C. Y. Hui

X-ray observations of RX J0822-4300 and Puppis-A

Based on observations with the X-ray observatories Chandra and XMM-Newton we present results from a detailed spectro-imaging and timing analysis of the central compact X-ray source RX J0822-4300 in the supernova remnant Puppis−A. The superior angular resolution of Chandra allows for the first time to pinpoint the point source nature of this object down to 0.59 ± 0.01 arcsec (FWHM) and to determine its position: RA = 08 h 21 m 57.40 s ,D ec= −43 ◦ 00 � 16.69 �� (J2000) with sub-arcsecond accuracy. Spectral fits based on Chandra and XMM-Newton data provide a tight constraint on the emission properties of RX J0822−4300. Most of its X-ray emission seems to be of thermal origin. A model spectrum consisting of two blackbody components with T1 � 2.6 × 10 6 K, T2 � 5.0 × 10 6 K and R1 � 3. 3k m,R2 � 0.75 km for the blackbody temperatures and the size of the projected emitting regions, respectively, provides the best model description of its spectrum. A search for X-ray pulsations from RX J0822−4300 revealed an interesting periodicity candidate which, if confirmed, does not support a scenario of steady spin-down.

Radio and X-ray nebulae associated with PSR J1509-5850

We have discovered a long radio trail at 843 MHz which is apparently associated with middle-age pulsar PSR J1509−5850. The radio trail has a length of ∼7 arcmin. In X-rays, Chandra observation of PSR J1509−5850 reveals an associated X-ray trail which extends in the same orientation as the radio trail. Moreover, two clumpy structures are observed along the radio trail. The larger one is proposed to be the supernova remnant (SNR) candidate MSC 319.9-0.7. Faint X-ray enhancement at the position of the SNR candidate is found in the Chandra data.

Exploring the X-ray emission properties of the supernova remnant G67.7+1.8 and its central X-ray sources

We have studied the supernova remnant G67.7+1.8 with the Chandra X-ray observatory. The remnant’s X-ray morphology correlates well with the double-arc structure seen at radio wavelength. The X-ray spectra of the northern and southern rim of G67.7+1.8 exhibit emission line features of highly ionized metals, which suggests that most of the observed X-rays originate in a thermal plasma. We find magnesium , silicon, and sulphur overabundant relative to the solar values. Gaussian emission lines at ∼4 keV and ∼7 keV are detected. The ∼4 keV line is consistent with K-emission lines from 44 Ca and/or 44 Sc whereas the ∼7 keV line feature may arise from unresolved Fe-K lines. Chandra’s sub-arcsecond angular resolution allowed us to detect four faint point sources located within ∼1.5 arcmin of the geometrical remnant center. Among these objects, CXOU195424.75+312824.9 and CXOU195429.82+312834.1 do not have optical counterparts, leaving them as candidates for a possible compact stellar remnant.

Resolving the bow-shock nebula around the old pulsar PSR B1929+10 with multi-epoch Chandra observations

We have studied the nearby old pulsar PSR B1929+10 and its surrounding interstellar medium utilizing the sub-arcsecond angular resolution of the Chandra X-ray Observatory. The Chandra data are found to be fully consistent with the results obtained from deep XMM-Newton observations as far as the pulsar is concerned. We confirm the non-thermal emission nature of the pulsar’s X-radiation. In addition to the X-ray trail already seen in previous observations by the ROSAT and XMM-Newton X-ray observatories, we discovered an arc-like nebula surrounding the pulsar. We interpret the feature as a bow-shock nebula and discuss its energetics in the context of standard shock theory.