• P. Petitjean

      Articles written in Journal of Astrophysics and Astronomy

    • Determination of the Mean HI Absorption of the Intergalactic Medium

      A. Aghaee P. Petitjean R. Srianand C. S. Stalin R. Guimarães

      More Details Abstract Fulltext PDF

      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.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.