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I. H. Stairs

Publications and source records attributed to I. H. Stairs.

At least 181 records · Page 10Linked to original sources
arXiv2003

Pulsar Birthrate from Parkes Multi-beam Survey

We report on calculations of the pulsar birthrate based on the results of the Parkes multibeam survey. From the observed sample of more than 800 pulsars, we compute the pulsar current, accounting as accurately as possible for all known selection effects. The main goal of this work is to understand the pulsar birthrate as a function of the surface dipole magnetic field strengths. We show that pulsars with magnetic fields greater than 10**12.5 G account for about half of the total birthrate.

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arXiv2003

PSR J1847-0130: A Radio Pulsar with Magnetar Spin Characteristics

We report the discovery of PSR J1847-0130, a radio pulsar with a 6.7-s spin period, in the Parkes multibeam survey of the Galactic plane. The slowdown rate for the pulsar, 1.3x10^{-12} s/s, is high and implies a surface dipole magnetic field strength of 9.4x10^{13} G. This inferred dipolar magnetic field strength is the highest by far among all known radio pulsars and over twice the ``quantum critical field'' above which some models predict radio emission should not occur. The inferred dipolar magnetic field strength and period of this pulsar are in the same range as those of the anomalous X-ray pulsars, which have been identified as being "magnetars" whose luminous X-ray emission is powered by their large magnetic fields. We have examined archival ASCA data and place an upper limit on the X-ray luminosity of J1847-0130 which is lower than the luminosities of all but one AXP. The properties of this pulsar prove that inferred dipolar magnetic field strength and period cannot alone be responsible for the unusual high-energy properties of the magnetars and creates new challenges for understanding the possible relationship between these two manifestations of young neutron stars.

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arXiv2003

The Parkes multibeam pulsar survey: III. Young pulsars & the discovery and timing of 200 pulsars

The Parkes multibeam pulsar survey has unlocked vast areas of the Galactic plane which were previously invisible to earlier low-frequency and less-sensitive surveys. The survey has discovered more than 600 new pulsars so far, including many that are young and exotic. In this paper we report the discovery of 200 pulsars for which we present positional and spin-down parameters, dispersion measures, flux densities and pulse profiles. A large number of these new pulsars are young and energetic, and we review possible associations of $γ$-ray sources with the sample of about 1300 pulsars for which timing solutions are known. Based on a statistical analysis, we estimate that about $19\pm6$ associations are genuine. The survey has also discovered 12 pulsars with spin properties similar to those of the Vela pulsar, nearly doubling the known population of such neutron stars. Studying the properties of all known `Vela-like' pulsars, we find their radio luminosities to be similar to normal pulsars, implying that they are very inefficient radio sources. Finally, we review the use of the newly discovered pulsars as Galactic probes and discuss the implications of the new NE2001 Galactic electron density model for the determination of pulsar distances and luminosities.

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arXiv2003

Yet MORE PM Survey Discoveries....?

The Parkes Multibeam (PM) survey has found nearly 50% of the >1400 known pulsars and detected 20% of the pulsars in binary systems (75% within the survey area), few of these are millisecond pulsars with orbits of less than one day. It is known that the normal search techniques used in the PM Survey have selected against finding binary pulsars, due to the long integration times used. The relative performance of the search techniques used and the improvements made prior to the complete reprocessing of the data currently being undertaken are discussed. The processing is being done on COBRA - the new supercomputer at Jodrell Bank. The results of the reprocessing, as well as adding more solitary pulsars, will give more confidence on the population and types of binaries in the Galactic plane. However, it can be shown that for millisecond pulsars in binary orbits of between 20min and a few hours, the search techniques are still relatively insensitive.

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arXiv2003

Polarisation Observations at Jodrell Bank Observatory

Some of the issues concerning polarisation calibration in the context of pulsar observations are outlined along with the existing calibration system in Jodrell Bank Observatory. The principle behind the back-calibration of the Jodrell Bank database of 16 years is presented along with plans for exploiting the database in the future.

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arXiv2002

Recent Globular Cluster Searches with Arecibo and the Green Bank Telescope

We report the discovery of seven new millisecond pulsars during 20 cm searches of 19 globular clusters using the recently upgraded Arecibo Telescope and the new Green Bank Telescope (GBT). Five of the pulsars are in compact binaries, three of which are eclipsing. One of the systems is in an eccentric orbit which is almost certainly highly relativistic. Additional searches and timing observations are underway.

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arXiv2002

The Massive Binary Pulsar J1740-3052

The young pulsar J1740-3052 is in an 8-month orbit with a companion of at least 11 solar masses. We present multifrequency GBT and Parkes timing observations, and discuss implications for the nature of the companion.

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arXiv2002

Studies of the Relativistic Binary Pulsar PSR B1534+12: I. Timing Analysis

We have continued our long term study of the double-neutron-star binary pulsar PSR B1534+12, using new instrumentation to make very high precision measurements at the Arecibo Observatory. We have significantly improved our solution for the astrometric, spin, and orbital parameters of the system, as well as for the five "post-Keplerian" orbital parameters that can be used to test gravitation theory. The results are in good agreement with the predictions of general relativity. With the assumption that general relativity is the correct theory of gravity in the classical regime, our measurements allow us to determine the masses of the pulsar and its companion neutron star with high accuracy: 1.3332 \pm 0.0010 Msun and 1.3452 \pm 0.0010Msun, respectively. The small but significant mass difference is difficult to understand in most evolutionary models, as the pulsar is thought to have been born first from a more massive progenitor star and then undergone a period of mass accretion before the formation of the second neutron star. PSR B1534+12 has also become a valuable probe of the local interstellar medium. We have now measured the pulsar distance to be 1.02 \pm 0.05 kpc, giving a mean electron density along this line of sight of 0.011/cc. We continue to measure a gradient in the dispersion measure, though the rate of change is now slower than in the first years after the pulsar's discovery.

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arXiv2002

A Very Large Glitch in PSR J1806-2125

PSR J1806-2125 is a pulsar discovered in the Parkes multibeam pulsar survey with a rotational period of 0.4s and a characteristic age of 65kyr. Between MJDs 51462 and 51894 this pulsar underwent an increase in rotational frequency of $Δν/ν\approx 16 \times 10^{-6}$. The magnitude of this glitch is approximately 2.5 times greater than any previously observed in any pulsar and 16 times greater than the mean glitch size. This letter gives the parameters of the glitch and compares its properties to previously observed events. The existence of such large and rare glitches offers new hope for attempts to observe thermal X-ray emission from the internal heat released following a glitch, and suggests that pulsars which previously have not been observed to glitch may do so on long timescales.

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arXiv2002

The Parkes Multibeam Pulsar Survey -- II. Discovery and Timing of 120 Pulsars

The Parkes multibeam pulsar survey is a sensitive survey of a strip of the Galactic plane with $|b|<5\degr$ and $260\degr < l < 50\degr$ 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, $B_s = 5.4\times10^{13}$ G, and PSR J1830$-$1135, the second slowest radio pulsar known, with a 6-s period.

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arXiv2002

Discovery of radio pulsations from the X-ray pulsar J0205+6449 in supernova remnant 3C58 with the Green Bank Telescope

We report the discovery with the 100 m Green Bank Telescope of 65 ms radio pulsations from the X-ray pulsar J0205+6449 at the center of supernova remnant 3C58, making this possibly the youngest radio pulsar known. From our observations at frequencies of 820 and 1375 MHz, the free electron column density to PSR J0205+6449 is found to be 140.7 +- 0.3 pc/cc. The barycentric pulsar period P and period derivative determined from a phase-coherent timing solution are consistent with the values previously measured from X-ray observations. The averaged radio profile of PSR J0205+6449 consists of one sharp pulse of width ~ 3 ms ~ 0.05 P. The pulsar is an exceedingly weak radio source, with pulse-averaged flux density in the 1400 MHz band of 0.045 mJy and a spectral index of ~ -2.1. Its radio luminosity of ~ 0.5 mJy kpc^2 at 1400 MHz is lower than that of ~ 99% of known pulsars and is the lowest among known young pulsars.

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arXiv2001

Young Pulsars from the Parkes Multibeam Pulsar Survey and their Associations

The Parkes multibeam pulsar survey is covering a 10deg-wide strip of the southern Galactic plane from l=260deg to l=50deg. It utilizes a 13-beam receiver operating in the 20-cm band on the Parkes 64-m radio telescope and is much more sensitive than any previous large-scale survey. Most of the 608 pulsars discovered so far are relatively distant and many are young, with 37 having a characteristic age of less than 10^5 years. At least one of these is associated with a supernova remnant and four other probable associations are suggested. Several multibeam pulsars have high values of the parameter Edot/d^2 and are within the position error contours of unidentified EGRET gamma-ray sources. These possible associations will be tested with the advent of new gamma-ray telescopes.

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arXiv2001

PSR J1016-5857: a young radio pulsar with possible supernova remnant, X-ray, and gamma-ray associations

We report the discovery of a young and energetic pulsar in the Parkes multibeam survey of the Galactic plane. PSR J1016-5857 has a rotation period of 107 ms and period derivative of 8e-14, implying a characteristic age of 21 kyr and spin-down luminosity of 2.6e36 erg/s. The pulsar is located just outside, and possibly interacting with, the shell supernova remnant G284.3-1.8. Archival X-ray data show a source near the pulsar position which is consistent with emission from a pulsar wind nebula. The pulsar is also located inside the error box of the unidentified EGRET source 3EG J1013-5915, for which it represents a plausible counterpart.

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arXiv2001

The Parkes Multibeam Pulsar Survey: I. Observing and Data Analysis Systems, Discovery and Timing of 100 Pulsars

The Parkes multibeam pulsar survey is a sensitive survey of a strip along the Galactic plane with |b|<5 deg and l=260 deg to l=50 deg. It uses a 13-beam receiver on the 64-m Parkes radio telescope, receiving two polarisations per beam over a 288 MHz bandwidth centred on 1374 MHz. Receiver and data acquisition systems are described in some detail. For pulsar periods in the range 0.1 - 2 s and dispersion measures of less than 300 cm^{-3} pc, the nominal limiting flux density of the survey is about 0.2 mJy. At shorter or longer periods or higher dispersions, the sensitivity is reduced. Timing observations are carried out for pulsars discovered in the survey for 12 - 18 months after confirmation to obtain accurate positions, spin parameters, dispersion measures, pulse shapes and mean flux densities. The survey is proving to be extremely successful, with more than 600 pulsars discovered so far. We expect that, when complete, this one survey will come close to finding as many pulsars as all previous pulsar surveys put together. The newly discovered pulsars tend to be young, distant and of high radio luminosity. They will form a valuable sample for studies of pulsar emission properties, the Galactic distribution and evolution of pulsars, and as probes of interstellar medium properties. This paper reports the timing and pulse shape parameters for the first 100 pulsars timed at Parkes, including three pulsars with periods of less than 100 ms which are members of binary systems. These results are briefly compared with the parameters of the previously known population.

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arXiv2001

Pulsar Timing Observations and Tests of General Relativity in Double-Neutron-Star Binaries

We describe the techniques used in pulsar timing observations, and show how these observations may be applied to tests of strong-field general relativity for double-neutron-star binary systems. We describe the tests of GR resulting from the PSRs B1913+16 and B1534+12 systems. For the latter pulsar, 5 "Post-Keplerian" timing parameters are measurable, including the orbital period derivative and the two Shapiro delay parameters.

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arXiv2001

PSR J1740-3052 - a pulsar with a massive companion

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-day, highly eccentric orbit with a companion whose mass exceeds 11 M_sun. An accurate position for the pulsar was obtained using the Australia Telescope Compact Array. Near-infrared 2.2-um observations make 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 pulsar's companion, because a typical star of this spectral type and required mass would extend beyond the pulsar's orbit. 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 the companion is probably an early B star, making the system similar to the binary PSR J0045-7319.

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arXiv2000

Discovery of Five Binary Radio Pulsars

We report on five binary pulsars discovered in the Parkes multibeam Galactic plane survey. All of the pulsars are old, with characteristic ages 1-11 Gyr, and have relatively small inferred magnetic fields, 5-90e8 G. The orbital periods range from 1.3 to 15 days. As a group these objects differ from the usual low-mass binary pulsars (LMBPs): their spin periods of 9-88 ms are relatively long; their companion masses, 0.2-1.1 Msun, are, in at least some cases, suggestive of CO or more massive white dwarfs; and some of the orbital eccentricities, 1e-5 < e < 0.002, are unexpectedly large. We argue that these observed characteristics reflect binary evolution that is significantly different from that of LMBPs. We also note that intermediate-mass binary pulsars apparently have a smaller scale-height than LMBPs.

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