Detection of radio emission from the gamma-ray pulsar J1732-3131 at 327 MHz

Although originally discovered as a radio-quiet gamma-ray pulsar, J1732-3131 has exhibited intriguing detections at decameter wavelengths. We report an extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope. Using the previously observed radio characteristics, and with an effective integration time of 60 hrs, we present a detection of the pulsar at a confidence level of 99.82%. The 327 MHz mean flux density is estimated to be 0.5-0.8 mJy, which establishes the pulsar to be a steep spectrum source and one of the least-luminous pulsars known to date. We also phase-aligned the radio and gamma-ray profiles of the pulsar, and measured the phase-offset between the main peaks in the two profiles to be 0.24$\pm$0.06. We discuss the observed phase-offset in the context of various trends exhibited by the radio-loud gamma-ray pulsar population, and suggest that the gamma-ray emission from J1732-3131 is best explained by outer magnetosphere models. Details of our analysis leading to the pulsar detection, and measurements of various parameters and their implications relevant to the pulsar's emission mechanism are presented.Comment: 8 pages, 6 figures; Accepted for publication in MNRA

Modeling the non-recycled Fermi gamma-ray pulsar population

We use Fermi Gamma-ray Space Telescope detections and upper limits on non-recycled pulsars obtained from the Large Area Telescope (LAT) to constrain how the gamma-ray luminosity L depends on the period P and the period derivative \dot{P}. We use a Bayesian analysis to calculate a best-fit luminosity law, or dependence of L on P and \dot{P}, including different methods for modeling the beaming factor. An outer gap (OG) magnetosphere geometry provides the best-fit model, which is L \propto P^{-a} \dot{P}^{b} where a=1.36\pm0.03 and b=0.44\pm0.02, similar to but not identical to the commonly assumed L \propto \sqrt{\dot{E}} \propto P^{-1.5} \dot{P}^{0.5}. Given upper limits on gamma-ray fluxes of currently known radio pulsars and using the OG model, we find that about 92% of the radio-detected pulsars have gamma-ray beams that intersect our line of sight. By modeling the misalignment of radio and gamma-ray beams of these pulsars, we find an average gamma-ray beaming solid angle of about 3.7{\pi} for the OG model, assuming a uniform beam. Using LAT-measured diffuse fluxes, we place a 2{\sigma} upper limit on the average braking index and a 2{\sigma} lower limit on the average surface magnetic field strength of the pulsar population of 3.8 and 3.2 X 10^{10} G, respectively. We then predict the number of non-recycled pulsars detectable by the LAT based on our population model. Using the two-year sensitivity, we find that the LAT is capable of detecting emission from about 380 non-recycled pulsars, including 150 currently identified radio pulsars. Using the expected five-year sensitivity, about 620 non-recycled pulsars are detectable, including about 220 currently identified radio pulsars. We note that these predictions significantly depend on our model assumptions.Comment: 26 pages, 10 figures, Accepted by ApJ on 8 September 201

The Theory of Generalised Hydrodynamics for the One-dimensional Bose Gas

This article reviews the recent developments in the theory of generalised hydrodynamics (GHD) with emphasis on the repulsive one-dimensional Bose gas. We discuss the implications of GHD on the mechanisms of thermalisation in integrable quantum many-body systems as well as its ability to describe far-from-equilibrium behaviour of integrable and near integrable systems in a variety of quantum quench scenarios. We outline the experimental tests of GHD in cold-atom gases and its benchmarks with other microscopic theoretical approaches. Finally, we offer some perspectives on the future direction of the development of GHD.Comment: 13 pages, 10 figure

Light-curve modelling constraints on the obliquities and aspect angles of the young Fermi pulsars

In more than four years of observation the Large Area Telescope on board the Fermi satellite has identified pulsed $\gamma$-ray emission from more than 80 young pulsars, providing light curves with high statistics. Fitting the observations with geometrical models can provide estimates of the magnetic obliquity $\alpha$ and aspect angle $\zeta$, yielding estimates of the radiation beaming factor and luminosity. Using $\gamma$-ray emission geometries (Polar Cap, Slot Gap, Outer Gap, One Pole Caustic) and radio emission geometry, we fit $\gamma$-ray light curves for 76 young pulsars and we jointly fit their $\gamma$-ray plus radio light curves when possible. We find that a joint radio plus $\gamma$-ray fit strategy is important to obtain ($\alpha$, $\zeta$) estimates that can explain simultaneous radio and $\gamma$-ray emission. The intermediate-to-high altitude magnetosphere models, Slot Gap, Outer Gap, and One pole Caustic, are favoured in explaining the observations. We find no evolution of $\alpha$ on a time scale of a million years. For all emission geometries our derived $\gamma$-ray beaming factors are generally less than one and do not significantly evolve with the spin-down power. A more pronounced beaming factor vs. spin-down power correlation is observed for Slot Gap model and radio-quiet pulsars and for the Outer Gap model and radio-loud pulsars. For all models, the correlation between $\gamma$-ray luminosity and spin-down power is consistent with a square root dependence. The $\gamma$-ray luminosities obtained by using our beaming factors not exceed the spin-down power. This suggests that assuming a beaming factor of one for all objects, as done in other studies, likely overestimates the real values. The data show a relation between the pulsar spectral characteristics and the width of the accelerator gap that is consistent with the theoretical prediction for the Slot Gap model.Comment: 90 pages, 80 figures (63 in Appendices), accepted for publication in Astronomy and Astrophysic

Not all the bots are created equal:the Ordering Turing Test for the labelling of bots in MMORPGs

This article contributes to the research on bots in Social Media. It takes as its starting point an emerging perspective which proposes that we should abandon the investigation of the Turing Test and the functional aspects of bots in favor of studying the authentic and cooperative relationship between humans and bots. Contrary to this view, this article argues that Turing Tests are one of the ways in which authentic relationships between humans and bots take place. To understand this, this article introduces the concept of Ordering Turing Tests: these are sort of Turing Tests proposed by social actors for purposes of achieving social order when bots produce deviant behavior. An Ordering Turing Test is method for labeling deviance, whereby social actors can use this test to tell apart rule-abiding humans and rule-breaking bots. Using examples from Massively Multiplayer Online Role-Playing Games, this article illustrates how Ordering Turing Tests are proposed and justified by players and service providers. Data for the research comes from scientific literature on Machine Learning proposed for the identification of bots and from game forums and other player produced paratexts from the case study of the game Runescape