58 research outputs found
SS 433: Radio/X-ray anti-correlation and fast-time variability
We briefly review the Galactic microquasar SS 433/W50 and present a new RXTE
spectral and timing study. We show that the X-ray flux decreases during radio
flares, a behavior seen in other microquasars. We also find short time-scale
variability unveiling emission regions from within the binary system.Comment: 4 pages, 3 figures, mq.sty included. A higher resolution version can
be found at http://aurora.physics.umanitoba.ca/~samar/4MQ/ss433/. Proceedings
of the 4th Microquasar Workshop, eds. Ph. Durouchoux, Y. Fuchs and J.
Rodriguez, published by the Center for Space Physics: Kolkata (in press
Millimeter Light Curve with Abrupt Jump in Cyg X-3 2008 April-May Outburst
Cyg X-3 is a well-known microquasar with a bipolar relativistic jet. Its
famous giant radio outbursts have been repeated once every several years.
However, the behavior of the millimeter wave emission has remained unclear
because of limitations of time resolution in previous observations. We report
here millimeter wave observations of Cyg X-3 experiencing giant outbursts with
one of the finest time resolutions. We find a series of short-lived flares with
amplitude of 1-2 Jy in the millimeter light curve of the 2008 April-May
outburst. They have flat spectra around 100 GHz. We also find abrupt and large
amplitude flux density changes with e-folding time of 3.6 minutes or less. The
source size of Cyg X-3 is constrained within 0.4 AU and the brightness
temperature is estimated to be K.Comment: 4 figures, PASJ, in pres
Optically Thick Outflows of Supercritical Accretion Discs: Radiative Diffusion Approach
Highly supercritical accretion discs are probable sources of dense optically
thick axisymmetric winds. We introduce a new approach based on diffusion
approximation radiative transfer in a funnel geometry and obtain an analytical
solution for the energy density distribution inside the wind assuming that all
the mass, momentum and energy are injected well inside the spherization radius.
This allows to derive the spectrum of emergent emission for various inclination
angles. We show that self-irradiation effects play an important role altering
the temperature of the outcoming radiation by about 20% and the apparent X-ray
luminosity by a factor of 2-3. The model has been successfully applied to two
ULXs. The basic properties of the high ionization HII-regions found around some
ULXs are also easily reproduced in our assumptions.Comment: 32 pages, 9 figures, 1 table; accepted to PAS
Evidence for Jet Collimation in SS 433 with the Chandra HETGS
High-resolution X-ray spectra of SS 433 obtained after a binary egress with
the Chandra High Energy Transmission Grating Spectrometer (HETGS) were studied.
Many Doppler-shifted X-ray emission lines from highly ionized elements were
detected. The initial temperature of the jets is estimated to be 20 keV. The
lines are found to generally be broader than the instrumented resolution. The
widths of the Fe XXV K-alpha and Si XIII K-alpha lines correspond to velocity
dispersions of 2100 (+600/-340) km/s and 840 (+180/-150) km/s respectively, in
terms of Gaussian sigma. Neither the measured line widths nor their dependence
on the atomic number can be explained by thermal broadening alone. Alternative
explanations of the observed line widths are discussed, including in particular
a progressive jet collimation along its axis.Comment: 20 pages, 8 figur
Isolated Millimeter Flares of Cyg X-3
Cygnus X-3 (Cyg X-3) is a well-known microquasar with relativistic jets. Cyg
X-3 is especially famous for its giant radio outbursts, which have been
observed once every few years since their first discovery. Each giant outburst
presumably consists of a series of short-duration flares. The physical
parameters of the flares in the giant outbursts are difficult to derive because
the successive flares overlap. Here, we report isolated flares in the quiescent
phase of Cyg X-3, as observed at 23, 43, and 86 GHz with the 45-m radio
telescope at Nobeyama Radio Observatory. The observed flares have small
amplitude (0.5--2 Jy) and short duration (1--2 h). The millimeter fluxes
rapidly increase and then exponentially decay. The lifetime of the decay is
shorter at higher frequency. The radio spectrum of Cyg X-3 during the flares is
flat or inverted around the peak flux density. After that, the spectrum
gradually becomes steeper. The observed characteristics are consistent with
those of adiabatic expanding plasma. The brightness temperature of the plasma
at the peak is estimated to be K. The magnetic
field in the plasma is calculated to be G.Comment: 2012, PASJ 64, in press. 7 pages, 2 figure
Suzaku and Optical Spectroscopic Observations of SS 433 in the 2006 April Multiwavelength Campaign
We report results of the 2006 April multi-wavelengths campaign of SS 433,
focusing on X-ray data observed with Suzaku at two orbital phases (in- and
out-of- eclipse) and simultaneous optical spectroscopic observations. By
analyzing the Fe25 K_alpha lines originating from the jets, we detect rapid
variability of the Doppler shifts, dz/dt ~ 0.019/0.33 day^-1, which is larger
than those expected from the precession and/or nodding motion. This phenomenon
probably corresponding to "jitter" motions observed for the first time in
X-rays, for which significant variability both in the jet angle and intrinsic
speed is required. From the time lag of optical Doppler curves from those of
X-rays, we estimate the distance of the optical jets from the base to be ~(3-4)
\times 10^14 cm. Based on the radiatively cooling jet model, we determine the
innermost temperature of the jets to be T_0 = 13 +/- 2 keV and 16 +/- 3 keV
(the average of the blue and red jets) for the out-of-eclipse and in-eclipse
phase, respectively, from the line intensity ratio of Fe25 K_alpha and Fe26
K_alpha. While the broad band continuum spectra over the 5--40 keV band in
eclipse is consistent with a multi-temperature bremsstrahlung emission expected
from the jets, and its reflection component from cold matter, the
out-of-eclipse spectrum is harder than the jet emission with the base
temperature determined above, implying the presence of an additional hard
component.Comment: 12 pages, 15 figures, accepted for publication in PAS
Promoter methylation of the bone morphogenetic protein-6 gene in association with adult T-cell leukemia
Postprandial Paraoxonase 1 Activity Following Consumption of Recommended Amounts of Mixed Meals in Healthy Males
Aim: Postprandial lipid level increases induce oxidative stress, which is involved in atherogenesis. The antioxidant properties of paraoxonase 1 (PON1) have attracted attention. However, changes in postprandial PON1 levels differ across prior studies, and changes in PON1 lactonase activity, potentially relevant to PON1 physiology, after the consumption of ordinary meals are unknown. Herein we evaluated postprandial serum lipid levels and PON1 changes following mixed-meal consumption of the amounts recommended for ordinary meals.Methods: Nine healthy male volunteers consumed three different meals in a randomized cross-over design. The test meals were as follows: S, white rice; SMF, S with fat-containing protein-rich main dishes; and SMFV: SMF with vegetable dishes. The serum lipid concentrations and PON1 lactonase and arylesterase activities were determined during a three-hour period after the consumption of these meals.Results: The postprandial triglyceride levels were higher after consuming the SMF and SMFV meals than after consuming the S meal. Despite postprandial high-density lipoprotein cholesterol being unchanged, PON1 lactonase activity was decreased, while PON1 arylesterase activity was increased in the postprandial state after all test meals. Postprandial changes in lactonase and arylesterase activities did not differ among the test meals.Conclusions: Inverse changes in PON1 lactonase and arylesterase activities were observed after consuming recommended ordinary meals. This observation provides useful information for choosing PON1 species as postprandial markers
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