* Astronomy

Blobrana · L

RE: Quasar 3C 186

Blobrana · L

Title: X-ray Cluster Associated with the z=1.063 CSS Quasar 3C 186: The Jet is NOT Frustrated
Authors: Aneta Siemiginowska (1), C.C. Cheung (2,3), Stephanie LaMassa (1), D.J. Burke (1), Thomas L. Aldcroft (1), Jill Bechtold (4), Martin Elvis (1), D.M. Worrall (5); ((1) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (2) MIT Kavli Institute for Astrophysics & SpaceResearch, Cambridge, MA (3) Jansky Postdoctoral Fellow; National Radio Astronomy Observatory; (4) Steward Observatory, University of Arizona, Tucson, AZ; (5) Department of Physics, University of Bristol, Bristol, UK.)

We report the Chandra discovery of an X-ray cluster at redshift z = 1.063 associated with the Compact Steep Spectrum radio loud quasar 3C 186 (Q0740+380). Diffuse X-ray emission is detected out to ~120 kpc from the quasar and contains 741±40 net counts. The X-ray spectrum of the extended emission shows strong Fe-line emission (EW=412eV) at the quasar redshift and confirms the thermal nature of this diffuse component. We measure a cluster temperature of 5.2(+1.2/-0.9) keV and an X-ray luminosity L(0.5-2 keV) ~ 6e44 erg/sec, which are in agreement with the luminosity-temperature relation for high-redshift clusters. This is the first detection of a bright X-ray cluster around a luminous (L_bol ~1e47 erg/sec) CSS quasar at high redshift and only the fifth z>1 X-ray cluster detected. We find that the CSS radio source is highly overpressured with respect to the thermal cluster medium by about 3 orders of magnitude. This provides direct observational evidence that the radio source is not thermally confined as posited in the "frustrated'' scenario for CSS sources. Instead, it appears that the radio source may be young and we are observing it at an early stage of its evolution. In that case the radio source could supply the energy into the cluster and potentially prevent its cooling.

Read more (514kb, PDF)

Blobrana · L

NASA's Chandra X-ray Observatory has observed an unusual galaxy cluster that contains a bright core of relatively cool gas surrounding a quasar called 3C 186. This is the most distant such object yet observed, and could provide insight into the triggering of quasars and the growth of galaxy clusters.
This composite image of the cluster surrounding 3C 186 includes a new, deep image from Chandra (blue) showing emission from gas surrounding the point-like quasar near the center of the cluster. Chandra X-ray spectra show that the temperature of the gas drops from 80 million degrees on the outskirts of the cluster down to 30 million in the core. This drop in temperature occurs because intense X-ray emission from the gas cools it. Optical data from the Gemini telescope in yellow show the stars and galaxies in the field of view.
Read more