1,724,749 research outputs found
Multi-wavelength observations of the radio magnetar PSR J1622-4950 and discovery of its possibly associated supernova remnant
Get PDFWe present multi-wavelength observations of the radio magnetar PSR J1622-4950 and its environment. Observations of PSR J1622-4950 with Chandra (in 2007 and 2009) and XMM (in 2011) show that the X-ray flux of PSR J1622-4950 has decreased by a factor of ~50 over 3.7 years, decaying exponentially with a characteristic time of τ = 360 ± 11 days. This behavior identifies PSR J1622-4950 as a possible addition to the small class of transient magnetars. The X-ray decay likely indicates that PSR J1622-4950 is recovering from an X-ray outburst that occurred earlier in 2007, before the 2007 Chandra observations. Observations with the Australia Telescope Compact Array show strong radio variability, including a possible radio flaring event at least one and a half years after the 2007 X-ray outburst that may be a direct result of this X-ray event. Radio observations with the Molonglo Observatory Synthesis Telescope reveal that PSR J1622-4950 is 8' southeast of a diffuse radio arc, G333.9+0.0, which appears non-thermal in nature and which could possibly be a previously undiscovered supernova remnant (SNR). If G333.9+0.0 is an SNR then the estimates of its size and age, combined with the close proximity and reasonable implied velocity of PSR J1622-4950, suggest that these two objects could be physically associated
Spin-down Evolution and Radio Disappearance of the Magnetar PSR J1622-4950
No full textWe report on 2.4 yr of radio timing measurements of the magnetar PSR. J1622-4950 using the Parkes Observatory, between 2011 November and 2014 March. During this period the torque on the neutron star (inferred from the rotational frequency derivative) varied greatly, though much less erratically than during the 2 yr following its discovery in 2009. During the last year of our measurements the frequency derivative decreased in magnitude monotonically by 20%, to a value of -1.3. x. 10(-13) s(-2), a factor of 8 smaller than when it was discovered. The flux density continued to vary greatly during our monitoring through 2014 March, reaching a relatively steady low level after late 2012. The pulse profile varied secularly on a similar timescale as the flux density and torque. A relatively rapid transition in all three properties was evident in early 2013. After PSR. J1622-4950 was detected in all of our 87 observations up to 2014 March, we did not detect the magnetar in our resumed monitoring starting in 2015 January and have not detected it in any of the 30 observations conducted through 2016 September
Poster Presentations, History 4950
No full textDr. Lynne Curry’s students will give presentations and display posters. Posters will be put on display in Marvin Foyer after their presentations until the close of the exhibi
Radio emission evolution, polarimetry and multifrequency single pulse analysis of the radio magnetar PSRJ1622-4950
No full textHere we report on observations of the radio magnetar PSRJ1622-4950 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 100percent 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
The radio-loud magnetar PSR J1622-4950
No full textThe High Time Resolution Universe survey for pulsars and fast transients has yielded the discovery of a slow radio pulsar, PSR J1622-4950, that despite its high dispersion measure exhibited a highly variable flux density and integrated pulse profile. The pulsar shares many properties with the two previously known magnetars that emit radio pulsations, including a similarly high inferred magnetic field strength. In contrast to other magnetars, PSR J1622-4950 shows no observed variations in X-ray emission. © 2011 American Institute of Physics
Block Card 4950 Stengel Avenue
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: Ranch houses | 4950 Stengel Avenue (Toledo, Ohio) | Dwelling | Southern Woods (Toledo, Ohio) | South Toledo Area (Toledo, Ohio
[Veto of H. 4950, R-427]
Get PDFThis veto message from Governor Mark Sanford vetoes H. 4950, R-427, a bill that clarifies the definition of a textile mill in order to qualify for incentives included in the South Carolina Textiles Communities Revitalization Act of2004
Linked collectors and determiners for: Hypogean Quedius of Taiwan and their biogeographic significance (Coleoptera: Staphylinidae: Staphylininae).
No full textNatural history specimen data linked to collectors and determiners held within, "Hypogean Quedius of Taiwan and their biogeographic significance (Coleoptera: Staphylinidae: Staphylininae)". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/70213048-4950-4064-b085-e13bb570ae0a">https://bionomia.net/dataset/70213048-4950-4064-b085-e13bb570ae0a</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/70213048-4950-4064-b085-e13bb570ae0a">https://gbif.org/dataset/70213048-4950-4064-b085-e13bb570ae0a</a>. Formatted as a Frictionless Data package
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
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