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Title: Determination of the mean HI absorption of the intergalactic medium
Authors: Aghaee, A
Petitjean, P
Srianand, R
Stalin, C. S
Guimaraes, R
Keywords: Quasar: Absorption Lines;Galaxies: Intergalactic Medium
Issue Date: Jun-2010
Publisher: Indian Academy of Sciences
Citation: Journal of Astrophysics and Astronomy, Vol. 31, No.2, pp. 59 - 79
Abstract: In recent years, the Lyman-α forest in quasar spectra has been used, together with N-body simulations, to determine the underlying matter distribution in the intergalactic medium (IGM). One of the key parameters to be known in order to compare observations and numerical simulations is the mean HI absorption in the IGM. To derive the latter, one has first to fit the quasar continuum.We have observed 20 high redshift and highly luminous QSOs (mV ≤ 17.5 and 2.40 ≤ zem ≤ 3.91) at intermediate spectral resolution, with either EMMI (ESO Multi-Mode Instrument) on the ESO-NTT telescope or CARELEC at the OHP (Observatoire de Haute-Provence), and applied different methods of determining the QSO continuum to this QSO sample. We have measured the amount of absorption, known as the flux decrement, DA, in the Lyman-α forest for these different methods and compared the results. In addition, we have compared DA values measured along the same lines of sight observed at high and intermediate spectral resolutions.We discuss the systematics resulting from the use of automatic continuum fitting methods.
Description: Open Access
ISSN: 0250-6335 (Print)
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Appears in Collections:IIAP Publications

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