We present results from the archival Chandra observations of the 0.3 s X-ray pulsar PSR J1846Ϫ0258 associated with the supernova remnant (SNR) Kes 75. The pulsar has the highest spin-down luminosity ( p 8.3 # 10 36 E ergs s ) among all the high magnetic field pulsars (HBPs) and has been classified as a Crab-like pulsar despite Ϫ1 its magnetic field (5 # 10 13 G) being above the quantum critical field. It is the only HBP described by a nonthermal Crab-like spectrum, powering a bright pulsar wind nebula (PWN). Our spectroscopic study shows evidence of spectral softening (photon index G p 1.32 to 1.97 ) and temporal brightening [unabsorbed ϩ0.08 ϩ0.05 Ϫ0.09 Ϫ0.07 flux F unabs p (4.3 ‫ע‬ 0.2) # 10 to # 10 ergs cm s ] of the pulsar by ∼6 times from 2000 to Ϫ12 ϩ0.1 Ϫ11 Ϫ2 Ϫ1 2.7 Ϫ0.2 2006. The 0.5-10 keV luminosity of the pulsar at the revised distance of 6 kpc has also increased from L X p (1.85 ‫ע‬ 0.08) # 10 34 to 1.16 # 10 35 ergs s , and the X-ray efficiency increased from 0.2% ‫ע‬ 0.01 to ϩ0.03 Ϫ1 % Ϫ0.07 1.4 . The observed X-ray brightening and softening of the pulsar suggests for the first time that this HBP ϩ0.04 % Ϫ0.08is revealing itself as a magnetar.

We present a Chandra and XMM-Newton study of the supernova remnant (SNR) Kes 73 hosting the anomalous X-ray pulsar 1E 1841−045. The Chandra image reveals clumpy structures across the remnant with enhanced emission along the western rim. The X-ray emission fills the radio shell and spatially correlates with the infrared image. The global X-ray spectrum is described by a twocomponent thermal model with a column density N H = 2.6 +0.4 −0.3 ×10 22 cm −2 and a total luminosity of L X = 3.3 +0.7 −0.5 ×10 37 ergs s −1 (0.5-10 keV, at an assumed distance of 8.5 kpc). The soft component is characterized by a temperature kT s = 0.5 +0.1 −0.2 keV, a high ionization timescale, and enhanced Si and S abundances suggesting emission that is dominated by shocked ejecta. The hard component has a temperature kT h = 1.6 +0.8 −0.7 keV, a relatively low ionization timescale, and mostly solar abundances suggesting emission that is dominated by interstellar/circumstellar shocked material. A spatially resolved spectroscopy study reveals no significant variations in the spectral properties. We infer an SNR age ranging between 750 yr and 2100 yr, an explosion energy of 3.0 +2.8 −1.8 ×10 50 ergs and a shock velocity of (1.2 ± 0.3)×10 3 km s −1 (under the Sedov phase assumption). We also discuss the possible scenario for Kes 73 expanding into the late red supergiant wind phase of its massive progenitor. Comparing the inferred metal abundances to core-collapse nucleosynthesis model yields, we estimate a progenitor mass 20 M ⊙ , adding a candidate to the growing list of highly magnetized neutron stars proposed to be associated with very massive progenitors.

We present results on the Soft Gamma Repeater (SGR) 0501+4516, discovered by the Swift Burst Alert Telescope (BAT) on 2008 August 22. More than 50 bursts were identified from this source, out of which 18 bursts had enough counts to carry out spectral analysis. We performed time-averaged spectral analysis on these 18 bursts using 8 models, among which the cut-off powerlaw and the twoblackbody models provided the best fit in the 15-150 keV energy range. The cut-off powerlaw model fit yields a mean photon index Γ CP L = 0.54±0.11 and a cut-off energy E C = 19.1±1.8 keV for the bursts. The mean hard and soft blackbody temperatures are found to be kT BB h = 12.8±0.7 keV and kT BBs = 4.6±0.5 keV, respectively, and are anti-correlated with the square of the radii of the hard and soft emitting regions (R BB h and R BBs ) as R 2 BB h ∝ kT −5.8 and R 2 BBs ∝ kT −2.7 , respectively. The soft and hard component temperatures with different indices support the idea of two distinct emitting regions with the hard component corresponding to a smaller radius and the soft component corresponding to a larger radius, which further corroborate the idea of the propagation of extraordinary (E) and ordinary (O) mode photons across the photosphere, as predicted in the magnetar model. We notice strong burst fluence-duration correlation as well as hardness ratio-duration and hardness ratio-fluence anticorrelations for the SGR 0501+4516 bursts. The burst fluences range from ∼ 4.4×10 −9 ergs cm −2 to ∼ 2.7×10 −6 ergs cm −2 , consistent with those observed for typical short SGR bursts.

We present the first detailed imaging and spatially resolved spectroscopic study of the Galactic supernova remnant (SNR) G292.2-0.5, associated with the high-magnetic field radio pulsar (PSR) J1119-6127, using Chandra and XMM-Newton. The high-resolution X-ray images reveal a partially limbbrightened morphology in the west, with diffuse emission concentrated towards the interior of the remnant unlike the complete shell-like morphology observed at radio wavelengths. The spectra of most of the diffuse emission regions within the remnant are best described by a two-component thermal+nonthermal model. The thermal component is described by a plane-parallel, non-equilibrium ionization plasma model with a temperature kT ranging from 1.3 +0.3 −0.2 keV in the western side of the remnant to 2.3 +2.9 −0.5 keV in the east, a column density increasing from 1.0 +0.1 −0.6 ×10 22 cm −2 in the west to 1.8 +0.2 −0.4 ×10 22 cm −2 in the east, and a low ionization timescale ranging from (5.7 +0.8 −0.7 )×10 9 cm −3 s in the SNR interior to (3.6 +0.7 −0.6 )×10 10 cm −3 s in the western side -suggestive of expansion of a young remnant in a low-density medium. The spatial and spectral differences across the SNR are consistent with the presence of a dark cloud in the eastern part of the SNR, absorbing the soft X-ray emission, as also revealed by the optical image of that region. The spectra from some of the regions also show slightly enhanced metal abundances from Ne, Mg and Si, hinting at the first evidence for ejecta heated by the reverse shock. Comparing our inferred metal abundances to core-collapse nucleosynthesis models yields, we estimate a high progenitor mass of ∼30M ⊙ suggesting a type Ib/c supernova. We confirm the presence of non-thermal X-ray emission from regions close to the pulsar, with the emission characterized by a power-law model with a hard photon index similar to that seen in the compact pulsar wind nebula. We estimate an SNR age range between 4.2 kyr (free expansion phase) and 7.1 kyr (Sedov phase) at an assumed distance of 8.4 kpc, a factor of a few higher than the measured pulsar's age upper limit of 1.9 kyr.

PSR J1119À6127 is a high magnetic field (B ¼ 4:1 ; 10 13 G), young ( 1700 year old), and slow (P ¼ 408 ms) radio pulsar associated with the supernova remnant (SNR) G292.2À0.5. In 2003, Chandra allowed the detection of the X-ray counterpart of the radio pulsar and provided the first evidence for a compact and faint pulsar wind nebula ( PWN). We here present new Chandra observations that allowed for the first time an imaging and spectroscopic study of the pulsar and PWN independently of each other. The PWN is only evident in the hard band (above $2 keV) and consists of jetlike structures extending at least 7 00 from the pulsar, with the southern ''jet'' being longer than the northern ''jet.'' The spectrum of the PWN is described by a power law with a photon index À $ 1:1 for the compact PWN and $1.4 for the southern long jet (at a column density N H ¼ 1:8 ; 10 22 cm À2 ), and a total luminosity L X (0:5Y7:0 keV ) $ 4 ; 10 32 ergs s À1 , at a distance of 8.4 kpc. We rule out a single blackbody model for the pulsar and present the first evidence of nonthermal emission that dominates above $3 keV. A two-component model consisting of a power-law component (with photon index À $ 1:5Y2:0) plus a thermal component provides the best fit. The thermal component can be fit by either a blackbody model with a temperature kT $ 0:21 keV, or a neutron star atmospheric model with a temperature kT $ 0:14 keV. The efficiency of the pulsar in converting its rotational power,Ė, into nonthermal X-ray emission from the pulsar and PWN is %5 ; 10 À4 , comparable to other rotation-powered pulsars with a similarĖ. We discuss our results in the context of the X-ray manifestation of high magnetic field radio pulsars in comparison with rotation-powered pulsars and magnetars. Subject headingg s: ISM: individual (G292.2À0.5) -pulsars: individual ( PSR J1119À6127) -supernova remnants -X-rays: ISM