NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
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status of the development of SOFIA as the Observatory nears the date of the first test flight in the summer of 2004.<br />
Author<br />
Elevation Angle; Functional Design Specifications; Stratosphere<br />
20040070913 <strong>NASA</strong> Marshall Space Flight Center, Huntsville, AL, USA<br />
Revealing the X-Ray Emission Processes of Old Rotation-Powered Pulsars: XMM-Newton Observations of PSR<br />
B0950+08, PSR B0823+26 <strong>and</strong> PSR J2043+2740<br />
Becker, Werner; Weisskopf, Martin C.; Tenant, Allyn F.; Jessmer, Axel; Zhang, Shiang N.; 2004; 2 pp.; In English; No<br />
Copyright; Avail: Other Sources; Abstract Only<br />
We have completed part of a program to study the X-ray emission properties of old rotation-powered pulsars with<br />
XMM-Newton in order to probe <strong>and</strong> identify the origin of their X radiation. The X-ray emission from these old pulsars is<br />
largely dominated by non-thermal processes. None of the observed spectra required adding a thermal component consisting<br />
of either a hot polar cap or surface cooling emission to model the data. The energy spectrum of PSR B0950+08 is best<br />
described by a single power law of photon-index alpha = 1.93(sup +0.14)(sub -0.12). Three-sigma temperature upper limits<br />
for possible contributions from a heated polar cap or the whole neutron star surface are T(sup infinity)(sub pc) < 0.87 x<br />
10(exp 6) K <strong>and</strong> T(sup infinity)(sub s) < 0.48 x 10(exp 6) K, respectively. We also find that the X-ray emission from PSR<br />
B0950+08 is pulsed with two peaks per rotation period. The phase separation between the two X-ray peaks is approx. 144 deg<br />
(maximum to maximum) which is similar to the pulse peak separation observed in the radio b<strong>and</strong> at 1.4 GHz. The fraction<br />
of X-ray pulsed photons is approx. 30%. A phase resolved spectral analysis confirms the nonthermal nature of the pulsed<br />
emission <strong>and</strong> finds power law slopes of alpha = 2.4(sup +0.52)(sub -0.42) <strong>and</strong> alpha = 1.93(sup +0.29)(sub -0.24) for the pulse<br />
peaks P1 <strong>and</strong> P2, respectively. The spectral emission properties observed for PSR B0823+26 are similar to those of PSR<br />
B0950+08. Its energy spectrum is very well described by a single power law with photon-index alpha = 2.5(sup +0.52)(sub<br />
-0.24. Three-sigma temperature upper limits for thermal contributions from a hot polar cap or from the entire neutron star<br />
surface are T(sup infinity)(sub pc) < 1.17 x 10(exp 6) K <strong>and</strong> T(sup infinity)(sub s) < 0.5 x 10(exp 6) K, respectively. There<br />
is evidence for pulsed X-ray emission at the - 97% confidence level with a pulsed fraction of 49 +/- 22%. For PSR 52043+2740<br />
we report the first detection of X-ray emission. A power law spectrum, or a combination of a thermal <strong>and</strong> a power law spectrum<br />
all yield acceptable descriptions of its X-ray spectrum. No X-ray pulses are detected from PSR J2043+2740 but the sensitivity<br />
is low - the 2-sigma pulsed fraction upper limit is 57% assuming a sinusoidal pulse profile.<br />
Author<br />
X Ray Astronomy; Pulsars; Spectral Emission<br />
20040071009 <strong>NASA</strong> Marshall Space Flight Center, Huntsville, AL, USA<br />
On the Nature of the Bright Short-Period X-Ray Source in the Circinus Galaxy Field<br />
Weisskopf, Martin C.; Wu, Kinwah; Tennant, Allyn F.; Swartz, Douglas A.; Ghosh, Kajal K.; The Astrophysical Journal; 10<br />
Apr. 2004; Vol. 605, pp. 360-367; In English; Copyright; Avail: Other Sources<br />
The spectrum <strong>and</strong> light curve of the bright X-ray source CG X-1 in the field of the Circinus galaxy are reexamined.<br />
Previous analyses have concluded that the source is an accreting black hole of mass > or approx. 50 solar masses although<br />
it has been noted that the light curve resembles that of an AM Herculis system. Here we show that the short period <strong>and</strong> an<br />
assumed main-sequence companion constrain the mass of the companion to less than 1 solar mass. Furthermore, a possible<br />
eclipse seen during one of the Ch<strong>and</strong>ra observations <strong>and</strong> a subsequent XMM-Newton observation constrain the mass of the<br />
compact object to less than 60 solar masses. If such a system lies in the Circinus galaxy, then the accreting object must either<br />
radiate anisotropically or strongly violate the Eddington limit. Even if the emission is beamed, then the companion star that<br />
intercepts this flux during eclipse will be driven out of thermal equilibrium <strong>and</strong> evaporate within approx. 10(exp 3) yr. We find<br />
that the observations cannot rule out an AM Herculis system in the Milky Way <strong>and</strong> that such a system can account for the<br />
variations seen in the light curve.<br />
Author<br />
X Ray Binaries; Black Holes (Astronomy); Emission Spectra; X Ray Astronomy<br />
20040071107 California Inst. of Tech., Pasadena, CA, USA<br />
A XMM Survey for Compact Objects in Supernova Remnants<br />
Kulkarni, Shrinivas R.; [2004]; 1 pp.; In English<br />
Contract(s)/Grant(s): NAG5-12925<br />
Report No.(s): CIT-SRK.00049-1-<strong>NASA</strong>.000147; No Copyright; Avail: CASI; A01, Hardcopy<br />
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