TheChandra X‐Ray ObservatoryResolves the X‐Ray Morphology and Spectra of a Jet in PKS 0637−752

Abstract

The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a variety of detector configurations contribute to a total exposure time with the Chandra Advanced CCD Imaging Spectrometer (ACIS; Garmire et al. 2000, in preparation) of about 100 ks. A spatial analysis of all the available X-ray data, making use of Chandra's spatial resolving power of about 0.4 arcsec, reveals a jet that extends about 10 arcsec to the west of the nucleus. At least four X-ray knots are resolved along the jet, which contains about 5% of the overall X-ray luminosity of the source. Previous observations of PKS 0637-752 in the radio band (Tingay et al. 1998) had identified a kpc-scale radio jet extending to the West of the quasar. The X-ray and radio jets are similar in shape, intensity distribution, and angular structure out to about 9 arcsec, after which the X-ray brightness decreases more rapidly and the radio jet turns abruptly to the north. The X-ray luminosity of the total source is log L X ≈ 45.8 erg s −1 (2 − 10 keV), a and appears not to have changed since it was observed with ASCA in November 1996. We present the results of fitting a variety of emission models to the observed spectral distribution, comment on the non-existence of emission lines recently reported in the ASCA observations of PKS 0637-752, and briefly discuss plausible X-ray emission mechanisms. a We use H0 = 50 km s −1 Mpc −1 and q0 = 0 throughout

AChandraObservation of the Circinus Galaxy

“…8), the most prominent being those at (consistent with Si 1.775~0 .025 0.025 VIIÈX Ka) and keV (consistent with Fe IIÈXX Ka). 6.37~0 .06 0.10 The line at 1.78 keV is close in energy to the Si Ka Ñuores-cence line in the background of the S3 chip (see Table 3 of Chartas et al 2000). Thus, we consider whether this line might be an artifact left over from the background subtraction or modeling.…”

“…The total efficiency curve of the back-illuminated S3 chip contains structures at the Al K edge (1.55È1.56 keV) and the M edge of iridium (D2 keV), which arise from X-ray absorption in the optical blocking Ðlter and mirror surfaces, respectively (Chartas et al 2000). Thus, the lack of line emission in the ACIS spectrum at 1.471 and 2.006 keV may be due to inac- NOTE.ÈTable 2 is also available in machine-readable form in the electronic edition of the Astrophysical Journal.…”

X‐Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 withChandra

“…To investigate further the effects of pile-up on our results, the nuclear spectrum was also fitted with the simulatorbased fitting tool LYNX (Chartas et al 2000). LYNX utilizes XSPEC (Arnaud 1996) to generate the incident spectrum, the PSF simulator MARX (Wise, Huenemoerder, & Davis 1997) to simulate the mirror response, and the Penn State ACIS simulator (Townsley et al 2002a) to propagate X-rays through the detector.…”

A survey of X-ray emission from 100 kpc radio jets

“…From that parent population we selected objects for which either we predicted an X-ray detection in a 5 ks observation, or which had a one-sided linear radio morphology. Those two selection criteria were motivated by the serendipitous Chandra observation of PKS 0637-752 (Schwartz et al (2000), Chartas et al (2000)), scaling the predictions of X-ray flux from the X-ray to radio jet ratio for that object, and considering that one-sided linear morphology might indicate bulk relativistic motion. Such a relativistically beamed jet was the basis of the interpretations of the PKS 0637 X-ray emission as inverse Compton Figure 1.…”