Star-forming filaments in warm dark matter models

Gao, L.; Theuns, T.; Springel, V.

Abstract

We performed a hydrodynamical cosmological simulation of the formation of a Milky Way-like galaxy in a warm dark matter (WDM) cosmology. Smooth and dense filaments, several comoving mega parsec long, form generically above z ∼ 2 in this model. Atomic line cooling allows gas in the centres of these filaments to cool to the base of the cooling function, resulting in a very striking pattern of extended Lyman-limit systems (LLSs). Observations of the correlation function of LLSs might hence provide useful limits on the nature of the dark matter. We argue that the self-shielding of filaments may lead to a thermal instability resulting in star formation. We implement a sub-grid model for this, and find that filaments rather than haloes dominate star formation until z ∼ 6, although this depends on how stars form in WDM. Reionization decreases the gas density in filaments, and the more usual star formation in haloes dominates below z ∼ 6, although star formation in filaments continues until z = 2. 15 per cent of the stars of the z = 0 galaxy formed in filaments. At higher redshift, these stars give galaxies a stringy appearance, which, if observed, might be a strong indication that the dark matter is warm.

Citation

Gao, L., Theuns, T., & Springel, V. (2015). Star-forming filaments in warm dark matter models. Monthly Notices of the Royal Astronomical Society, 450(1), 45-52. https://doi.org/10.1093/mnras/stv643

• Journal Article Type: Article
• Acceptance Date: Mar 24, 2015
• Publication Date: Jun 11, 2015
• Deposit Date: Feb 10, 2016
• Publicly Available Date: Feb 18, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 450
• Issue: 1
• Pages: 45-52
• DOI: https://doi.org/10.1093/mnras/stv643
• Keywords: Galaxies: formation, Intergalactic medium, Dark matter.
• Public URL: https://durham-repository.worktribe.com/output/1392043