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A. Possenti - One of the best experts on this subject based on the ideXlab platform.
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Discovery of 28 Pulsars using new techniques for sorting pulsar candidates
Monthly Notices of the Royal Astronomical Society, 2009Co-Authors: Michael Keith, Felivel Camilo, Michael Kramer, Ralph Eatough, Andrew Lyne, A. Possenti, R N ManchesterAbstract:Modern pulsar surveys produce many millions of candidate Pulsars, far more than can be individually inspected. Traditional methods for filtering these candidates, based upon the signal-to-noise ratio of the detection, cannot easily distinguish between interference signals and Pulsars. We have developed a new method of scoring candidates using a series of heuristics which test for pulsar-like properties of the signal. This significantly increases the sensitivity to weak Pulsars and Pulsars with periods close to interference signals. By applying this and other techniques for ranking candidates from a previous processing of the Parkes Multi-beam Pulsar Survey, 28 previously unknown Pulsars have been discovered. These include an eccentric binary system and a young pulsar which is spatially coincident with a known supernova remnant.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
Monthly Notices of the Royal Astronomical Society, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A. PossentiAbstract: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 30 000 ± 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc 2 . Adopting the Tauris & Manchester beaming model, this translates to a total of 155 000 ± 6000 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 1.4 ± 0.2 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.
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The Parkes Multibeam Pulsar Survey - V. Finding binary and millisecond Pulsars
Monthly Notices of the Royal Astronomical Society, 2004Co-Authors: A. J. Faulkner, R N Manchester, Duncan R. Lorimer, Michael Kramer, Andrew Lyne, A. Possenti, George Hobbs, Ingrid H. Stairs, Maura Mclaughlin, Nicolo' D'amicoAbstract: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).
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The Parkes multibeam pulsar survey: IV. Discovery of 180 Pulsars and parameters for 281 previously known Pulsars
Monthly Notices of the Royal Astronomical Society, 2004Co-Authors: George Hobbs, Michael Kramer, Andrew Lyne, Ingrid H. Stairs, Victoria M. Kaspi, Richard N. Manchester, Andrew Faulkner, Fernando Camilo, N. D'amico, A. PossentiAbstract: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 > 6s and are therefore among the slowest rotating radio Pulsars known. Conversely, with P = 1.8ms, PSR J1843-1113 has the third shortest period of Pulsars currently known. This pulsar and PSR J1905+0400 (P = 3.8ms) are both solitary. We also provide orbital parameters for a new binary system, PSR J1420-5625, which has P = 34ms, an orbital period of 40 days and a minimum companion mass of 0.4 solar masses. The 10 degree-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.
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The Parkes Multibeam Pulsar Survey – II. Discovery and timing of 120 Pulsars
Monthly Notices of the Royal Astronomical Society, 2002Co-Authors: D. J. Morris, R N Manchester, Felivel Camilo, A. Possenti, George Hobbs, A. G. Lyne, Ingrid H. Stairs, J. F. Bell, Victoria M. Kaspi, Nichi D. AmicoAbstract: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, Bs = 5.4 × 10 13 G, and PSR J1830−1135, the second slowest radio pulsar known,
R N Manchester - One of the best experts on this subject based on the ideXlab platform.
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PULSAR SEARCHING AND TIMING
International Journal of Modern Physics D, 2013Co-Authors: R N ManchesterAbstract:More than 2000 Pulsars are now known. These Pulsars may be divided into a number of different classes according to their period, period derivative, binary properties, emission characteristics and so on. Some important classes have relatively few members, e.g. double-neutron-star binary systems, and so continued searches for currently unknown Pulsars are important. Such searches are being undertaken at various observatories around the world. Somewhat unexpectedly, the Fermi Gamma-ray Observatory, has proved to be an efficient pulsar detector, especially for millisecond Pulsars (MSPs). The great stability of pulsar periods, especially for MSPs, leads to a number of important applications of pulsar timing. The detection and study of relativistic orbit perturbations in double-neutron-star systems has proved to be a powerful tool with measurements of the original binary pulsar, PSR B1913+16, and more recently the double pulsar, PSR J0737-3039A/B, showing that Einstein's general theory of relativity accurately describes these gravitational interactions. Direct detection of gravitational waves using pulsar timing is close to being achieved with the development of pulsar timing arrays (PTAs) in Europe, North America and Australia. Combining data from these PTAs to form the International Pulsar Timing Array (IPTA) will lead to improved significance of such a detection. Ultimately, detailed study of gravitational-wave sources will be possible using future large radio telescopes such as FAST and the SKA.
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Discovery of 28 Pulsars using new techniques for sorting pulsar candidates
Monthly Notices of the Royal Astronomical Society, 2009Co-Authors: Michael Keith, Felivel Camilo, Michael Kramer, Ralph Eatough, Andrew Lyne, A. Possenti, R N ManchesterAbstract:Modern pulsar surveys produce many millions of candidate Pulsars, far more than can be individually inspected. Traditional methods for filtering these candidates, based upon the signal-to-noise ratio of the detection, cannot easily distinguish between interference signals and Pulsars. We have developed a new method of scoring candidates using a series of heuristics which test for pulsar-like properties of the signal. This significantly increases the sensitivity to weak Pulsars and Pulsars with periods close to interference signals. By applying this and other techniques for ranking candidates from a previous processing of the Parkes Multi-beam Pulsar Survey, 28 previously unknown Pulsars have been discovered. These include an eccentric binary system and a young pulsar which is spatially coincident with a known supernova remnant.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
Monthly Notices of the Royal Astronomical Society, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A. PossentiAbstract: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 30 000 ± 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc 2 . Adopting the Tauris & Manchester beaming model, this translates to a total of 155 000 ± 6000 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 1.4 ± 0.2 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.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
arXiv: Astrophysics, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A PossentiAbstract:[ABRIDGED] 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 30000 +/- 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc squared. Using a pulsar current analysis, we derive the birth rate of this population to be 1.4 +/- 0.2 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 scale height 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 scale height of 330 pc.
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Pulsars and Gravity
Progress of Theoretical Physics Supplement, 2006Co-Authors: R N ManchesterAbstract:Pulsar periods are extremely stable, making possible many interesting and important applications ranging from determining the proper motion of globular clusters to detecting gravitational waves. Many Pulsars, especially millisecond Pulsars, are in binary orbit with another star. The first-known pulsar binary system, PSR B1913+16, discovered by Hulse and Taylor in 1974, provided the first observational evidence for the existence of gravitational waves and verified that Einstein's general theory of relativity is an accurate theory of gravitation. Surveys with Parkes multibeam receiver have in the past few years more than doubled the number of known Pulsars. Prominent among the discoveries is the first-known double pulsar, PSR J0737-3039A/B. This system is even more relativistic than PSR B1913+16 and in just two years has provided a more stringent test of general relativity, with five post-Keplerian parameters already determined. An important prediction of general relativity is the existence of gravitational waves. Precise timing of a very stable millisecond pulsar has already put limits on the energy density of a stochastic gravitational-wave background at the Earth. Timing measurements of an ensemble of millisecond Pulsars distributed over the celestial sphere can in principle make a direct detection of this stochastic background. The Parkes Pulsar Timing Array (PPTA) project is making regular timing measurements of 20 millisecond Pulsars with the ultimate aim of detecting the gravitational-wave background at the Earth. With a five-year data span the PPTA should have sufficient sensitivity to detect the gravitational-wave background from binary super-massive black holes in the cores of galaxies.
D R Lorimer - One of the best experts on this subject based on the ideXlab platform.
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the green bank telescope 350 mhz drift scan survey ii data analysis and the timing of 10 new Pulsars including a relativistic binary
The Astrophysical Journal, 2013Co-Authors: M A Mclaughlin, Ryan S Lynch, S.m. Ransom, D R Lorimer, Jason Boyles, I H Stairs, J W T HesselsAbstract:We have completed a 350 MHz Drift-scan Survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio Pulsars, especially millisecond Pulsars that can be timed to high precision. This survey covered ~10,300 deg2 and all of the data have now been fully processed. We have discovered a total of 31 new Pulsars, 7 of which are recycled Pulsars. A companion paper by Boyles et al. describes the survey strategy, sky coverage, and instrumental setup, and presents timing solutions for the first 13 Pulsars. Here we describe the data analysis pipeline, survey sensitivity, and follow-up observations of new Pulsars, and present timing solutions for 10 other Pulsars. We highlight several sources—two interesting nulling Pulsars, an isolated millisecond pulsar with a measurement of proper motion, and a partially recycled pulsar, PSR J0348+0432, which has a white dwarf companion in a relativistic orbit. PSR J0348+0432 will enable unprecedented tests of theories of gravity.
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the green bank telescope 350 mhz drift scan survey ii data analysis and the timing of 10 new Pulsars including a relativistic binary
arXiv: High Energy Astrophysical Phenomena, 2012Co-Authors: M A Mclaughlin, Ryan S Lynch, S.m. Ransom, D R Lorimer, Jason Boyles, I H Stairs, J W T HesselsAbstract:We have completed a 350 MHz drift scan survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio Pulsars, especially millisecond Pulsars that can be timed to high precision. This survey covered ~10300 square degrees and all of the data have now been fully processed. We have discovered a total of 31 new Pulsars, seven of which are recycled Pulsars. A companion paper by Boyles et al. (2012) describes the survey strategy, sky coverage, and instrumental set-up, and presents timing solutions for the first 13 Pulsars. Here we describe the data analysis pipeline, survey sensitivity, and follow-up observations of new Pulsars, and present timing solutions for 10 other Pulsars. We highlight several sources---two interesting nulling Pulsars, an isolated millisecond pulsar with a measurement of proper motion, and a partially recycled pulsar, PSR J0348+0432, which has a white dwarf companion in a relativistic orbit. PSR J0348+0432 will enable unprecedented tests of theories of gravity.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
Monthly Notices of the Royal Astronomical Society, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A. PossentiAbstract: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 30 000 ± 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc 2 . Adopting the Tauris & Manchester beaming model, this translates to a total of 155 000 ± 6000 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 1.4 ± 0.2 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.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
arXiv: Astrophysics, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A PossentiAbstract:[ABRIDGED] 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 30000 +/- 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc squared. Using a pulsar current analysis, we derive the birth rate of this population to be 1.4 +/- 0.2 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 scale height 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 scale height of 330 pc.
M A Mclaughlin - One of the best experts on this subject based on the ideXlab platform.
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the green bank telescope 350 mhz drift scan survey ii data analysis and the timing of 10 new Pulsars including a relativistic binary
The Astrophysical Journal, 2013Co-Authors: M A Mclaughlin, Ryan S Lynch, S.m. Ransom, D R Lorimer, Jason Boyles, I H Stairs, J W T HesselsAbstract:We have completed a 350 MHz Drift-scan Survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio Pulsars, especially millisecond Pulsars that can be timed to high precision. This survey covered ~10,300 deg2 and all of the data have now been fully processed. We have discovered a total of 31 new Pulsars, 7 of which are recycled Pulsars. A companion paper by Boyles et al. describes the survey strategy, sky coverage, and instrumental setup, and presents timing solutions for the first 13 Pulsars. Here we describe the data analysis pipeline, survey sensitivity, and follow-up observations of new Pulsars, and present timing solutions for 10 other Pulsars. We highlight several sources—two interesting nulling Pulsars, an isolated millisecond pulsar with a measurement of proper motion, and a partially recycled pulsar, PSR J0348+0432, which has a white dwarf companion in a relativistic orbit. PSR J0348+0432 will enable unprecedented tests of theories of gravity.
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the green bank telescope 350 mhz drift scan survey ii data analysis and the timing of 10 new Pulsars including a relativistic binary
arXiv: High Energy Astrophysical Phenomena, 2012Co-Authors: M A Mclaughlin, Ryan S Lynch, S.m. Ransom, D R Lorimer, Jason Boyles, I H Stairs, J W T HesselsAbstract:We have completed a 350 MHz drift scan survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio Pulsars, especially millisecond Pulsars that can be timed to high precision. This survey covered ~10300 square degrees and all of the data have now been fully processed. We have discovered a total of 31 new Pulsars, seven of which are recycled Pulsars. A companion paper by Boyles et al. (2012) describes the survey strategy, sky coverage, and instrumental set-up, and presents timing solutions for the first 13 Pulsars. Here we describe the data analysis pipeline, survey sensitivity, and follow-up observations of new Pulsars, and present timing solutions for 10 other Pulsars. We highlight several sources---two interesting nulling Pulsars, an isolated millisecond pulsar with a measurement of proper motion, and a partially recycled pulsar, PSR J0348+0432, which has a white dwarf companion in a relativistic orbit. PSR J0348+0432 will enable unprecedented tests of theories of gravity.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
Monthly Notices of the Royal Astronomical Society, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A. PossentiAbstract: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 30 000 ± 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc 2 . Adopting the Tauris & Manchester beaming model, this translates to a total of 155 000 ± 6000 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 1.4 ± 0.2 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.
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the parkes multibeam pulsar survey vi discovery and timing of 142 Pulsars and a galactic population analysis
arXiv: Astrophysics, 2006Co-Authors: M A Mclaughlin, R N Manchester, M Kramer, George Hobbs, A. G. Lyne, A. J. Faulkner, D R Lorimer, A PossentiAbstract:[ABRIDGED] 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 30000 +/- 1100 potentially detectable Pulsars (i.e. those beaming towards us) having 1.4-GHz luminosities above 0.1 mJy kpc squared. Using a pulsar current analysis, we derive the birth rate of this population to be 1.4 +/- 0.2 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 scale height 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 scale height of 330 pc.
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The Gamma Ray Pulsar Population
The Astrophysical Journal, 2000Co-Authors: M A Mclaughlin, James M. CordesAbstract:We apply a likelihood analysis to pulsar detections, pulsar upper limits, and diffuse background measurements from the OSSE and EGRET instruments on the Compton Gamma Ray Observatory to constrain the luminosity law for gamma-ray Pulsars and some properties of the gamma-ray pulsar population. We find that the dependence of luminosity on spin period and dipole magnetic field is much steeper at OSSE than at EGRET energies (50-200 keV and >100 MeV, respectively), suggesting that different emission mechanisms are responsible for low- and high-energy gamma-ray emission. Incorporating a spin-down model and assuming a pulsar spatial distribution, we estimate the fraction of the Galactic gamma-ray background due to unidentified Pulsars and find that Pulsars may be an important component of the OSSE diffuse flux but are most likely not important at EGRET energies. Using measurements of the diffuse background flux from these instruments, we are able to place constraints on the braking index, initial spin period, and magnetic field of the Galactic pulsar population and are also able to constrain the pulsar birthrate to be between 1/25 yr-1 and 1/500 yr-1. Our results are based on a large gamma-ray beam, but they do not scale in a simple way with beam size. We estimate that about 20 of the 169 unidentified EGRET sources are probably gamma-ray Pulsars. We use our model to predict the pulsar population that will be seen by future gamma-ray instruments and estimate that Gamma Ray Large Area Space Telescope will detect roughly 750 gamma-ray Pulsars as steady sources, only 120 of which are currently known radio Pulsars.
M Kramer - One of the best experts on this subject based on the ideXlab platform.
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The Einstein@Home Gamma-ray Pulsar Survey. II. Source Selection, Spectral Analysis, and Multiwavelength Follow-up
Astrophys.J., 2018Co-Authors: C.j. Clark, P. S. Ray, D J Champion, L. Guillemot, H.j. Pletsch, T.j. Johnson, P. Torne, J. Deneva, D. Salvetti, M KramerAbstract:We report on the analysis of 13 gamma-ray Pulsars discovered in the Einstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8 data. The 13 new gamma-ray Pulsars were discovered by searching 118 unassociated LAT sources from the third LAT source catalog (3FGL), selected using the Gaussian Mixture Model machine-learning algorithm on the basis of their gamma-ray emission properties being suggestive of pulsar magnetospheric emission. The new gamma-ray Pulsars have pulse profiles and spectral properties similar to those of previously detected young gamma-ray Pulsars. Follow-up radio observations have revealed faint radio pulsations from two of the newly discovered Pulsars and enabled us to derive upper limits on the radio emission from the others, demonstrating that they are likely radio-quiet gamma-ray Pulsars. We also present results from modeling the gamma-ray pulse profiles and radio profiles, if available, using different geometric emission models of Pulsars. The high discovery rate of this survey, despite the increasing difficulty of blind pulsar searches in gamma rays, suggests that new systematic surveys such as presented in this article should be continued when new LAT source catalogs become available.
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a cosmic census of radio Pulsars with the ska
arXiv: Instrumentation and Methods for Astrophysics, 2014Co-Authors: E F Keane, B Bhattacharyya, M Kramer, B W Stappers, S D Bates, M Burgay, S Chatterjee, D J Champion, Ralph P Eatough, J W T HesselsAbstract:The Square Kilometre Array (SKA) will make ground breaking discoveries in pulsar science. In this chapter we outline the SKA surveys for new Pulsars, as well as how we will perform the necessary follow-up timing observations. The SKA's wide field-of-view, high sensitivity, multi-beaming and sub-arraying capabilities, coupled with advanced pulsar search backends, will result in the discovery of a large population of Pulsars. These will enable the SKA's pulsar science goals (tests of General Relativity with pulsar binary systems, investigating black hole theorems with pulsar-black hole binaries, and direct detection of gravitational waves in a pulsar timing array). Using SKA1-MID and SKA1-LOW we will survey the Milky Way to unprecedented depth, increasing the number of known Pulsars by more than an order of magnitude. SKA2 will potentially find all the Galactic radio-emitting Pulsars in the SKA sky which are beamed in our direction. This will give a clear picture of the birth properties of Pulsars and of the gravitational potential, magnetic field structure and interstellar matter content of the Galaxy. Targeted searches will enable detection of exotic systems, such as the ~1000 Pulsars we infer to be closely orbiting Sgr A*, the supermassive black hole in the Galactic Centre. In addition, the SKA's sensitivity will be sufficient to detect Pulsars in local group galaxies. To derive the spin characteristics of the discoveries we will perform live searches, and use sub-arraying and dynamic scheduling to time Pulsars as soon as they are discovered, while simultaneously continuing survey observations. The large projected number of discoveries suggests that we will uncover currently unknown rare systems that can be exploited to push the boundaries of our understanding of astrophysics and provide tools for testing physics, as has been done by the pulsar community in the past.
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Six Faint Gamma-ray Pulsars Seen with the Fermi Large Area Telescope -- Towards a Sample Blending into the Background
Astronomy and Astrophysics - A&A, 2014Co-Authors: X Hou, I Cognard, M Kramer, D.a. Smith, C M Espinoza, Lucas Guillemot, C.c. Cheung, H.a. Craig, S. Johnston, O. ReimerAbstract:Context: GeV gamma-ray pulsations from over 140 Pulsars have been characterized using the Fermi Large Area Telescope, enabling improved understanding of the emission regions within the neutron star magnetospheres, and the contributions of Pulsars to high energy electrons and diffuse gamma rays in the Milky Way. The first gamma-ray Pulsars to be detected were the most intense and/or those with narrow pulses. Aims: As the Fermi mission progresses, progressively fainter objects can be studied. In addition to more distant Pulsars (thus probing a larger volume of the Galaxy), or ones in high background regions (thus improving the sampling uniformity across the Galactic plane), we detect Pulsars with broader pulses or lower luminosity. Adding Pulsars to our catalog with inclination angles that are rare in the observed sample, and/or with lower spindown power, will reduce the bias in the currently known gamma-ray pulsar population. Methods: We use rotation ephemerides derived from radio observations to phase-fold gamma rays recorded by the Fermi Large Area Telescope, to then determine the pulse profile properties. Spectral analysis provides the luminosities and, when the signal-to-noise ratio allows, the cutoff energies. We constrain the pulsar distances by different means in order to minimize the luminosity uncertainties. Results: We present six new gamma-ray Pulsars with an eclectic mix of properties. Three are young, and three are recycled. They include the farthest, the lowest power, two of the highest duty-cycle Pulsars seen, and only the fourth young gamma-ray pulsar with a radio interpulse. We discuss the biases existing in the current gamma-ray pulsar catalog, and steps to be taken to mitigate the bias.
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a study of 315 glitches in the rotation of 102 Pulsars
Monthly Notices of the Royal Astronomical Society, 2011Co-Authors: C M Espinoza, M Kramer, B W Stappers, A. G. LyneAbstract:The rotation of more than 700 Pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 Pulsars. Combining these new data with those already published, we present a data base containing 315 glitches in 102 Pulsars. The data base was used to study the glitch activity among the pulsar population, finding that it peaks for Pulsars with a characteristic age τ c ∼ 10 kyr and decreases for longer values of τ c, disappearing for objects with τ c > 20 Myr. The glitch activity is also smaller in the very young Pulsars (τ c 1 kyr). The cumulative effect of glitches, a collection of instantaneous spin-up events, acts to reduce the regular long-term spin-down rate |u ν| of the star. The percentage of |u ν| reversed by glitch activity was found to vary between 0.5 and 1.6 per cent for Pulsars with spin-down rates |u ν| between 10 −14 and 3.2 × 10 −11 Hz s −1 , decreasing to less than 0.01 per cent at both higher and lower spin-down rates. These ratios are interpreted in terms of the amount of superfluid involved in the generation of glitches. In this context, the activity of the youngest pulsar studied, the Crab pulsar, may be explained by quake-like activity within the crust. Pulsars with low spin-down rates seem to exhibit mostly small glitches, matching well the decrease of their crustal superfluid. Through the analysis of glitch sizes, it was found that the particular glitching behaviour of PSR J0537−6910 and the Vela pulsar may be shared by most Vela-like Pulsars. These objects present most of their glitches with characteristic frequency and frequency derivative jumps, occurring at regular intervals of time. Their behaviour is different from other glitching Pulsars of similar characteristic age.
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a study of 315 glitches in the rotation of 102 Pulsars
arXiv: High Energy Astrophysical Phenomena, 2011Co-Authors: C M Espinoza, M Kramer, B W Stappers, A. G. LyneAbstract:The rotation of more than 700 Pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 Pulsars. Combining these new data with those already published we present a database containing 315 glitches in 102 Pulsars. The database was used to study the glitch activity among the pulsar population, finding that it peaks for Pulsars with a characteristic age tau_c ~ 10kyr and decreases for longer values of tau_c, disappearing for objects with tau_c > 20Myr. The glitch activity is also smaller in the very young Pulsars (tau_c <~ 1kyr). The cumulative effect of glitches, a collection of instantaneous spin up events, acts to reduce the regular long term spindown rate |nudot| of the star. The percentage of |nudot| reversed by glitch activity was found to vary between 0.5% and 1.6% for Pulsars with spindown rates |nudot| between 10^(-14) and 3.2*10^(-11) Hz/s, decreasing to less than 0.01% at both higher and lower spindown rates. These ratios are interpreted in terms of the amount of superfluid involved in the generation of glitches. In this context the activity of the youngest pulsar studied, the Crab pulsar, may be explained by quake-like activity within the crust. Pulsars with low spindown rates seem to exhibit mostly small glitches, matching well the decrease of their crustal superfluid. Through the analysis of glitch sizes it was found that the particular glitching behaviour of PSR J0537-6910 and the Vela pulsar may be shared by most Vela-like Pulsars. These objects present most of their glitches with characteristic frequency and frequency derivative jumps, occurring at regular intervals of time. Their behaviour is different from other glitching Pulsars of similar characteristic age.
