English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

ABSTRACT  We revisit the proximity effect produced by quasars (QSOs) at redshifts 2.1–3.3 applying the From Lines to Overdensities (FLO) approach to a sample of ∼6300 Lyα lines fitted in 21 high resolution, high signal‐to‐noise spectra. This new technique allows to recover the hydrogen‐density field from the H  i  column densities of the lines in the Lyα forest, on the basis of simple assumptions on the physical state of the gas. To minimize the systematic uncertainties that could affect the density recovering in the QSO vicinity, we carefully determined the redshifts of the QSOs in our sample and modelled in detail their spectra to compute the corresponding ionizing fluxes. The mean density field obtained from the observed spectra shows a significant overdensity in the region within 4 proper Mpc from the QSO position, confirming that QSOs are hosted in high‐density peaks. The absolute value of ρ/〈ρ〉 for the peak is uncertain by a factor of ∼3, depending on the assumed QSO spectral slope and the minimum H  i  column density detectable in the spectra. We do not confirm the presence of a significant overdensity extending to separations of ∼15 proper Mpc from the QSO, claimed in previous works at redshifts 〈 z 〉≃ 2.5 and 3.8. Our best guess for the ultraviolet background (UVB) ionization rate based on the intergalactic medium (IGM) mean density recovered by FLO is  Γ UVB ≃ 10 −12  s −1  . However, values of  Γ UVB ≃ 3 × 10 −12  s −1   could be viable if an inverted temperature–density relation with index α≃−0.5 is adopted.

The quasar proximity effect at redshift 〈 z 〉≃ 2.6 with the From Lines to Overdensities approach ★