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We present statistical properties of diffuse Lyα haloes (LAHs) around high-z star-forming galaxies with large Subaru samples of Lyα emitters (LAEs) at z = 2.2. We make subsamples defined by the physical quantities of LAEs' central Lyα luminosities, ultraviolet (UV) magnitudes, Lyα equivalent widths, and UV slopes, and investigate LAHs' radial surface brightness (SB) profiles and scale lengths rn as a function of these physical quantities. We find that there exist prominent LAHs around LAEs with faint Lyα luminosities, bright UV luminosities, and small Lyα equivalent widths in cumulative radial Lyα SB profiles. We confirm this trend with the anticorrelation between rn and Lyα luminosities (equivalent widths) based on the Spearman's rank correlation coefficient that is ρ = -0.9 (-0.7) corresponding to the 96 per cent (93 per cent) confidence level, although the correlation between rn and UV magnitudes is not clearly found in the rank correlation coefficient. Our results suggest that LAEs with properties similar to typical Lyman-break galaxies (with faint Lyα luminosities and small equivalent widths) possess more prominent LAHs. We investigate scenarios for the major physical origins of LAHs with our results. Because we find relatively small Lyα equivalent widths up to 77 Å in LAHs that include LAEs' central components, these results suggest that the cold stream scenario is not preferred. There remain two possible scenarios of Lyα scattering in circumgalactic medium and satellite galaxies that cannot be tested with our observational data. [ABSTRACT FROM AUTHOR]

We present an unprecedentedly large catalog consisting of 2230 ≳ L* Lyα emitters (LAEs) at z = 5.7 and 6.6 on the 13.8 and 21.2deg2 sky, respectively, that are identified by the SILVERRUSH program with the first narrow-band imaging data of the Hyper Suprime-Cam (HSC) survey. We confirm that the LAE catalog is reliable on the basis of 96 LAEs whose spectroscopic redshifts are already determined by this program and previous studies. This catalogue is also available online. Based on this catalogue, we derive the rest-frame Lyα equivalent-width distributions of LAEs at z ≃ 5.7~6.6 that are reasonably explained by the exponential profiles with scale lengths of ≃ 120~170Å, showing no significant evolution from z ≃ 5.7 to z ≃ 6.6. We find that 275 LAEs with large equivalent widths (LEWs) of >240Å are candidates of young metal poor galaxies and AGNs. We also find that the fraction of LEW LAEs to all LAEs is 4% and 21% at z ≃ 5.7 and z ~ 6.6, respectively. Our LAE catalog includes 11 Lyα blobs (LABs) that are LAEs with spatially extended Lyα emission with a profile that is clearly distinguished from those of stellar objects at the ≳3σ level. The number density of the LABs at z = 6~7 is ~10~7~10~6Mpc~3, being ~10~100 times lower than those claimed for LABs at z ≃ 2~3, suggestive of disappearing LABs at z ≳ 6, albeit with the different selection methods and criteria for the low and high-z LABs. [ABSTRACT FROM AUTHOR]

We present initial results from the Subaru Strategic Program (SSP) with Hyper Suprime-Cam (HSC) on a comprehensive survey of emission-line galaxies at z < 1.5 based on narrowband imaging. The first Public Data Release provides us with data from two narrowband filters, specifically NB816 and NB921 over 5.7 deg2 and 16.2 deg2 respectively. The 5 σ limiting magnitudes are 25.2 mag (UltraDeep layer, 1.4 deg2) and 24.8 mag (Deep layer, 4.3 deg2) for NB816, and 25.1 mag (UltraDeep, 2.9 deg2) and 24.6-24.8 mag (Deep, 13.3 deg2) for NB921. The wide-field imaging allows us to construct unprecedentedly large samples of 8054 H α emitters at z ≈ 0.25 and 0.40, 8656 [O III] emitters at z ≈ 0.63 and 0.84, and 16877 [O II] emitters at z ≈ 1.19 and 1.47. We map the cosmic web on scales out to about 50 comoving Mpc that includes galaxy clusters, identified by red sequence galaxies, located at the intersection of filamentary structures of star-forming galaxies. The luminosity functions of emission-line galaxies are measured with precision and are consistent with published studies. The wide field coverage of the data enables us to measure the luminosity functions up to brighter luminosities than previous studies. The comparison of the luminosity functions between the different HSC-SSP fields suggests that a survey volume of >5 × 105 Mpc3 is essential to overcome cosmic variance. Since the current data have not reached the full depth expected for the HSC-SSP, the color cut in i - NB816 or z - NB921 induces a bias towards star-forming galaxies with large equivalent widths, primarily seen in the stellar mass functions for the H α emitters at z ≈ 0.25-0.40. Even so, the emission-line galaxies clearly cover a wide range of luminosity, stellar mass, and environment, thus demonstrating the usefulness of the narrowband data from the HSC-SSP for investigating star-forming galaxies at z < 1.5. [ABSTRACT FROM AUTHOR]

The 21-cm line brightness temperature brings rich information about Epoch of Reionizaton (EoR) and high-z universe (Cosmic Dawn and Dark Age). While the power spectrum is a useful tool to investigate the EoR signal statistically, higher order statistics such as bispectrum are also valuable because the EoR signal is expected to be highly non-Gaussian. In this paper, we develop a formalism to calculate the bispectrum contributed from the thermal noise taking array configuration of telescopes into account, by extending a formalism for the power spectrum. We apply our formalism to the ongoing and future telescopes such as expanded Murchison Widefield Array (MWA), LOw Frequency AR-ray (LOFAR), Hydrogen Epoch of Reionization Array (HERA) and Square Kilometre Array (SKA). We find that expanded MWA does not have enough sensitivity to detect the bispectrum signal. On the other hand, LOFAR has better sensitivity and will be able to detect the peaks of the bispectrum as a function of redshift at large scales with comoving wavenumber k ≲ 0.03 Mpc-1. The SKA has enough sensitivity to detect the bispectrum for much smaller scales k ≲ 0.3 Mpc-1 and redshift z ≲ 20. [ABSTRACT FROM AUTHOR]

The 21-cm line brightness temperature brings rich information about Epoch of Reionizaton (EoR) and high-z universe (Cosmic Dawn and Dark Age). While the power spectrum is a useful tool to investigate the EoR signal statistically, higher order statistics such as bispectrum are also valuable because the EoR signal is expected to be highly non-Gaussian. In this paper, we develop a formalism to calculate the bispectrum contributed from the thermal noise taking array configuration of telescopes into account, by extending a formalism for the power spectrum. We apply our formalism to the ongoing and future telescopes such as expanded Murchison Widefield Array (MWA), LOw Frequency ARray (LOFAR), Hydrogen Epoch of Reionization Array (HERA) and Square Kilometre Array (SKA). We find that expanded MWA does not have enough sensitivity to detect the bispectrum signal. On the other hand, LOFAR has better sensitivity and will be able to detect the peaks of the bispectrum as a function of redshift at large scales with comoving wavenumber k ≲ 0.03 Mpc-1. The SKA has enough sensitivity to detect the bispectrum for much smaller scales k &#8818 0.3Mpc-1 and redshift z ≲ 20. [ABSTRACT FROM AUTHOR]

Lyα halos are observed ubiquitously around star-forming galaxies at high redshift, but their origin is still a matter of debate. We demonstrate that the emission from faint unresolved satellite sources, , clustered around the central galaxies may play a major role in generating spatially extended Lyα, continuum (UV + VIS), and Hα halos. We apply the analytic formalism developed in Mas-Ribas & Dijkstra to model the halos around Lyman Alpha Emitters (LAEs) at z = 3.1, for several different satellite clustering prescriptions. In general, our UV and Lyα surface brightness profiles match the observations well at physical kpc from the centers of LAEs. We discuss how our profiles depend on various model assumptions and how these can be tested and constrained with future Hα observations by the James Webb Space Telescope (JWST). Our analysis shows how spatially extended halos constrain (i) the presence of otherwise undetectable satellite sources, (ii) the integrated, volumetric production rates of Lyα and LyC photons, and (iii) their population-averaged escape fractions. These quantities are all directly relevant for understanding galaxy formation and evolution and, for high enough redshifts, cosmic reionization. [ABSTRACT FROM AUTHOR]

Lyα photons scattered by neutral hydrogen atoms in the circumgalactic media or produced in the halos of star-forming galaxies are expected to lead to extended Lyα emission around galaxies. Such low surface brightness Lyα halos (LAHs) have been detected by stacking Lyα images of high-redshift star-forming galaxies. We study the origin of LAHs by performing radiative transfer modeling of nine z = 3.1 Lyα emitters (LAEs) in a high resolution hydrodynamic cosmological galaxy formation simulation. We develop a method of computing the mean Lyα surface brightness profile of each LAE by effectively integrating over many different observing directions. Without adjusting any parameters, our model yields an average Lyα surface brightness profile in remarkable agreement with observations. We find that observed LAHs cannot be accounted for solely by photons originating from the central LAE and scattered to large radii by hydrogen atoms in the circumgalactic gas. Instead, Lyα emission from regions in the outer halo is primarily responsible for producing the extended LAHs seen in observations, which potentially includes both star-forming and cooling radiation. With the limit on the star formation contribution set by the ultraviolet halo measurement, we find that cooling radiation can play an important role in forming the extended LAHs. We discuss the implications and caveats of such a picture. [ABSTRACT FROM AUTHOR]