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

An Energetic Magnetar in HESS J1713-381/CTB 37B

We obtained a second Chandra timing measurement of the 3.82 s pulsar CXOU J171405.7-381031 in the supernova remnant (SNR) CTB 37B, which shows that it is spinning down rapidly. The average period derivative of (5.88+/-0.08)E-11 over the 1 year time span corresponds to a dipole magnetic field strength B = 4.8E14 G, well into the magnetar range. The spin-down power E-dot = 4.2E34 erg/s is among the largest for magnetars, and the corresponding characteristic age Tau = P/2P-dot = 1030 years is comparable to estimates of the age of the SNR. The period derivative enables us to recover probable pulsations in an ASCA observation taken in 1996, which yields a mean characteristic age of 860 years over the longer 13 year time span. The source is well detected up to 10 keV, and its composite spectrum is typical of a magnetar. CTB 37B hosts HESS J1713-381, the first TeV source that is coincident with a magnetar. While the TeV emission has been attributed to the SNR shell, it is possibly centrally peaked, and we hypothesize that this particularly young, energetic magnetar may contribute to the HESS source. We also searched for pulsations from another source in a HESS SNR, XMMU J173203.3-344518 in HESS J1731-347/G353.6-0.7 but could not confirm pulsations or long-term flux variability, making it more likely that this source is a weakly magnetized central compact object.Comment: 9 pages, 6 figures, version accepted by The Astrophysical Journa

Proper Motion and Timing of Two Unusual Pulsars: Calvera and 1E 1207.4-5209

Using pairs of images from the Chandra High-Resolution Camera we examine the proper motion of the central compact object (CCO) 1E 1207.4-5209 in the supernova remnant (SNR) PKS 1209-51/52, and the unusual pulsar Calvera that is possibly a CCO descendant. For 1E 1207.4-5209, an insignificant proper motion of 15+/-7 mas/yr is measured, corresponding to a corrected tangential velocity of <180 km/s at the distance of 2 kpc. This proves that the previously noted large offset of the pulsar from the apparent geometric center of the SNR is not due to high proper motion; evidently the symmetry of the remnant does not indicate its center of expansion. Calvera has a marginally significant proper motion of 69+/-26 mas/yr, corresponding to 86+/-33 km/s for a hypothetical distance of 0.3 kpc. Notably, its vector is away from the Galactic plane, although its high Galactic latitude of b = +37 deg may be more a consequence of its proximity than its velocity. We also provide updated timing solutions for each pulsar. Spanning 14.5 yr, the ephemeris of 1E 1207.4-5209 has a small and steady frequency derivative that, because of the negligible proper motion, requires no kinematic correction. The derived surface dipole magnetic field strength of 1E 1207.4-5209 thus remains B_s = 9.8e10 G. Calvera has B_s = 4.4e11 G, intermediate between those of ordinary young pulsars and CCOs, suggesting that it may be on a trajectory of field growth that could account for the absence of descendants in the neighborhood of CCOs in the P-Pdot diagram.Comment: 7 pages, 2 figures, accepted for publication in Ap

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

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 $j$ in each twisted sector $\sigma$ of the general case, verifying in particular the previously-conjectured algebra $[Q_{i}(\sigma),Q_{j}(\sigma)]_{+} =0$ 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 $\hat{c}_{j}(\sigma)=26f_{j}(\sigma)$ where $f_{j}(\sigma)$ is the length of cycle $j$.Comment: 31 page