bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for an intermediate-mass black hole in NGC 6624
Authors: Perera B. B. P. , Stappers B. W. , Lyne A. G. , Bassa C. G. , Cognard I. , Guillemot L. , Kramer M. , Theureau G. , Desvignes G. 
Published: June 2018

AbstractPSR B1820–30A is located in the globular cluster NGC 6624 and has the smallest projected distance to the centre of any globular cluster in the sky plane. We observe this millisecond pulsar over more than 25 years and obtain higher-order rotational frequency time derivative measurements through high-precision timing. Modelling these higher-order derivatives as being due to orbital motion, we find that the pulsar is in either a low-eccentricity smaller orbit with a low mass companion or a high-eccentricity larger orbit with a massive companion. The cluster mass properties and the observed properties of other nearby sources indicate that the high-eccentricity solution is more probably. This reveals that the pulsar is orbiting around an intermediate-mass black hole (IMBH) of mass >7500 M⊙ located at the cluster centre. This contribution is based on previous work published in MNRAS 471, 1258 (2017).
The Multiple Outputs of Energetic Pulsars
Authors: Romani Roger W. 
Published: June 2018

AbstractThis talk commented on our progress in understanding high Ė pulsar output, with the photon power dominated by GeV radiation and the total power dominated by the e±/B wind. We are increasingly appreciating the anisotropy in these outflows, with high energy pulsar beaming probed by the distribution of γ-ray pulse profiles and wind anisotropy mapped by synchrotron images of PWNe. Possible hemispheric asymmetry and the prospects for additional probes of pulsar spindown, particularly from compact binaries in the black widow class, are briefly mentioned.
Pulsar Glitches
Authors: Manchester R. N. 
Published: June 2018

AbstractThe first known pulsar glitch was discovered in the Vela pulsar at both Parkes and Goldstone in March 1969. Since then the number of known glitches has grown enormously, with more than 520 glitches now known in more than 180 pulsars. Details of glitch parameters and post-glitch recoveries are described and some implications for the physics of neutron stars are discussed.
The first binary pulsars and what they told us about binary evolution
Authors: Bhattacharya Dipankar 
Published: June 2018

AbstractThe first few binary pulsars revealed the richness of evolution possible in binary systems containing neutron stars. Products of different evolutionary routes, in high and low mass binaries, as well as examples of evolution affected by the pulsar wind were among the first ten objects discovered. This article presents a historical review of the impact of binary pulsars on the early development of ideas regarding the evolution of neutron stars in binary systems.
The effect of the Solar wind on low-frequency observations of pulsars
Authors: Tiburzi C. , Verbiest J. P. W. 
Published: June 2018

AbstractWe operate the six German stations of the LOw Frequency ARray as standalone telescopes to observe more than 100 pulsars every week. To date, we have collected almost four years of high-quality data at an unprecedented weekly cadence. This allows us to perform a wide variety of analyses aimed at characterising the magnetoionic plasma crossed by pulsar radiation. In particular, our studies are focused on electron density variations in the interstellar and interplanetary media, the Galactic and interplanetary magnetic field, scintillation, and extreme scattering events. Here we report the first results from our Solar wind monitoring campaign.
On sub-pulse drift related profile mode-changes studied with a new technique
Authors: Joshi Bhal Chandra 
Published: June 2018

AbstractSub-pulse drift related profile mode-changes provide a useful probe of pulsar radio emission. Measurements on modal profiles of PSRs B0031–07, J1822–2256 and B2319+60 are presented for different drift modes in this communication. The width of profile increases with the drift rate, while no such trend is seen for the pulsed flux density for all these pulsars. A brief discussion of implications for models is presented.
The Noisy Ageing of Slow Pulsars: New Thoughts on the Evolution of the Pulsar Population
Authors: Karastergiou Aris , Johnston Simon 
Published: June 2018

AbstractOver the last decade or so, it has become clear that pulsars exhibit sudden and significant changes in their spin properties. At the same time, a better understanding of the geometry of young and older pulsars, is providing clues about the long-term evolution of the magnetic inclination angle. In this talk, we present a simple simulation of the pulsar population that takes into account current observational facts. We show how, with very few assumptions, the observed P-Ṗ diagram can be reproduced for a synthesized population. The implications are interesting and testable.
Verifying the low frequency pulsar polarimetry of the MWA
Authors: Tremblay Steven E. , Xue Mengyao , Bhat N. D. Ramesh , Tiburzi Caterina 
Published: June 2018

AbstractStudying the polarised properties of pulsars has a rich history giving unique geometric information about pulsars as well as testing the theories of pulsar emission physics. Performing such studies with the MWA has the attraction that the percentage of linear polarisation of many pulsars increases as the observing frequency decreases. Here we discuss the strategies being employed to verify the polarimetric response of the MWA’s high time resolution data.
Single Pulses and the Plasma-physical Processes of Pulsar Radio Emission
Authors: Rankin Joanna M. 
Published: June 2018

AbstractPulsars were discovered on the basis of their individual pulses, first by Jocelyn Bell and then by many others. This was chart-recorder science as computers were not yet in routine use. Single pulses carry direct information about the emission process as revealed in the detailed properties of their polarization characteristics. Early analyses of single pulses proved so dizzyingly complex that attention shifted to study of average profiles. This is turn led to models of pulsar emission beams—in particular the core/double-cone model—which now provides a foundation for understanding single-pulse sequences. We mention some of the 21stC single-pulse surveys and conclude with a brief discussion of our own recent analyses leading to the identification of the pulsar radio-emission mechanism of both slow and millsecond pulsars.
LOFT-e: Localisation Of Fast Transients with e-MERLIN
Authors: Walker C. R. H. , Breton R. P. , Harrison P. A. , Holloway A. , Keith M. J. , Kramer M. , Malenta M. , Mickaliger M. B. , Roy J. , Scragg T. W. , Stappers B. W. 
Published: June 2018

AbstractThe majority of fast radio bursts (FRBs) are poorly localised, hindering their potential scientific yield as galactic, intergalactic, and cosmological probes. LOFT-e, a digital backend for the U.K.’s e-MERLIN seven-telescope interferometer will provide commensal search and real-time detection of FRBs, taking full advantage of its field of view (FoV), sensitivity, and observation time. Upon burst detection, LOFT-e will store raw data offline, enabling the sub-arcsecond localisation provided by e-MERLIN and expanding the pool of localised FRBs. The high-time resolution backend will additionally introduce pulsar observing capabilities to e-MERLIN.
Pulsar polarization: the view from the southern hemisphere
Authors: Johnston Simon 
Published: June 2018

AbstractPulsar polarization has been a fruitful area of study since the first discovery of pulsars 50 years ago. Polarization gives information on the geometry of the star, the location of the radio emission in the magnetosphere, the physics behind the radio emission mechanism and a plethora of phenomenology. Here, I will restrict myself to a brief outline of recent work in pulsar polarization using observations taken with the Parkes radio telescope over the past decade.
High Time Resolution Astronomical Polarimetry with GASP
Authors: O’Connor Eoin G.P. , Shearer Andrew , Gouiffes Christian , Laurent Philippe 
Published: June 2018

AbstractThe Galway Astronomical Stokes Polarimeter (GASP) is a high time resolution, full-Stokes imaging polarimeter which utilises a Fresnel rhomb prism as a beam-splitter and quarter wave retarder. The ability to perform optical photometry and polarimetry at high frame rates enables more detailed studies of a multitude of compact objects including; optical pulsars, magnetars and Active Galactic Nuclei (AGN). We present a brief discussion of the instruments’ current capabilities and hardware design. GASP is currently configured with two Electron Multiplying Charge-Coupled Devices (EMCCDs), which offer sub-millisecond frame readout speeds over a defined region of interest on the sensor. We will report results from an observational campaign at the William Herschel Telescope (WHT) in December, 2015. During this campaign GASP was used to study the Crab Pulsar, V404 Cygni and polarisation standards. As a subset of our analysis we have identified a significant contribution from the Interstellar Medium (ISM) and the interaction of a varying polarised source with the ISM, the subsequent conversion of linearly polarised light to circular, and its dependence on the angle of the source emission electric field orientation. Further to the presentation of results we will discuss future observational work, which is planned for September 2017 and subsequent improvements to increase the temporal resolution of the detectors.
Pulsar science with the CHIME telescope
Authors: Ng Cherry 
Published: June 2018

AbstractThe CHIME telescope (the Canadian Hydrogen Intensity Mapping Experiment) recently built in Penticton, Canada, is currently being commissioned. Originally designed as a cosmology experiment, it was soon recognized that CHIME has the potential to simultaneously serve as an incredibly useful radio telescope for pulsar science. CHIME operates across a wide bandwidth of 400–800 MHz and will have a collecting area and sensitivity comparable to that of the 100-m class radio telescopes. CHIME has a huge field of view of ~250 square degrees. It will be capable of observing 10 pulsars simultaneously, 24-hours per day, every day, while still accomplishing its missions to study Baryon Acoustic Oscillations and Fast Radio Bursts. It will carry out daily monitoring of roughly half of all pulsars in the northern hemisphere, including all NANOGrav pulsars employed in the Pulsar Timing Array project. It will cycle through all pulsars in the northern hemisphere with a range of cadence of no more than 10 days.
Core/Double-Cone Emission-Beam Structure in a Millisecond Pulsar
Authors: Rankin Joanna M. 
Published: June 2018

AbstractSlow pulsars show a great deal of qualitative and quantitative regularity in the structure of their radio emission beams as described by the core/double-cone model; however, millisecond pulsars (MSPs) have shown little. It is thus arresting to encounter a 2.7-s MSP with what appears to be a double-cone/core profile—and even more so to find that the arrangement of the cones around the core suggest aberration/retardation emission heights that are very reasonable. This and several other pulsars then represent rare opportunities for analysis and raise questions about why a few MSPs show such orderly beam structure while so many do not.
Strong field tests of gravity with PSR J1141–6545
Authors: Krishnan V. Venkatraman , van Straten W. , Rosado P. A. , Bailes M. , Keane E. F. , Bhat R. , Flynn C. 
Published: June 2018

AbstractThe initial results from timing observations of PSR J1141–6545, a relativistic pulsar-white dwarf binary system, are presented. Predictions from the timing baseline hint at the most stringent test of gravity by an asymmetric binary yet. The timing precision has been hindered by the dramatic variations of the pulse profile due to geodetic precession, a pulsar glitch and red timing noise. Methods to overcome such timing irregularities are briefly presented along with preliminary results from the test of the General Theory of Relativity (GR) from this pulsar.
Probing neutron star interiors with pulsar glitches
Authors: Haskell Brynmor 
Published: June 2018

AbstractPulsar glitches are thought to be probes of the superfluid interior of neutron stars. These sudden jumps in frequency observed in many pulsars are generally assumed to be the macroscopic manifestation of superfluid vortex motion on a microscopic scale. Resolving and modelling such phenomena on the scale of a neutron star is, however, a challenging problem which still remains open, fifty years after the discovery of pulsars. In this article I will review recent theoretical progress, both on the microscopic level and on the macroscopic level, and discuss which constraints on the models can be provided by observations.
X-rays from Radio Millisecond Pulsars
Authors: Bogdanov Slavko 
Published: June 2018

AbstractThe Galactic population of rotation-powered (aka radio) millisecond pulsars (MSPs) exhibits diverse X-ray properties. Energetic MSPs show pulsed non-thermal radiation from their magnetospheres. Eclipsing binary MSPs predominantly have X-ray emission from a pulsar wind driven intra-binary shock. Typical radio MSPs emit X-rays from their heated magnetic polar caps. These thermally emitting MSPs offer the opportunity to place interesting constraints on the long sought after dense matter equation of state, making them important targets of investigation of the recently deployed Neutron Star Interior Composition Explorer (NICER) X-ray mission.
A multi-wavelength view of the pulsar environments
Authors: Zanin Roberta 
Published: June 2018

AbstractSometimes the explosion of a supernova can generate a pulsar, most of whose rotational energy is carried away by an energetic wind of particles and magnetic fields expanding into its surroundings and eventually forming extended nebulae, i.e. the pulsar wind nebulae. The experimental advances reached in the last decades, from radio frequencies up to the highest gamma-ray energies, with instruments like VLA, VLBA, Chandra, NuStar, Fermi-LAT and H.E.S.S. among the others, led to the discovery of hundreds of this kind of sources allowing for population studies. In addition, this variety of high-precision spectral and morphological measurement provided an unprecedented opportunity to test and push forward the state-of-the-art theoretical models. In this contribution, we will review the latest, and most significant theoretical and experimental results.
Feasibility of WHO mhGAP-intervention guide in reducing experienced discrimination in people with mental disorders: a pilot study in a rural Kenyan setting
Authors: Mutiso V. N. , Pike K. , Musyimi C. W. , Rebello T. J. , Tele A. , Gitonga I. , Thornicroft G. , Ndetei D. M. 
Published: June 2018

AimsStigma can have a negative impact on help-seeking behaviour, treatment adherence and recovery of people with mental disorders. This study aimed to determine the feasibility of the WHO Mental Health Treatment Gap Interventions Guidelines (mhGAP-IG) to reduce stigma in face-to-face contacts during interventions for specific DSM-IV/ICD 10 diagnoses over a 6-month period.MethodsThis study was conducted in 20 health facilities across Makueni County in southeast Kenya which has one of the poorest economies in the country and has no psychiatrist or clinical psychologist. We recruited 2305 participants from the health facilities catchment areas that had already been exposed to community mental health services. We measured stigma using DISC-12 at baseline, followed by training to the health professionals on intervention using the WHO mhGAP-IG and then conducted a follow-up DISC-12 assessment after 6 months. Proper management of the patients by the trained professionals would contribute to the reduction of stigma in the patients.ResultsThere was 59.5% follow-up at 6 months. Overall, there was a significant decline in ‘reported/experienced discrimination’ following the interventions. A multivariate linear mixed model regression indicated that better outcomes of ‘unfair treatment’ scores were associated with: being married, low education, being young, being self-employed, higher wealth index and being diagnosed with depression. For ‘stopping self’ domain, better outcomes were associated with being female, married, employed, young, lower wealth index and a depression diagnosis. In regards to ‘overcoming stigma’ domain; being male, being educated, employed, higher wealth index and being diagnosed with depression was associated with better outcomes.ConclusionsThe statistically significant (p < 0.05) reduction of discrimination following the interventions by trained health professionals suggest that the mhGAP-IG may be a useful tool for reduction of discrimination in rural settings in low-income countries.
Uranus's Northern Polar Cap in 2014
Authors: Toledo Daniel , Irwin Patrick G. J. , Teanby Nicholas A. , Simon Amy A. , Wong Michael H. , Orton Glenn S. 
Published: June 2018

AbstractIn October and November 2014, spectra covering the 1.436 to 1.863‐μm wavelength range from the SINFONI Integral Field Unit Spectrometer on the Very Large Telescope showed the presence of a vast bright north polar cap on Uranus, extending northward from about 40°N and at all longitudes observed. The feature, first detected in August 2014 from Keck telescope images, has a morphology very similar to the southern polar cap that was seen to fade before the 2007 equinox. At strong methane‐absorbing wavelengths (for which only the high troposphere or stratosphere is sampled) the feature is not visible, indicating that it is not a stratospheric phenomenon. We show that the observed northern bright polar cap results mainly from a decrease in the tropospheric methane mixing ratio, rather than from a possible latitudinal variation of the optical properties or abundance of aerosol, implying an increase in polar downwelling near the tropopause level.
Solitary Waves Across Supercritical Quasi‐Perpendicular Shocks
Authors: Vasko I. Y. , Mozer F. S. , Krasnoselskikh V. V. , Artemyev A. V. , Agapitov O. V. , Bale S. D. , Avanov L. , Ergun R. , Giles B. , Lindqvist P.‐A. , Russell C. T. , Strangeway R. , Torbert R. 
Published: June 2018

AbstractWe consider intense electrostatic solitary waves (ESW) observed in a supercritical quasi‐perpendicular Earth's bow shock crossing by the Magnetospheric Multiscale Mission. The ESW have spatial scales of a few tens of meters (a few Debye lengths) and propagate oblique to a local quasi‐static magnetic field with velocities from a few tens to a few hundred kilometers per second in the spacecraft frame. Because the ESW spatial scales are comparable to the separation between voltage‐sensitive probes, correction factors are used to compute the ESW electric fields. The ESW have electric fields with amplitudes exceeding 600 mV/m (oriented oblique to the local magnetic field) and negative electrostatic potentials with amplitudes of a few tenths of the electron temperature. The negative electrostatic potentials indicate that the ESW are not electron phase space holes, while interpretation in terms of ions phase space holes is also questionable. Whatever is their nature, we show that due to the oblique electric field orientation the ESW are capable of efficient pitch‐angle scattering and isotropization of thermal electrons. Due to the negative electrostatic potentials the ESW Fermi reflects a significant fraction of the thermal electrons streaming from upstream (downstream) back to upstream (downstream) region, thereby affecting the shock dynamics. The role of the ESW in electron heating is discussed.
Revisiting the Mystery of Recent Stratospheric Temperature Trends
Authors: Maycock Amanda C. , Randel William J. , Steiner Andrea K. , Karpechko Alexey Yu , Christy John , Saunders Roger , Thompson David W. J. , Zou Cheng‐Zhi , Chrysanthou Andreas , Luke Abraham N. , Akiyoshi Hideharu , Archibald Alex T. , Butchart Neal , Chipperfield Martyn , Dameris Martin , Deushi Makoto , Dhomse Sandip , Di Genova Glauco , Jöckel Patrick , Kinnison Douglas E. , Kirner Oliver , Ladstädter Florian , Michou Martine , Morgenstern Olaf , O'Connor Fiona , Oman Luke , Pitari Giovanni , Plummer David A. , Revell Laura E. , Rozanov Eugene , Stenke Andrea , Visioni Daniele , Yamashita Yousuke , Zeng Guang 
Published: June 2018

AbstractSimulated stratospheric temperatures over the period 1979–2016 in models from the Chemistry‐Climate Model Initiative are compared with recently updated and extended satellite data sets. The multimodel mean global temperature trends over 1979–2005 are −0.88 ± 0.23, −0.70 ± 0.16, and −0.50 ± 0.12 K/decade for the Stratospheric Sounding Unit (SSU) channels 3 (~40–50 km), 2 (~35–45 km), and 1 (~25–35 km), respectively (with 95% confidence intervals). These are within the uncertainty bounds of the observed temperature trends from two reprocessed SSU data sets. In the lower stratosphere, the multimodel mean trend in global temperature for the Microwave Sounding Unit channel 4 (~13–22 km) is −0.25 ± 0.12 K/decade over 1979–2005, consistent with observed estimates from three versions of this satellite record. The models and an extended satellite data set comprised of SSU with the Advanced Microwave Sounding Unit‐A show weaker global stratospheric cooling over 1998–2016 compared to the period of intensive ozone depletion (1979–1997). This is due to the reduction in ozone‐induced cooling from the slowdown of ozone trends and the onset of ozone recovery since the late 1990s. In summary, the results show much better consistency between simulated and satellite‐observed stratospheric temperature trends than was reported by Thompson et al. (2012, https://doi.org/10.1038/nature11579) for the previous versions of the SSU record and chemistry‐climate models. The improved agreement mainly comes from updates to the satellite records; the range of stratospheric temperature trends over 1979–2005 simulated in Chemistry‐Climate Model Initiative models is comparable to the previous generation of chemistry‐climate models.
Effects of Confining Stress on the Semipermeability of Siliceous Mudstones: Implications for Identifying Geologic Membrane Behaviors of Argillaceous Formations
Authors: Takeda M. , Manaka M. 
Published: June 2018

AbstractThe semipermeability arising from filtration effects on ionic species at the pore spaces in clay minerals has been recognized as a fundamental transport property of argillites. However, little is known about the dependence of the semipermeability on the confining stress that controls the pore sizes. Thus, we investigated the evolution of the semipermeability during cyclic loading by performing chemical osmosis experiments on siliceous mudstones. Results show that the semipermeability irreversibly increases with increasing confining stress, but once the stress exceeds the past maximum effective burial stress, it reversibly changes in accordance with the change in the stress. The net increase in the semipermeability from the first loading cycle to the last unloading cycle implies the irreversible shrinking of pores that should have expanded owing to stress relief before testing. The reversible change in the semipermeability probably reflects the reversible pore deformation due to the elasticity of argillites in the overconsolidated state.