Observational Constraints on Cosmic Reionization

By Xiaohui Fan, C. Carilli, B. Keating. 2006

502 citations recorded by the source corpus.

Observations have set the first constraints on the epoch of reionization (EoR), corresponding to the formation epoch of the first luminous objects. Studies of GunnPeterson (GP) absorption indicate a rapid increase in the neutral fraction of the intergalactic medium (IGM) from xHI 10 −3 , perhaps up to 0.1, at z ∼ 6, while the large scale polarization of the cosmic microwave background (CMB) implies a significant ionization fraction extending to higher redshifts, z ∼ 11 ± 3. These results, as well as observations of galaxy populations, suggest that reionization is a process that begins as early as z ∼ 14, and ends with the “percolation” phase at z ∼ 6 to 8. Low luminosity star-forming galaxies are likely the dominant sources of reionizing photons. Future low-frequency radio telescopes will make direct measurements of HI 21-cm emission from the neutral IGM during the EoR, and measurements of secondary CMB temperature anisotropy will provide details of the dynamics of the reionized IGM.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a82c72f9389255d06793a3521bb2582cee0d0ad3

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Citations in the corpus

Distant radio galaxies and their environments (2008, background): “Recent observational constraints on suggest that cosmic reionization may have taken place between z ∼ 11 and z ∼ 6 (Fan et al 2006).”
MOLECULAR GAS IN z ∼ 6 QUASAR HOST GALAXIES (2010, methodology): “The Gunn-Peterson absorption seen in their rest-frame UV spectra indicates that they exist close to the epoch of the cosmic reionization, and thus, are among the first generation of the most luminous objects in the universe (Fan et al. 2006b; Fan et al. 2006c).”
Pathways to massive black holes and compact star clusters in pre-galactic dark matter haloes with virial temperatures ≳10 000 K (2008, background): “The presence of super-massive black holes (SMBHs) as massive as 3 × 109 at these early times (Haiman & Loeb 2001; Fan 2001; Fan et al. 2006) requires a rapid and efficient build-up of SMBHs, challenging models based on Eddington limited growth of stellar mass black holes (e.g. Volonteri et al.…”
An ALMA [C ii] Survey of 27 Quasars at z > 5.94 (2018, background): “The steep evolution of the average UV transmission due to neutral hydrogen’s Lyα line points to a rapid change in the ionization properties of the intergalactic medium, suggesting that we are entering the epoch of reionization at these redshifts (Fan et al. 2006).”
BRIGHT SOURCE SUBTRACTION REQUIREMENTS FOR REDSHIFTED 21 cm MEASUREMENTS (2010, background): “These results suggest signiﬁcant variance in both space and time, starting perhaps as far back as z ∼ 11 (Komatsu et al. (2010); WMAP 7 year data) and extending to z ∼ 6 (Fan et al. 2006).”
Cool Gas in High-Redshift Galaxies (2013, background): “Research in recent years has resulted in an explosion in the number and type of galaxies detected in molecular line emission, as well as in atomic fine structure line emission, in the distant Universe.”
Probing the first stars and black holes in the early Universe with the Dark Ages Radio Explorer (DARE) (2008, background): “This epoch provides the key connection between telescopic images of the structures and galaxies seen at redshifts z<5 and observations of the extraordinarily smooth Universe 400,000 years after the Big Bang (z~1100) seen via the Cosmic Microwave Background (e.g., Samtleben et al. 2007).”
Feedback from winds and supernovae in massive stellar clusters – I. Hydrodynamics (2012, background): “Ionizing radiation from massive stars is also important for the ionization of galaxies (Reynolds 1984) and the reionization of the early universe (Fan et al. 2006).”
GALAXY PROPERTIES AND UV ESCAPE FRACTIONS DURING THE EPOCH OF REIONIZATION: RESULTS FROM THE RENAISSANCE SIMULATIONS (2016, background): “…from these observed “bright galaxies” are not enough to fully ionize the universe by z=6 (Robertson et al. 2013), as implied by quasar observations (Fan et al. 2006), thus fainter galaxies and other ionizing sources (e.g., accreting black holes) are needed to provide the remaining ionizing…”
The Evolution of the Intergalactic Medium (2015, methodology): “…forests cannot be used to directly detect neutral regions,19 the z > 5 Lymanseries forest exhibits dramatic evolution in the mean opacity as well as extremely large spatial fluctuations in the transmission (Becker et al. 2001; Fan et al. 2002, 2006; Mortlock et al. 2011; Becker et al. 2015).”
Planck2018 results (2018, background): “Values of σ8 inferred from the CMB power-spectrum data in a given theoretical model cannot be arbitrarily low because the reionization optical depth cannot be arbitrarily small; observations of high-redshift quasars (Fan et al. 2006) indicate that reionization was largely complete by redshift z ' 6.”
REIONIZATION AFTER PLANCK: THE DERIVED GROWTH OF THE COSMIC IONIZING EMISSIVITY NOW MATCHES THE GROWTH OF THE GALAXY UV LUMINOSITY DENSITY (2015, background): “The most important constraints make use of the Gunn–Peterson optical depth measured from bright z ∼ 6 quasars (Becker et al. 2001; Fan et al. 2006a, 2006b) and also by looking at the distribution of dark gaps in z = 6 quasar spectra (McGreer et al. 2015) which suggest that cosmic reionization is…”
MontePython 3: Boosted MCMC sampler and other features (2018, background): “0 SC [66] hst Hubble Space Telescope H0 prior 3.”