Lyα emitters at z= 6.5 in the SSA22 field: an area more neutral or void at the end of the re-ionization epoch★

Nakamura, Etsuko; Inoue, Akio; Hayashino, T.; Horie, Masaaki; Kousai, K.; Fujii, Takeshi; Matsuda, Yoshihisa

doi:10.1111/j.1365-2966.2010.18077.x

Cited by 26 publications

(28 citation statements)

References 39 publications

(60 reference statements)

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“…Observing such enhanced clustering would confirm the prediction that the HII regions during reionization are large (McQuinn et al 2007). This prediction has arguably gained some tentative observational support from the latest large-area surveys for Lyα emitters at z ≃ 6.5, where it has been found that, depending on luminosity, the number density of LAEs varies by a factor of 2 − 10 between different ≃ 1/4 deg 2 fields (Ouchi et al 2010;Nakamura et al 2011). However, Ouchi et al (2010) report no evidence for any significant clustering amplitude boost at z ≃ 6.6, and it seems clear that the meaningful search for this effect must await surveys of large samples of LAEs and LBGs at z > 7 covering many square degrees.…”

Section: Lyman-α Emissionmentioning

confidence: 95%

Observing the First Galaxies

Dunlop

2012

The First Galaxies

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I endeavour to provide a thorough overview of our current knowledge of galaxies and their evolution during the first billion years of cosmic time, corresponding to redshifts z > 5. After first summarizing progress with the seven different techniques which have been used to date in the discovery of objects at z > 5, I focus thereafter on the two selection methods which have yielded substantial samples of galaxies at early times, namely Lyman-break and Lyman-α selection. I discuss a decade of progress in galaxy sample selection at z ≃ 5 − 8, including issues of completeness and contamination, and address some of the confusion which has been created by erroneous reports of extreme-redshift objects. Next I provide an overview of our current knowledge of the evolving ultraviolet continuum and Lyman-α galaxy luminosity functions at z ≃ 5 − 8, and discuss what can be learned from exploring the relationship between the Lyman-break and Lyman-α selected populations.

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Section: Lyman-α Emissionmentioning

confidence: 95%

Observing the First Galaxies

Dunlop

2012

The First Galaxies

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“…Hu et al (2010) report significantly different LF parameters from the observations and analysis of a spectroscopically confirmed sample of NB selected LAEs. Similarly, Nakamura et al (2011) report significantly lower number counts that they tentatively attribute to cosmic variance. Differences in the selection criteria and in extrapolations of the spectroscopic samples to photometric samples might partly explain the discrepancies between the various Lyα LAE LFs available in the literature: Kashikawa et al (2011) have carried out extended spectroscopic confirmation of their earlier photometric sample, resulting in luminosity functions closer to the ones of Hu et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Evolution of the observed Lyαluminosity function fromz= 6.5 toz= 7.7: evidence for the epoch of reionization?

Clément¹,

Cuby²,

Courbin³

et al. 2012

A&A

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Aims. Lyα emitters (LAEs) can be detected out to very high redshifts during the epoch of reionization. The evolution of the LAE luminosity function with redshift is a direct probe of the Lyα transmission of the intergalactic medium (IGM), and therefore of the IGM neutral-hydrogen fraction. Measuring the Lyα luminosity function (LF) of Lyα emitters at redshift z = 7.7 therefore allows us to constrain the ionizing state of the Universe at this redshift. Methods. We observed three 7. ′ 5×7. ′ 5 fields with the HAWK-I instrument at the VLT with a narrow band filter centred at 1.06 µm and targeting Lyα emitters at redshift z ∼ 7.7. The fields were chosen for the availability of multiwavelength data. One field is a galaxy cluster, the Bullet Cluster, which allowed us to use gravitational amplification to probe luminosities that are fainter than in the field. The two other fields are subareas of the GOODS Chandra Deep Field South and CFHTLS-D4 deep field. We selected z = 7.7 LAE candidates from a variety of colour criteria, in particular from the absence of detection in the optical bands. Results. We do not find any LAE candidates at z = 7.7 in ∼ 2.4 × 10 4 Mpc 3 down to a narrow band AB magnitude of ∼ 26, which allows us to infer robust constraints on the Lyα LAE luminosity function at this redshift. Conclusions. The predicted mean number of objects at z = 6.5, derived from somewhat different luminosity functions of Hu et al. (2010), Ouchi et al. (2010), and Kashikawa et al. (2011. Depending on which of these luminosity functions we refer to, we exclude a scenario with no evolution from z = 6.5 to z = 7.7 at 85% confidence without requiring a strong change in the IGM Lyα transmission, or at 99% confidence with a significant quenching of the IGM Lyα transmission, possibly from a strong increase in the high neutral-hydrogen fraction between these two redshifts.

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“…Astrophysical evidences for this phase transition include the measurements of the total Thompson scattering optical depth due to reionization from CMB anisotropies [7], the specific luminosity density of the observed galaxy population at 6 < z < 8 [101,102], and the Gunn-Peterson [103] absorption troughs in the spectrum of high redshift bright sources such as quasars, Lyman-α emitters and γ-ray bursts [4,5,105,106,107]. Starting when the very first sources of ionizing photons appeared, the epoch of reionization was concluded around 6 z 12, according to the latest observational tests [5,7,101,102,106,107]. In addition, duration of reionization has been constrained to ∆z < 7.9 by measuring the kinetic Sunyaev-Zeldovich effect [108].…”

Section: Effects Of V Bc During Reionizationmentioning

confidence: 99%

Supersonic relative velocity between dark matter and baryons: A review

Fialkov

2014

Int. J. Mod. Phys. D

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Our understanding of astrophysical and cosmological phenomena in recent years has improved enormously thanks to precision measurements of various cosmic signals such as Cosmic Microwave Background radiation, emission of galaxies and dust, spectral lines attributed to various elements etc. Despite this, our knowledge at intermediate redshifts (10 < z < 1100) remains fragmentary and incomplete, and as a consequence, various physical processes happening between the epochs of hydrogen recombination and reionization remain still highly unconstrained. Moreover, some important fragments of the theoretical description that are less decisive for the Universe today, but that had an important impact at intermediate redshifts, have been omitted in some of the studies concerning the Universe at high redshifts. One such neglected phenomenon, only recently brought to the attention of the community by D. Tseliakhovich and C. M. Hirata (2010) [1], is the fact that after hydrogen recombination the large-scale baryons and dark matter fluctuations had supersonic relative velocities: the central topic of this review. The relative velocities between dark matter and baryons formally introduce a second order effect on the standard results and thus have been neglected in the framework of linear theory. However, when properly considered, the velocities yield a non-perturbative contribution to the growth of structures which is then inherited by the majority of cosmic signals coming from redshifts above z ∼ 10, and in certain cases may even propagate to various low-redshift observables such as the Baryon Acoustic Oscillations measured from the distribution of galaxies. At higher redshifts, the supersonic velocities have thus strong impact affecting the abundance of M ∼ 10 6 M⊙ halos in an inhomogeneous way, hindering the formation of first stars, leaving traces in the redshifted 21-cm signal of neutral hydrogen, as well as having other important contributions at high redshifts all of which we review in this manuscript.

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Lyα emitters at z= 6.5 in the SSA22 field: an area more neutral or void at the end of the re-ionization epoch★

Cited by 26 publications

References 39 publications

Observing the First Galaxies

Observing the First Galaxies

Evolution of the observed Lyαluminosity function fromz= 6.5 toz= 7.7: evidence for the epoch of reionization?

Supersonic relative velocity between dark matter and baryons: A review

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