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

ABSTRACT We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H α and [O iii] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H α luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H α luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [O iii] emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H α and [O iii] emission line galaxies for three different line flux limits: 5 × 10−17erg s−1 cm−2, 1 × 10−16 erg s−1 cm−2 (6.5σ nominal depth for WFIRST GRS), and 2 × 10−16 erg s−1 cm−2 (3.5σ depth of Euclid GRS). At redshift 2 < z < 3, our model predicts that WFIRST can observe hundreds of [O iii] emission line galaxies per square degree with a line flux limit of 1 × 10−16 erg s−1 cm−2. This will provide accurate measurement of large-scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H α/[O iii] within the redshift range of 0 < z < 3. Our results show the known trend of increasing H α/[O iii] flux ratio with H α flux at low redshift, which becomes a weaker trend at higher redshifts.

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IMPROVEMENTS TO THE SPHERICAL COLLAPSE MODEL

International Journal of Modern Physics D ◽

10.1142/s0218271806008553 ◽

2006 ◽

Vol 15 (07) ◽

pp. 1067-1088 ◽

Cited By ~ 1

Author(s):

ANTONINO DEL POPOLO

Keyword(s):

Cosmological Constant ◽

Galaxy Formation ◽

Spherical Model ◽

Mass Function ◽

Joint Effect ◽

Dynamical Friction ◽

Spherical Collapse ◽

Theoretical Mass ◽

Collapse Model ◽

Tidal Torques

We study the joint effect of dynamical friction, tidal torques and cosmological constant on clusters of galaxy formation. We show that within high-density environments, such as rich clusters of galaxies, both dynamical friction and tidal torques slow down the collapse of low-ν peaks producing an observable variation in the time of collapse of the perturbation and, as a consequence, a reduction in the mass bound to the collapsed perturbation. Moreover, the delay of the collapse produces a tendency for less dense regions to accrete less mass, with respect to a classical spherical model, inducing a biasing of over-dense regions toward higher mass. We show how the threshold of collapse is modified if dynamical friction, tidal torques and a non-zero cosmological constant are taken into account and we use the Extended Press–Schecter (EPS) approach to calculate the effects on the mass function. Then, we compare the numerical mass function given in D. Reed, Mon. Not. R. Astron. Soc.346, 565 (2003) with the theoretical mass function obtained in the present paper. We show that the barrier obtained in the present paper gives rise to a better description of the mass function evolution with respect to other previous models, R. K. Sheth and G. Tormen, Mon. Not. R. Astron. Soc.308, 119 (1999) and R. K. Sheth and G. Tormen, Mon. Not. R. Astron. Soc.329, 61 (2002).

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Elemental abundances in Milky Way-like galaxies from a hierarchical galaxy formation model

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stu1752 ◽

2014 ◽

Vol 445 (1) ◽

pp. 970-987 ◽

Cited By ~ 44

Author(s):

Gabriella De Lucia ◽

Luca Tornatore ◽

Carlos S. Frenk ◽

Amina Helmi ◽

Julio F. Navarro ◽

...

Keyword(s):

Galaxy Formation ◽

Milky Way ◽

Formation Model ◽

Elemental Abundances

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Massive quiescent galaxies at z > 3 in the Millennium simulation populated by a semi-analytic galaxy formation model

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slx099 ◽

2017 ◽

Vol 471 (1) ◽

pp. L36-L40 ◽

Cited By ~ 5

Author(s):

Yu Rong ◽

Yingjie Jing ◽

Liang Gao ◽

Qi Guo ◽

Jie Wang ◽

...

Keyword(s):

Galaxy Formation ◽

Formation Model

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Chemical enrichment of ICM in a hierarchical galaxy formation model including SNe Ia

Proceedings of the International Astronomical Union ◽

10.1017/s1743921304000614 ◽

2004 ◽

Vol 2004 (IAUC195) ◽

Author(s):

Masahiro Nagashima ◽

Cedric G. Lacey ◽

Carlton M. Baugh ◽

Carlos S. Frenk ◽

Shaun Cole

Keyword(s):

Galaxy Formation ◽

Formation Model ◽

Chemical Enrichment

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A New Chemodynamical Galaxy Formation Model with Radiative Transfer

EAS Publications Series ◽

10.1051/eas:2007017 ◽

2007 ◽

Vol 24 ◽

pp. 107-112

Author(s):

A. Ibukiyama

Keyword(s):

Radiative Transfer ◽

Galaxy Formation ◽

Formation Model

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The Quantum World

Journal of Interdisciplinary Studies ◽

10.5840/jis2015271/24 ◽

2015 ◽

Vol 27 (1) ◽

pp. 45-60

Author(s):

A. James Melnick ◽

Keyword(s):

Quantum Mechanics ◽

Cosmological Constant ◽

Albert Einstein ◽

Fine Tuning ◽

Anthropic Reasoning ◽

The Mind

Scientific measurements of fine-tuning factors, especially the cosmological constant, have forced non-theists to fall back on anthropic reasoning and multiverse theories to try to explain away the implications of a theistically-designed universe. Whatever its other uses, employing anthropic reasoning in this way is questionable. It is unscientific to posit trillions upon trillions of universes--as many multiverse proponents and string theorists do--in order to try to explain away the fine-tuned existence of our own. Albert Einstein would likely dismiss many current multiverse theories. Yet, might we still live in a multiversal reality? This essay posits such a reality--a Triverse--as a more parsimonious view over popular multiverse theories. The proposed Triverse has some similarity to, but is distinct from, Roger Penrose’s “three worlds” in his Shadows of the Mind. A multiversal Triverse reality might also eventually be reconciled with some of the evidence and indicators that support quantum mechanics, and thus help define a more deterministic universe.

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Cosmic archaeology with massive stellar black hole binaries

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slaa063 ◽

2020 ◽

Vol 495 (1) ◽

pp. L81-L85 ◽

Cited By ~ 2

Author(s):

L Graziani ◽

R Schneider ◽

S Marassi ◽

W Del Pozzo ◽

M Mapelli ◽

...

Keyword(s):

Black Hole ◽

Star Formation ◽

Gravitational Wave ◽

Galaxy Formation ◽

Population Synthesis ◽

Formation Model ◽

Black Hole Binaries ◽

The Galaxy ◽

Low Metallicity ◽

Black Hole Masses

ABSTRACT The existence of massive stellar black hole binaries (MBHBs), with primary black hole masses $\ge 31 \, \mathrm{ M}_\odot$, was proven by the detection of the gravitational wave (GW) event GW150914 during the first LIGO/Virgo observing run (O1), and successively confirmed by seven additional GW signals discovered in the O1 and O2 data. By adopting the galaxy formation model gamesh coupled with binary population synthesis (BPS) calculations, here we investigate the origin of these MBHBs by selecting simulated binaries compatible in mass and coalescence redshifts. We find that their cosmic birth rates peak in the redshift range 6.5 ≤ z ≤ 10, regardless of the adopted BPS. These MBHBs are then old systems forming in low-metallicity ($Z \sim [0.01\!-\!0.1] \, Z_{\odot }$), low-stellar-mass galaxies, before the end of cosmic reionization, i.e. significantly beyond the peak of cosmic star formation. GW signals generated by coalescing MBHBs open up new possibilities to probe the nature of stellar populations in remote galaxies, at present too faint to be detected by available electromagnetic facilities.

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A random-walk model for dark matter halo spins

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1777 ◽

2020 ◽

Vol 496 (3) ◽

pp. 3371-3380 ◽

Cited By ~ 2

Author(s):

Andrew Benson ◽

Christoph Behrens ◽

Yu Lu

Keyword(s):

Dark Matter ◽

Random Walk ◽

Galaxy Formation ◽

Random Walk Model ◽

Dark Matter Halo ◽

Orbital Parameter ◽

Formation Model ◽

Angular Momenta ◽

Very High ◽

Over Time

ABSTRACT We extend the random-walk model of Vitvitska et al. for predicting the spins of dark matter haloes from their merger histories. Using updated merger rates, orbital parameter distributions, and N-body constraints, we show that this model can accurately reproduce the distribution of spin parameters measured in N-body simulations when we include a weak correlation between the spins of haloes and the angular momenta of infalling subhaloes. We further show that this model is in approximate agreement with the correlation of the spin magnitude over time as determined from N-body simulations, while it slightly underpredicts the correlation in the direction of the spin vector measured from the same simulations. This model is useful for predicting spins from merger histories derived from non-N-body sources, thereby circumventing the need for very high resolution simulations to permit accurate measurements of spins. It may be particularly relevant to modelling systems that accumulate angular momentum from haloes over time (such as galactic discs) – we show that this model makes small but significant changes in the distribution of galactic disc sizes computed using the galacticus semi-analytic galaxy formation model.

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