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GrailQuest (Gamma Ray Astronomy International Laboratory for QUantum Exploration of Space-Time) is a mission concept based on a constellation (hundreds/thousands) of nano/micro/small-satellites in low (or near) Earth orbits. Each satellite hosts a non-collimated array of scintillator crystals coupled with Silicon Drift Detectors with broad energy band coverage (keV-MeV range) and excellent temporal resolution (≤ 100 nanoseconds) each with effective area ∼ 100 cm 2 . This simple and robust design allows for mass-production of the satellites of the fleet. This revolutionary approach implies a huge reduction of costs, flexibility in the segmented launching strategy, and an incremental long-term plan to increase the number of detectors and their performance; this will result in a living observatory for next-generation, space-based astronomical facilities. GrailQuest is conceived as an all-sky monitor for fast localisation of high signal-to-noise ratio transients in the X-/gamma-ray band, e.g. the elusive electromagnetic counterparts of gravitational wave events. Robust temporal triangulation techniques will allow unprecedented localisation capabilities, in the keV-MeV band, of a few arcseconds or below, depending on the temporal structure of the transient event. The ambitious ultimate goal of this mission is to perform the first experiment, in quantum gravity, to directly probe space-time structure down to the minuscule Planck scale, by constraining or measuring a first-order dispersion relation for light in vacuo. This is obtained by detecting delays between photons of different energies in the prompt emission of Gamma-Ray Bursts. [ABSTRACT FROM AUTHOR]

Context. XB 1916-053 is a low mass X-ray binary system (LMXB) hosting a neutron star (NS) and showing periodic dips. The spectrum of the persistent emission was modeled with a blackbody component having a temperature between 1.31 and 1.67 keV and with a Comptonization component with an electron temperature of 9.4 keV and a photon index Γ between 2.5 and 2.9. The presence of absorption features associated with highly ionized elements suggested the presence of partially ionized plasma in the system. Aims. In this work we performed a study of the spectrum of XB 1916-053, which aims to shed light on the nature of the seed photons that contribute to the Comptonization component. Methods. We analyzed three Suzaku observations of XB 1916-053: the first was performed in November 2006 and the others were carried out in October 2014. We extracted the persistent spectra from each observation and combined the spectra of the most recent observations, obtaining a single spectrum with a higher statistic. We also extracted and combined the spectra of the dips observed during the same observations. Results. On the basis of the available data statistics, we infer that the scenario in which the corona Comptonizes photons emitted both by the innermost region of the accretion disk and the NS surface is not statistically relevant with respect to the case in which only photons emitted by the NS surface are Comptonized. We find that the source is in a soft spectral state in all the analyzed observations. We detect the Kα absorption lines of Fe XXV and Fe XXVI, which have already been reported in literature, and for the first time the Kβ absorption lines of the same ions. We also detect an edge at 0.876 keV, which is consistent with a O VIII K absorption edge. The dip spectrum is well described by a model that considers material in different ionization states covering the persistent spectrum and absorbing part of the rear radiation. From this model we rescale the distance of the absorber to a distance that is lower than 1 × 1010 cm. [ABSTRACT FROM AUTHOR]

Context. Most of the X-ray binary systems containing neutron stars classified as Atoll sources show two different spectral states, referred to as soft and hard. Moreover, a large number of these systems show a reflection component relativistically smeared in their spectra, which provides information on the innermost region of the system. Aims. Our aim is to investigate the poorly studied broadband spectrum of the low-mass X-ray binary system 4U 1702-429, which was recently analysed combining XMM-Newton and INTEGRAL data. The peculiar value of the reflection fraction brought us to analyse further broadband spectra of 4U 1702-429. Methods. We re-analysed the spectrum of the XMM-Newton/INTEGRAL observation of 4U 1702-429 in the 0.3–60 keV energy range and we extracted three 0.1–100 keV spectra of the source analysing three observations collected with the BeppoSAX satellite. Results. We find that the XMM-Newton/INTEGRAL spectrum is well fitted using a model composed of a disc blackbody plus a Comptonised component and a smeared reflection component. We used the same spectral model for the BeppoSAX spectra, finding that the addition of a smeared reflection component is statistically significant. The best-fit values of the parameters are compatible to each other for the BeppoSAX spectra. We find that the reflection fraction is 0.05−0.01+0.3 0. 05 − 0.01 + 0.03 $ 0.05^{+0.03}_{-0.01} $ for the XMM-Newton/INTEGRAL spectrum and between 0.15 and 0.4 for the BeppoSAX ones. Conclusions. The relative reflection fraction and the ionisation parameter are incompatible between the XMM-Newton/INTEGRAL and the BeppoSAX observations and the characteristics of the Comptonising corona suggest that the source was in a soft state in the former observation and in a hard state in the latter. [ABSTRACT FROM AUTHOR]

Despite considerations of mass-loss from stellar evolution suggesting otherwise, the content of gas in globular clusters seems poor and hence its measurement very elusive. One way of constraining the presence of ionized gas in a globular cluster is through its dispersive effects on the radiation of the millisecond pulsars included in the cluster. This effect led Freire et al. to the first detection of any kind of gas in a globular cluster in the case of 47 Tucanae. By exploiting the results of 12 additional years of timing, as well as the observation of new millisecond pulsars in 47 Tucanae, we revisited this measurement: we first used the entire set of available timing parameters in order to measure the dynamical properties of the cluster and the three-dimensional position of the pulsars. Then we applied and tested various gas distribution models: assuming a constant gas density, we confirmed the detection of ionized gas with a number density of n  = 0.23 ± 0.05 cm−3, larger than the previous determination (at 2σ uncertainty). Models predicting a decreasing density or following the stellar distribution density are highly disfavoured. We are also able to investigate the presence of an intermediate mass black hole in the centre of the cluster, showing that is not required by the available data, with an upper limit for the mass at ∼4000 M⊙. [ABSTRACT FROM AUTHOR]

This paper is the second in a series where we report the results of the long-term timing of the millisecond pulsars (MSPs) in 47 Tucanae with the Parkes 64-m radio telescope. We obtain improved timing parameters that provide additional information for studies of the cluster dynamics: (a) the pulsar proper motions yield an estimate of the proper motion of the cluster as a whole (μα = 5.00 ± 0.14 mas yr−1, μδ = -2.84 ± 0.12 mas yr-1) and the motion of the pulsars relative to each other. (b) We measure the second spin-period derivatives caused by the change of the pulsar line-of-sight accelerations; 47 Tuc H, U and possibly J are being affected by nearby objects. (c) For 10 binary systems, we now measure changes in the orbital period caused by their acceleration in the gravitational field of the cluster. From all these measurements, we derive a cluster distance no smaller than ~4.69 kpc and show that the characteristics of these MSPs are very similar to their counterparts in the Galactic disc. We find no evidence in favour of an intermediate mass black hole at the centre of the cluster. Finally, we describe the orbital behaviour of four 'black widow' systems. Two of them, 47 Tuc J and O, exhibit orbital variability similar to that observed in other such systems, while for 47 Tuc I and R the orbits seem to be remarkably stable. It appears therefore that not all 'black widows' have unpredictable orbital behaviour. [ABSTRACT FROM AUTHOR]

Multi-decade observing campaigns of the globular clusters 47 Tucanae and M15 have led to an outstanding number of discoveries. Here, we report on the latest results of the long-term observations of the pulsars in these two clusters. For most of the pulsars in 47 Tucanae we have measured, among other things, their higher-order spin period derivatives, which have in turn provided stringent constraints on the physical parameters of the cluster, such as its distance and gravitational potential. For M15, we have studied the relativistic spin precession effect in PSR B2127+11C. We have used full-Stokes observations to model the precession effect, and to constrain the system geometry. We find that the visible beam of the pulsar is swiftly moving away from our line of sight and may very soon become undetectable. On the other hand, we expect to see the opposite emission beam sometime between 2041 and 2053. [ABSTRACT FROM AUTHOR]

For the past couple of decades, the Parkes radio telescope has been regularly observing the millisecond pulsars in 47 Tucanae (47 Tuc). This long-term timing programme was designed to address a wide range of scientific issues related to these pulsars and the globular cluster where they are located. In this paper, the first of a series, we address one of these objectives: the characterization of four previously known binary pulsars for which no precise orbital parameters were known, namely 47 Tuc P, V, W and X (pulsars 47 Tuc R and Y are discussed elsewhere).We determined the previously unknown orbital parameters of 47 Tuc V and X and greatly improved those of 47 Tuc P and W. For pulsars W and X we obtained, for the first time, full coherent timing solutions across the whole data span, which allowed a much more detailed characterization of these systems. 47 Tuc W, a well-known tight eclipsing binary pulsar, exhibits a large orbital period variability, as expected for a system of its class. 47 Tuc X turns out to be in a wide, extremely circular, 10.9-d long binary orbit and its position is ~3.8 arcmin away from the cluster centre, more than three times the distance of any other pulsar in 47 Tuc. These characteristics make 47 Tuc X a very different object with respect to the other pulsars of the cluster. [ABSTRACT FROM AUTHOR]

We present timing observations of 4-ms pulsars discovered in the Parkes 20-cm multibeam pulsar survey of the Galactic plane. PSRs J1552-4937 and J1843-1448 are isolated objects with spin periods of 6.28 and 5.47 ms, respectively. PSR J1727-2946 is in a 40-d binary orbit and has a spin period of 27 ms. The 4.43-ms pulsar J1813-2621 is in a circular 8.16-d binary orbit around a low-mass companion star with a minimum companion mass of 0.2 M⊙. Combining these results with detections from five other Parkes multibeam surveys, gives a well-defined sample of 56 pulsars with spin periods below 20 ms. We develop a likelihood analysis to constrain the functional form which best describes the underlying distribution of spin periods for millisecond pulsars. The best results were obtained with a lognormal distribution. A gamma distribution is less favoured, but still compatible with the observations. Uniform, power-law and Gaussian distributions are found to be inconsistent with the data. Galactic millisecond pulsars being found by current surveys appear to be in agreement with a lognormal distribution which allows for the existence of pulsars with periods below 1.5 ms. [ABSTRACT FROM AUTHOR]

The article discusses the findings of a study on the use of neutron interrogation techniques for concealed substances detection in port containers. This study aims to seek control international borders movement of nuclear material and dangerous chemical substances. Detection of pure substances including nitrogen, uranium and chlorine is discussed.

The Perseus Arm Pulsar Survey covers the region of the sky enclosed by Galactic longitudes 200° < l < 260° and Galactic latitudes |b| < 5°. It has been designed to be the continuation towards longitudes further from the Galactic Centre of the very successful Parkes Multibeam Pulsar Survey (PMPS) with the aim of finding interesting individual pulsars for follow-up observations, and better understanding the radial distribution of the pulsar population in the outer Galaxy. As for the PMPS, the observations have been performed using the 21-cm multibeam receiver on the Parkes 64-m radio telescope, the only difference on the set-up being the sampling time, halved to 125 μs. A total of 913 pointings, each of duration 2100 s, were collected. The system provided a limiting flux density, for long-period pulsars with 5 per cent duty cycle, of ∼0.22 mJy. Data analysis resulted in the detection of 32 pulsars of which 14 were new discoveries. One of these, J0721−2038, has a period of 15.5 ms and is in a binary orbit with a period of 5.5 d around an intermediate-mass (>0.46 M⊙) companion. We present timing parameters, obtained with the Parkes and Lovell telescopes for all new pulsars and update the results of the pulsar population studies in light of the new discoveries. Our knowledge of the radial density function of pulsars continues to be dominated by uncertainties in the Galactic distribution of free electrons. [ABSTRACT FROM AUTHOR]

ABSTRACT We present 75 pulsars discovered in the mid-latitude portion of the High Time Resolution Universe survey, 54 of which have full timing solutions. All the pulsars have spin periods greater than 100 ms, and none of those with timing solutions is in binaries. Two display particularly interesting behaviour; PSR J1054−5944 is found to be an intermittent pulsar, and PSR J1809−0119 has glitched twice since its discovery. In the second half of the paper we discuss the development and application of an artificial neural network in the data-processing pipeline for the survey. We discuss the tests that were used to generate scores and find that our neural network was able to reject over 99 per cent of the candidates produced in the data processing, and able to blindly detect 85 per cent of pulsars. We suggest that improvements to the accuracy should be possible if further care is taken when training an artificial neural network; for example, ensuring that a representative sample of the pulsar population is used during the training process, or the use of different artificial neural networks for the detection of different types of pulsars. [ABSTRACT FROM AUTHOR]

ABSTRACT We report on the pulse-to-pulse energy distributions and phase-resolved modulation properties for catalogued pulsars in the southern High Time Resolution Universe intermediate-latitude survey. We selected the 315 pulsars detected in a single-pulse search of this survey, allowing a large sample unbiased regarding any rotational parameters of neutron stars. We found that the energy distribution of many pulsars is well described by a log-normal distribution, with few deviating from a small range in log-normal scale and location parameters. Some pulsars exhibited multiple energy states corresponding to mode changes, and implying that some observed 'nulling' may actually be a mode-change effect. PSR J1900−2600 was found to emit weakly in its previously identified 'null' state. We found evidence for another state-change effect in two pulsars, which show bimodality in their nulling time-scales; that is, they switch between a continuous-emission state and a single-pulse-emitting state. Large modulation occurs in many pulsars across the full integrated profile, with increased sporadic bursts at leading and trailing sub-beam edges. Some of these high-energy outbursts may indicate the presence of 'giant pulse' phenomena. We found no correlation with modulation and pulsar period, age or other parameters. Finally, the deviation of integrated pulse energy from its average value was generally quite small, despite the significant phase-resolved modulation in some pulsars; we interpret this as tenuous evidence of energy regulation between distinct pulsar sub-beams. [ABSTRACT FROM AUTHOR]

ABSTRACT Here we report on observations of the radio magnetar PSR J1622−4950 at frequencies from 1.4 to 17 GHz. We show that although its flux density is varying up to a factor of ∼10 within a few days, it has on average decreased by a factor of 2 over the last 700 days. At the same time, timing analysis indicates a trend of decreasing spin-down rate over our entire data set, again of about a factor of 2 over 700 days, but also an erratic variability in the spin-down rate within this time span. Integrated pulse profiles are often close to 100 per cent linearly polarized, but large variations in both the profile shape and fractional polarization are regularly observed. Furthermore, the behaviour of the position angle of the linear polarization is very complex - offsets in both the absolute position angle and the phase of the position angle sweep are often seen and the occasional presence of orthogonal mode jumps further complicates the picture. However, model fitting indicates that the magnetic and rotation axes are close to aligned. Finally, a single pulse analysis has been carried out at four observing frequencies, demonstrating that the wide pulse profile is built up of narrow spikes of emission, with widths that scale inversely with observing frequency. All three of the known radio magnetars seem to have similar characteristics, with highly polarized emission, time-variable flux density and pulse profiles, and with spectral indices close to zero. [ABSTRACT FROM AUTHOR]

We present the first optical observations of the unique system J0737-3039 (composed of two pulsars, hereafter PSR-A and PSR-B). Ultra-deep optical observations, performed with the High Resolution Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope, could not detect any optical emission from the system down to mF435W = 27.0 and mF606W = 28.3. The estimated optical flux limits are used to constrain the three-component (two thermal and one non-thermal) model recently proposed to reproduce the XMM-Newton X-ray spectrum. They suggest the presence of a break at low energies in the non-thermal power-law component of PSR-A and are compatible with the expected blackbody emission from the PSR-B surface. The corresponding efficiency of the optical emission from PSR-A's magnetosphere would be comparable to that of other Myr-old pulsars, thus suggesting that this parameter may not dramatically evolve over a timescale of a few Myr. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the discovery of six millisecond pulsars (MSPs) in the High Time Resolution Universe (HTRU) survey for pulsars and fast transients carried out with the Parkes radio telescope. All six are in binary systems with approximately circular orbits and are likely to have white dwarf companions. PSR J1017−7156 has a high flux density and a narrow pulse width, making it ideal for precision timing experiments. PSR J1446−4701 and PSR J1125−5825 are coincident with gamma-ray sources, and folding the high-energy photons with the radio timing ephemeris shows evidence of pulsed gamma-ray emission. PSR J1502−6752 has a spin period of 26.7 ms, and its low period derivative implies that it is a recycled pulsar. The orbital parameters indicate it has a very low mass function, and therefore a companion mass much lower than usually expected for such a mildly recycled pulsar. In addition we present polarization profiles for all 12 MSPs discovered in the HTRU survey to date. Similar to previous observations of MSPs, we find that many have large widths and a wide range of linear and circular polarization fractions. Their polarization profiles can be highly complex, and although the observed position angles often do not obey the rotating vector model, we present several examples of those that do. We speculate that the emission heights of MSPs are a substantial fraction of the light cylinder radius in order to explain broad emission profiles, which then naturally leads to a large number of cases where emission from both poles is observed. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the discovery of five millisecond pulsars found in the mid-Galactic latitude portion of the High Time Resolution Universe (HTRU) survey. The pulsars have rotational periods from ∼2.3 ms to ∼7.5 ms, and all are in binary systems with orbital periods ranging from ∼0.3 to ∼150 d. In four of these systems, the most likely companion is a white dwarf, with minimum masses of ∼0.2 M⊙. The other pulsar, J1731−1847, has a very low mass companion and exhibits eclipses and is thus a member of the 'black widow' class of pulsar binaries. These eclipses have been observed in bands centred near frequencies of 700, 1400 and 3000 MHz, from which measurements have been made of the electron density in the eclipse region. These measurements have been used to examine some possible eclipse mechanisms. The eclipse and other properties of this source are used to perform a comparison with the other known eclipsing and 'black widow' pulsars. These new discoveries occupy a short-period and high-dispersion measure (DM) region of parameter space, which we demonstrate is a direct consequence of the high time and frequency resolution of the HTRU survey. The large implied distances to our new discoveries make observation of their companions unlikely with both current optical telescopes and the Fermi Gamma-ray Space Telescope. The extremely circular orbits make any advance of periastron measurements highly unlikely. No relativistic Shapiro delays are obvious in any of the systems although the low flux densities would make their detection difficult unless the orbits were fortuitously edge-on. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the search methods and initial results for transient radio signals in the High Time Resolution Universe (HTRU) survey. The HTRU survey's single-pulse search, the software designed to perform the search and a determination of the HTRU survey's sensitivity to single pulses are described. Initial processing of a small fraction of the survey has produced 11 discoveries, all of which are sparsely emitting neutron stars, as well as provided confirmation of two previously unconfirmed neutron stars. Most of the newly discovered objects lie in regions surveyed previously, indicating both the improved sensitivity of the HTRU survey observing system and the dynamic nature of the radio sky. The cycles of active and null states in nulling pulsars, rotating radio transients (RRATs) and long-term intermittent pulsars are explored in the context of determining the relationship between these populations and of the sensitivity of a search to the various radio-intermittent neutron star populations. This analysis supports the case that many RRATs are in fact high-null-fraction pulsars (i.e. with a null fraction of ≳0.95) and indicates that intermittent pulsars appear distinct from nulling pulsars in their activity cycle time-scales. We find that in the measured population, there is a deficit of pulsars with typical emission time-scales greater than ∼300 s that is not readily explained by selection effects. The HTRU low-latitude survey will be capable of addressing whether this deficit is physical. We predict that the HTRU survey will explore pulsars with a broad range of nulling fractions (up to and beyond 0.999), and at its completion is likely to increase the currently known RRATs by a factor of more than 2. [ABSTRACT FROM AUTHOR]

BSTRACT [ABSTRACT FROM AUTHOR]

We have embarked on a survey for pulsars and fast transients using the 13-beam multibeam receiver on the Parkes Radio Telescope. Installation of a digital backend allows us to record 400 MHz of bandwidth for each beam, split into 1024 channels and sampled every 64 μs. Limits of the receiver package restrict us to a 340 MHz observing band centred at 1352 MHz. The factor of 8 improvement in frequency resolution over previous multibeam surveys allows us to probe deeper into the Galactic plane for short-duration signals such as the pulses from millisecond pulsars. We plan to survey the entire southern sky in 42 641 pointings, split into low, mid and high Galactic latitude regions, with integration times of 4200, 540 and 270 s, respectively. Simulations suggest that we will discover 400 pulsars, of which 75 will be millisecond pulsars. With ∼30 per cent of the mid-latitude survey complete, we have redetected 223 previously known pulsars and discovered 27 pulsars, five of which are millisecond pulsars. The newly discovered millisecond pulsars tend to have larger dispersion measures than those discovered in previous surveys, as expected from the improved time and frequency resolution of our instrument. [ABSTRACT FROM AUTHOR]

We present results of near-infrared spectroscopy of the late-type star coincident with the young pulsar PSR J 3052. High-spectral-resolution K-band ( m) observations were obtained in 2003 with the Infrared Spectrometer and Array Camera instrument on the Very Large Telescope and with Phoenix on the Gemini Telescope. We find no consistent evidence of a radial velocity shift in the star compatible with the known pulsar orbit, setting a limit on the minimum mass of the star, if it is the companion, of . We therefore conclude that the observed star is likely to be a foreground object. No sign of the previously reported Brackett-γ emission was found in this analysis. Our findings support previous suggestions that the companion to PSR J 3052 is most likely a massive B-type star that has been obscured by the bright late-type star in the foreground. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We present the discovery and follow-up observations of 142 pulsars found in the Parkes 20-cm multibeam pulsar survey of the Galactic plane. These new discoveries bring the total number of pulsars found by the survey to 742. In addition to tabulating spin and astrometric parameters, along with pulse width and flux density information, we present orbital characteristics for 13 binary pulsars which form part of the new sample. Combining these results from another recent Parkes multibeam survey at high Galactic latitudes, we have a sample of 1008 normal pulsars which we use to carry out a determination of their Galactic distribution and birth rate. We infer a total Galactic population of potentially detectable pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc2. Adopting the Tauris & Manchester beaming model, this translates to a total of active radio pulsars in the Galaxy above this luminosity limit. Using a pulsar current analysis, we derive the birth rate of this population to be pulsars per century. An important conclusion from our work is that the inferred radial density function of pulsars depends strongly on the assumed distribution of free electrons in the Galaxy. As a result, any analyses using the most recent electron model of Cordes & Lazio predict a dearth of pulsars in the inner Galaxy. We show that this model can also bias the inferred pulsar scaleheight with respect to the Galactic plane. Combining our results with other Parkes multibeam surveys we find that the population is best described by an exponential distribution with a scaleheight of 330 pc. Surveys underway at Parkes and Arecibo are expected to improve the knowledge of the radial distribution outside the solar circle, and to discover several hundred new pulsars in the inner Galaxy. [ABSTRACT FROM AUTHOR]

We report on observations of four southern Anomalous X-ray Pulsars (1RXS J170849.0−400910, 1E 1048.1−5937, 1E 1841−045 and AX J1845−0258) obtained at 1.4 GHz using the Parkes Radio Telescope. Radio pulsations from these sources have been searched (i) by directly folding the time-series at a number of trial periods centred on the value of the spin rate obtained from the X-ray observations; (ii) by performing a blind search and (iii) by using a code sensitive to single de-dispersed pulses, with the aim to detect signals similar to those of the recently discovered Rotating Radio Transients. No evidence for radio pulsations with an upper limit of ∼0.1 mJy for any of the four targets has been found. The blind search led to the serendipitous discovery of two new pulsars, rotating with a spin period of about 0.7 s and 92 m s, respectively, and to the further detection of 18 known pulsars, two of which were also detected in the single-pulse search. [ABSTRACT FROM AUTHOR]

The Parkes High-Latitude pulsar survey covers a region of the sky enclosed by Galactic longitudes 220° < l < 260° and Galactic latitudes | b| < 60°. The observations have been performed using the 20-cm multibeam receiver on the Parkes 64-m radio telescope. A total of 6456 pointings of 265 s each have been collected. The system adopted provided a sensitivity limit, for long-period pulsars with 5 per cent duty cycles, of ∼0.5 mJy. Data analysis resulted in the detection of 42 pulsars of which 18 were new discoveries. Four of these belong to the class of the millisecond – or recycled – pulsars; three of these four are in binary systems. The double pulsar system J0737−3039 is among those and has been presented elsewhere. Here, we discuss the other discoveries and provide timing parameters for the objects for which we have a phase-connected solution. [ABSTRACT FROM AUTHOR]

The radio sky is relatively unexplored for transient signals, although the potential of radio-transient searches is high. This was demonstrated recently by the discovery of a previously unknown type of source, varying on timescales of minutes to hours. Here we report a search for radio sources that vary on much shorter timescales. We found eleven objects characterized by single, dispersed bursts having durations between 2 and 30 ms. The average time intervals between bursts range from 4 min to 3 h with radio emission typically detectable for <1 s per day. From an analysis of the burst arrival times, we have identified periodicities in the range 0.4–7 s for ten of the eleven sources, suggesting origins in rotating neutron stars. Despite the small number of sources detected at present, their ephemeral nature implies a total Galactic population significantly exceeding that of the regularly pulsing radio pulsars. Five of the ten sources have periods >4 s, and the rate of change of the pulse period has been measured for three of them; for one source, we have inferred a high magnetic field strength of 5 × 1013 G. This suggests that the new population is related to other classes of isolated neutron stars observed at X-ray and γ-ray wavelengths. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

The Parkes multibeam pulsar survey has led to the discovery of more than 700 pulsars. In this paper, we provide timing solutions, flux densities and pulse profiles for 180 of these new discoveries. Two pulsars, PSRs J1736–2843 and J1847–0130, have rotational periods P > 6 s and are therefore among the slowest rotating radio pulsars known. Conversely, with P = 1.8 ms, PSR J1843–1113 has the third-shortest period of pulsars currently known. This pulsar and PSR J1905+0400 (P = 3.8 ms) are both solitary. We also provide orbital parameters for a new binary system, PSR J1420–5625, which has P = 34 ms, an orbital period of 40 d and a minimum companion mass of 0.4 solar masses. The 10°-wide strip along the Galactic plane that was surveyed is known to contain 264 radio pulsars that were discovered prior to the multibeam pulsar survey. We have redetected almost all of these pulsars and provide new dispersion measure values and flux densities at 20cm for the redetected pulsars. [ABSTRACT FROM AUTHOR]