Including Star Formation and Supernova Feedback Within Cosmological Simulations of Galaxy Formation (original) (raw)

The Modelling of Feedback Processes in Cosmological Simulations of Disk Galaxy Formation

2009

We present a systematic study of stellar feedback processes in simulations of disk galaxy formation. Using a dark matter halo with properties similar to the ones for the Milky Way's stellar halo, we perform a comparison of different methods of distributing energy related to feedback processes to the surrounding gas. A most promising standard model is applied to halos spanning a range of masses in order to compare the results to disk galaxy scaling relations. With few exceptions we find little or no angular momentum deficiency for our galaxies and a good agreement with the angular momentum-size relation. Our galaxies are in good agreement with the baryonic Tully-Fisher relation and the slope of the photometric Tully-Fisher relation is reproduced. We find a zero-point offset of 0.7 to 1 magnitudes, depending on the employed IMF. We also study our standard feedback model in combination with additional physical processes like a UV background, kinetic feedback, a delayed energy deposition as expected for type Ia supernovae, mass return and metal-dependent cooling. Only a combination of effects yields a real improvement of the resulting galaxy by reducing the bulge, while including metal-dependent cooling increases the bulge again. We find that in general the stellar mass fraction of our galaxies is too high. In an ad-hoc experiment we show that an removal of the bulge could reconcile this. However, the fit of the Tully-Fisher relation can only be improved by delaying the star formation, but not suppressing it completely. Our models do not seem to be efficient enough to achieve either effect. We conclude that disk formation is a complex, highly interconnected problem and we expect a solution to come from a combination of small effects.

Hydrodynamical simulations of galaxy formation: effects of supernova feedback

In this paper we numerically simulate some of the most critical physical processes in galaxy formation: The supernova feedback loop, in conjunction with gas dynamic processes and gravitational condensations, plays a crucial role in determining how the observable properties of galaxies arise within the context of a model for large-scale structure. Our treatment incorporates a multi-phase model of the interstellar medium and includes the effects of cooling, heating and metal enrichment by supernovae, and evaporation of cold clouds. The star formation happens inside the clouds of cold gas, which are produced via thermal instability. In this paper we simulate the galaxy formation in standard biased Cold Dark Matter (CDM) model for a variety of parameters and for several resolutions. In our picture, supernova feedback regulates the evolution of the gas components and star formation. The efficiency of cold cloud evaporation by supernova strongly influences star formation rates. This feedback results in a steady rate of star formation in "large" galaxies (mass larger than (2 − 3) × 10 11 M ⊙ within 100 kpc radius) at a level of (1 − 10)M ⊙ per year for z < 3 (H 0 = 50 Km s −1 Mpc −1 ). Supernova feedback has an even stronger effect on the evolution of "dwarf" galaxies. Most of the dwarf galaxies in our models have a small fraction of stars and extremely low luminosities: M R > −15 for parent dark-halo masses M tot < (2 − 3) × 10 10 M ⊙ within a 50 kpc radius. The observational properties (colors, luminosities) of galaxies identified in the simulations are computed using a stellar population synthesis model. In the case of both large and small galaxies, the distribution of luminous matter (stars) is strongly biased with respect to the dark matter. For a range of parameter values and resolutions we find an approximate biasing measure of the form ρ lum = (ρ dm /133) 1.7 , for overdensities exceeding about 1000. Deviations from this relation depend strongly on the environment. For halo masses exceeding 2 × 10 10 M ⊙ , the dependence of the absolute visual magnitude M V on the total mass can be approximated as M V = −18.5 − 4 log(M tot /10 11 M ⊙ ), with a scatter of less than 1/2 magnitude.

Making Galaxies in a Cosmological Context: The Need for Early Stellar Feedback

2012

We introduce the Making Galaxies in a Cosmological Context (MaGICC) program of smoothed particle hydrodynamics (SPH) simulations. We describe a parameter study of galaxy formation simulations of an L* galaxy that uses early stellar feedback combined with supernova feedback to match the stellar mass--halo mass relationship. While supernova feedback alone can reduce star formation enough to match the stellar mass--halo mass relationship, the galaxy forms too many stars before z=2 to match the evolution seen using abundance matching. Our early stellar feedback is purely thermal and thus operates like a UV ionization source as well as providing some additional pressure from the radiation of massive, young stars. The early feedback heats gas to >10^6 K before cooling to 10^4 K. The pressure from this hot gas creates a more extended disk and prevents more star formation prior to z=1 than supernovae feedback alone. The resulting disk galaxy has a flat rotation curve, an exponential surface brightness profile, and matches a wide range of disk scaling relationships. The disk forms from the inside-out with an increasing exponential scale length as the galaxy evolves. Overall, early stellar feedback helps to simulate galaxies that match observational results at low and high redshifts.

A model for cosmological simulations of galaxy formation physics: multi-epoch validation

Monthly Notices of the Royal Astronomical Society, 2014

We present a multi-epoch analysis of the galaxy populations formed within the cosmological hydrodynamical simulations presented in . These simulations explore the performance of a recently implemented feedback model which includes primordial and metal line radiative cooling with self-shielding corrections; stellar evolution with associated mass loss and chemical enrichment; feedback by stellar winds; black hole seeding, growth and merging; and AGN quasar-and radio-mode heating with a phenomenological prescription for AGN electro-magnetic feedback. We illustrate the impact of the model parameter choices on the resulting simulated galaxy population properties at high and intermediate redshifts. We demonstrate that our scheme is capable of producing galaxy populations that broadly reproduce the observed galaxy stellar mass function extending from redshift z = 0 to z = 3. We also characterise the evolving galactic B-band luminosity function, stellar mass to halo mass ratio, star formation main sequence, Tully-Fisher relation, and gas-phase massmetallicity relation and confront them against recent observational estimates. This detailed comparison allows us to validate elements of our feedback model, while also identifying areas of tension that will be addressed in future work.

The modelling of feedback processes in cosmological simulations of disc galaxy formation

Monthly Notices of the Royal Astronomical Society, 2011

A thermal-kinetic subgrid model for supernova feedback in simulations of galaxy formation

Cornell University - arXiv, 2022

We present a subgrid model for supernova feedback designed for simulations of galaxy formation. The model uses thermal and kinetic channels of energy injection, which are built upon the stochastic kinetic and thermal models for stellar feedback used in the and simulations, respectively. In the thermal channel, the energy is distributed statistically isotropically and injected stochastically in large amounts per event, which minimizes spurious radiative energy losses. In the kinetic channel, we inject the energy in small portions by kicking gas particles in pairs in opposite directions. The implementation of kinetic feedback is designed to conserve energy, linear momentum and angular momentum, and is statistically isotropic. To test and validate the model, we run simulations of isolated Milky Way-mass and dwarf galaxies, in which the gas is allowed to cool down to 10 K. Using the thermal and kinetic channels together, we obtain smooth star formation histories and powerful galactic winds with realistic mass loading factors. Furthermore, the model produces spatially resolved star formation rates and velocity dispersions that are in agreement with observations. We vary the numerical resolution by several orders of magnitude and find excellent convergence of the global star formation rates and the mass loading of galactic winds. We show that large thermal-energy injections generate a hot phase of the interstellar medium (ISM) and modulate the star formation by ejecting gas from the disc, while the low-energy kicks increase the turbulent velocity dispersion in the neutral ISM, which in turn helps suppress star formation.

Galaxy formation with radiative and chemical feedback

MNRAS, 2015

Here we introduce GAMESH, a novel pipeline which implements self-consistent ra-diative and chemical feedback in a computational model of galaxy formation. By combining the cosmological chemical-evolution model GAMETE with the radiative transfer code CRASH, GAMESH can post process realistic outputs of a N-body simulation describing the redshift evolution of the forming galaxy. After introducing the GAMESH implementation and its features, we apply the code to a low-resolution N-body simulation of the Milky Way formation and we investigate the combined effects of self-consistent radiative and chemical feedback. Many physical properties, which can be directly compared with observations in the Galaxy and its surrounding satellites, are predicted by the code along the merger-tree assembly. The resulting redshift evolution of the Local Group star formation rates, reionisation and metal enrichment along with the predicted Metallicity Distribution Function of halo stars are critically compared with observations. We discuss the merits and limitations of the first release of GAMESH, also opening new directions to a full implementation of feedback processes in galaxy formation models by combining semi-analytic and numerical methods.

Simulating galaxy clusters - II. Global star formation histories and the galaxy populations

Monthly Notices of the Royal Astronomical Society, 2005

We performed N-body + hydrodynamical simulations of the formation and evolution of galaxy groups and clusters in a cold dark matter cosmology. The simulations invoke star formation, chemical evolution with non-instantaneous recycling, metal-dependent radiative cooling, strong starbursts and (optionally) active galactic nucleus (AGN) driven galactic superwinds, effects of a meta-galactic ultraviolet field and thermal conduction. The properties of the galaxy populations in two clusters, one Virgo-like (T ∼ 3 keV) and one (sub)Coma-like (T ∼ 6 keV), are discussed. The global star formation rates of the cluster galaxies are found to decrease very significantly from redshift z = 2 to 0, in agreement with observations. The total K-band luminosity of the cluster galaxies correlates tightly with total cluster mass, and for models without additional AGN feedback, the zero-point of the relation matches the observed one fairly well. Compared to the observed galaxy luminosity function (LF), the simulations nicely match the number of intermediate-mass galaxies (−20 M B −17, smaller galaxies being affected by resolution limits) but they show a deficiency of bright galaxies in favour of an overgrown central dominant (cD) galaxy. High-resolution tests indicate that this deficiency is not simply due to numerical 'overmerging'.

Physical Models of Galaxy Formation in a Cosmological Framework

Annual Review of Astronomy and Astrophysics, 2015

Modeling galaxy formation in a cosmological context presents one of the greatest challenges in astrophysics today due to the vast range of scales and numerous physical processes involved. Here we review the current status of models that employ two leading techniques to simulate the physics of galaxy formation: semianalytic models and numerical hydrodynamic simulations. We focus on a set of observational targets that describe the evolution of the global and structural properties of galaxies from roughly cosmic high noon (z ∼ 2–3) to the present. Although minor discrepancies remain, overall, models show remarkable convergence among different methods and make predictions that are in qualitative agreement with observations. Modelers have converged on a core set of physical processes that are critical for shaping galaxy properties. This core set includes cosmological accretion, strong stellar-driven winds that are more efficient at low masses, black hole feedback that preferentially supp...

A systematic look at the effects of radiative feedback on disc galaxy formation

Galaxy formation models and simulations rely on various feedback mechanisms to reproduce the observed baryonic scaling relations and galaxy morphologies. Although dwarf galaxy and giant elliptical properties can be explained using feedback from supernova and active galactic nuclei, Milky Way-sized galaxies still represent a challenge to current theories of galaxy formation. In this paper, we explore the possible role of feedback from stellar radiation in regulating the main properties of disc galaxies such as our own Milky Way. We have performed a suite of cosmological simulations of the same ∼ 10 12 M halo selected based on its rather typical mass accretion history. We have implemented radiative feedback from young stars using a crude model of radiative transfer for ultraviolet (UV) and infrared (IR) radiation. However, the model is realistic enough such that the dust opacity plays a direct role in regulating the efficiency of our feedback mechanism. We have explored various models for the dust opacity, assuming different constant dust temperatures, as well as a varying dust temperature model. We find that while strong radiative feedback appears as a viable mechanism to regulate the stellar mass fraction in massive galaxies, it also prevents the formation of discs with reasonable morphologies. In models with strong stellar radiation feedback, stellar discs are systematically too thick while the gas disc morphology is completely destroyed due to the efficient mixing between the feedback-affected gas and its surroundings. At the resolution of our simulation suite, we find it impossible to preserve spiral disc morphology while at the same time expelling enough baryons to satisfy the abundance matching constraints.

Including Star Formation and Supernova Feedback Within Cosmological Simulations of Galaxy Formation (original) (raw)

Related papers