(1):295-308
We have used the 76-m Lovell, 94-m equivalent Westerbork Synthesis Radio Telescope (WSRT) and 100-m Effelsberg radio telescopes to investigate the simultaneous single-pulse properties of the radio emitting magnetar Anomalous X-ray Pulsar (AXP) XTE J1810−197 at frequencies of 1.4, 4.8 and 8.35 GHz during 2006 May and July. We study the magnetar's pulse-energy distributions which are found to be very peculiar as they are changing on time-scales of days and cannot be fit by a single statistical model. The magnetar exhibits strong spiky single giant-pulse-like subpulses, but they do not fit the definition of the giant pulse or giant micropulse phenomena. Measurements of the longitude-resolved modulation index reveal a high degree of intensity fluctuations on day-to-day time-scales and dramatic changes across pulse phase. We find the frequency evolution of the modulation index values differs significantly from what is observed in normal radio pulsars. We find that no regular drifting subpulse phenomenon is present at any of the observed frequencies at any observing epoch. However, we find a quasi-periodicity of the subpulses present in the majority of the observing sessions. A correlation analysis indicates a relationship between components from different frequencies. We discuss the results of our analysis in light of the emission properties of normal radio pulsars and a recently proposed model which takes radio emission from magnetars into consideration. 相似文献
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P. C. C. Freire N. Wex M. Kramer D. R. Lorimer M. A. McLaughlin I. H. Stairs R. Rosen A. G. Lyne 《Monthly notices of the Royal Astronomical Society》2009,396(3):1764-1770
In 2004, McLaughlin et al. discovered a phenomenon in the radio emission of PSR J0737−3039B (B) that resembles drifting subpulses. The repeat rate of the subpulses is equal to the spin frequency of PSR J0737−3039A (A); this led to the suggestion that they are caused by incidence upon B's magnetosphere of electromagnetic radiation from A. Here, we describe a geometrical model which predicts the delay of B's subpulses relative to A's radio pulses. We show that measuring these delays is equivalent to tracking A's rotation from the point of view of a hypothetical observer located near B. This has three main astrophysical applications: (i) to determine the sense of rotation of A relative to its orbital plane, (ii) to estimate where in B's magnetosphere the radio subpulses are modulated and (iii) to provide an independent estimate of the mass ratio of A and B. The latter might improve existing tests of gravitational theories using this system. 相似文献