473 research outputs found
Plerionic Supernova Remnants
Plerions represent ideal laboratories for the search for neutron stars, the
study of their relativistic winds, and their interaction with their surrounding
supernova ejecta and/or the interstellar medium. As well, they are widely
believed to represent efficient engines for particle acceleration up to the
knee of the cosmic ray spectrum (at about 1E15 eV). Multi-wavelength
observations from the radio to the highest TeV energies, combined with
modelling, have opened a new window to study these objects, and particularly
shed light on their intrinsic properties, diversity, and evolution.
High-resolution X-ray observations are further revealing the structure and
sites for shock acceleration. The missing shells in the majority of these
objects remain puzzling, and the presence of plerions around highly magnetized
neutron stars is still questionable. I review the current status and statistics
of observations of plerionic supernova remnants (SNRs), highlighting combined
radio and X-ray observations of a growing class of atypical, non Crab-like,
plerionic SNRs in our Galaxy. I will also briefly describe the latest
developments to our high-energy SNRs catalogue recently released to the
community, and finally highlight the key questions to be addressed in this
field with future high-energy missions, including Astro-H in the very near
future.Comment: AIP Conference Proceedings of the 5th International Symposium on
High-Energy Gamma-Ray Astronomy, Heidelberg, July 9-13 (2012). Eds: F.
Aharonian, W. Hofmann, F. Rieger. Solicited review, 8 pages, 4 colour
figures. The figures resolution has been reduced for astro-ph. Original
article can be found at:
http://www.physics.umanitoba.ca/~samar/arxiv/safiharb-plerions-gamma2012.pd
A Multi-Wavelength Study of the Western Lobe of W50 Powered by the Galactic Microquasar SS 433
W50 remains the only supernova remnant (SNR) confirmed to harbor a
microquasar: the powerful enigmatic source SS 433. Our past study of this
fascinating SNR revealed two X-ray lobes distorting the radio shell as well as
non-thermal X-rays at the site of interaction between the SS 433 eastern jet
and the eastern lobe of W50. In this paper we present the results of a 75 ksec
CHANDRA ACIS-I observation of the peak of W50-west targeted to 1) determine the
nature of the X-ray emission and 2) correlate the X-ray emission with that in
the radio and infrared domains. We have confirmed that at the site of
interaction between the western jet of SS 433 and dense interstellar gas the
X-ray emission is non-thermal in nature. The helical pattern observed in radio
is also seen with CHANDRA. No correlation was found between the infrared and
X-ray emission.Comment: A refereed publication, submitted Sept. 30, 2004, accepted Jan. 12,
2005, to appear in Advances in Space Research. 7 pages, including 4 figures
(3 color) & 1 table (the resolution of most figures has been reduced for
astro-ph submission only). A gzipped postscript or pdf version of the paper
with high-resolution images can be downloaded from:
http://aurora.physics.umanitoba.ca/~moldowan/Astro-Ph
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
XMM-Newton, Chandra, and CGPS observations of the Supernova Remnants G85.4+0.7 and G85.9-0.6
We present an XMM-Newton detection of two low radio surface brightness SNRs,
G85.4+0.7 and G85.9-0.6, discovered with the Canadian Galactic Plane Survey
(CGPS). High-resolution XMM-Newton images revealing the morphology of the
diffuse emission, as well as discrete point sources, are presented and
correlated with radio and Chandra images. The new data also permit a
spectroscopic analysis of the diffuse emission regions, and a spectroscopic and
timing analysis of the point sources. Distances have been determined from HI
and CO data to be 3.5 +/- 1.0 kpc for SNR G85.4+0.7 and 4.8 +/- 1.6 kpc for SNR
G85.9-0.6. The SNR G85.4+0.7 is found to have a temperature of ~12-13 MK and a
0.5-2.5 keV luminosity of ~1-4 x 10^33 D(3.5)^2 erg/s (where D(3.5) is the
distance in units of 3.5 kpc), with an electron density n_e of
~0.07-0.16(fD(3.5))^-1/2 cm^-3 (where f is the volume filling factor), and a
shock age of ~9-49(fD(3.5))^1/2 kyr. The SNR G85.9-0.6 is found to have a
temperature of ~15-19 MK and a 0.5-2.5 keV luminosity of ~1-4 x 10^34 D(4.8)^2
erg/s (where D(4.8) is the distance in units of 4.8 kpc), with an electron
density n_e of ~0.04-0.10(fD(4.8))^-1/2 cm^-3 and a shock age of
~12-42(fD(4.8))^1/2 kyr. Based on the data presented here, none of the point
sources appears to be the neutron star associated with either SNR.Comment: 30 pages using emulateapj, 16 figures with quality reduced for
astro-ph only. The original version with high-resolution figures can be
downloaded from:
http://www.physics.umanitoba.ca/~samar/astro-ph/G85s-ms09102007.pdf To appear
in ApJ (Jan 20 2008 issue, v673, n1
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