An X-Ray Jet from a White Dwarf - Detection of the Collimated Outflow from CH Cygni with Chandra

Most symbiotic stars consist of a white dwarf accreting material from the wind of a red giant. An increasing number of these objects have been found to produce jets. Analysis of archival Chandra data of the symbiotic system CH Cygni reveals faint extended emission to the south, aligned with the optical and radio jets seen in earlier HST and VLA observations. CH Cygni thus contains only the second known white dwarf with an X-ray jet, after R Aquarii. The X-rays from symbiotic-star jets appear to be produced when jet material is shock-heated following collision with surrounding gas, as with the outflows from some protostellar objects and bipolar planetary nebulae.Comment: 4 & a bit pages, 4 figures, accepted by ApJL; uses emulateapj.cls and revtex4. Minor changes following referees report, & shortened to meet page limi

The Highest Resolution Chandra View of Photoionization and Jet-Cloud Interaction in the Nuclear Region of NGC 4151

We report high resolution imaging of the nucleus of the Seyfert 1 galaxy NGC 4151 obtained with a 50 ks Chandra HRC observation. The HRC image resolves the emission on spatial scales of 0.5", ~30 pc, showing an extended X-ray morphology overall consistent with the narrow line region (NLR) seen in optical line emission. Removal of the bright point-like nuclear source and image deconvolution techniques both reveal X-ray enhancements that closely match the substructures seen in the Hubble Space Telescope [OIII] image and prominent knots in the radio jet. We find that most of the NLR clouds in NGC 4151 have [OIII] to soft X-ray ratio ~10, despite the distance of the clouds from the nucleus. This ratio is consistent with the values observed in NLRs of some Seyfert 2 galaxies, which indicates a uniform ionization parameter even at large radii and a density decreasing as $r^{-2}$ as expected for a nuclear wind scenario. The [OIII]/X-ray ratios at the location of radio knots show an excess of X-ray emission, suggesting shock heating in addition to photoionization. We examine various mechanisms for the X-ray emission and find that, in contrast to jet-related X-ray emission in more powerful AGN, the observed jet parameters in NGC 4151 are inconsistent with synchrotron emission, synchrotron self-Compton, inverse Compton of CMB photons or galaxy optical light. Instead, our results favor thermal emission from the interaction between radio outflow and NLR gas clouds as the origin for the X-ray emission associated with the jet. This supports previous claims that frequent jet-ISM interaction may explain why jets in Seyfert galaxies appear small, slow, and thermally dominated, distinct from those kpc scale jets in the radio galaxies.Comment: Accepted for publication in ApJ. 28 pages, 9 figures, 3 table