Mode Change of a Gamma-Ray Pulsar, PSR J2021+4026

Zhao, J.,Ng, C. W.,Lin, L. C. C.,Takata, J.,Cai, Y.,Hu, C.-P.,Yen, D. C. C.,Tam, P. H. T.,Hui, C. Y.,Kong, A. K. H.,Cheng, K. S. American Astronomical Society 2017 The Astrophysical journal Vol.842 No.1

<P>A glitch of a pulsar is known as a sudden increase in the spin frequency and spin-down rate (frequency time derivative), and it can be caused by a sudden release of the stress built up in the solid crust of the star or pinned vortices in the superfluid interior. PSR J2021+4026 is the first pulsar that shows a significant change in the gamma-ray flux and pulse profile at the glitch that occurred around 2011 October 16. We report the results of timing and spectral analysis of PSR J2021+4026 using similar to 8 yr Fermi. Large Area Telescope data. We find that the pulsar stayed at a high spin-down rate (similar to 4% higher than the pre-glitch value) and a low gamma-ray state (similar to 18% lower) for about 3 yr. after the glitch. Around 2014 December, the spin-down rate and gamma-ray flux gradually returned to pre-glitch values within a timescale of a. few months. The phase-resolved spectra and pulse profiles after the relaxation are also consistent with those before the glitch. The observed long-term evolution of the spin-down rate and the gamma-ray flux indicates that the glitch triggered a mode change in the global magnetosphere. We speculate that the glitch changed. the local magnetic field structure around the polar cap and/or the inclination angle of the. dipole axis, leading to. a change in the electric current circulating in the. magnetosphere.</P>

A<i>NuSTAR</i>Observation of the Gamma-Ray Emitting Millisecond Pulsar PSR J1723-2837

Kong, A. K. H.,Hui, C. Y.,Takata, J.,Li, K. L.,Tam, P. H. T. American Astronomical Society 2017 The Astrophysical journal Vol.839 No.2

<P>We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723-2837. X-ray radiation up to 79 keV is clearly detected, and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power law with a photon index of similar to 1.3. We also find X-ray modulations in the 3-10, 10-20, 20-79, and 3-79 keV bands at the 14.8. hr binary orbital period. All of these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723-2837 provides strong evidence that the X-rays are from the intrabinary shock via an interaction between the pulsar wind and the outflow from the companion star. We discuss how the NuSTAR observation constrains the physical parameters of the intrabinary shock model.</P>

Effect of Ear Acupuncture plus Dry Cupping on Activities and Quality of Life in the Adults with Chronic Back Pain: a Randomized Trial

Caroline de Castro Moura,Chaves Erika de Cássia Lopes,Nogueira Denismar Alves,Iunes Denise Hollanda,Azevedo Cissa,Corrêa Hérica Pinheiro,Pereira Gabriela Aparecida,Silvano Higor Magalhães,Macieira Tam 사단법인약침학회 2022 Journal of Acupuncture & Meridian Studies Vol.15 No.2

Background: Chronic pain is a complex phenomenon that brings physical and emotional impairments negatively impacting people’s quality of life. The adoption of interventions such as ear acupuncture and dry cupping can represent a treatment option for people with chronic back pain. Objectives: To investigate the effects of ear acupuncture combined with dry cupping therapy on the interference of pain with the daily activities and quality of life of adults with chronic back pain. Methods: An open-label, randomized, parallel-group controlled clinical trial. One hundred and ninety-eight adults were randomized into control (CG - ear acupuncture) or experimental (EG - ear acupuncture combined with dry cupping) groups. Interventions were performed in five sessions, once a week, lasting five weeks. Evaluations were performed before the first session, after the last session, and seven days after the second evaluation, using the Brief Pain Inventory to assess the impact of pain on daily activities and the World Health Organization Quality of Life-BREF (WHOQOL-BREF) to assess the quality of life. Results: Between the initial and final sessions, there were significant changes in daily activities , activity, work, mood, relationships, sleep, and in the physical, psychological and social relationships domains for both the control and experimental groups. Improved perception of quality of life and satisfaction with health were observed for the participants in the experimental group. Conclusion: Ear acupuncture combined with dry cupping showed better results in terms of perception of quality of life and satisfaction with health when compared to ear acupuncture by itself.

Rapid X-Ray Variations of the Geminga Pulsar Wind Nebula

Hui, C. Y.,Lee, Jongsu,Kong, A. K. H.,Tam, P. H. T.,Takata, J.,Cheng, K. S.,Ryu, Dongsu American Astronomical Society 2017 The Astrophysical journal Vol.846 No.2

<P>A recent study by Posselt et al. reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using Chandra X-ray Observatory. In comparison with previous studies of this system, a number of new findings have been reported, and we found that these suggest the possible variabilities in various components of this PWN. This motivates us to carry out a dedicated search for the morphological and spectral variations of this complex nebula. We have discovered variabilities on timescales from a few days to a few months from different components of the nebula. The fastest change occurred in the circumstellar environment at a rate of 80% of the speed of light. One of the most spectacular results is the wiggling of a half light-year long tail as an extension of the jet, which is significantly bent by the ram pressure. The jet wiggling occurred at a rate of about 20% of the speed of light. This twisted structure could possibly be a result of a propagating torsional Alfv'en wave. We have also found evidence of spectral hardening along this tail for a period of about nine months.</P>

A Non-thermal Pulsed X-Ray Emission of AR Scorpii

Takata, J.,Hu, C.-P.,Lin, L. C. C.,Tam, P. H. T.,Pal, P. S.,Hui, C. Y.,Kong, A. K. H.,Cheng, K. S. American Astronomical Society 2018 The Astrophysical journal Vol.853 No.2

<P>We report the analysis result of UV/X-ray emission from AR. Scorpii, which is an intermediate polar (IP) composed of a magnetic white dwarf and an M-type star, with the XMM-Newton data. The X-ray/UV emission clearly shows a large variation over the orbit, and their intensity maximum (or minimum) is located at the superior conjunction (or inferior conjunction) of the M star orbit. The hardness ratio of the X-ray emission shows a small variation over the orbital phase and shows no indication of the absorption by an accretion column. These properties are naturally explained by the emission from the M star surface rather than that from the accretion column on the white dwarf's (WD) star, which is similar to usual IPs. Additionally, the observed X-ray emission also modulates with the WD's spin with a pulse fraction of similar to 14%. The peak position is aligned in the optical/UV/X-ray band. This supports the hypothesis that the electrons in AR. Scorpii are accelerated to a relativistic speed and emit non-thermal photons via the synchrotron radiation. In the X-ray bands, evidence of the power-law spectrum is found in the pulsed component, although the observed emission is dominated by the optically thin thermal plasma emissions with several different temperatures. It is considered that the magnetic dissipation/reconnection process on the M star surface heats up the plasma to a temperature of several keV and also accelerates the electrons to the relativistic speed. The relativistic electrons are trapped in the WD's closed magnetic field lines by the magnetic mirror effect. In this model, the observed pulsed component is explained by the emissions from the first magnetic mirror point.</P>

EXPLORING THE X-RAY AND gamma-RAY PROPERTIES OF THE REDBACK MILLISECOND PULSAR PSR J1723-2837

Hui, C. Y.,Tam, P. H. T.,Takata, J.,Kong, A. K. H.,Cheng, K. S.,Wu, J. H. K.,Lin, L. C. C.,Wu, E. M. H. University of Chicago Press for the American Astro 2014 ASTROPHYSICAL JOURNAL LETTERS - Vol.781 No.1

We have investigated the X-ray and gamma-ray properties of the redback millisecond pulsar PSR J1723-2837 with XMM-Newton, Chandra, and Fermi. We have discovered the X-ray orbital modulation of this binary system with a minimum that coincides with the phases of radio eclipse. The X-ray emission is clearly non-thermal in nature, which can be described well by a simple power law with a photon index of similar to 1.2. The phase-averaged luminosity is similar to 9 x 10(31) erg s(-1) in 0.3-10 keV, which consumes similar to 0.2% of the spin-down power. We have detected the gamma-ray emission in 0.1-300 GeV from this system at a significance of similar to 6 sigma for the first time. The gamma-rays in this energy range consume similar to 2% of the spin-down power and can be modeled by a power law with a photon index of similar to 2.6. We discuss the high energy properties of the new redback in the context of an intrabinary shock model.

DISCOVERY OF AN UNIDENTIFIED <i>FERMI</i> OBJECT AS A BLACK WIDOW-LIKE MILLISECOND PULSAR

Kong, A. K. H.,Huang, R. H. H.,Cheng, K. S.,Takata, J.,Yatsu, Y.,Cheung, C. C.,Donato, D.,Lin, L. C. C.,Kataoka, J.,Takahashi, Y.,Maeda, K.,Hui, C. Y.,Tam, P. H. T. IOP Publishing 2012 ASTROPHYSICAL JOURNAL LETTERS - Vol.747 No.1

<P>The Fermi gamma-ray Space Telescope has revolutionized our knowledge of the gamma-ray pulsar population, leading to the discovery of almost 100 gamma-ray pulsars and dozens of gamma-ray millisecond pulsars (MSPs). Although the outer-gap model predicts different sites of emission for the radio and gamma-ray pulsars, until now all of the known gamma-ray MSPs have been visible in the radio. Here we report the discovery of a 'radio-quiet' gamma-ray-emitting MSP candidate by using Fermi, Chandra, Swift, and optical observations. The X-ray and gamma-ray properties of the source are consistent with known gamma-ray pulsars. We also found a 4.63 hr orbital period in optical and X-ray data. We suggest that the source is a black widow-like MSP with a similar to 0.1 M-circle dot late-type companion star. Based on the profile of the optical and X-ray light curves, the companion star is believed to be heated by the pulsar while the X-ray emissions originate from pulsar magnetosphere and/or from intrabinary shock. No radio detection of the source has been reported yet, and although no gamma-ray/radio pulsation has been found we estimate that the spin period of the MSP is similar to 3-5 ms based on the inferred gamma-ray luminosity.</P>

Rheology of hydrophobic-alkali-soluble-emulsions (HASE) and the effects of surfactants

Lau, A.K.M.,Tiu, C.,Kealy, T.,Tam, K.C. The Korean Society of Rheology 2002 Korea-Australia rheology journal Vol.14 No.1

Steady and dynamic shear properties of two hydrophobically modified alkali soluble emulsions (HASE), NPJI and NPJ2, were experimentally investigated. At the same polymer concentration, NPJ1 is appreciably more viscous and elastic than NPJ2. The high hydrophobicity of NPJ1 allows hydrophobic associations and more junction sites to be created, leading to the formation of a network structure. Under shear deformation, NPJ1 exhibits shear-thinning behaviour as compared with Newtonian characteristics of NPJ2. NPJ1 and NPJ2 exhibit a very high and a low level of elasticity respectively over the frequency range tested. For NPJ1, a crossover frequency appears, which is shifted to lower frequencies and hence, longer relaxation times, as concentration increases. Three different surfactants anionic SDS, cationic CTAB, and non-ionic TX-100 were employed to examine the effects of surfactants on the rheology of HASE. Due to the different ionic behaviour of the surfactant, each type of surfactant imposed different electrostatic interactions on the two HASE polymers. In general, at low surfactant concentration, a gradual increase in viscosity is observed until a maximum is reached, beyond which a continuous reduction of viscosity ensues. Viscosity development is a combined result of HASE-surfactant interactions, accompanied by constant rearrangement of the hydrophobic associative junctions, and electrostatic interactions.

High-energy Emissions from the Pulsar/Be Binary System PSR J2032+4127/MT91 213

Takata, J.,Tam, P. H. T.,Ng, C. W.,Li, K. L.,Kong, A. K. H.,Hui, C. Y.,Cheng, K. S. American Astronomical Society 2017 The Astrophysical journal Vol.836 No.2

<P>PSR. J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25-50 years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises a young pulsar and a Be type star, which is similar to the so-called gamma-ray binary PSR. B1259-63/LS2883. It is expected therefore that PSR. J2032+4127 shows an enhancement of high-energy emission caused by the interaction between the pulsar wind and Be wind/disk around periastron. Ho et al. recently reported a rapid increase in the X-ray flux from this system. In this paper, we also confirm a rapid increase in the X-ray flux along the orbit, while the GeV flux shows no significant change. We discuss the high-energy emissions from the shock caused by the pulsar wind and stellar wind interaction and examine the properties of the pulsar wind in this binary system. We argue that the rate of increase of the X-ray flux observed by Swift indicates (1) a variation of the momentum ratio of the two-wind interaction region along the orbit, or (2) an evolution of the magnetization parameter of the pulsar wind with the radial distance from the pulsar. We also discuss the pulsar wind/Be disk interaction at the periastron passage, and propose the possibility of formation of an accretion disk around the pulsar. We model high-energy emissions through the inverse-Compton scattering process of the cold-relativistic pulsar wind off soft photons from the accretion disk.</P>

HIGH-ENERGY OBSERVATIONS OF PSR B1259-63/LS 2883 THROUGH THE 2014 PERIASTRON PASSAGE: CONNECTING X-RAYS TO THE GeV FLARE

Tam, P. H. T.,Li, K. L.,Takata, J.,Okazaki, A. T.,Hui, C. Y.,Kong, A. K. H. IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.798 No.1

<P>The binary system PSR B1259-63/LS 2883 is well sampled in radio, X-rays, and TeV gamma-rays, and shows orbital-phase-dependent variability in these frequencies. The first detection of GeV gamma-rays from the system was made around the 2010 periastron passage. In this Letter, we present an analysis of X-ray and gamma-ray data obtained by the Swift/XRT, NuSTAR/FPM, and Fermi/LAT, through the recent periastron passage which occurred on 2014 May 4. While PSR B1259-63/LS 2883 was not detected by the Large Area Telescope before and during this passage, we show that the GeV flares occurred at a similar orbital phase as in early 2011, thus establishing the repetitive nature of the post-periastron GeV flares. Multiple flares each lasting for a few days have been observed and short-term variability is seen as well. We also found X-ray flux variation contemporaneous with the GeV flare for the first time. Strong evidence of the keV-to-GeV connection came from the broadband high-energy spectra, which we interpret as synchrotron radiation from the shocked pulsar wind.</P>