Testing anthropic reasoning for the cosmological constant with a realistic galaxy formation model

Abstract

The anthropic principle is one of the possible explanations for the cosmological constant ($\Lambda$) problem. In previous studies, a dark halo mass threshold comparable with our Galaxy must be assumed in galaxy formation to get a reasonably large probability of finding the observed small value, $P(<$${\Lambda }_{\mathrm{obs}})$, though stars are found in much smaller galaxies as well. Here we examine the anthropic argument by using a semi-analytic model of cosmological galaxy formation, which can reproduce many observations such as galaxy luminosity functions. We calculate the probability distribution of $\Lambda$ by running the model code for a wide range of $\Lambda$, while other cosmological parameters and model parameters for baryonic processes of galaxy formation are kept constant. Assuming that the prior probability distribution is flat per unit $\Lambda$, and that the number of observers is proportional to stellar mass, we find $P(<$${\Lambda }_{\mathrm{obs}})=6.7\%$ without introducing any galaxy mass threshold. We also investigate the effect of metallicity; we find $P(<$${\Lambda }_{\mathrm{obs}})=9.0\%$ if observers exist only in galaxies whose metallicity is higher than the solar abundance. If the number of observers is proportional to metallicity, we find $P(<$${\Lambda }_{\mathrm{obs}})=9.7\%$. Since these probabilities are not extremely small, we conclude that the anthropic argument is a viable explanation, if the value of $\Lambda$ observed in our universe is determined by a probability distribution.

arXiv comment6 pages, 4 figures, accepted for publication in MNRAS

References in corpus (32)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Efficient Computation of CMB anisotropies in closed FRW models
• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• The Cosmological Constant
• Dark Energy and the Accelerating Universe
• Planck 2013 results. I. Overview of products and scientific results
• Observational Probes of Cosmic Acceleration
• The Mass-Metallicity Relation at z~2
• The Milky Way's Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of ~2400 SDSS Blue Horizontal Branch Stars
• A primer on hierarchical galaxy formation: the semi-analytical approach
• The Physics of Cosmic Acceleration
• The Gemini Deep Deep Survey. VII. The Redshift Evolution of the Mass-Metallicity Relation
• On Extending the Mass-Metallicity Relation of Galaxies by 2.5 Decades in Stellar Mass
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• The Cosmological Constant is Back
• The Metallicity-Luminosity Relation, Effective Yields, and Metal Loss in Spiral and Irregular Galaxies
• The Cosmological Constant Problem and Quintessence
• Likely Values of the Cosmological Constant
• Why is the CMB fluctuation level 10^{-5}?
• Strong Gravitational Lensing and Velocity Function as Tools to Probe Cosmological Parameters: Current Constraints and Future Predictions
• The cosmological constant and the time of its dominance
• Lyman Alpha Emitters in the Hierarchically Clustering Galaxy Formation
• Hierarchical Formation of Galaxies with Dynamical Response to Supernova-Induced Gas removal
• The Cold Big-Bang Cosmology as a Counter-example to Several Anthropic Arguments
• Lyman Alpha Emitters in Hierarchical Galaxy Formation II. UV Continuum Luminosity Function and Equivalent Width Distribution
• Anthropic Distribution for Cosmological Constant and Primordial Density Perturbations
• Testing anthropic predictions for Lambda and the CMB temperature
• The New Numerical Galaxy Catalog (${\nu }^2$GC): An Updated Semi-analytic Model of Galaxy and AGN with Large Cosmological N-body Simulation
• Theories of the Cosmological Constant
• Initial Conditions of Inhomogeneous Universe and the Cosmological Constant Problem

Cited by in corpus (7)

• The Degree of Fine-Tuning in our Universe -- and Others
• Galaxy Formation Efficiency and the Multiverse Explanation of the Cosmological Constant with EAGLE Simulations
• The impact of dark energy on galaxy formation. What does the future of our Universe hold?
• The impact of the cosmological constant on past and future star formation
• Lethal radiation from nearby supernovae helps to explain the small cosmological constant
• Gravity with free initial conditions: a solution to the cosmological constant problem testable by CMB B-mode polarization
• Extended Hernquist-Springel formalism for cosmic star formation