The First Cosmic Structures and Their Effects

Ciardi, B.; Ferrara, Andrea

doi:10.1007/s11214-005-3592-0

Cited by 386 publications

(427 citation statements)

References 647 publications

(877 reference statements)

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“…A natural implication of these models is a strong coupling between reionization and galaxy formation caused by ionizing radiative feedback (e.g., Ciardi & Ferrara 2005). Photoionization heating by star-forming galaxies typically raises the temperature in the reionized gas to a few times 10 4 K. The associated increase in gas pressure increases the Jeans scale, i.e., the scale below which pressure prevents the collapse of gas into gravitationally bound objects (e.g., Gnedin 2000b).…”

Section: Introductionmentioning

confidence: 99%

Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

Pawlik

Schaye

Vecchia

2015

Monthly Notices of the Royal Astronomical Society

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We present a suite of cosmological radiation-hydrodynamical simulations of the assembly of galaxies driving the reionization of the intergalactic medium (IGM) at z 6. The simulations account for the hydrodynamical feedback from photoionization heating and the explosion of massive stars as supernovae (SNe). Our reference simulation, which was carried out in a box of size 25 h −1 comoving Mpc using 2 × 512 3 particles, produces a reasonable reionization history and matches the observed UV luminosity function of galaxies. Simulations with different box sizes and resolutions are used to investigate numerical convergence, and simulations in which either SNe or photoionization heating or both are turned off, are used to investigate the role of feedback from star formation. Ionizing radiation is treated using accurate radiative transfer at the high spatially adaptive resolution at which the hydrodynamics is carried out. SN feedback strongly reduces the star formation rates (SFRs) over nearly the full mass range of simulated galaxies and is required to yield SFRs in agreement with observations. Photoheating helps to suppress star formation in low-mass galaxies, but its impact on the cosmic SFR is small. Because the effect of photoheating is masked by the strong SN feedback, it does not imprint a signature on the UV galaxy luminosity function, although we note that our resolution is insufficient to model star-forming minihaloes cooling through molecular hydrogen transitions. Photoheating does provide a strong positive feedback on reionization because it smooths density fluctuations in the IGM, which lowers the IGM recombination rate substantially. Our simulations demonstrate a tight non-linear coupling of galaxy formation and reionization, motivating the need for the accurate and simultaneous inclusion of photoheating and SN feedback in models of the early Universe.

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Section: Introductionmentioning

confidence: 99%

Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

Pawlik

Schaye

Vecchia

2015

Monthly Notices of the Royal Astronomical Society

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“…A further complication is introduced by supernova feedback and (to a lesser extent) the ultraviolet background (UVB) built up during reionization in suppressing the gas content (and hence star formation) in low-mass galaxies which are the main sources of H I ionizing photons (see e.g. Barkana & Loeb 2001;Ciardi & Ferrara 2005;Maio et al 2011;Sobacchi & Mesinger 2013;Wyithe & Loeb 2013;Dayal et al 2015, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Clustering and lifetime of Lyman Alpha Emitters in the Epoch of Reionization

Hutter

Dayal

Müller

2015

Monthly Notices of the Royal Astronomical Society

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We calculate Lyman Alpha Emitter (LAE) angular correlation functions (ACFs) at z 6.6 and the fraction of lifetime (for the 100 Myrs preceding z 6.6) galaxies spend as Lyman Break Galaxies (LBGs) or as LBGs with Lyman Alpha (Lyα) emission using a model that combines SPH cosmological simulations (GADGET-2), dust attenuation and a radiative transfer code (pCRASH). The ACFs are a powerful tool that significantly narrows the 3D parameter space allowed by LAE Lyα and UV luminosity functions (LFs) alone. With this work, we simultaneously constrain the escape fraction of ionizing photons f esc = 0.05 − 0.5, the mean fraction of neutral hydrogen in the intergalactic medium (IGM) χ HI < ∼ 0.01 and the dust-dependent ratio of the escape fractions of Lyα and UV continuum photons f α /f c = 0.6 − 1.2. Our results show that reionization has the largest impact on the amplitude of the ACFs, and its imprints are clearly distinguishable from those of f esc and f α /f c . We also show that galaxies with a critical stellar mass of M * = 10 8.5 (10 9.5 )M produce enough luminosity to stay visible as LBGs (LAEs). Finally, the fraction of time during the past 100 Myrs prior to z = 6.6 a galaxy spends as a LBG or as a LBG with Lyα emission increases with the UV magnitude (and the stellar mass M * ): considering observed (dust and IGM attenuated) luminosities, the fraction of time a galaxy spends as a LBG (LAE) increases from 65% to 100% ( 0 − 100%) as M U V decreases from M U V = −18.0 to −23.5 (M * increases from 10 8 − 10 10.5 M ). Thus in our model the brightest (most massive) LBGs most often show Lyα emission.

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“…Cosmic structures such as galaxies and galaxy clusters develop from the gravitational collapse (Gunn & Gott 1972;Press & Schechter 1974;White & Rees 1978;Peebles 1993;Sheth & Tormen 1999;Peacock 1999;Barkana & Loeb 2001;Peebles & Ratra 2003;Ciardi & Ferrara 2005;Bromm & Yoshida 2011) of primeval small density perturbations originated during the inflationary era (Starobinsky 1980;H.Guth 1981;Linde 1990). To study the non-linear evolution of cosmic structures a popular analytical model, the spherical collapse model, was first introduced by Gunn & Gott (1972) and extended and improved by several following works (Fillmore & Goldreich 1984;Bertschinger 1985;Hoffman & Shaham 1985;Ryden & Gunn 1987;Avila-Reese et al 1998;Subramanian et al 2000;Ascasibar et al 2004;Williams et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Evolution of spherical overdensities in holographic dark energy models

Naderi¹,

Malekjani²,

Pace³

2015

Monthly Notices of the Royal Astronomical Society

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In this work we investigate the spherical collapse model in flat FRW dark energy universes. We consider the Holographic Dark Energy (HDE) model as a dynamical dark energy scenario with a slowly time-varying equation-of-state (EoS) parameter w de in order to evaluate the effects of the dark energy component on structure formation in the universe. We first calculate the evolution of density perturbations in the linear regime for both phantom and quintessence behavior of the HDE model and compare the results with standard Einstein-de Sitter (EdS) and ΛCDM models. We then calculate the evolution of two characterizing parameters in the spherical collapse model, i.e., the linear density threshold δ c and the virial overdensity parameter ∆ vir . We show that in HDE cosmologies the growth factor g(a) and the linear overdensity parameter δ c fall behind the values for a ΛCDM universe while the virial overdensity ∆ vir is larger in HDE models than in the ΛCDM model. We also show that the ratio between the radius of the spherical perturbations at the virialization and turn-around time is smaller in HDE cosmologies than that predicted in a ΛCDM universe. Hence the growth of structures starts earlier in HDE models than in ΛCDM cosmologies and more concentrated objects can form in this case. It has been shown that the non-vanishing surface pressure leads to smaller virial radius and larger virial overdensity ∆ vir . We compare the predicted number of halos in HDE cosmologies and find out that in general this value is smaller than for ΛCDM models at higher redshifts and we compare different mass function prescriptions. Finally, we compare the results of the HDE models with observations.

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The First Cosmic Structures and Their Effects

Abstract: Despite much recent theoretical and observational progress in our knowledge of the early universe, many fundamental questions remain only partially answered. Here, we review the latest achievements and persisting problems in the understanding of first cosmic structure formation.

Cited by 386 publications

References 647 publications

Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

Clustering and lifetime of Lyman Alpha Emitters in the Epoch of Reionization

Evolution of spherical overdensities in holographic dark energy models

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