Cosmic ray feedback in hydrodynamical simulations of galaxy formation

By M. Jubelgas, Volker Springel, Torsten A. Ensslin, Christoph Pfrommer Mpa, Cita. 2006

161 citations recorded by the source corpus.

It is well known that cosmic rays contribute significantly to the pressure of the interstellar medium in our own Galaxy, suggesting that they may play an important role in regulating star formation during the formation and evolution of galaxies. We here discuss a novel numerical treatment of the physics of cosmic rays and its implementation in the parallel smoothed particle hydrodynamics code GADGET-2. In our methodology, the non-thermal cosmic ray population of each gaseous fluid element is approximated by a simple power law spectrum in particle momentum, characterized by an amplitude, a cut-off, and a fixed slope. Adiabatic compression and a number of physical source and sink terms are modelled which modify the cosmic ray pressure of each particle. The most important sources considered are injection by supernovae and diffusive shock acceleration, while the primary sinks are thermalization by Coulomb interactions, and catastrophic losses by hadronic interactions. We also include diffusion of cosmic rays. Using a number of test problems, we show that our scheme is numerically robust and efficient, allowing us to carry out the first cosmological structure formation simulations that account for cosmic ray physics, together with radiative cooling and star formation. In simulations of isolated galaxies, we find that cosmic rays can significantly reduce the star formation efficiencies of small galaxies, with virial velocities below ~$80~{\rm km\,s}^{-1}$, an effect that becomes progressively stronger towards low-mass scales. In cosmological simulations of the formation of dwarf galaxies at high redshift, we find that the total mass-to-light ratio of small halos and the faint end of the luminosity function are affected. The latter becomes slightly flatter. When cosmic ray acceleration in shock waves is followed as well, we find that up to $40\%$ of the energy dissipated at structure formation shocks can appear as cosmic ray pressure at redshifts around $z\sim 3{-}6$, but this fraction drops to ~$10\%$ at low redshifts when the shock distribution becomes increasingly dominated by lower Mach numbers. Despite this large cosmic ray energy content in the high-redshift intergalactic medium, the flux power spectrum of the Lyman- α forest is only affected on very small scales of $k>0.1~{\rm km^{-1}s}$, and at a weak level of $5{-}15\%$. Within virialized objects, we find lower contributions of CR-pressure, due to the increased efficiency of loss processes at higher densities, the lower Mach numbers of shocks inside halos, and the softer adiabatic index of CRs, which disadvantages them when a composite of thermal gas and cosmic rays is adiabatically compressed. The total energy in cosmic rays relative to the thermal energy within the virial radius drops from 20% for $10^{12}\,h^{-1}~{M}_\odot$ halos to 5% for rich galaxy clusters of mass $10^{15}\,h^{-1}~{M}_\odot$ in non-radiative simulations. Interestingly, the lower effective adiabatic index also increases the compressibility of the intrahalo medium, an effect that slightly increases the central concentration of the gas and the baryon fraction within the virial radius. We find that this can enhance the cooling rate onto central cluster galaxies, even though the galaxies in the cluster periphery become slightly less luminous as a result of cosmic ray feedback.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7d1a35d5ba917fa4d3719f9cd9be0c8953b32828

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Citations in the corpus

THE PHYSICS OF THE FAR-INFRARED–RADIO CORRELATION. I. CALORIMETRY, CONSPIRACY, AND IMPLICATIONS (2009, background): “Jubelgas et al. (2008) have also explored the dynamical importance of CRs in galaxies, and conclude that they are not important for starbursts.”
Galactic winds driven by cosmic ray streaming (2012, methodology): “…time, the CR pressure is dissipated such that the gas can collapse again, triggering another ‘cycle’ of star formation and causing an oscillatory mode of star formation with substantial suppression of the stellar mass formed by a factor of 8 for a halo of mass M200 109 M (Jubelgas et al. 2008).”
Theoretical Challenges in Galaxy Formation (2016, background): “This is treated approximately either by streaming (Uhlig et al. 2012) or by isotropic diffusion with a typical diffusion coefficient (Booth et al. 2013, Enßlin et al. 2007, Jubelgas et al. 2008, Salem & Bryan 2014).”
THE ATACAMA COSMOLOGY TELESCOPE: COSMOLOGY FROM GALAXY CLUSTERS DETECTED VIA THE SUNYAEV–ZEL'DOVICH EFFECT (2010, background): “Simulations and observations suggest contributions to the total pressure from cosmic rays to be about 5%–10% (Jubelgas et al. 2008; Pfrommer & Enßlin 2004) and from turbulent pressure to be between 5% and 20% (Lau et al. 2009; Meneghetti et al. 2010; Burns et al. 2010), with only the latter work…”
Introducing the Illustris Project: the evolution of galaxy populations across cosmic time (2014, background): “…Quataert & Murray 2011), black hole growth and feedback (Springel, Di Matteo & Hernquist 2005a; Sijacki & Springel 2006; Booth & Schaye 2009; Dubois et al. 2012), magnetic fields (Dolag 2006; Pakmor, Marinacci & Springel 2014), and cosmic rays (Jubelgas et al. 2008; Vazza, Gheller & Brüggen 2014).”
Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation (2013, background): “Other physics such as c© 0000 RAS, MNRAS 000, 000–000 magnetic fields, anisotropic conduction, and cosmic rays may be important as well, and their consequences are just beginning to be explored (e.g. Jubelgas et al. 2008; Hanasz et al. 2013; Salem & Bryan 2013).”
Numerical simulations of the dark universe: State of the art and the next decade (2012, background): “• Modeling non-thermal support provided by unresolved turbulence, magnetic fields, and cosmic ray propagation [411, 412].”
The birth of a galaxy – II. The role of radiation pressure (2012, background): “There are various relevant physics, such as photoheating (e.g. Gnedin 2000), momentum input from radiation (e.g. Haehnelt 1995), cosmic rays (e.g. Jubelgas et al. 2008), and magnetic fields (e.g. Wang & Abel 2009; Kotarba et al. 2011), that can play an important role in star and galaxy formation.”
ON THE CLUSTER PHYSICS OF SUNYAEV–ZEL'DOVICH AND X-RAY SURVEYS. I. THE INFLUENCE OF FEEDBACK, NON-THERMAL PRESSURE, AND CLUSTER SHAPES ON Y–M SCALING RELATIONS (2011, background): “…with star formation, supernova (SN) energy feedback and cosmic rays (CRs) from structure formation shocks (for more information on CRs, see Pfrommer et al. 2006a, 2007; Enßlin et al. 2007; Jubelgas et al. 2008); (3)AGN feedback in addition to radiative cooling, star formation, and SN feedback.”
The Local Group on FIRE: dwarf galaxy populations across a suite of hydrodynamic simulations (2018, background): “An additional, constant source of feedback (e.g. cosmic rays; Jubelgas et al. 2008) that acts to smooth out the burstiness in the star formation, leading to lessviolent feedback episodes, may be required to explain these objects.”
The Aquila comparison project: the effects of feedback and numerical methods on simulations of galaxy formation (2011, methodology): “The non-thermal pressure of this CR population is then given by PCR = CmpC2 6 B 1 1+q2 ( α − 2 2 , 3 − α 2 ) , (A3) which is added to the ordinary gas pressure (Jubelgas et al. 2008).”
Galactic star formation and accretion histories from matching galaxies to dark matter haloes (2012, background): “Furthermore the amount of cooled gas is reduced by the presence of a UV and an X-ray background (Navarro & Steinmetz 1997; Gnedin 2000; Benson et al. 2002; Hambrick et al. 2011) and by cosmic rays (Jubelgas et al. 2008; Wadepuhl & Springel 2011).”
An origin for multiphase gas in galactic winds and haloes (2015, background): “…grains (Murray et al. 2005, 2010, 2011; Hopkins et al. 2012; Zhang & Thompson 2012; Krumholz & Thompson 2013; Davis et al. 2014; Thompson & Krumholz 2014; Thompson et al. 2015), and cosmic rays (Breitschwerdt & Schmutzler 1994, 1999; Jubelgas et al. 2008; Socrates et al. 2008; Hanasz et al. 2013).”
DIRECT NUMERICAL SIMULATION OF RADIATION PRESSURE-DRIVEN TURBULENCE AND WINDS IN STAR CLUSTERS AND GALACTIC DISKS (2012, background): “The turbulence could also be driven by cosmic ray rather than radiation pressure (Ipavich 1975; Breitschwerdt et al. 1991; Jubelgas et al. 2008; Socrates et al. 2008).”
Cusp-core transformations in dwarf galaxies: observational predictions (2012, background): “…unresolved turbulence, magnetic field amplification and cosmic ray propagation and radiative losses in the framework of galaxy formation is at its infancy, although some recent progresses have been reported (Hanasz et al. 2006; Jubelgas et al. 2008; Scannapieco & Brüggen 2010; Uhlig et al. 2012).”
Cosmic ray transport in galaxy clusters: implications for radio halos, gamma-ray signatures, and cool core heating (2010, background): “Then, the required turbulent re-acceleration is also present, in order to power a radio halo in 5 Miniati (2001, 2002, 2007); Miniati et al. (2007); Pfrommer et al. (2006); Enßlin et al. (2007); Jubelgas et al. (2008).”
Simulations of magnetic fields in isolated disc galaxies (2012, methodology): “Our disk galaxy simulations start from slowly rotating spherical gas clouds embedded in equilibrium into a collisionless dark matter halo (using the setup of Jubelgas et al. 2008).”
The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations (2015, background): “…since there are sources of energy feedback other than Type II SNe, and indeed such sources are often invoked in simulations of galaxy formation, for example stellar winds and radiation pressure (Stinson et al. 2013; Hopkins et al. 2014) or cosmic rays (Jubelgas et al. 2008; Booth et al. 2013).”