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We investigate the star-forming properties of 23 Lyman continuum (LyC) leakers at z > 3 in the Great Observatories Origins Deep Survey-South field based on a systematic review of LyC observations from the literature. Using data from the Hubble Space Telescope and the James Webb Space Telescope, we construct the spectral energy distributions for these LyC leakers, covering the spectrum from rest-frame ultraviolet to near-infrared. Through the application of a unified modeling approach, we measure the ultraviolet slope ( β ), star formation rate, and stellar mass for these LyC leakers in a consistent manner. These high-redshift LyC leakers demonstrate statistically blue UV-continuum slopes ( β ), which is consistent with their high escape fraction of LyC photons. We find that these high-redshift LyC leakers span a wide range of specific star formation rate ( $\mathrm{log}(\mathrm{sSFR}$ /yr) from −8.6 to −6.7). Ten of these LyC leakers are located on the star formation main sequence, instead of all being in the starburst mode. The results indicate that intense bursts of star formation are not necessarily required for the leakage of LyC photons for galaxies at z > 3.

Lyman continuum (LyC) emitters at z > 3 provide critical samples for studying the contribution of galaxies to the ionizing background in the epoch of reionization. We collect a sample of z > 3 LyC emitters, a dominant fraction (∼60%–70%) of which show spatial offsets between LyC emission and the nonionizing continuum. From this sample, especially, we find a case of an offset LyC emitter, CDFS-6664 ( z = 3.797), which shows two components in the high-resolution Hubble Space Telescope and James Webb Space Telescope images. The exceptionally rich data set of CDFS-6664 enables us to extract the two components across multiple wavelengths and estimate their physical properties. We show that CDFS-6664 is consistent with a major merger system with boosted star formation in both components and that the offset LyC emission is most likely associated with the bluer and younger component in this merging system. Our result offers an example in which the offset can be caused by a merger. Future observations of more offset LyC emitters would elucidate the role that mergers play in the escape of LyC photons.

We present the first results of the Hubble Deep Hydrogen Alpha (HDH α ) project, which analyzes the space-borne deep H α narrowband imaging data in the GOODS-S region. The HDH α data comprises 72 orbits’ images taken with the Hubble Space Telescope (HST) Advanced Camera for Surveys/Wide Field Channel F658N filter. The exposure time varies across a total area of ∼76.1 arcmin ^2 , adding up to a total exposure time of 195.7 ks, among which 68.8 ks are spent in the deepest region. These images are aligned, reprojected, and combined to have the same pixel grid as the Hubble Legacy Fields. The scientific goals of the HDH α include establishing a sample of emission-line galaxies (ELGs) including [O iii ] emitters at z ∼ 0.3, [O ii ] emitters at z ∼ 0.8, and Ly α emitters (LAEs) at z ∼ 4.4, studying the line morphology of ELGs with high resolution imaging data, and statistically analyzing the line luminosity functions and line equivalent-width distributions of ELGs selected with HST. Furthermore, the HDH α project enhances the legacy value of the GOODS-S field by contributing the first HST-based narrowband image to the existing data sets, which includes the HST broadband data and other ancillary data from X-ray to radio taken by other facilities. In this paper, we describe the data reduction process of the HDH α , select ELGs based on HST's F658N and broadband data, validate the redshifts of the selected candidates by crossmatching with the public spectroscopic catalogs in the GOODS-S, and present a final catalog of the confirmed [O iii ] emitters at z ∼ 0.3, [O ii ] emitters at z ∼ 0.8, and LAEs at z ∼ 4.4.

Efficient, stable and cost-effective oxygen evolution catalysts (OECs) operating in near-neutral or weak acid media have highly practical applications in electrochemical (EC) and photoelectrochemical (PEC) fields. However, conventional catalysts are mostly based on precious metals, while those based on earth-abundant elements that are efficient in alkaline solution generally suffer from dissolution in such media. Herein, we show that novel manganese silicate-based film materials prepared from thermal vapor deposition and a subsequent microwave reaction can act as potential oxygen evolution reaction (OER) catalysts in near-neutral media. Pristine manganese silicate displays excellent intrinsic catalytic activity. With W doping, the catalysts exhibit remarkably better apparent catalytic activity as it leads to the exposure of more active sites without impairing the bulk conductivity. W doping also serves to significantly adjust the elementary valence states of Mn and enrich the surface hydroxyl groups, resulting in much improved stability. DFT calculations reveal that the theoretical overpotential of manganese silicate is comparable to that of other reported manganese oxide OER catalysts. These results demonstrate manganese silicates as a new class of OECs for stable water splitting in near-neutral media. They also illustrate a new pathway of improving stability in near-neutral media by introducing high-valency metal elements for the design of nonprecious OEC. [ABSTRACT FROM AUTHOR]