AX J0049.4-7323 - a close look at a neutron star interacting with a circumstellar disk

Detailed evidence on the system AX J0049.4-7323 is presented here to show how the passage of the neutron star in the binary system disrupts the circumstellar disk of the mass donor Be star. A similar effect is noted in three other Be/X-ray binary systems. Together the observational data should provide valuable tools for modelling these complex interactions.Comment: 4 pages, accepted for publication in MNRA

A major outburst from the X-ray binary RX J0520.5-6932

We report on the analysis of 8 years of MAssive Compact Halo Objects (MACHO) data for the source RX J0520.5-6932. A regular period of 24.4 days has been confirmed, however this is manifest almost entirely in the red part of the spectrum. A major outburst, lasting approximately 200 days, was observed which increased the apparent brightness of the object by approximately 0.15 magnitudes without significantly altering its V-R colour index. This outburst was also seen in X-ray data. The evidence from this analysis points to the identification of this object as a Be/X-ray binary with a periodically variable circumstellar disk and a very early optical counterpart.Comment: Paper has been accepted by MNRA

Real-time broadening of non-equilibrium density profiles and the role of the specific initial-state realization

The real-time broadening of density profiles starting from non-equilibrium states is at the center of transport in condensed-matter systems and dynamics in ultracold atomic gases. Initial profiles close to equilibrium are expected to evolve according to linear response, e.g., as given by the current correlator evaluated exactly at equilibrium. Significantly off equilibrium, linear response is expected to break down and even a description in terms of canonical ensembles is questionable. We unveil that single pure states with density profiles of maximum amplitude yield a broadening in perfect agreement with linear response, if the structure of these states involves randomness in terms of decoherent off-diagonal density-matrix elements. While these states allow for spin diffusion in the XXZ spin-1/2 chain at large exchange anisotropies, coherences yield entirely different behavior.Comment: 7 pages, 7 figures, accepted for publication in Phys. Rev.

Discovery of 16.6 and 25.5 s Pulsations from the Small Magellanic Cloud

We report the serendipitous detection of two previously unreported pulsars from the direction of the Small Magellanic Cloud, with periods of 16.6 and 25.5 seconds. The detections are based on archival PCA data from the Rossi X-ray Timing Explorer (RXTE). The observation leading to these detections occurred in September 2000 extending over 2.1 days with an exposure of 121 ks. A possible identification of the 16.6 s pulsar with an X-ray source RX J0051.8-7310 seen by both ROSAT and ASCA imaging X-ray satellites is presented.Comment: 9 pages with 3 figures. Submitted to ApJ Letter

Orbital Period Determinations for Four SMC Be/X-ray Binaries

We present an optical and X-ray study of four Be/X-ray binaries located in the Small Magellanic Cloud (SMC). OGLE I-band data of up to 11 years of semi-continuous monitoring has been analysed for SMC X-2, SXP172 and SXP202B, providing both a measurement of the orbital period (Porb = 18.62, 68.90, and 229.9 days for the pulsars respectively) and a detailed optical orbital profile for each pulsar. For SXP172 this has allowed a direct comparison of the optical and X-ray emission seen through regular RXTE monitoring, revealing that the X-ray outbursts precede the optical by around 7 days. Recent X-ray studies by XMM-Newton have identified a new source in the vicinity of SXP15.3 raising doubt on the identification of the optical counterpart to this X-ray pulsar. Here we present a discussion of the observations that led to the proposal of the original counterpart and a detailed optical analysis of the counterpart to the new X-ray source, identifying a 21.7 d periodicity in the OGLE I-band data. The optical characteristics of this star are consistent with that of a SMC Be/X-ray binary. However, this star was rejected as the counterpart to SXP15.3 in previous studies due to the lack of H{\alpha} emission.Comment: Accepted for publication in MNRAS, 11 pages, 17 figure

An Investigation of Be/X-ray Pulsars with OGLE-III Data

We have studied five seasons of OGLE-III data for eight SMC Be/X-ray pulsars for which no other survey data were available. We have determined orbital periods for four of these binary systems, one of which also shows nonradial pulsations. Optical identification of SMC X-2 is reconsidered, but no periods were found for either of the two possible candidates

Tc-Glutathione Complex (Tc -GSH) : Labelling, Chemical Characterization and Biodistribution in Rats

The chemical structure of 99mTc-GSH has been estabilished using the 99Tc isotope. Labeling of glutathione with technetium in the presence of stanous chloride gave a high yield result. In a comparative study between 99Tc and 99Tc glutathione, the Tc-GSH complex obtained was purified and characterized by uv, visible spectroscopy, HPLC, Biogel chromatography, mass and NMR spectroscopy. Stoichiometric analysis showed a 2 : 1 molar ratio of GSH/Tc for the reaction. The molecular mass assessed by mass spectroscopy was 727 Da corresponding to an oxo(bis) glutathione technetate. NMR studies demonstrated that each glutathione molecule was coordinated to technetium via cysteinyl sulfur and nitrogen atoms. The biodistribution of the complex was studied in normal rats. Blood clearance was rapid during the first hour involving a biexponential curve ( t1/2 (1) : 50 min, t1/2 (2) : 400 min ). No radioactive accumulation was found in any specific organ except kidney and bladder. All the activity excreted was found unchanged in urine. In conclusion, Tc-GSH displayed an anionic dimer form as GSH-Tc-GSH. We assume that the complex is a tetradentate (2N,2S) complex containing a pentavalent technetium coordinated by two thiol and nitrogen atoms of both GSH ligands, and an apical oxo group

FUSE Observations of RX J0513.9-6951

FUSE observations were obtained in July 2003 during 1.2 cycles of the 0.76-day binary orbit of RX J0513.9-6951. Radial velocity measurements of the broad O VI emission profile show a semiamplitude of K~26 km/sec, which is much smaller than the value of 117 km/sec measured from 2001 FUSE data. Narrow O VI emissions show no measurable velocity variation. The mean velocity of the broad O VI emission is red-shifted by ~500 km/sec with respect to both the systemic and narrow emission-line velocities. Spectral difference plots show phase-related changes in the broad emission profile. Other phase-related changes such as line and continuum variations are also smaller than in the 2001 spectra. We describe a moving broad absorption feature near 1020A as possible O VI outflow associated with a precessing jet. We discuss the implications for the stellar masses if the 2003 broad O VI velocities outline the compact star's orbital motion.Comment: 16 pages, including 7 figures. To appear in A