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Physical conditions in broad and associated narrow absorption-line systems toward APM 08279+5255

Srianand, R ; Petitjean, P

Astronomy and astrophysics (Berlin), 2000, Vol.357, p.414-428 [Periódico revisado por pares]

EDP Sciences

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  • Título:
    Physical conditions in broad and associated narrow absorption-line systems toward APM 08279+5255
  • Autor: Srianand, R ; Petitjean, P
  • Assuntos: Physics - Astrophysics of Galaxies ; Physics - Cosmology and Nongalactic Astrophysics ; Physics - Earth and Planetary Astrophysics ; Physics - High Energy Astrophysical Phenomena ; Physics - Instrumentation and Methods for Astrophysics ; Physics - Solar and Stellar Astrophysics ; Sciences of the Universe
  • É parte de: Astronomy and astrophysics (Berlin), 2000, Vol.357, p.414-428
  • Descrição: Results of a careful analysis of the absorption systems with zabs = zem seen toward the bright, z_em ~ 3.91, gravitationally lensed quasar APM 08279+5255 are presented. Two of the narrow-line systems, at z_abs = 3.8931 and z_abs = 3.9135, show absorptions from singly ionized species with weak or no NV and O V absorptions at the same redshift. Absorption due to fine structure transitions of C II and Si II (excitation energies corresponding to, respectively, 156$\mu$m and 34$\mu$m) are detected at z_abs = 3.8931. Excitation by IR radiation is favored as the column density ratios are consistent with the shape of APM 08279+5255 IR spectrum. The low-ionization state of the system favors a picture where the cloud is closer to the IR source than to the UV source, supporting the idea that the extension of the IR source is larger than ~ 200 pc. The absence of fine structure lines at z_abs = 3.9135 suggests that the gas responsible for this system is farther away from the IR source. Abundances are ~ 0.01 and 1$Z_{\odot}$ at z_abs = 3.913 and 3.8931 and aluminum could be over-abundant with respect to silicon and carbon by at least a factor of two and five. All this suggests that whereas the \zabs = 3.8931 system is probably located within 200 pc from the QSO and ejected at a velocity larger than 1000 kms^{-1}, the \zabs = 3.9135 system is farther away and part of the host-galaxy. (abridged)
  • Editor: EDP Sciences
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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