First Results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) Survey: Cosmological Reionization at z ∼ 7

Zheng, Zuduo; Wang, Junxian; Rhoads, James E.; Infante, L.; Malhotra, Sangeeta; Hu, Weida; Walker, A. R.; Jiang, Linhua; Jiang, Chunyan; Hibon, Pascale; Gonzalez, Alicia; Kong, Xu; Zheng, Xianzhong; Galaz, Gaspar; Barrientos, L. Felipe

doi:10.3847/2041-8213/aa794f

Cited by 161 publications

(213 citation statements)

References 59 publications

Supporting

Mentioning

183

Contrasting

Order By: Relevance

“…For z = 6.6, similar results are also claimed by some previous studies (e.g., Matthee et al 2015;Santos et al 2016;Castellano et al 2016;Bagley et al 2017;Zheng et al 2017). Although our results suggest that the LF fittings including the bright-end LF results may reveal the true shapes of the Lyα LFs, it is also possible that the bright-end LF results are enhanced by some systematic effects.…”

Section: Lae (Ii)supporting

confidence: 59%

“…One possibility is the contribution of AGNs, which is the same as the origin of the bright-end excess at z ∼ 2 − 3 (e.g., Konno et al 2016). Another possibility is the formation of large ionized bubbles in the IGM around bright LAEs during the epoch of reionization (EoR; e.g., Santos et al 2016;Bagley et al 2017;Zheng et al 2017). The possibility of the gravitational lensing effect also needs to be considered (e.g., Wyithe et al 2011;Takahashi et al 2011;Mason et al 2015).…”

Section: Systematic Effects In the Lyα Lf Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

SILVERRUSH. IV. Lyα luminosity functions at z = 5.7 and 6.6 studied with ∼1300 Lyα emitters on the 14–21 deg2 sky

Konno

Ouchi

Shibuya

et al. 2017

Publications of the Astronomical Society of Japan

184

156

View full text Add to dashboard Cite

We present the Lyα luminosity functions (LFs) at z = 5.7 and 6.6 derived from a new large sample of 1266 Lyα emitters (LAEs) identified in total areas of 14 and 21 deg2, respectively, based on the early narrowband data of the Subaru/Hyper Suprime-Cam survey. Together with careful Monte Carlo simulations that account for the incompleteness of the LAE selection and the flux estimate systematics in the narrowband imaging, we have determined the Lyα LFs with unprecedentedly small statistical and systematic uncertainties in a wide Lyα luminosity range of 1042.8–43.8 erg s−1. We obtain best-fit Schechter parameters of $L^{*}_{\mathrm{Ly}\alpha } = 1.6^{+2.2}_{-0.6} \ (1.7^{+0.3}_{-0.7}) \times 10^{43}\:\mathrm{erg}\:\mathrm{s}^{-1}$, $\phi ^{*}_{\mathrm{Ly}\alpha } = 0.85^{+1.87}_{-0.77} \ (0.47^{+1.44}_{-0.44}) \times 10^{-4}\:\mathrm{Mpc}^{-3}$, and $\alpha = -2.6^{+0.6}_{-0.4} \ (-2.5^{+0.5}_{-0.5})$ at z = 5.7 (6.6). We confirm that our best-estimate Lyα LFs are consistent with the majority of the previous studies, but find that our Lyα LFs do not agree with the high number densities of LAEs recently claimed by Matthee/Santos et al.’s studies that may overcorrect the incompleteness and the flux systematics. Our Lyα LFs at z = 5.7 and 6.6 show an indication that the faint-end slope is very steep (α ≃ −2.5), although it is also possible that the bright-end LF results are enhanced by systematic effects such as the contribution from AGNs, blended merging galaxies, and/or large ionized bubbles around bright LAEs. Comparing our Lyα LF measurements with four independent reionization models, we estimate the neutral hydrogen fraction of the intergalactic medium to be $x_\mathrm{H\,{\small I}} = 0.3 \pm 0.2$ at z = 6.6, which is consistent with the small Thomson scattering optical depth obtained by Planck 2016.

show abstract

Section: Lae (Ii)supporting

confidence: 59%

Section: Systematic Effects In the Lyα Lf Measurementsmentioning

confidence: 99%

SILVERRUSH. IV. Lyα luminosity functions at z = 5.7 and 6.6 studied with ∼1300 Lyα emitters on the 14–21 deg2 sky

Konno

Ouchi

Shibuya

et al. 2017

Publications of the Astronomical Society of Japan

184

156

View full text Add to dashboard Cite

show abstract

“…The challenge is at least partly due to IGM attenuation of Lyα line flux at z 7 (e.g. Zheng et al 2017;Konno et al 2014;Shibuya et al 2012;Tilvi et al 2010;Matthee et al 2014). Much larger samples of z 7 LAEs, particularly spectroscopically confirmed ones, are essential to probe the physics of reionization and galaxy formation/evolution in the early universe.…”

Section: Introductionmentioning

confidence: 99%

“…In the first LAGER field (COSMOS), we have selected 23 LAE candidates at z ∼ 6.9 (Zheng et al 2017). The Lyα luminosity function shows a rapid faint-end evolution from z ∼ 6.9 to z ∼ 6.6 and 5.7, suggesting an IGM neutral hydrogen fraction of x HI =0.4-0.6 at z ∼ 6.9.…”

Section: Introductionmentioning

confidence: 99%

First Spectroscopic Confirmations of z ∼ 7.0 Lyα Emitting Galaxies in the LAGER Survey

Wang

Zheng

et al. 2017

ApJL

Self Cite

View full text Add to dashboard Cite

Narrowband imaging is a highly successful approach for finding large numbers of high redshift Lyα emitting galaxies (LAEs) up to z ∼ 6.6. However, at z 7 there are as yet only 3 narrowband selected LAEs with spectroscopic confirmations (two at z ∼ 6.9 − 7.0, one at z ∼ 7.3), which hinders extensive studies on cosmic reionization and galaxy evolution at this key epoch. We have selected 23 candidate z ∼ 6.9 LAEs in COSMOS field with the large area narrowband survey LAGER (Lyman-Alpha Galaxies at the End of Reionization). In this work we present spectroscopic followup observations of 12 candidates using IMACS on Magellan. For 9 of these, the observations are sufficiently deep to detect the expected lines. Lyα emission lines are identified in six sources (yielding a success rate of 2/3), including 3 luminous LAEs with Lyα luminosities of L Lyα ∼ 10 43.5 erg s −1 , the highest among known spectroscopically confirmed galaxies at 7.0. This triples the sample size of spectroscopically confirmed narrowband selected LAEs at z 7, and confirms the bright end bump in the Lyα luminosity function we previously derived based on the photometric sample, supporting a patchy reionization scenario. Two luminous LAEs appear physically linked with projected distance of 1.1 pMpc and velocity difference of ∼ 170 km s −1 . They likely sit in a common ionized bubble produced by themselves or with close neighbors, which reduces the IGM attenuation of Lyα. A tentative narrow N vλ1240 line is seen in one source, hinting at activity of a central massive black hole with metal rich line emitting gas.

show abstract

“…Observational studies of reionization, including GunnPeterson measurements of quasi-stellar objects (Fan et al 2006) and Cosmic Microwave Background temperature and anisotropy measurements (CMB; Planck Collaboration et al 2016), the kinetic Sunyaev-Zel'dovich effect (Zahn et al 2012;George et al 2015;Smith & Ferraro 2016) and Lyman alpha galaxy observations (Zheng et al 2017;Rhoads et al 2012;McQuinn et al 2007) have given us indications of the rough time frame of reionization, but only limited constraints on the finer spatial and temporal structures. A surge of recent radio-astronomical experiments of reionization focus on measuring the "spin-flip" transition of neutral hydrogen with a characteristic wavelength of 21 cm (Furlanetto et al 2006;Pritchard & Loeb 2012).…”

mentioning

confidence: 99%

Unlocking Sensitivity for Visibility-based Estimators of the 21 cm Reionization Power Spectrum

Zhang

Liu

Parsons

2018

ApJ

View full text Add to dashboard Cite

Radio interferometers designed to measure the cosmological 21 cm power spectrum require high sensitivity. Several modern low-frequency interferometers feature drift-scan antennas placed on a regular grid to maximize the number of instantaneously coherent (redundant) measurements. However, even for such maximum-redundancy arrays, significant sensitivity comes through partial coherence between baselines. Current visibility-based power spectrum pipelines, though shown to ease control of systematics, lack the ability to make use of this partial redundancy. We introduce a method to leverage partial redundancy in such power spectrum pipelines for drift-scan arrays. Our method cross-multiplies baseline pairs at a time lag and quantifies the sensitivity contributions of each pair of baselines. Using the configurations and beams of the 128-element Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER-128) and staged deployments of the Hydrogen Epoch of Reionization Array (HERA), we illustrate how our method applies to different arrays and predict the sensitivity improvements associated with pairing partially coherent baselines. As the number of antennas increases, we find partial redundancy to be of increasing importance in unlocking the full sensitivity of upcoming arrays.

show abstract

First Results from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) Survey: Cosmological Reionization at z ∼ 7

Cited by 161 publications

References 59 publications

SILVERRUSH. IV. Lyα luminosity functions at z = 5.7 and 6.6 studied with ∼1300 Lyα emitters on the 14–21 deg2 sky

SILVERRUSH. IV. Lyα luminosity functions at z = 5.7 and 6.6 studied with ∼1300 Lyα emitters on the 14–21 deg2 sky

First Spectroscopic Confirmations of z ∼ 7.0 Lyα Emitting Galaxies in the LAGER Survey

Unlocking Sensitivity for Visibility-based Estimators of the 21 cm Reionization Power Spectrum

Contact Info

Product

Resources

About