Self-regulated reionization

By Ilian Iliev, G. Mellema, P. Shapiro, Ue-Li Pen Cita, S. University, U. Texas. 2006

158 citations recorded by the source corpus.

Recently, we have presented the first, truly large-scale radiative transfer simulations of inhomogeneous cosmic reionization which resolve all the possible halo sources down to the dwarf galaxy mass range, M ≥ 10 9 M⊙, in a comoving volume (100 h - 1 Mpc) 3 . This is large enough to sample the global mean history, geometry and statistical properties of reionization fairly and accurately for the first time. Here we present new simulations which extend the source halo mass range downward to 10 8 M⊙, to capture the full range of halo masses thought to be primarily responsible for reionization by their star formation following atomic hydrogen radiative cooling and gravitational collapse. Haloes below about 10 9 M⊙, however, are subject to Jeans-mass filtering in the ionized regions, which suppresses their baryonic content and their ability to release ionizing radiation. By including these smaller mass haloes but accounting for their suppression, too, we find that reionization is 'self-regulating', as follows. As the mean ionized fraction rises, so does the fraction of the volume within which suppression occurs. Hence, the degree of suppression is related to the mean ionized fraction. Since low-mass haloes with high efficiency (i.e. high emissivity) achieve a given mean ionized fraction earlier than do those with low efficiency, Jeans-mass filtering compensates for the difference in the emissivity of the suppressible haloes in these two cases. As a result, in the presence of lower mass source haloes, reionization begins earlier, but the later stages of reionization and the time of overlap are dictated by the efficiency of the higher mass haloes, independent of the efficiency of the suppressible, lower mass haloes. Hence, while the lower mass haloes do not alter the overlap redshift, Z ov , they serve to boost the electron-scattering optical depth of the universe, τ es . This may explain why observations of quasar absorption spectra at high redshift find that reionization ended late (Z ov 11). We present results for the Lambda cold dark matter universe with cosmological parameters from both 1- and 3-yr data releases of Wilkinson Microwave Anisotropy Probe. Reionization histories consistent with current constraints on Z ov and τ es are shown to be achievable with standard stellar sources in haloes above 10 8 M⊙. Neither minihaloes nor exotic sources are required, and the phenomenon of 'double reionization' previously suggested does not occur.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/b8a6971cd79e2ef9255f99d48e1d4cb1b7b72943

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Citations in the corpus

The physics of the intergalactic medium (2007, methodology): “On the basis of high resolution simulations, Iliev et al. (2007) find the recombination clumping factor is well-fit over the redshift range 6 < z < 30 by C(z) ≃ 26.2917 exp[−0.1822z+ 0.003505z2], (114) for models using the preferred WMAP 3-year cosmological parameters (Spergel et al., 2007).”
Conditions for Reionizing the Universe with a Low Galaxy Ionizing Photon Escape Fraction (2019, background): “…cool, and Jeans filtering due to the reionizationdriven UV background, as shown by a variety of simulations (e.g., Bullock et al. 2000; Gnedin 2000; Iliev et al. 2007; Mesinger & Dijkstra 2008; Okamoto et al. 2008; Finlator et al. 2011, 2012; Alvarez et al. 2012; Oñorbe et al. 2017; Jaacks et al.…”
The Atacama Cosmology Telescope: likelihood for small-scale CMB data (2013, background): “, [27, 33, 45], as well as from the motion of galaxy clusters at later times.”
Simulating cosmic reionization: how large a volume is large enough? (2013, methodology): “LMACHs are assumed to be suppressed within ionized regions (f r ionization fraction higher than 10%), through Jeans-mass filtering, as discussed in Iliev et al. (2007).”
Hydrogen Epoch of Reionization Array (HERA) (2016, background): “Lower frequency observations also test feedback mechanisms that interact with lowmass halos at high redshifts (Iliev et al. 2007, 2012; Ahn et al. 2012).”
COSMIC MICROWAVE BACKGROUND CONSTRAINTS ON THE DURATION AND TIMING OF REIONIZATION FROM THE SOUTH POLE TELESCOPE (2011, background): “For instance, low-mass sources might suffer from thermal feedback onto their host galaxies during early stages of reionization (Hultman Kramer et al. 2006; Iliev et al. 2007).”
Reionization and Cosmology with 21-cm Fluctuations (2009, background): “In large modern simulations, the most common approach to address this issue is to begin with an N-body code to generate a distribution of halos (e.g. Ciardi, Stoehr & White 2003, Sokasian et al. 2003, Iliev et al. 2007, Zahn et al. 2007, Trac & Cen 2007).”
Radiative Transfer Simulations of Cosmic Reionization. I. Methodology and Initial Results (2006, methodology): “Large-volume but low-resolution simulations (e.g., Sokasian et al. 2003; Ciardi et al. 2003; Kohler et al. 2007; Iliev et al. 2006, 2007; Zahn et al. 2007;McQuinn et al. 2007) enable the study of the large-scale structure of dark matter, baryons, sources, and H ii regions, but theymust correct for…”
Cosmic Dawn (CoDa): the first radiation-hydrodynamics simulation of reionization and galaxy formation in the Local Universe (2015, methodology): “A common variation in simulations of the EoR, producing a similar effect, is to use a threshold in ionized fraction, as in Iliev et al. (2007, 2011); Ocvirk et al. (2014); Gillet et al. (2015).”
Escape fraction of ionizing photons from high-redshift galaxies in cosmological SPH simulations (2010, methodology): “Earlier, Gnedin & Ostriker (1997) suggested C = 30 at z ∼ 6, however Iliev et al. (2007) reported C = 10 using higher c© 2008 RAS, MNRAS 000, 1–13 resolution simulations with a RT treatment.”
Keeping the Universe ionized: photoheating and the clumping factor of the high-redshift intergalactic medium (2008, methodology): “Iliev et al. (2007) provided the following fit to the evolution of the clumping factor in their simulation, CIliev07(z) = 26.2917 exp(−0.1822z + 0.003505z2), (6) which is valid over the range 6 < z < 30.”
Inside-out or outside-in: the topology of reionization in the photon-starved regime suggested by Lyα forest data (2008, methodology): “…2 http://web.phys.cmu.edu/ past/ 3 http://www.haystack.mit.edu/ast/arrays/mwa/ 4 http://www.lofar.org/ 5 http://www.skatelescope.org/ 2000; Ciardi, Ferrara, & White 2003; Paschos & Norman 2005; Iliev et al. 2006b; Iliev et al. 2006a; Iliev et al. 2007; McQuinn et al. 2007).”