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1.
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   

2.
There are two ways of expressing the precession of orbital plane of a binary pulsar system, given by Barker & O'Connell, Apostolatos et al. and Kidder, respectively. We point out that these two ways actually come from the same Lagrangian under different degrees of freedom. Damour & Schafer and Wex & Kopeikin applied Barker & O'Connell's orbital precession velocity in pulsar timing measurement. This paper applies Apostolatos et al.'s and Kidder's orbital precession velocity. We show that Damour & Schafer's treatment corresponds to negligible Spin-Orbit induced precession of periastron, while Wex & Kopeikin and this paper both found significant (but not equivalent) effects. The observational data of two typical binary pulsars, PSR J2051-0827 and PSR J1713+0747, apparently support a significant Spin-Orbit coupling effect. Specific binary pulsars with orbital plane nearly edge on could discriminate between Wex & Kopeikin and this paper: if the orbital period derivative of the double-pulsar system PSRs J0737-3039 A and B, with orbital inclination angle i = 87.7129 deg, is much larger than that of the gravitational radiation induced one, then the expression in this paper is supported, otherwise Wex & Kopeikin's is supported.  相似文献   

3.
Using the Australia Telescope Compact Array (ATCA) we have imaged the fields around five promising pulsar candidates to search for radio pulsar wind nebulae (PWNe). We have used the ATCA in its pulsar-gating mode; this enables an image to be formed containing only off-pulse visibilities, thereby dramatically improving the sensitivity to any underlying PWN. Data from the Molonglo Observatory Synthesis Telescope were also used to provide sensitivity on larger spatial scales. This survey found a faint new PWN around PSR B0906−49; here we report on non-detections of PWNe towards PSRs B1046−58, B1055−52, B1610−50 and J1105−6107. Our radio observations of the field around PSR B1055−52 argue against previous claims of an extended X-ray and radio PWN associated with the pulsar. If these pulsars power unseen, compact radio PWNe, upper limits on the radio flux indicate that a fraction of less than 10−6 of their spin-down energy is used to power this emission. Alternatively, PSRs B1046−58 and B1610−50 may have relativistic winds similar to other young pulsars and the unseen PWN may be resolved and fainter than our surface brightness sensitivity threshold. We can then determine upper limits on the local interstellar medium (ISM) density of 2.2×10−3 and 1×10−2 cm−3, respectively. Furthermore, we derive the spatial velocities of these pulsars to be ∼450 km s−1 and thus rule out the association of PSR B1610−50 with supernova remnant (SNR) G332.4+00.1 (Kes 32). Strong limits on the ratio of unpulsed to pulsed emission are also determined for three pulsars.  相似文献   

4.
Large glitches were recently observed in the spin rates of two pulsars, B1046−58 and B1737−30. The glitches were characterized by fractional increases in rotation rate of 0.77 and  1.44×10−6  respectively. PSR B1737−30 is the most frequently glitching pulsar and this is the largest glitch so far observed from it. Most of the jump in the spin-down rate accompanying these glitches decayed away on short time-scales of a few days. For PSR B1737−30, there appears to be a cumulative shift in spin-down rate resulting from its frequent glitches. This probably accounts for its braking index of  −4±2  suggested by the available data, while a value of  2.1±0.2  is obtained for B1046−58.  相似文献   

5.
We discuss the formation of pulsars with massive companions in eccentric orbits. We demonstrate that the probability for a non-recycled radio pulsar to have a white dwarf as a companion is comparable to that of having an old neutron star as a companion. Special emphasis is given to PSR B1820−11 and PSR B2303+46. Based on population synthesis calculations we argue that PSR B1820−11 and PSR B2303+46 could very well be accompanied by white dwarfs with mass ≳1.1 M⊙. For PSR B1820−11, however, we cannot exclude the possibility that its companion is a main-sequence star with a mass between ∼0.7 M⊙ and ∼5 M⊙.  相似文献   

6.
In binary radio pulsars with a main-sequence star companion, the spin-induced quadrupole moment of the companion gives rise to a precession of the binary orbit. As a first approximation one can model the secular evolution caused by this classical spin-orbit coupling by linear-in-time changes of the longitude of periastron and the projected semi-major axis of the pulsar orbit. This simple representation of the precession of the orbit neglects two important aspects of the orbital dynamics of a binary pulsar with an oblate companion. First, the quasiperiodic effects along the orbit, owing to the anisotropic 1/ r 3 nature of the quadrupole potential. Secondly, the long-term secular evolution of the binary orbit, which leads to an evolution of the longitude of periastron and the projected semi-major axis, which is non-linear in time.   In this paper a simple timing formula for binary radio pulsars with a main-sequence star companion is presented which models the short-term secular and most of the short-term periodic effects caused by the classical spin-orbit coupling. I also give extensions of the timing formula that account for long-term secular changes in the binary pulsar motion. It is shown that the short-term periodic effects are important for the timing observations of the binary pulsar PSR B1259–63. The long-term secular effects are likely to become important in the next few years of timing observations of the binary pulsar PSR J0045–7319. They could help to restrict or even determine the moments of inertia of the companion star and thus probe its internal structure.   Finally, I reinvestigate the spin-orbit precession of the binary pulsar PSR J0045–7319 since the analysis given in the literature is based on an incorrect expression for the precession of the longitude of periastron. A lower limit of 20° for the inclination of the B star with respect to the orbital plane is derived.  相似文献   

7.
The correlation of subpulse phases across nulls is investigated in the radio pulsar PSR B0031−07, using 29 849 periods of high-quality data obtained with the Ooty Radio Telescope (ORT) which operates at 327 MHz. Assuming that the turn-off and turn-on subpulse phases (the phase of the subpulse in the last period before the null and that in the first period after the null, respectively) are independent random variables, the expected distribution of their difference (i.e. the total drift) is inconsistent with the observed distribution for null transitions within the same drift mode; this implies a correlation of subpulse phase across nulls. However, this correlation decreases with null duration for both the dominant drift modes. Substantial drifting occurs during short nulls (one to four periods); the drift rate during the short nulls appears to be constant for a class A transition, whereas it decreases with null duration for class B transitions. These results, together with the reported behaviour of PSR B1944+17 and PSR B0809+74, seem to imply different time-scales for phase correlation in different pulsars.  相似文献   

8.
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   

9.
We report on searches of the globular cluster Terzan 5 for low-luminosity and accelerated radio pulsars using the 64-m Parkes radio telescope. One new millisecond pulsar, designated PSR J1748−2446C, was discovered, having a period of 8.44 ms. Timing measurements using the 76-m Lovell radio telescope at Jodrell Bank show that it is a solitary pulsar and lies close to the core of the cluster. We also present the results of timing measurements which show that the longer period pulsar PSR J1748−2444 (formerly known as PSR B1744−24B) lies 10 arcmin from the core of the cluster and is unlikely to be associated with the cluster. We conclude that there are further pulsars to be detected in the cluster.  相似文献   

10.
We are undertaking a high-frequency survey of the Galactic plane for radio pulsars, using the 13-element multibeam receiver on the 64-m Parkes radio telescope. We describe briefly the survey system and some of the initial results. PSR J1811−1736, one of the first pulsars discovered with this system, has a rotation period of 104 ms. Subsequent timing observations using the 76-m radio telescope at Jodrell Bank show that it is in an 18.8-d, highly eccentric binary orbit. We have measured the rate of advance of periastron which indicates a total system mass of 2.6±0.9 M⊙, and the minimum companion mass is about 0.7 M⊙. This, the high orbital eccentricity and the recycled nature of the pulsar suggest that this system is composed of two neutron stars, only the fourth or fifth such system known in the disc of the Galaxy.  相似文献   

11.
New images of the supernova remnant (SNR) G351.7+0.8 are presented based on 21-cm H  i -line emission and continuum emission data from the Southern Galactic Plane Survey. SNR G351.7+0.8 has a flux density of 8.4 ± 0.7 Jy at 1420 MHz. Its spectral index is 0.52 ± 0.25 ( S = v −α) between 1420 and 843 MHz, typical of adiabatically expanding shell-like remnants. H  i observations show structures possibly associated with the SNR in the radial velocity range of −10 to −18 km s−1, and suggest a distance of 13.2 kpc and a radius of 30.7 pc. The estimated Sedov age for G351.7+0.8 is less than  6.8×104 yr  . A young radio pulsar PSR J1721−3532 lies close to SNR G351.7+0.8 on the sky. The new distance and age of G351.7+0.8 and recent proper motion measurements of the pulsar strongly argue against an association between SNR G351.7+0.8 and PSR J1721−3532. There is an unidentified, faint X-ray point source 1RXS J172055.3−353937 which is close to G351.7+0.8. This may be a neutron star potentially associated with G351.7+0.8.  相似文献   

12.
In the three years following the discovery of PSR J2051−0827, we have observed a large number of eclipse traverses over a wide frequency range. These data show that the pulsar usually undergoes complete eclipse at frequencies below 1 GHz. At higher frequencies the pulsar is often detected throughout this low-frequency eclipse region with pulse times of arrival being significantly delayed relative to the best-fitting timing model. Variability in the magnitude of the delay is clearly seen and occurs on time-scales shorter than the orbital period. Simultaneous dual frequency observations highlight the difference in the eclipse behaviour for two widely separated frequencies. The low-frequency eclipses are accompanied by a significant decrease in pulsed flux density, while the flux density variations during higher frequency eclipses are not well defined. We consider a number of eclipse mechanisms and find that scattering and cyclotron absorption in the magnetosphere of the companion are consistent with the phenomena presented here.  相似文献   

13.
PSR J1833−1034 and its associated pulsar wind nebula (PWN) have been investigated in depth through X-ray observations ranging from 0.1 to 200 keV. The low-energy X-ray data from Chandra reveal a complex morphology that is characterized by a bright central plerion, no thermal shell and an extended diffuse halo. The spectral emission from the central plerion softens with radial distance from the pulsar, with the spectral index ranging from  Γ= 1.61  in the central region to  Γ= 2.36  at the edge of the PWN. At higher energy, INTEGRAL detected the source in the 17–200 keV range. The data analysis clearly shows that the main contribution to the spectral emission in the hard X-ray energy range is originated from the PWN, while the pulsar is dominant above 200 keV. Recent High Energy Stereoscopic System (HESS) observations in the high-energy gamma-ray domain show that PSR J1833−1034 is a bright TeV emitter, with a flux corresponding to ∼2 per cent of the Crab in 1–10 TeV range. In addition, the spectral shape in the TeV energy region matches well with that in the hard X-rays observed by INTEGRAL . Based on these findings, we conclude that the emission from the pulsar and its associated PWN can be described in a scenario where hard X-rays are produced through synchrotron light of electrons with Lorentz factor  γ∼ 109  in a magnetic field of ∼10 μG. In this hypothesis, the TeV emission is due to inverse-Compton interaction of the cooled electrons off the cosmic microwave background photons. Search for PSR J1833−1034 X-ray pulsed emission, via RXTE and Swift X-ray observations, resulted in an upper limit that is about 50 per cent.  相似文献   

14.
Six glitches have been recently observed in the rotational frequency of the young pulsar PSR B1737−30 (J1740−3015) using the 25-m Nanshan telescope of Urumqi Observatory. With a total of 20 glitches in 20 yr, it is one of the most frequently glitching pulsars of the ∼1750 known pulsars. Glitch amplitudes are very variable with fractional increases in rotation rate ranging from 10−9 to 10−6. Interglitch intervals are also very variable, but no relationship is observed between interval and the size of the preceding glitch. There is a persistent increase in     , opposite in sign to that expected from slowdown with a positive braking index, which may result from changes in the effective magnetic dipole moment of the star during the glitch.  相似文献   

15.
We report on the discovery of a binary pulsar, PSR J1740−3052, during the Parkes multibeam survey. Timing observations of the 570-ms pulsar at Jodrell Bank and Parkes show that it is young, with a characteristic age of 350 kyr, and is in a 231-d, highly eccentric orbit with a companion whose mass exceeds 11 M⊙. An accurate position for the pulsar was obtained using the Australia Telescope Compact Array. Near-infrared 2.2-μm observations made with the telescopes at the Siding Spring observatory reveal a late-type star coincident with the pulsar position. However, we do not believe that this star is the companion of the pulsar, because a typical star of this spectral type and required mass would extend beyond the orbit of the pulsar. Furthermore, the measured advance of periastron of the pulsar suggests a more compact companion, for example, a main-sequence star with radius only a few times that of the Sun. Such a companion is also more consistent with the small dispersion measure variations seen near periastron. Although we cannot conclusively rule out a black hole companion, we believe that the companion is probably an early B star, making the system similar to the binary PSR J0045−7319.  相似文献   

16.
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   

17.
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   

18.
In an earlier paper, based on simultaneous multifrequency observations with the Giant Metrewave Radio Telescope (GMRT), we reported the variation of pulsar dispersion measures (DMs) with frequency. A few different explanations are possible for such frequency dependence, and a possible candidate is the effect of pulse shape evolution on the DM estimation technique. In this paper we describe extensive simulations we have done to investigate the effect of pulse profile evolution on pulsar DM estimates. We find that it is only for asymmetric pulse shapes that the DM estimate is significantly affected due to profile evolution with frequency. Using multifrequency data sets from our earlier observations, we have carried out systematic analyses of PSR B0329+54 and PSR B1642−03. Both these pulsars have central core-dominated emission which does not show significant asymmetric profile evolution with frequency. Even so, we find that the estimated DM shows significant variation with frequency for these pulsars. We also report results from new, simultaneous multifrequency observations of PSR B1133+16 carried out using the GMRT in phased array mode. This pulsar has an asymmetric pulse profile with significant evolution with frequency. We show that in such a case, amplitude of the observed DM variations can be attributed to profile evolution with frequency. We suggest that genuine DM variations with frequency could arise due to propagation effects through the interstellar medium and/or the pulsar magnetosphere.  相似文献   

19.
HESS J1616−508 is one of the brightest emitters in the TeV sky. Recent observations with the IBIS/ISGRI telescope onboard the INTEGRAL spacecraft have revealed that a young, nearby and energetic pulsar, PSR J1617−5055, is a powerful emitter of soft γ-rays in the 20–100 keV domain. In this paper, we present an analysis of all available data from the INTEGRAL , Swift , BeppoSAX and XMM–Newton telescopes with a view to assessing the most likely counterpart to the High Energy Stereoscopic System (HESS) source. We find that the energy source that fuels the X/γ-ray emissions is derived from the pulsar, both on the basis of the positional morphology, the timing evidence and the energetics of the system. Likewise the 1.2 per cent of the pulsar's spin-down energy loss needed to power the 0.1–10 TeV emission is also fully consistent with other HESS sources known to be associated with pulsars. The relative sizes of the X/γ-ray and very high energy sources are consistent with the expected lifetimes against synchrotron and Compton losses for a single source of parent electrons emitted from the pulsar. We find that no other known object in the vicinity could be reasonably considered as a plausible counterpart to the HESS source. We conclude that there is good evidence to assume that the HESS J1616−508 source is driven by PSR J1617−5055 in which a combination of synchrotron and inverse-Compton processes combine to create the observed morphology of a broad-band emitter from keV to TeV energies.  相似文献   

20.
The recently discovered young supernova remnant (SNR) RX J0852.0−4622 has attracted much interest since its discovery because of the possibility that it may have been generated by the nearest supernova in recent history. We note the presence of two Parkes Multibeam Survey pulsars within the boundary of the remnant. We discuss the properties of the two pulsars and the likelihood of either of them being physically linked to the SNR. We tentatively suggest that, given the current uncertainties in the distance to RX J0852.0−4622, one of these pulsars, the 65-ms period PSR J0855−4644 could indeed be the compact remnant of this supernova explosion. If the pulsar birth site is at the geometrical centre of the nebula, then, for the transverse pulsar velocity to be reasonable, the SNR must be nearby (around 250 pc) and no younger than about 3000 yr old.  相似文献   

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