1,721,007 research outputs found
The 69 millisecond radio pulsar near the supernova remnant RCW 103
No full textWe report the detection of the radio pulsar counterpart to the 69 ms X-ray pulsar discovered near the supernova remnant RCW 103 (G332.4-0.4). Our detection confirms that the pulsations arise from a rotation-powered neutron star, which we name PSR J1617-5055. The observed barycentric period derivative confirms that the pulsar has a characteristic age of only 8 kyr, the sixth youngest of all known pulsars. The unusual apparent youth of the pulsar and its proximity to a young remnant require that an association be considered. Although the respective ages and distances are consistent within substantial uncertainties, the large inferred pulsar transverse velocity is difficult to explain given the observed pulsar velocity distribution, the absence of evidence for a pulsar wind nebula, and the symmetry of the remnant. Rather, we argue that the objects are likely superposed on the sky; this is reasonable given the complex area. Without an association, the question of where is the supernova remnant left behind following the birth of PSR J1617-5055 remains open. We also discuss a possible association between PSR J1617-5055 and the gamma-ray source 2CG 333+01. Although an association is energetically plausible, it is unlikely given that EGRET did not detect 2CG 333+01
Discovery of two high magnetic field radio pulsars
No full textWe report the discovery of two young isolated radio pulsars with very high inferred magnetic fields. PSR J1119-6127 has period P = 0.407 s, and the largest period derivative known among radio pulsars, P = 4.0 x 10(-12). Under standard assumptions these parameters imply a characteristic spin-down age of only tau(c) = 1.6 kyr and a surface dipole magnetic field strength of B = 4.1 x 10(13) G. We have measured a stationary period second derivative for this pulsar, resulting in a braking index of n = 2.91 +/- 0.05. We have also observed a glitch in the rotation of the pulsar, with fractional period change Delta P/P = -4.4 x 10(-9). Archival radio imaging data suggest the presence of a previously uncataloged supernova remnant centered on the pulsar. The second pulsar, PSR J1814-1744 has P = 3.975 s and P = 7.4 x 10(-13). These parameters imply tau(c) = 85 kyr, and B = 5.5 x 1013 G, the largest of any known radio pulsar. Both PSR J1119-6127 and PSR J1814-1744 show apparently normal radio emission in a regime of magnetic field strength where some models predict that no emission should occur. Also, PSR J1814-1744 has spin parameters similar to the anomalous X-ray pulsar (AXP) 1E 2259 + 586, but shows no discernible X-ray emission. If AXPs are isolated, high magnetic field neutron stars ("magnetars"), these results suggest that their unusual attributes are unlikely to be merely a consequence of their very high inferred magnetic fields
Radio pulsars in the Magellanic Clouds
No full textWe report the results of a survey of the Small Magellanic Cloud (SMC) for radio pulsars conducted with the 20 cm multibeam receiver of the Parkes 64 m telescope. This survey targeted a more complete region of the SMC than a previous pulsar search and had an improvement in sensitivity by a factor of about 2 for most pulsar periods. This survey is much more sensitive to fast young pulsars (with P less than or similar to 100 ms) and is the first survey of the SMC with any sensitivity to millisecond pulsars. Two new pulsars were discovered in the survey, one of which is located within the SMC. The number of pulsars found in the survey is consistent with the expected number derived using several methods. We also report the serendipitous discovery of a new pulsar in the 30 Doradus region of the Large Magellanic Cloud (LMC). These discoveries bring the total number of rotation-powered pulsars currently known in the Magellanic Clouds to eight. We have also made refined timing measurements for the new discoveries as well as for three previously known LMC pulsars. The age distribution of luminous Magellanic Cloud pulsars supports the conjecture that pulsars younger than about 5 Myr are more luminous on average than older pulsars
A very large glitch in PSR J1806-2125
No full textPSR J1806-2125 is a pulsar discovered in the Parkes multibeam pulsar survey with a rotational period of 0.4 s and a characteristic age of 65 kyr. Between MJDs 51462 and 51894 this pulsar underwent an increase in rotational frequency of Deltanu /nu approximate to16x10(-6). The magnitude of this glitch is similar to2.5 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 with those of 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 time-scales
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Two young radio pulsars coincident with EGRET sources
No full textWe report the discovery and follow-up timing observations of two young energetic radio pulsars. PSR J1420-6048 has a period P = 68 ms and period derivative (P) over dot = 83 x 10(-15), implying a characteristic age tau (c) = 13 kyr and a surface dipole magnetic field strength B = 2.4 x 10(12) G. PSR J1837-0604 has P = 96 ms and (P) over dot = 45 x 10(-15), implying tau (c) = 34 kyr and B = 2.1 x 10(12) G. The two objects have large spin-down luminosities, and, on the basis of an empirical comparison of their properties with those of other young radio pulsars, they are expected to be observable as pulsed gamma -ray sources. In fact, they lie within the error circles of gamma -ray sources detected by the EGRET instrument on the Gamma Ray Observatory. We show that the pulsars are plausibly associated with the EGRET sources
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
PSR J1016-5857: A young radio pulsar with possible supernova remnant, X-ray, and gamma-ray associations
No full textWe 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 8.0 x 10(-14), implying a characteristic age of 21 kyr and spin-down luminosity of 2.6 x 10(36) ergs s(-1). 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 that 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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