1,107 research outputs found
X-ray Evolution of SN 1987A
The X-ray observations of SN 1987A over the previous 20 years have seen the
emergence of soft X-rays from the interaction of the explosion shock wave with
the ambient medium. This shock wave is now interacting strongly with the inner
ring and might have passed already the highest density regions. The emission
can be described by thermal models with two temperatures, with perhaps some but
little change over time. Relative to the elemental abundances prevailing in the
LMC the inner ring shows an overabundance of Si and S compared to the lighter
elements and Fe, which suggests that the ring consists of highly processed
matter dredged up in a binary merger event well before the explosion. The X-ray
lightcurves between 0.5--2 keV and 3--10 keV differ significantly in slope,
with the latter being much flatter but very similar to the radio light curve.Comment: 10 pages, 9 figures; review talk to appear in the AIP Proceedings of
the Conference " Supernova 1987A: 20 Years after - Supernovae and Gamma-Ray
Bursters" held in Aspen Co USA, Feb 19-23, 200
X-rays from Supernova Remnants
A summary of X-ray observations of supernova remnants is presented including
the explosion fragment A of the Vela SNR, Tycho, N132D, RX J0852-4622, the Crab
Nebula and the 'bulls eye', and SN 1987A, high-lighting the progress made with
Chandra and XMM-Newton and touching upon the questions which arise from these
observations and which might inspire future research.Comment: 13 pages, 18 figures. To appear in the Proceedings of the 270.
WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants, Jan.
21-25, 2002, Physikzentrum Bad Honnef, eds W. Becker, H. Lesch & J. Truemper.
Proceedings are available as MPE-Report 27
Measurement of Mass and Spin of Black Holes with QPOs
There are now four low mass X-ray binaries with black holes which show twin
resonant-like HFQPOs. Similar QPOs might have been found in Sgr A*. I review
the power spectral density distributions of the three X-ray flares and the six
NIR flares published for Sgr A* so far, in order to look for more similarities
than just the frequencies between the microquasar black holes and Sgr A*. The
three X-ray flares of Sgr A* are re-analysed in an identical way and white
noise probabilities from their power density distributions are given for the
periods reported around 1100 s. Progress of the resonant theory using the
anomalous orbital velocity effect is summarized.Comment: 7 pages, talk given at the 2007 Frascati workshop, acc. for
publication in the Chin. J. Astron. Astrophy
Temporal Variability of the X-ray Emission of the Crab Nebula Torus
We have analyzed five ROSAT HRI images of the Crab Nebula spanning the years
1991 to 1997 and have found significant changes in the emission structure of
the X-ray torus surrounding the pulsar. Certain regions increase in brightness
by about 20% over the six years, while others show decreases in surface
brightness. The origin of these changes is unclear, but a possible explanation
is that the bulk velocity of the synchrotron radiating electrons has decreased
on the order of 20% as well.Comment: 15 pages plus 6 figures, figure 1 and figure 6 are in color, to
appear in The Astrophysical Journal, Jan 1, 1999, Vol. 510, #
XMM-Newton observation of SN1993J in M81
In April 2001 SN1993J was observed with both the PN and MOS cameras of the
XMM-Newton observatory, resulting in about 7. x 10^4 s of acceptable
observation time. Fit results with both the PN and MOS2 camera spectra studying
different spectral models are presented. The spectra are best fitted in the
energy range between 0.3 and 11 keV by a 2-component thermal model with
temperatures of kT_1 = 0.34+-0.04 keV and kT_2 = 6.54+-4 keV, adopting
ionization equilibrium. A fit with a shock model also provides acceptable
results. Combining the XMM-Newton data with former X-ray observations of the
supernova, we discuss the general trend of L_x propto t^{-0.30} and the bump of
the X-ray light curve as well as former and recent spectral results in the
light of the standard SN model as first proposed by Chevalier in 1982.Comment: 7 pages, 3 figure
Spectroscopic Study of the Vela-Shrapnel
Several shrapnels have been detected in the vicinity of Vela SNR by the ROSAT
all-sky survey. We present here the spectral properties of shrapnel `A'
observed with the ASCA satellite. A prominent Si-K emission line with
relatively weak emission lines from other elements have been detected,
revealing that the relative abundance of Si is a few ten-times higher than
those of other elements. Combining with the ROSAT PSPC results, we obtained the
electron temperature, , to be keV. The total mass
of shrapnel `A' is estimated to be . If it is an ejecta of a
supernova explosion, the interstellar matter (ISM) would be swept up in the
leading edge while the ejecta material would be peeled off in the trailing
edge, which should be confirmed by future observations.Comment: 19pages, 5 figures, 1 table; Accepted for Publications of the
Astronomical Society of Japa
In-orbit performance of the XMM-Newton X-ray telescopes: images and spectra
The performance of the three X-ray telescopes on-board of XMM-Newton is
evaluated addressing imaging characteristics and effective collecting area. The
agreement with ground calibration data is excellent. The analysis of images and
spectra of cosmic X-ray sources, emphazising supernova and supernova remnants,
prooves that the telescopes are even better than originally required.Comment: 13 pages, 20 jpg figures, for SPIE Proc. 4496, paper 0
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