7,523 research outputs found
The Orbifold-String Theories of Permutation-Type: I. One Twisted BRST per Cycle per Sector
We resume our discussion of the new orbifold-string theories of
permutation-type, focusing in the present series on the algebraic formulation
of the general bosonic prototype and especially the target space-times of the
theories. In this first paper of the series, we construct one twisted BRST
system for each cycle in each twisted sector of the general case,
verifying in particular the previously-conjectured algebra
of the BRST charges. The BRST systems
then imply a set of extended physical-state conditions for the matter of each
cycle at cycle central charge where
is the length of cycle .Comment: 31 page
Imaging the Nearby Seyfert 2 Galaxy NGC 1068, and Spectrum and Variability of Geminga
The results of the research for NASA Grant NAG5-1606 are summarized in the following publications: (1) A ROSAT high resolution image of NGC 1068; (2) Discovery of soft x-ray pulsations from the gamma-ray source Geminga; and (3) Soft x-ray properties of the Geminga pulsar
X-ray Observations and Infrared Identification of the Transient 7.8 s X-ray Binary Pulsar XTE J1829-098
XMM-Newton and Chandra observations of the transient 7.8 s pulsar XTE
J1829-098 are used to characterize its pulse shape and spectrum, and to
facilitate a search for an optical or infrared counterpart. In outburst, the
absorbed, hard X-ray spectrum with Gamma = 0.76+/-0.13 and N_H = (6.0+/-0.6) x
10^{22} cm^{-2} is typical of X-ray binary pulsars. The precise Chandra
localization in a faint state leads to the identification of a probable
infrared counterpart at R.A. = 18h29m43.98s, decl. = -09o51'23.0" (J2000.0)
with magnitudes K=12.7, H=13.9, I>21.9, and R>23.2. If this is a highly
reddened O or B star, we estimate a distance of 10 kpc, at which the maximum
observed X-ray luminosity is 2x10^{36} ergs s^{-1}, typical of Be X-ray
transients or wind-fed systems. The minimum observed luminosity is
3x10^{32}(d/10 kpc)^2 ergs s^{-1}. We cannot rule out the possibility that the
companion is a red giant. The two known X-ray outbursts of XTE J1829-098 are
separated by ~1.3 yr, which may be the orbital period or a multiple of it, with
the neutron star in an eccentric orbit. We also studied a late M-giant
long-period variable that we found only 9" from the X-ray position. It has a
pulsation period of ~1.5 yr, but is not the companion of the X-ray source.Comment: 6 pages, 7 figures. To appear in The Astrophysical Journa
- …