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Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances (1-8). Previous follow-up observations have failed to find additional bursts at [...]

Asymmetry is required by most numerical simulations of stellar core-collapse explosions, but the form it takes differs significantly among models. The spatial distribution of radioactive [sup.44]Ti, synthesized in an exploding star near the boundary between material falling back onto the collapsing core and that ejected into the surrounding medium (1), directly probes the explosion asymmetries. Cassiopeia A is a young (2), nearby (3), core-collapse (4) remnant from which [sup.44]Ti emission has previously been detected (5-8) but not imaged. Asymmetries in the explosion have been indirectly inferred from a high ratio of observed [sup.44]Ti emission to estimated [sup.56]Ni emission (9), from optical light echoes (10), and from jet-like features seen in the X-ray (11) and optical (12) ejecta. Here we report spatial maps and spectral properties of the [sup.44]Ti in Cassiopeia A. This may explain the unexpected lack of correlation between the [sup.44]Ti and iron X-ray emission, the latter being visible only in shock-heated material. The observed spatial distribution rules out symmetric explosions even with a high level of convective mixing, as well as highly asymmetric bipolar explosions resulting from a fast-rotating progenitor. Instead, these observations provide strong evidence for the development of low-mode convective instabilities in core-collapse supernovae., Titanium-44 is produced in Si burning in the innermost regions of the material ejected in core-collapse supernovae, in the same processes that produce Fe and [56.sup]Ni (ref. 13). The decay [...]

Gravitationally bound three-body systems have been studied for hundreds of years (1,2) and are common in our Galaxy (3,4). They show complex orbital interactions, which can constrain the compositions, masses and interior structures of the bodies (5) and test theories of gravity (6), if sufficiently precise measurements are available. A triple system containing a radio pulsar could provide such measurements, but the only previously known such system, PSR B1620-26 (refs (7,8); with a millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of several decades), shows only weak interactions. Here we report precision timing and multiwavelength observations of PSR J0337+1715, a millisecond pulsar in ahierarchical triple system with two other stars. Strong gravitational interactions are apparent and provide the masses of the pulsar (1.4378(13)[M.sub.[dot in a circle]], where [M.sub.[dot in a circle]] is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15)[M.sub.[dot in a circle]] and 0.4101(3)[M.sub.[dot in a circle]]), as well as the inclinations of the orbits (both about 39.2°). The unexpectedly coplanar and nearly circular orbits indicate a complex and exotic evolutionary past that differs from those of known stellar systems. The gravitational field of the outer white dwarf strongly accelerates the inner binary containing the neutron star, and the system will thus provide an ideal laboratory in which to test the strong equivalence principle of general relativity., Millisecond pulsars (MSPs) are neutron stars that rotate hundreds of times per second and emit beams of radio waves much as a lighthouse emits light. They are thought to form [...]

Magnetars are neutron stars with X-ray and soft γ-ray outbursts thought to be powered by intense internal magnetic fields (1). Like conventional neutron stars in the form of radio pulsars, [...]

We have detected an x-ray nebula around the binary millisecond pulsar B1957+20. A narrow tail corresponding to the shocked pulsar wind, is seen interior to the known Hα bow shock [...]

Misalignment of the angular momentum of the pulsar PSR J0045 - 7319 that is revolving around a B star provides evidence for birth kicks to neutron stars by supernova explosions that form the stars. Radio studies of the pulsar shows that the B star's spin axis is inclined at between a 25 and 41 degree angle rather than the 44 plus or minus 5 degrees expected for the orbital angular momentum vector. Angular momenta of the system were aligned before the supernova explosion due to tidal effects and mass transfer or primordial effects. Misalignment after the explosion is probably due to the kick velocity of the neutron star induced by the explosion.

The pulsar PSR J0437-4715 was first recorded on Feb 13, 1992, and confirmed on Jul 11 as possibly the closest pulsar to the Earth during a survey for millisecond pulsars in the southern sky. A possible optical companion has been determined because of no other stars are close to the radio signal. This pulsar can be used to confirm or deny the theory that millisecond pulsars generate gamma rays and contribute to the galactic gamma ray background.

PSR1706-44 is the fourth radio pulsar to be identified as a source of pulsed gamma-radiation. PSR1706-44's gamma rays, measured at more than 100 MeV in energy and with a pulse period of 102 minutes, are emitted as one broad peak rather than as two narrow peaks as with the other three radio pulsars. The geometry of the magnetic and rotation axes and the line of sight probably accounts for this difference. Further research on gamma-radiation emissions from these pulsars is needed since such radiation comprises at least 1% of total neutron-star spin-down energy.

The Parkes Multibeam Pulsar Survey is a sensitive survey of a strip of the Galactic plane with |b| < 5° and 260° < l < 50° at 1374 MHz. Here we report the discovery of 120 new pulsars and subsequent timing observations, primarily using the 76-m Lovell radio telescope at Jodrell Bank. The main features of the sample of 370 published pulsars discovered during the multibeam survey are described. Furthermore, we highlight two pulsars: PSR J1734-3333, a young pulsar with the second highest surface magnetic field strength among the known radio pulsars, B[sub s]= 5.4 × 10[sup 13] G , and PSR J1830-1135, the second slowest radio pulsar known, with a 6-s period. [ABSTRACT FROM AUTHOR]

Examines the performance of Parkes multi-beam pulsar survey along the Galactic plane. Inclusion of the concept of receiver and data acquisition system; Emphasis of the pulsar emission properties; Consideration of high radio luminosity.

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[sub ⊙]. 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. [ABSTRACT FROM AUTHOR]

Timing observations of 40 mostly young pulsars using the ATNF Parkes radio telescope between 1990 January and 1998 December are reported. In total, 20 previously unreported glitches and 10 other glitches were detected in 11 pulsars. These included 12 glitches in PSR J1341-6220, corresponding to a glitch rate of 1.5 glitches per year. We also detected the largest known glitch, in PSR J1614-5047, with Δν[sub g]ν≈6.5×10[sup -6], where ν=1/P is the pulse frequency. Glitch parameters were determined both by extrapolating timing solutions to interglitch intervals and by phase-coherent timing fits across the glitch(es). These fits also give improved positions and dispersion measures for many of the pulsars. Analysis of glitch parameters, both from this work and from previously published results, shows that most glitches have a fractional amplitude Δν[sub g]ν of between 10[sup -8] and 10[sup -6]. There is no consistent relationship between glitch amplitude and the time since the previous glitch or the time to the following glitch, either for the ensemble or for individual pulsars. As previously recognized, the largest glitch activity is seen in pulsars with ages of order 10[sup 4] yr, but for about 30 per cent of such pulsars, no glitches were detected in the 8-year data span. There is some evidence for a new type of timing irregularity in which there is a significant increase in pulse frequency over a few days, accompanied by a decrease in the magnitude of the slow-down rate. Fits of an exponential recovery to post-glitch data show that for most older pulsars, only a small fraction of the glitch decays. In some younger pulsars a large fraction of the glitch decays, but in others there is very little decay. Apart from the Crab pulsar, there is no clear dependence of recovery time-scale on pulsar age. [ABSTRACT FROM AUTHOR]

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[sub ⊙], and the minimum companion mass is about 0.7 M[sub ⊙]. 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. [ABSTRACT FROM AUTHOR]

Investigates magnetar-like x-ray bursts from an anomalous x-ray pulsar (AXP). Soft-gamma-ray (SGR) repeaters thought to be magnetars; Suggestion that AXPs might also be magnetars; Close relationship between AXPs and SGRs with both being magnetars.