66 research outputs found
Deconvolution of Images Taken with the Suzaku X-ray Imaging Spectrometer
We present a non-iterative method to deconvolve the spatial response function
or the point spread function (PSF) from images taken with the Suzaku X-ray
Imaging Spectrometer (XIS). The method is optimized for analyses of extended
sources with high photon statistics. Suzaku has four XIS detectors each with
its own X-ray CCD and X-Ray Telescope (XRT) and has been providing unique
opportunities in spatially-resolved spectroscopic analyses of extended objects.
The detectors, however, suffer from broad and position-dependent PSFs with
their typical half-power density (HPD) of about 110''. In the authors' view,
this shortcoming has been preventing the high collecting area and high spectral
resolution of Suzaku to be fully exploited. The present method is intended to
recover spatial resolution to ~15'' over a dynamic range around 1:100 in the
brightness without assuming any source model. Our deconvolution proceeds in two
steps: An XIS image is multiplied with the inverse response matrix calculated
from its PSF after rebinning CCD pixels to larger-size tiles (typically 6''x
6''); The inverted image is then adaptively smoothed to obtain the final
deconvolved image. The PSF is modeled on a ray-tracing program and an observed
point-source image. The deconvolution method has been applied to images of
Centaurus A, PSR B1509-58 and RCW 89 taken by one XIS (XIS-1). The results have
been compared with images obtained with Chandra to conclude that the spatial
resolution has been recovered to ~20'' down to regions where surface brightness
is about 1:50 of the brightest tile in the image. We believe the spatial
resolution and the dynamic range can be improved in the future with higher
fidelity PSF modeling and higher precision pointing information.Comment: 21 pages, accepted for publication in PASJ. A PS file with
original-quality figures is available at
http://www.slac.stanford.edu/~sugizaki/preprint/pasj3256/sugizaki_No3256.p
The physical connection between G337.2+0.1 and AX J1635.9-4719
We present evidence supporting a SNR origin for the radio source G337.2+0.1, which was discovered in the MOST 843-MHz radio survey. The radio source is spatially coincident with the unidentified ASCA source AX J1635.9-4719. A deep study of this latter source reveals that its X-ray spectrum, extended nature, and non-variable flux are consistent with what is expected for a SNR. In addition, we have used HI-line observations of the region to look for any effect of the presumed remnant in the ISM. We have found a welldefined minimum centered at the position of the radio source in the velocity range of −25 to −19 km/s. This feature appears as a sharp absorption dip in the spectrum that might be produced when the continuum emission from the SNR candidate is absorbed by foreground gas. Hence we have used it to constrain the distance to the source, which seems to be a young (age ∼ a few 103 yr) and distant (d ∼ 14 kpc) SNR. G337.2+0.1 and AX J1635.9- 4719 would be the radio/X-ray manifestations of this remnant.Fil: Combi, Jorge Ariel. Universidad de Jaén; España. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Benaglia, Paula. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Sugizaki, Mutsumi. Stanford Linear Accelerator Center; Estados Unido
Average spectral properties of galactic X-ray binaries with 3 years of MAXI data
The energy spectra of X-ray binaries (XRBs) have been investigated during the
last few decades with many observatories in different energy bands and with
different energy resolutions. However, these studies are carried out in
selected states of XRBs like during outbursts, transitions, quiescent states,
and are always done in limited time windows of pointed observations. It is now
possible to investigate the long term averaged spectra of a large number of
X-ray binaries with the all sky monitor MAXI, which also has a broad energy
band. Here we present the average spectral behaviour of a few representative
XRBs. The long term averaged spectrum of Cyg X-1 is described by a sum of two
power-laws having ~ 2.8 and ~ 1.2, along with a multi
color disk blackbody having an inner disk temperature of 0.5 keV, GX 301-2 is
described by a power-law with a high energy cut-off at ~ 15 keV and a
blackbody component at 0.2 keV and that of Aql X-1 is described by a multi
color disk blackbody at 2 keV and a power-law of ~ 2.2. We have also
constructed the combined X-ray spectrum of the X-ray binaries in the Milky Way,
which can be compared to the XRBs spectra of other galaxies observed with
Chandra and XMM-Newton. These measurements are also relevant to investigate the
X-ray interaction with the ISM and its contribution to the ionising X-ray
background in the early universe.Comment: To be published in ASI Conference Series on "Recent Trends in the
Study of Compact Objects: Theory and Observation
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