1,101 research outputs found
The Suzaku Observation of NGC 3516: Complex Absorption and the Broad and Narrow Fe K Lines
We present results from a 150 ksec Suzaku observation of the Seyfert 1.5 NGC
3516 in October 2005. The source was in a relatively highly absorbed state. Our
best-fit model is consistent with the presence of a low-ionization absorber
which has a column density near 5 * 10^{22} cm^{-2} and covers most of the
X-ray continuum source (covering fraction 96-100%). A high-ionization absorbing
component, which yields a narrow absorption feature consistent with Fe K XXVI,
is confirmed. A relativistically broadened Fe K alpha line is required in all
fits, even after the complex absorption is taken into account; an additional
partial-covering component is an inadequate substitute for the continuum
curvature associated with the broad Fe line. A narrow Fe K alpha emission line
has a velocity width consistent with the Broad Line Region. The low-ionization
absorber may be responsible for producing the narrow Fe K alpha line, though a
contribution from additional material out of the line of sight is possible. We
include in our model soft band emission lines from He- and H-like ions of N, O,
Ne and Mg, consistent with photo-ionization, though a small contribution from
collisionally-ionized emission is possible.Comment: Accepted for publication in PASJ (Suzaku second special issue). 36
pages, 10 figure
Dispersion Interferometer Using a Modulation Amplitude on LHD
Since a dispersion interferometer is insensitive to mechanical vibrations, a vibration compensation system is not necessary. The CO2 laser dispersion interferometer with phase modulations on the Large Helical Device utilizes the new phase extraction method which uses modulation amplitudes and can improve a disadvantage of the original dispersion interferometer: measurement errors caused by variations of detected intensities. The phase variation within ±2 × 1017 m?3 is obtained without vibration compensation system. The measured line averaged electron density with the dispersion interferometer shows good agreement with that with the existing far infrared laser interferometer. Fringe jump errors in high density ranging up to 1.5 × 1020 m?3 can be overcome by a sufficient sampling rate of about 100 kHz
In-depth studies of the NGC 253 ULXs with XMM-Newton: remarkable variability in ULX1, and evidence for extended coronae
We examined the variability of three ultra-luminous X-ray sources (ULXs) in
the 2003, 110 ks XMM-Newton observation of NGC253. Remarkably, we discovered
ULX1 to be three times more variable than ULX2 in the 0.3--10 keV band, even
though ULX2 is brighter. Indeed, ULX1 exhibits a power density spectrum that is
consistent with the canonical high state or very high/steep power law state,
but not the canonical low state. The 0.3--10 keV emission of ULX1 is
predominantly non-thermal, and may be related to the very high state. We also
fitted the ULX spectra with disc blackbody, slim disc and convolution
Comptonization (SIMPL x DISKBB) models. The brightest ULX spectra are usually
described by a two emission components (disc blackbody + Comptonized
component); however, the SIMPL model results in a single emission component,
and may help determine whether the well known soft excess is a feature of ULX
spectra or an artifact of the two-component model. The SIMPL models were
rejected for ULX3 (and also for the black hole + Wolf-Rayet binary IC10 X-1);
hence, we infer that the observed soft-excesses are genuine features of ULX
emission spectra. We use an extended corona scenario to explain the soft excess
seen in all the highest quality ULX spectra, and provide a mechanism for
stellar mass black holes to exhibit super-Eddington luminosities while
remaining locally sub-Eddington.Comment: Accepted for publication in MNRAS. 7 pages, 5 figure
Design and tests of the hard X-ray polarimeter X-Calibur
X-ray polarimetry promises to give qualitatively new information about
high-energy astrophysical sources, such as binary black hole systems,
micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built
and tested a hard X-ray polarimeter X-Calibur to be used in the focal plane of
the InFOCuS grazing incidence hard X-ray telescope. X-Calibur combines a low-Z
Compton scatterer with a CZT detector assembly to measure the polarization of
10-80 keV X-rays making use of the fact that polarized photons Compton scatter
preferentially perpendicular to the electric field orientation. X-Calibur
achieves a high detection efficiency of order unity.Comment: 9 pages, 5 figures, conference proceedings: SPIE 2011 (San Diego
Two color far infrared laser interferometer
Two color interferometer using a short wavelength far infrared laser has been developed for high performance plasmas on large helical device and for future fusion devices such as ITER. High power laser lines simultaneously oscillating at 57.2 and 47.6 ?m were achieved in a CO_2-laser-pumped CH_3OD laser. By introducing Ge:Ga photoconductive detectors operating at liquid He temperature, we have successfully detected two color beat signals (0.55 and 1.2 MHz) with excellent signal-to-noise ratio (~40 dB). These beat signals were fed into phase comparators for phase measurement after passing through intermediate frequency bandpass filters. Two color far infraned laser interferometer work was successful in the demonstration of mechanical vibration compensation
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