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The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite

Sijacki, Debora; Puchwein, Ewald; Haehnelt, Martin G.; Nasir, Fahad; Bolton, James S.; Viel, Matteo; Kim, Tae-Sun

The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite Thumbnail


Debora Sijacki

Ewald Puchwein

Martin G. Haehnelt

Fahad Nasir

Matteo Viel

Tae-Sun Kim


We study the effect of different feedback prescriptions on the properties of the low redshift (z ≤ 1.6) Ly α forest using a selection of hydrodynamical simulations drawn from the Sherwood simulation suite. The simulations incorporate stellar feedback, AGN feedback and a simplified scheme for efficiently modelling the low column density Lyα forest. We confirm a discrepancy remains between Cosmic Origins Spectrograph (COS) observations of the Lyα forest column density distribution function (CDDF) at z ≃ 0.1 for high column density systems (NHI > 1014 cm−2), as well as Lyα velocity widths that are too narrow compared to the COS data. Stellar or AGN feedback – as currently implemented in our simulations – have only a small effect on the CDDF and velocity width distribution. We conclude that resolving the discrepancy between the COS data and simulations requires an increase in the temperature of overdense gas with Δ = 4–40, either through additional HeII photo-heating at z > 2 or fine-tuned feedback that ejects overdense gas into the IGM at just the right temperature for it to still contribute significantly to the Lyα forest. Alternatively a larger, currently unresolved turbulent component to the line width could resolve the discrepancy.

Journal Article Type Article
Acceptance Date Jun 27, 2017
Online Publication Date Jun 30, 2017
Publication Date Oct 11, 2017
Deposit Date Jul 11, 2017
Publicly Available Date Jul 11, 2017
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 471
Issue 1
Pages 1056-1069
Keywords Numerical methods, Intergalatic medium, Quasars, Absorption lines
Public URL
Publisher URL
Additional Information This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


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