Cosmological Simulations of Galaxy Formation With Cosmic Rays

Salem, M.; Bryan, Greg L.; Hummels, Cameron B.

doi:10.1088/2041-8205/797/2/l18

Cited by 60 publications

(35 citation statements)

References 34 publications

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“…We have performed a preliminary investigation into the impact of CRs on the formation and evolution of dwarf galaxies with rotation velocities in the 70-140 km/s range using cosmological simulations. This complements similar work (Salem, Bryan & Hummels 2014) which looked at a higher mass galaxy (with a rotation velocity above 200 km/s). As in that work, we found that the inclusion of CR feedback had a strong impact on the gas and stellar properties.…”

Section: Discussionsupporting

confidence: 84%

“…There are, of course, other parameters to vary, such as the IMF, the fraction of energy in SN, as well as other uncertainties in the subgrid model. In addition, there is some indication from H2 and the high-mass halo explored in Salem, Bryan & Hummels (2014) that an additional form of feedback is required in high-density regions -possibly radiative heating or pressure.…”

Section: Discussionmentioning

confidence: 99%

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Cosmological simulations of dwarf galaxies with cosmic ray feedback

Chen

Bryan

Salem

2016

Mon. Not. R. Astron. Soc.

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We perform zoom-in cosmological simulations of a suite of dwarf galaxies, examining the impact of cosmic-rays generated by supernovae, including the effect of diffusion. We first look at the effect of varying the uncertain cosmic ray parameters by repeatedly simulating a single galaxy. Then we fix the comic ray model and simulate five dwarf systems with virial masses range from 8 to 30 × 10 10 M . We find that including cosmic ray feedback (with diffusion) consistently leads to disk dominated systems with relatively flat rotation curves and constant star formation rates. In contrast, our purely thermal feedback case results in a hot stellar system and bursty star formation. The CR simulations very well match the observed baryonic Tully-Fisher relation, but have a lower gas fraction than in real systems. We also find that the dark matter cores of the CR feedback galaxies are cuspy, while the purely thermal feedback case results in a substantial core.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Cosmological simulations of dwarf galaxies with cosmic ray feedback

Chen

Bryan

Salem

2016

Mon. Not. R. Astron. Soc.

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“…They are accelerated through diffusive shock acceleration mostly in supernova remnants and jets of active galactic nuclei (first-order Fermi acceleration) and turbulence (second-order Fermi acceleration). Cosmic rays contribute to the pressure in the interstellar medium 209,210 , provide an important heating channel 211,212 , and potentially play a role in driving galactic gas outflows [213][214][215][216][217][218][219][220][221][222] due to their shallow equation of state (P cr ∝ ρ 4/3 cr ), their long cooling time, and their ability to transfer energy to outflows outside of star-forming discs 223 . The propagation of cosmic rays is dictated by the strength and topology of the underlying magnetic fields.…”

Section: Modeling Cosmic Magnetic Fieldsmentioning

confidence: 99%

Cosmological simulations of galaxy formation

et al. 2020

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Over the last decades, cosmological simulations of galaxy formation have been instrumental for advancing our understanding of structure and galaxy formation in the Universe. These simulations follow the nonlinear evolution of galaxies modeling a variety of physical processes over an enormous range of scales. A better understanding of the physics relevant for shaping galaxies, improved numerical methods, and increased computing power have led to simulations that can reproduce a large number of observed galaxy properties. Modern simulations model dark matter, dark energy, and ordinary matter in an expanding space-time starting from well-defined initial conditions. The modeling of ordinary matter is most challenging due to the large array of physical processes affecting this matter component. Cosmological simulations have also proven useful to study alternative cosmological models and their impact on the galaxy population. This review presents a concise overview of the methodology of cosmological simulations of galaxy formation and their different applications. arXiv:1909.07976v4 [astro-ph.GA] 23 Oct 2019 become important for cosmological studies since they can, for example, explore the impact of alternative cosmological models on the galaxy population. Cosmological simulations of galaxy formation therefore provide important insights into a wide range of problems in astrophysics and cosmology. The most important components of cosmological galaxy formation simulations are discussed in this review. A schematic overview of the different ingredients of cosmological simulations is presented in Figure 2. Cosmological FrameworkCosmological simulations of galaxy formation are performed within a cosmological model and start from specific initial conditions. Both of these ingredients are now believed to be known to high precision. Cosmological ModelVarious observations revealed that our Universe is geometrically flat and dominated by dark matter and dark energy accounting for about ∼ 95% of the energy density. Standard model particles make up for the remaining ∼ 5% and are collectively referred to as baryons. The leading model for structure formation assumes that dark matter is cold, with negligible random motions when decoupled from other matter, and collisionless, so-called cold dark matter, and dark energy is represented by a cosmological constant Λ, which drives the accelerated expansion of the Universe. This leads to the concordance ΛCDM model, which builds the framework for galaxy formation. Measurements of the cosmic microwave background combined with other observations such as the distance-redshift relation from Type Ia supernovae, abundances of galaxy clusters, and galaxy clustering constrain the fundamental parameters of the ΛCDM model 3 . Initial ConditionsInitial conditions for cosmological simulations specify the perturbations imposed on top of a homogeneous expanding background. The background model is generally taken to be a spatially flat Friedmann-Lemaître-Robertson-Walker space-time with a defined compositio...

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“…(4) CR pressure energizes the wind by means of Alfvén wave heating, which justifies the analogy of a 'CR battery' that is transported alongside and releases energy on a longer time, thereby modifying the thermal structure of such a wind. Indeed, recent hydrodynamical simulations of the formation and evolution of disk galaxies have shown that CR pressure can drive strong bipolar outflows in disk galaxies provided CRs are allowed to stream [41,42] or diffuse [43,44,45] relative to the rest frame of the gas.…”

Section: Introductionmentioning

confidence: 99%

Cosmic ray feedback in galaxies and active galactic nuclei

Pfrommer¹,

Pakmor²,

Schaal³

et al. 2017

AIP Conference Proceedings

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Recent cosmological simulations of galaxy formation have demonstrated that feedback by star formation, supernovae and active galactic nuclei appears to be critical in obtaining realistic disk galaxies, to slow down star formation to the small observed rates, to move gas and metals out of galaxies, and to balance radiative cooling of low-entropy gas at the centers of galaxy clusters. However the particular physical processes underlying these feedback processes still remain elusive. In particular, these simulations neglected cosmic rays (CRs) and magnetic fields, which provide a comparable pressure support in comparison to turbulence in our Galaxy, and are known to couple dynamically and thermally to the gas. We will present our recent efforts to model CR physics in the cosmological simulation code arepo and demonstrate that CRs matter on all scales relevant for galaxy formation. Presenting global simulations of galaxy formation that couple CRs to the magneto-hydrodynamics, we show how CRs can launch powerful galactic winds, which reduces the available amount of gas for star formation. In particular, we highlight the importance of the γ-ray window in understanding the properties of galactic winds and discuss the non-thermal radio and γ-ray emission of Milky-Way like galaxies with bubble-shaped outflows. On scales of galaxy clusters, we show that cosmic-ray heating can balance radiative cooling of the low-entropy gas at the centers of galaxy clusters and helps in mitigating the star formation of the brightest cluster galaxies. Combining low-frequency radio and γ-ray emission of M87, the closest active galaxy interacting with the cooling cluster plasma, enable us to put forward a comprehensive, physics-based model of feedback by active galactic nuclei.

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Cosmological Simulations of Galaxy Formation With Cosmic Rays

Cited by 60 publications

References 34 publications

Cosmological simulations of dwarf galaxies with cosmic ray feedback

Cosmological simulations of dwarf galaxies with cosmic ray feedback

Cosmological simulations of galaxy formation

Cosmic ray feedback in galaxies and active galactic nuclei

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