We present the Ly{alpha} luminosity function (LF), clustering measurements, and Ly{alpha} line profiles based on the largest sample to date of 207 Ly{alpha} emitters (LAEs) at z = 6.6 on the 1 deg{sup 2} sky of Subaru/XMM-Newton Deep Survey field. Our z = 6.6 Ly{alpha} LF including cosmic variance estimates yields the best-fit Schechter parameters of {phi}* = 8.5{sup +3.0}{sub -2.2} x 10{sup -4} Mpc{sup -3} and L*{sub Ly{alpha}} = 4.4{sup +0.6}{sub -0.6} x 10{sup 42} erg s{sup -1} with a fixed {alpha} = -1.5, and indicates a decrease from z = 5.7 at the {approx}>90% confidence level. However, this decrease is not large, only {approx_equal}30% in Ly{alpha} luminosity, which is too small to have been identified in the previous studies. A clustering signal of z = 6.6 LAEs is detected for the first time. We obtain the correlation length of r{sub 0}= 2-5 h {sup -1}{sub 100} Mpc and a bias of b= 3-6, and find no significant boost of clustering amplitude by reionization at z = 6.6. The average hosting dark halo mass inferred from clustering is 10{sup 10}-10{sup 11} M{sub sun}, and a duty cycle of LAE population is roughly {approx}1%, albeit with large uncertainties. The averagemore » of our high-quality Keck/DEIMOS spectra shows an FWHM velocity width of 251 {+-} 16 km s{sup -1}. We find no large evolution of the Ly{alpha} line profile from z = 5.7 to 6.6, and no anti-correlation between Ly{alpha} luminosity and line width at z = 6.6. The combination of various reionization models and our observational results about the LF, clustering, and line profile indicates that there would exist a small decrease of the intergalactic medium's (IGM's) Ly{alpha} transmission owing to reionization, but that the hydrogen IGM is not highly neutral at z = 6.6. Our neutral-hydrogen fraction constraint implies that the major reionization process took place at z {approx}> 7.« less

https://iopscience.iop.org/article/10.1088/0004-637X/723/1/869/pdf

STATISTICS OF 207 Lyα EMITTERS AT A REDSHIFT NEAR 7: CONSTRAINTS ON REIONIZATION AND GALAXY FORMATION MODELS*

The density and peculiar velocity fields of nearby galaxies

We present a test of different error estimators for two-point clustering statistics, appropriate for present and future large galaxy redshift surveys Using an ensemble of very large dark matter ACDM N-body simulations, we compare internal error estimators (jackknife and bootstrap) to external ones (Monte Carlo realizations) For three-dimensional clustering statistics, we find that none of the internal error methods investigated is able to reproduce either accurately or robustly the errors of external estimators on 1 to 25 h ―1 Mpc scales The standard bootstrap overestimates the variance of ξ (s) by ∼40 per cent on all scales probed, but recovers, in a robust fashion, the principal eigenvectors of the underlying covariance matrix The jackknife returns the correct variance on large scales, but significantly overestimates it on smaller scales This scale dependence in the jackknife affects the recovered eigenvectors, which tend to disagree on small scales with the external estimates Our results have important implications for fitting models to galaxy clustering measurements For example, in a two-parameter fit to the projected correlation function, we find that the standard bootstrap systematically overestimates the 95 per cent confidence interval, while the jackknife method remains biased, but to a lesser extent Ignoring the systematic bias, the scatter between realizations, for Gaussian statistics, implies that a 2σ confidence interval, as inferred from an internal estimator, corresponds in practice to anything from 1σ to 3σ By oversampling the subvolumes, we find that it is possible, at least for the cases we consider, to obtain robust bootstrap variances and confidence intervals that agree with external error estimates Our results are applicable to two-point statistics, like ξ(s) and w p (r p ), measured in large redshift surveys, and show that the interpretation of clustering measurements with internally estimated errors should be treated with caution

/pdf/statistical-analysis-of-galaxy-surveys-i-robust-error-45m6khzs1n.pdf

Statistical analysis of galaxy surveys – I. Robust error estimation for two-point clustering statistics

We have conducted a deep radio survey with the Very Large Array at 1.4 GHz of a region containing the Hubble Deep Field (HDF). This survey overlaps previous observations at 8.5 GHz allowing us to investigate the radio spectral properties of microjansky sources to flux densities greater than 40 μJy at 1.4 GHz and greater than 8 μJy at 8.5 GHz. A total of 371 sources have been cataloged at 1.4 GHz as part of a complete sample within 20' of the HDF. The differential source count for this region is only marginally sub-Euclidean and is given by n(S) = (8.3 ± 0.4)S-2.4±0.1 sr-1 Jy-1. Above about 100 μJy the radio source count is systematically lower in the HDF as compared to other fields. We conclude that there is clustering in our radio sample on size scales of 1'-40'. The 1.4 GHz-selected sample shows that the radio spectral indices are preferentially steep (1.4 = 0.85) and that the sources are moderately extended with average angular size θ = 18. Optical identification with disk-type systems at z ~ 0.1-1 suggests that synchrotron emission, produced by supernovae remnants, is powering the radio emission in the majority of sources. The 8.5 GHz sample contains primarily moderately flat spectrum sources (8.5 = 0.35), with less than 15% inverted. We argue that we may be observing an increased fraction of optically thin bremsstrahlung over synchrotron radiation in these distant star-forming galaxies.

http://iopscience.iop.org/article/10.1086/308684/pdf

The Nature of Radio Emission from Distant Galaxies: The 1.4 GHz Observations

We have measured the angular correlation function w(?) for a sample of 871 Lyman-break galaxies (LBGs) in five fields at redshift z ~ 3. Fitting the power law Aw ?-? to a weighted average of w(?) from the five fields over the range 12'' ? 330'', we find Aw ~ 2 arcsec? and ? ~ 0.9. The slope is, within the errors, the same as for galaxy samples in the local and intermediate-redshift universe, and a slope ? = 0.25 or shallower is ruled out by the data at the 99.9% confidence level. Because N(z) of LBGs is well determined from 376 spectroscopic LBG redshifts, the real-space correlation function can be accurately derived from the angular one through the Limber transform. The inversion of w(?) is rather insensitive to the still relatively large uncertainties on A? and ?, and the spatial correlation length is much more tightly constrained than either of these parameters. We estimate r -->0=3.3 -->+ 0.7?0.6(2.1 -->+ 0.4?0.5) h-1 Mpc (comoving) for q0 = 0.1 (0.5) at the median redshift of the survey, ${u{z}{"7016}}$ -->=3.04 (h is in units of 100 km s-1 Mpc-1 throughout this paper). The observed comoving correlation length of LBGs at z ~ 3 is comparable to that of present-day spiral galaxies and is only ~50% smaller than that of present-day ellipticals; it is as large or larger than any measured in recent intermediate-redshift galaxy samples (0.3 z 1). By comparing the observed galaxy correlation length to that of the mass predicted from cold dark matter (CDM) theory, we estimate a linear bias for LBGs of b ~ 1.5 (4.5) for q0 = 0.1 (0.5), in broad agreement with our previous estimates based on preliminary spectroscopy. The strong clustering and the large bias of the LBGs are consistent with biased galaxy formation theories and provide additional evidence that these systems are associated with massive dark matter halos. The results of the clustering of LBGs at z ~ 3 emphasize that apparent evolution in the clustering properties of galaxies may be due as much to variations in effective light-to-mass bias parameter among different galaxy samples as to evolution in the mass distribution through gravitational instability.

https://iopscience.iop.org/article/10.1086/306027/pdf

The Angular clustering of Lyman - break galaxies at redshift z approximately = 3

/pdf/uncertainties-in-the-cluster-cluster-correlation-function-2y3mwezm8u.pdf

E. Nigel Ling

Papers

Uncertainties in the cluster-cluster correlation function.