Efficient cold outflows driven by cosmic rays in high-redshift galaxies and their global effects on the IGM

2017/06/30 by Saumyadip Samui, Kandaswamy Subramanian, Raghunathan Srianand +1 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #COSMIC cancer database #Cosmic ray #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Galaxy #Intergalactic travel #Physics #Redshift #Supernova #astro-ph.CO #astro-ph.GA

paper · pdf · doi:10.1093/mnras/sty287

16 Pages, 9 figures, Revised version, Accepted for publication in MNRAS

arxiv created 2018/01/31 · openalex publication_date 2018/02/02 · arxiv updated 2018/02/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We present semi-analytical models of galactic outflows in high-redshift galaxies driven by both hot thermal gas and non-thermal cosmic rays. Thermal pressure alone may not sustain a large-scale outflow in low-mass galaxies (i.e. M ∼ 108 M⊙), in the presence of supernovae feedback with large mass loading. We show that inclusion of cosmic ray pressure allows outflow solutions even in these galaxies. In massive galaxies for the same energy efficiency, cosmic ray-driven winds can propagate to larger distances compared to pure thermally driven winds. On an average gas in the cosmic ray-driven winds has a lower temperature which could aid detecting it through absorption lines in the spectra of background sources. Using our constrained semi-analytical models of galaxy formation (that explains the observed ultraviolet luminosity functions of galaxies), we study the influence of cosmic ray-driven winds on the properties of the intergalactic medium (IGM) at different redshifts. In particular, we study the volume filling factor, average metallicity, cosmic ray and magnetic field energy densities for models invoking atomic cooled and molecular cooled haloes. We show that the cosmic rays in the IGM could have enough energy that can be transferred to the thermal gas in presence of magnetic fields to influence the thermal history of the IGM. The significant volume filling and resulting strength of IGM magnetic fields can also account for recent γ-ray observations of blazars.

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• Hadronic Interactions of Energetic Charged Particles in Protogalactic Outflow Environments and Implications for the Early Evolution of Galaxies