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Register a new userOutflowing material in the CSS quasar 3C48: evidence of jet-cloud interaction?
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Authors
Neeraj Gupta NCRA-TIFR
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We report the detection of a zabs=0.3654 associated absorption-line system in the UV spectrum of the CSS quasar 3C48. The absorbing material is blue shifted with respect to the quasar emission-line redshift, zem=0.3700, suggesting an outflow velocity of ~1000 km/s. We detect absorption lines over a range of ionization states from Ly-beta, Ly-gamma, CIV, NIV, SVI to OVI and possibly OIV and NeVIII. The kinematical properties of the absorption-line system are similar to the blue-shifted emission line gas seen in [OIII]lambda5007 (Chatzichristou, Vanderriest & Jaffe 1999), which is believed to have interacted with the radio jet. We study the properties of the absorbing material using CLOUDY and find that photoionization models with Solar abundance ratios (with overall metallicity in the range 0.1<Z/Z$_odot$<1.3) are enough to explain the observed column densities of all the species except NeVIII, detection of which requires confirmation. Since the cooling and recombination time for the gas is ~10^5 yr, the consistency with the photoionization models suggests that any possible interaction of absorbing material with the jet must have taken place before ~10^5 yr. The abundance ratio of nitrogen to carbon is close to Solar values, unlike in the case of most quasars, especially at high-redshifts, which have super-Solar values. We observed 3C48 with the Giant Metrewave Radio Telescope (GMRT) to search for redshifted 21cm HI absorption. However, we did not detect any significant feature in our spectra and estimate the 3-sigma upper limit to the optical depth to be in the range 0.001 to 0.003. However, due to the diffuse nature of the radio source, optical depths as high as 0.1 towards individual knots or compact components cannot be ruled out.
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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.
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