Unusually Large Fluctuations in the Statistics of Galaxy Formation at High Redshift

By R. Barkana, Abraham Loeb. 2003

241 citations recorded by the source corpus.

We show that various milestones of high-redshift galaxy formation, such as the formation of the first stars or the complete reionization of the intergalactic medium, occurred at different times in different regions of the universe. The predicted spread in redshift, caused by large-scale fluctuations in the number density of galaxies, is at least an order of magnitude larger than previous expectations, which argued for a sharp end to reionization. This cosmic scatter in the abundance of galaxies introduces new features that affect the nature of reionization and the expectations for future probes of reionization and may help explain the present properties of dwarf galaxies in different environments. The predictions can be tested by future numerical simulations and may be verified by upcoming observations. Current simulations, limited to relatively small volumes and periodic boundary conditions, largely omit cosmic scatter and its consequences. In particular, they artificially produce a sudden end to reionization, and they underestimate the number of galaxies by up to an order of magnitude at redshift 20.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/4ff18881f776061ae11da56c2b6fdda9f0638b54

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Citations in the corpus

Lyα Emitting Galaxies as a Probe of Reionisation (2014, background): “As a result, these galaxies were clustered on scales of tens of comoving Mpc (cMpc, Barkana & Loeb 2004).”
Detecting the Earliest Galaxies through Two New Sources of 21 Centimeter Fluctuations (2004, methodology): “On large scales, the change in the abundance of halos is linear in the density perturbation, for every halo mass (Mo & White 1996; Barkana & Loeb 2004), yielding a weighted biasb(z′) in the overall emission rate.”
The morphology of H ii regions during reionization (2006, methodology): “Previous estimates suggest that, in order to capture a representative sample of the Universe during reionization, one needs a simulation box with a side length of approximately 100 Mpc comoving (Barkana & Loeb 2004; Furlanetto et al. 2004b).”
The Evolution of the Intergalactic Medium (2015, background): “The most striking prediction of these models is that the bubble sizes reach many megaparsecs in size, engulfing thousands and even millions of galaxies (Barkana & Loeb 2004; Furlanetto, Zaldarriaga & Hernquist 2004; Iliev et al. 2006).”
Simulating Cosmic Reionization at Large Scales I: the Geometry of Reionization (2005, background): “…other hand, these ionizing sources were strongly clustered at high redshift and, as a consequence, the H II regions they created are expected to quickly overlap and grow to very large sizes,reaching up to tens of Mpc (e.g. Barkana & Loeb 2004; Furlanetto & Oh 2005; Cen 2005; Iliev et al. 2005c).”
COMPLETING THE CENSUS OF Lyα EMITTERS AT THE REIONIZATION EPOCH (2011, background): “The comoving survey volume was as large as 2.17× 105 Mpc3 and 1.80×105 for z = 6.5 and z = 5.7, respectively.”
21cmfast: a fast, seminumerical simulation of the high‐redshift 21‐cm signal (2010, unknown): “The collapsed fraction is computed according to a hybrid prescription, similar to Barkana & Loeb (2004, 2008): fcoll(x, z′′, R′′, Smin) = f̄ST f̄PS,nl erfc [ δc − δR′′nl√ 2[Smin − SR′′ ] ] , (14) where R′ ′ is the comoving, null-geodesic distance between z′ and z′ ′; Smin and SR ′′ are the mass…”
The halo mass function from the dark ages through the present day (2006, methodology): “Early attempts to simulate the formation of dark matter halos in the young universe suffered from effects resulting from the finite box sizes of the simulations, as noted by (e.g. White & Springel 2000; Barkana & Loeb 2004).”
The Halo Mass Function: High-Redshift Evolution and Universality (2007, methodology): “…use multiple boxes and average mass function results over the box ensemble, extended Press-Schechter theory can be used to correct for residual finite-volume effects (Mo & White 1996; Barkana & Loeb 2004); this approach is different from the individual box corrections applied by Reed et al. (2007).”
Keeping the Universe ionized: photoheating and the clumping factor of the high-redshift intergalactic medium (2008, background): “For threshold densities log10 ∆thr & 2 the clumping factor may, however, not yet have fully converged, indicating that even larger simulation boxes than that considered here may be required for its computation (see also the discussion in Barkana & Loeb 2004).”
Efficient Simulations of Early Structure Formation and Reionization (2007, background): “The dotted and short–dashed curves overlap at these redshifts due to our large box size (L = 100 Mpc), so we are immune to the finite box effects pointed out by Barkana & Loeb (2004).”
Lyα and C iii] emission in z = 7–9 Galaxies: accelerated reionization around luminous star-forming systems? (2016, background): “One possibility is that the most luminous galaxies trace overdense regions which produce the largest ionized bubbles at any given redshift (e.g., Barkana & Loeb 2004; Furlanetto et al. 2004).”
The halo mass function through the cosmic ages (2012, methodology): “Finally, Barkana & Loeb (2004) utilized the extended PS formalism to create a volume adjustment by taking the Sheth–Tormen (ST) mass function for a global volume and applying a correction to it to create a mass function suitable for a smaller volume.”
The Cosmic Dispersion Measure from Gamma-Ray Burst Afterglows: Probing the Reionization History and the Burst Environment (2003, background): “On the other hand, GRBs may be useful for probing high redshiftz (e.g., Miralda-Escude´ 1998; Barkana & Loeb 2004; Inoue, Yamazaki, & Nakamura 2004).”
Reionization and Cosmology with 21-cm Fluctuations (2009, background): “As pointed out by Barkana & Loeb (2004) a simulation which is too small does not contain the large scale density fluctuation modes which drive the clustering of galaxies on the largest scales.”
Inferring the astrophysics of reionization and cosmic dawn from galaxy luminosity functions and the 21-cm signal (2018, methodology): “…(HMF), dn dMh (Mh, z |R, δR), is obtained by normalizing the conditional Press-Schechter HMF (Lacey & Cole 1993; Somerville & Kolatt 1999) so as to have the mean of the Sheth-Tormen HMF (Sheth & Tormen 1999, 2002), as discussed in Mesinger et al. (2011) (see also Barkana & Loeb 2004, 2008).”