Partial covering of the emission regions of Q 0528-250 by intervening H<SUB>2</SUB> clouds - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2015

Partial covering of the emission regions of Q 0528-250 by intervening H2 clouds

V. V. Klimenko
  • Function : Author
S. A. Balashev
  • Function : Author
A. V. Ivanchik
  • Function : Author
C. Ledoux
  • Function : Author
P. Noterdaeme
R. Srianand
D. A. Varshalovich
  • Function : Author

Abstract

We present an analysis of the molecular hydrogen absorption system at zabs = 2.811 in the spectrum of the blazar Q 0528-250. We demonstrate that the molecular cloud does not cover the background source completely. The partial coverage reveals itself as a residual flux at the bottom of the saturated H2 absorption lines. This amounts to about (2.22 ± 0.54) per cent of the continuum and does not depend on the wavelength. This value is small and it explains why this effect has not been detected in previous studies of this quasar spectrum. However, it is robustly detected and is significantly higher than the zero-flux level at the bottom of the saturated lines of the Lyα forest, (-0.21 ± 0.22) per cent. The presence of the residual flux could be caused by unresolved quasar multicomponents, by light scattered by dust and/or by jet-cloud interaction. The H2 absorption system is very well described by a two-component model without the inclusion of additional components when we take partial coverage into account. The derived total column densities in the H2 absorption components A and B are log N(H2)(cm-2) = 18.10 ± 0.02 and 17.82 ± 0.02, respectively. HD molecules are present only in component B. Given the column density, log N(HD) = 13.33 ± 0.02, we find N(HD)/2N(H2) = (1.48 ± 0.10) × 10- 5, significantly lower than previous estimations. We argue that it is crucial to take into account the partial coverage effects in any analysis of H2 bearing absorption systems, in particular when studying the physical state of the high-redshift interstellar medium.
Fichier principal
Vignette du fichier
stu2672.pdf (3.57 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03644738 , version 1 (25-04-2022)

Identifiers

Cite

V. V. Klimenko, S. A. Balashev, A. V. Ivanchik, C. Ledoux, P. Noterdaeme, et al.. Partial covering of the emission regions of Q 0528-250 by intervening H2 clouds. Monthly Notices of the Royal Astronomical Society, 2015, 448, pp.280-298. ⟨10.1093/mnras/stu2672⟩. ⟨insu-03644738⟩
4 View
20 Download

Altmetric

Share

Gmail Facebook X LinkedIn More