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Spatially resolved optical images of high-redshift quasi-stellar objects

1991; IOP Publishing; Volume: 370; Linguagem: Inglês

10.1086/169794

1538-4357

Timothy M. Heckman, G. K. Miley, M. D. Lehnert, Wil van Breugel,

Stellar, planetary, and galactic studies

view Abstract Citations (154) References (72) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spatially Resolved Optical Images of High-Redshift Quasi-stellar Objects Heckman, Timothy M. ; Lehnert, Matthew D. ; van Breugel, Wil ; Miley, George K. Abstract We present and discuss the results of a program of deep optical imaging of 19 high-redshift (z >= 2) radio-loud QSOs. These data represent the first large body of nonradio detections of spatially resolved structure surrounding high-redshift QSOs. In 15 of 18 cases, the Lyα emission is spatially resolved, with a typical size of 100 kpc (for H_0_ = 75 km s^-1^ Mpc^-1^; q_0_ = 0). The luminosity of the resolved Lyα is ~10^44^ ergs s^-1^ (10% of the total Lyα luminosity). The nebulae are usually asymmetric and/or elongated with a morphological axis that aligns with the radio source axis to better than ~ 30^deg^. These properties are quite similar to those of the Lyα nebulae associated with high-z radio galaxies. The brighter side of the nebula is generally on the same side as the brighter radio emission and/or one-sided, jetlike radio structure. There is no strong correlation between the Lyα isophotal and radio sizes (the Lyα nebulae range from several times larger than the radio source to several times smaller). None of the properties of the nebulae correlate with the presence or strength of C IV "associated" absorption (z_abs_ ~ z_em_). It is likely that the nebulae are the interstellar or circumgalactic medium of young or even protogalaxies being photoionized by QSO radiation that escapes anisotropically along the radio axis. Photoionization equilibrium arguments imply that the Lyα emission arises in small (parsec-scale) dense (10^2^-10^3^ cm^-3^) clouds. If the clouds are not confined, their short lifetime to photoevaporation requires a total reservoir of a few times 10^11^ M_sun_ in dense gas. If the clouds are confined by a hot, diffuse intercloud medium at the Compton or Virial temperature (~ 10^7^ K), the mass of this ICM is ~ 10^12^ M_sun_. Cloud confinement by a "cocoon" inflated by the radio source or by a thermal QSO wind also entail a substantial total gas mass (>10^11^ M_sun_). The interaction of the radio jet with the ambient gaseous medium may enhance the (radio) visibility of the jet plasma, and lead directly to the small sizes and distorted and asymmetric structures of the radio sources. Indeed, the gas pressures inferred for the Lyα nebulae are far larger than those inferred around low-z radio galaxies and radio-loud QSOs. For at least six and probaly 10 of the QSOs, the UV continuum is also spatially resolved, with diameters of 40-80 kpc. The spatially resolved material is typically ~ 10% as bright as the QSO, with an average UV luminosity (λPlambda_ at ~ 1200 A) of ~ 2 x 10^45^ ergs s^-1^ (comparable to the UV luminosities of high-z radio galaxies). The morphological axes of the spatially extended continuum structures do not generally align with either the radio of Lyα morphological axes (contrary to the properties of high-z radio galaxies). This UV "fuzz" may be starlight from the QSO host galaxy, scattered QSO light, or even a foreground galaxy acting as a gravitational lens. By analogy to high-z radio galaxies, the first possibility is most likely, implying typical star-formation rates of several hundred M_sun_ per year. If sustained for a galaxy dynamcial time (several times 10^8^ yr) this would result in the formation of a galaxy's worth of stars. High-redshift radio-loud QSOs may be associated with the formation of some galaxies. Finally, we note that several QSOs have possible close (within 100 kpc of the QSO) companion galaxies with Lyα emission. These require spectroscopic confirmation. Publication: The Astrophysical Journal Pub Date: March 1991 DOI: 10.1086/169794 Bibcode: 1991ApJ...370...78H Keywords: Active Galactic Nuclei; Image Analysis; Interstellar Matter; Quasars; Red Shift; Spatial Resolution; Absorption Spectra; Astronomical Spectroscopy; Lyman Alpha Radiation; Nebulae; Radio Galaxies; Astrophysics; GALAXIES: INTERSTELLAR MATTER; QUASARS full text sources ADS | data products SIMBAD (19) NED (19)