Search

The 100% detection rate of Ly alpha emission in a sample of four luminous z similar to 8 galaxies with red Spitzer/IRAC colors suggests objects with unusual ionizing capabilities that created early ionized bubbles in a neutral era. Whether such bubbles reflect enhanced ionizing properties (nature) or an overdense environment (nurture), however, remains unclear. Here we aim to distinguish between these hypotheses via a search for Ly alpha emission in five fainter galaxies drawn from the CANDELS-GOODS fields using a similar IRAC excess and UV magnitudes that should reflect reduced clustering effects. Using Keck/MOSFIRE we tentatively detect >4 sigma line emission in only two targets at redshifts z(Ly alpha) = 7.1081 and 7.9622 with rest-frame EWs of 16-17 angstrom, similar to 1.5x weaker compared to their brighter counterparts. Thus, we find a reduced rate for Lya emission of 0.40(-0.25)(+0.30) compared to 1.00(-0.44)(+0.00) for more luminous examples. The lower rate agrees with predictions from simulations of a mostly neutral intergalactic medium and an intrinsic EW0, Ly alpha distribution for z similar to 6 galaxies. However, even with an extreme EW0, Ly alpha model, it is challenging to match the detection rate for the luminous objects. Spectral energy distribution fitting of our fainter sample indicates young and star-forming systems, albeit with less extreme star formation rates and ionization parameters compared to their luminous counterparts. The enhanced Ly alpha rate in luminous galaxies is thus likely a byproduct of both extreme ionizing properties as well as environmental effects. Further studies with JWST may be required to resolve the physical nature of this puzzling population.

Aims. The demographics of the production and escape of ionizing photons from UV-faint early galaxies is a key unknown that has hindered attempts to discover the primary drivers of reionization. With the advent of JWST, it is finally possible to observe the rest-frame optical nebular emission from individual sub-L similar to z > 3 galaxies to measure the production rate of ionizing photons, xi(ion).Methods. Here we study a sample of 370 z similar to 3 7 galaxies spanning 23 < M-UV < 15:5 (median M-UV approximate to 18) with deep multiband HST and JWST /NIRCam photometry that covers the rest-UV to the optical from the GLASS and UNCOVER JWST surveys. Our sample includes 102 galaxies with Lyman-alpha emission detected in MUSE spectroscopy. We used H ff fluxes inferred from NIRCam photometry to estimate the production rate of ionizing photons that do not escape these galaxies, xi(ion)(1 f(esc)).Results. We find median log(10) xi(ion)(1 f(esc)) = 25.33 similar to 0.47, with a broad intrinsic scatter of 0.42 dex, which implies a broad range of galaxy properties and ages in our UV-faint sample. Galaxies detected with Lyman-alpha have similar to 0.1 dex higher xi(ion)(1 f(esc)), which is explained by their higher H ff equivalent width distribution; this implies younger ages and higher specific star formation rates and, thus, more O /B stars. We find significant trends of increasing xi(ion)(1 f(esc)) with increasing H ff equivalent width, decreasing UV luminosity, and decreasing UV slope; this implies that the production of ionizing photons is enhanced in young galaxies with assumed low metallicities. We find no significant evidence for sources with very high ionizing escape fractions (f(esc) > 0.5) in our sample based on their photometric properties, even amongst the Lyman-alpha-selected galaxies.Conclusions. This work demonstrates that considering the full distribution of xi(ion) across galaxy properties is important for assessing the primary drivers of reionization.

Lyman-alpha (Ly$\alpha$) emission from galaxies can be used to trace neutral hydrogen in the epoch of reionization, however, there is a degeneracy between the attenuation of Ly$\alpha$ in the intergalactic medium (IGM) and the line profile emitted from the galaxy. Large shifts of Ly$\alpha$ redward of systemic due to scattering in the interstellar medium can boost Ly$\alpha$ transmission in the IGM during reionization. The relationship between Ly$\alpha$ velocity offset from systemic and other galaxy properties is not well-established at high-redshift or low luminosities, due to the difficulty of observing emission lines which trace systemic redshift. Rest-frame optical spectroscopy with JWST/NIRSpec has opened a new window into understanding of Ly$\alpha$ at z>3. We present a sample of 12 UV-faint galaxies ($-20 \lesssim$ MUV $\lesssim -16$) at $3 \lesssim z \lesssim 6$, with Ly$\alpha$ velocity offsets, $\Delta v_{\mathrm{Ly}\alpha}$, measured from VLT/MUSE and JWST/NIRSpec from the GLASS-JWST Early Release Program. We find median $\Delta v_{\mathrm{Ly}\alpha}$ of 205 km s$^{-1}$ and standard deviation 75 km s$^{-1}$, compared to 320 and 170km s$^{-1}$ for MUV < -20 galaxies in the literature. Our new sample demonstrates the previously observed trend of decreasing Ly$\alpha$ velocity offset with decreasing UV luminosity and optical line velocity dispersion, extends to MUV $\gtrsim$ -20, consistent with a picture where the Ly$\alpha$ profile is shaped by gas close to the systemic redshift. Our results imply that during reionization Ly$\alpha$ from UV-faint galaxies will be preferentially attenuated, but that detecting Ly$\alpha$ with low $\Delta v_{\mathrm{Ly}\alpha}$ can be an indicator of large ionized bubbles., Comment: 13 pages, 4 figures

The abundance of carbon relative to oxygen (C/O) is a promising probe of star formation history in the early universe, as the ratio changes with time due to production of these elements by different nucleosynthesis pathways. We present a measurement of $\log{\mathrm{(C/O)}} = -1.01\pm0.12$ (stat) $\pm0.15$ (sys) in a $z=6.23$ galaxy observed as part of the GLASS-JWST Early Release Science Program. Notably, we achieve good precision thanks to the detection of the rest-frame ultraviolet O III], C III], and C IV emission lines delivered by JWST/NIRSpec. The C/O abundance is $\sim$0.8 dex lower than the solar value and is consistent with the expected yield from core-collapse supernovae, indicating that longer-lived intermediate mass stars have not fully contributed to carbon enrichment. This in turn implies rapid buildup of a young stellar population with age $\lesssim100$ Myr in a galaxy seen $\sim$900 million years after the Big Bang. Our chemical abundance analysis is consistent with spectral energy distribution modeling of JWST/NIRCam photometric data, which indicates a current stellar mass $\log\,\mathrm{M}_* / \mathrm{M_{sun}} = 8.4^{+0.4}_{-0.2}$ and specific star formation rate sSFR $\simeq 20$ Gyr$^{-1}$. These results showcase the value of chemical abundances and C/O in particular to study the earliest stages of galaxy assembly., 16 pages, 4 figures, 2 tables. Accepted for publication in ApJL

We present images and a multi-wavelength photometric catalog based on all of the JWST NIRCam observations obtained to date in the region of the Abell 2744 galaxy cluster. These data come from three different programs, namely the GLASS-JWST Early Release Science Program, UNCOVER, and Director's Discretionary Time program 2756. The observed area in the NIRCam wide-band filters - covering the central and extended regions of the cluster, as well as new parallel fields - is 46.5 arcmin$^2$ in total. All images in eight bands (F090W, F115W, F150W, F200W, F277W, F356W, F410M, F444W) have been reduced adopting the latest calibration and reference files available. Data reduction has been performed using an augmented version of the official JWST pipeline, with improvements aimed at removing or mitigating defects in the raw images and improving the background subtraction and photometric accuracy. We obtain a F444W-detected multi-band catalog, including all NIRCam and available HST data, adopting forced aperture photometry on PSF-matched images. The catalog is intended to enable early scientific investigations and is optimized for the study of faint galaxies; it contains 24389 sources, with a 5$\sigma$ limiting magnitude in the F444W band ranging from 28.5 AB to 30.5 AB, as a result of the varying exposure times of the surveys that observed the field. We publicly release the reduced NIRCam images, associated multi-wavelength catalog and code adopted for $1/f$ noise removal with the aim of aiding users to familiarize themselves with JWST NIRCam data and identify suitable targets for follow-up observations., Comment: Accepted for publication in The Astrophysical Journal. Revised analysis with updated comparisons

The Near-Infrared Imager and Slitless Spectrograph (NIRISS) is the science module of the Canadian-built Fine Guidance Sensor (FGS) onboard the James Webb Space Telescope (JWST). NIRISS has four observing modes: 1) broadband imaging featuring seven of the eight NIRCam broadband filters, 2) wide-field slitless spectroscopy (WFSS) at a resolving power of $\sim$150 between 0.8 and 2.2 $\mu$m, 3) single-object cross-dispersed slitless spectroscopy (SOSS) enabling simultaneous wavelength coverage between 0.6 and 2.8 $\mu$m at R$\sim$700, a mode optimized for exoplanet spectroscopy of relatively bright ($J

We present a new high-precision, JWST-based, strong lensing model for the galaxy cluster Abell 2744 at $z=0.3072$. By combining the deep, high-resolution JWST imaging from the GLASS-JWST and UNCOVER programs and a Director's Discretionary Time program, with newly obtained VLT/MUSE data, we identify 32 multiple images from 11 background sources lensed by two external sub-clusters at distances of ~160" from the main cluster. The new MUSE observations enable the first spectroscopic confirmation of a multiple image system in the external clumps. Moreover, the re-analysis of the spectro-photometric archival and JWST data yields 27 additional multiple images in the main cluster. The new lens model is constrained by 149 multiple images ($\sim66\%$ more than in our previous Bergamini et al. 2023 model) covering an extended redshift range between 1.03 and 9.76. The subhalo mass component of the cluster includes 177 member galaxies down to $m_{\rm F160W}=21$, 163 of which are spectroscopically confirmed. Internal velocity dispersions are measured for 85 members. The new lens model is characterized by a remarkably low scatter between predicted and observed positions of the multiple images (0.43"). This precision is unprecedented given the large multiple image sample, the complexity of the cluster mass distribution, and the large modeled area. The improved accuracy and resolution of the cluster total mass distribution provides a robust magnification map over a $\sim\!45$ arcmin$^2$ area, which is critical for inferring the intrinsic physical properties of the highly magnified, high-$z$ sources. The lens model and the new MUSE redshift catalog are released with this publication., Comment: Submitted to ApJ., 23 pages, 10 figures, 3 tables

We study the morphological properties of mid-infrared selected galaxies at $1.0, Comment: 19 pages, 8 figures, submitted to ApJ

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit., Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figures

We present the results of a first search for galaxy candidates at z similar to 9-15 on deep seven-band NIRCam imaging acquired as part of the GLASS-James Webb Space Telescope (JWST) Early Release Science Program on a flanking field of the Frontier Fields cluster A2744. Candidates are selected via two different renditions of the Lyman-break technique, isolating objects at z similar to 9-11, and z similar to 9-15, respectively, supplemented by photometric redshifts obtained with two independent codes. We find five color-selected candidates at z > 9, plus one additional candidate with photometric redshift z (phot) >= 9. In particular, we identify two bright candidates at M (UV) similar or equal to -21 that are unambiguously placed at z similar or equal to 10.6 and z similar or equal to 12.2, respectively. The total number of galaxies discovered at z > 9 is in line with the predictions of a nonevolving luminosity function. The two bright ones at z > 10 are unexpected given the survey volume, although cosmic variance and small number statistics limits general conclusions. This first search demonstrates the unique power of JWST to discover galaxies at the high-redshift frontier. The candidates are ideal targets for spectroscopic follow-up in Cycle-2.

The distribution and properties of the first galaxies and quasars are critical pieces of the puzzle in understanding galaxy evolution and cosmic reionization. Previous studies have often excluded unresolved sources as potential low-redshift interlopers. We combine broadband color and photometric redshift analysis with morphological selections to identify a robust sample of candidates consistent with unresolved point sources at redshifts z similar to 8 using deep Hubble Space Telescope images. We also examine G141 grism spectroscopic data to identify and eliminate dwarf star contaminants. From these analyses, we identify three bright (M (UV) less than or similar to -22 AB mag) dropout point sources at 7.5 < z < 8.1. Spectral energy distribution analyses suggest that these sources are either quasars or compact star-forming galaxies. The flux captured by the IRAC 4.5 mu m channel suggests that they have moderate H beta + [O III] equivalent widths. We calculate the number density of point sources at z similar to 7-8, and find that a double-power-law model well describes the point-source distribution. We then extend our analysis to estimate the combined point-source + galaxy luminosity function and find that the point sources have a nonnegligible contribution to the bright-end excess. The fact that the point sources dominate only at M (UV) less than or similar to -22 suggests that their contribution to cosmic reionization is likely limited. While spectroscopic follow-up is needed to confirm the nature of these point sources, this work demonstrates that the inclusion of Lyman-dropout point sources is necessary for a complete census of early galaxies at the epoch of cosmic reionization.

We present new observations of MRG-M2129, a quiescent galaxy at z = 2.15 with the Atacama Large Millimeter/submillimeter Array (ALMA). With the combination of the gravitational lensing effect by the foreground cluster and the angular resolution provided by ALMA, our data reveal 1.2 mm continuum emission at $\sim130$ pc angular resolution. Compact dust continuum is detected at 7.9 $\sigma$ in the target but displaced from its stellar peak position by $62 \pm 38$ mas, or $\sim169 \pm 105$ pc in the source plane. We find considerably high dust-to-stellar mass ratio, $4 \times 10^{-4}$. From non-detection of the [C i] 3P2 -> 3P1 line, we then derive $3 \sigma$ upper limits on the molecular gas-to-dust mass ratio $\delta_\mathrm{GDR} < 60$ and the molecular gas-to-stellar mass ratio fH2 < 2.3%. The derived $\delta_\mathrm{GDR}$ is $>2\times$ smaller than the typical value assumed for quiescent galaxies in the literature. Our study supports that there exists a broad range of $\delta_\mathrm{GDR}$ and urges submillimeter follow-up observations of quenching/recently quenched galaxies at similar redshifts. Based on the derived low $\delta_\mathrm{GDR}$ and other observed dust properties, we argue that the central black hole is still active and regulates star formation in the system. Our study exhibits a rare case of a gravitationally lensed type 2 QSO harbored by a quiescent galaxy., Comment: Accepted for publication in ApJ

The 100% detection rate of Ly$\alpha$ emission in a sample of four luminous $z\sim8$ galaxies with red Spitzer/IRAC colors suggests objects with unusual ionizing capabilities that created early ionized bubbles in a neutral era. Whether such bubbles reflect enhanced ionizing properties (nature) or an overdense environment (nurture), however, remains unclear. Here we aim to distinguish between these hypotheses via a search for Ly$\alpha$ emission in five fainter galaxies drawn from the CANDELS-GOODS fields using a similar IRAC excess and UV magnitudes that should reflect reduced clustering effects. Using Keck/MOSFIRE we tentatively detect $>4\sigma$ line emission in only two targets at redshifts $z_{\rm Ly\alpha}$=7.1081 and $z_{\rm Ly\alpha}$=7.9622 with rest-frame EWs of 16-17 A, $\sim$1.5$\times$ weaker compared to their brighter counterparts. Thus we find a reduced rate for Ly$\alpha$ emission of $0.40^{+0.30}_{-0.25}$ compared to $1.00^{+0.00}_{-0.44}$ for more luminous examples. The lower rate agrees with predictions from simulations of a mostly neutral IGM and an intrinsic EW$_{0,\rm Ly\alpha}$ distribution for $z\sim6$ galaxies. However, even with an extreme EW$_{0,\rm Ly\alpha}$ model, it is challenging to match the detection rate for the luminous objects. SED-fitting of our fainter sample indicates young and star-forming systems, albeit with less extreme SFRs and ionization parameters compared to their luminous counterparts. The enhanced Ly$\alpha$ rate in luminous galaxies is thus likely a byproduct of both extreme ionizing properties as well as environment effects. Further studies with JWST may be required to resolve the physical nature of this puzzling population., Comment: 15 pages, 4 figures, 2 tables. Accepted for publication in ApJ (in press), uploaded to match accepted version

We determine the bright end of the rest-frame UV luminosity function at $z=8-10$ by selecting bright $z\gtrsim 8$ photometric candidates from the largest systematic compilation of HST (pure-)parallel observations to date, the Super-Brightest-of-Reionizing-Galaxies (SuperBoRG) data set. The data set includes $\sim300$ independent sightlines distributed across the sky with WFC3 observations, totalling $800-1300$ arcmin$^2$ (depending on redshift). We identify 31 $z\gtrsim8$ candidates via colour selection and photo-$z$ analysis with observed magnitude ($24.1< H_{160}, Comment: Submitted to MNRAS on 4 May 2022. 11 pages, 9 figures

The 100% detection rate of Ly$α$ emission in a sample of four luminous $z\sim8$ galaxies with red Spitzer/IRAC colors suggests objects with unusual ionizing capabilities that created early ionized bubbles in a neutral era. Whether such bubbles reflect enhanced ionizing properties (nature) or an overdense environment (nurture), however, remains unclear. Here we aim to distinguish between these hypotheses via a search for Ly$α$ emission in five fainter galaxies drawn from the CANDELS-GOODS fields using a similar IRAC excess and UV magnitudes that should reflect reduced clustering effects. Using Keck/MOSFIRE we tentatively detect $>4σ$ line emission in only two targets at redshifts $z_{\rm Lyα}$=7.1081 and $z_{\rm Lyα}$=7.9622 with rest-frame EWs of 16-17 A, $\sim$1.5$\times$ weaker compared to their brighter counterparts. Thus we find a reduced rate for Ly$α$ emission of $0.40^{+0.30}_{-0.25}$ compared to $1.00^{+0.00}_{-0.44}$ for more luminous examples. The lower rate agrees with predictions from simulations of a mostly neutral IGM and an intrinsic EW$_{0,\rm Lyα}$ distribution for $z\sim6$ galaxies. However, even with an extreme EW$_{0,\rm Lyα}$ model, it is challenging to match the detection rate for the luminous objects. SED-fitting of our fainter sample indicates young and star-forming systems, albeit with less extreme SFRs and ionization parameters compared to their luminous counterparts. The enhanced Ly$α$ rate in luminous galaxies is thus likely a byproduct of both extreme ionizing properties as well as environment effects. Further studies with JWST may be required to resolve the physical nature of this puzzling population., 15 pages, 4 figures, 2 tables. Accepted for publication in ApJ (in press), uploaded to match accepted version

We report the detection of a high density of redshift $z\approx 10$ galaxies behind the foreground cluster Abell 2744, selected from imaging data obtained recently with NIRCam onboard {\it JWST} by three programs -- GLASS-JWST, UNCOVER, and DDT\#2756. To ensure robust estimates of the lensing magnification $μ$, we use an improved version of our model that exploits the first epoch of NIRCam images and newly obtained MUSE spectra, and avoids regions with $μ>5$ where the uncertainty may be higher. We detect seven bright $z\approx 10$ galaxies with demagnified rest-frame $-22 \lesssim M_{\rm UV}\lesssim -19$ mag, over an area of $\sim37$ sq. arcmin. Taking into account photometric incompleteness and the effects of lensing on luminosity and cosmological volume, we find that the density of $z\approx 10$ galaxies in the field is about $10\times$ ($3\times$) larger than the average at $M_{UV}\approx -21~ (-20)$ mag reported so far. The density is even higher when considering only the GLASS-JWST data, which are the deepest and the least affected by magnification and incompleteness. The GLASS-JWST field contains 5 out of 7 galaxies, distributed along an apparent filamentary structure of 2 Mpc in projected length, and includes a close pair of candidates with $M_{\rm UV}< -20$ mag having a projected separation of only 16 kpc. These findings suggest the presence of a $z\approx 10$ overdensity in the field. In addition to providing excellent targets for efficient spectroscopic follow-up observations, our study confirms the high density of bright galaxies observed in early {\it JWST} observations, but calls for multiple surveys along independent lines of sight to achieve an unbiased estimate of their average density and a first estimate of their clustering., Accepted for publication in ApJL, 13 pages, 4 figures

We present a search and characterization of ultra-diffuse galaxies (UDGs) in the Frontier Fields cluster Abell~2744 at $z=0.308$. We use JWST/NIRISS F200W observations, acquired as part of the GLASS-JWST Early Release Science Program, aiming to characterize morphologies of cluster UDGs and their diffuse stellar components. A total number of 22 UDGs are identified by our selection criteria using morphological parameters, down to stellar mass of $\sim10^{7}M_{\odot}$. The selected UDGs are systematically larger in effective radius in F200W than in HST/ACS F814W images, which implies that some of them would not have been identified as UDGs when selected at rest-frame optical wavelengths. In fact, we find that about one third of the UDGs were not previously identified based on the F814W data. We observe a flat distribution of the UDGs in the stellar mass-size plane, similar to what is found for cluster quiescent galaxies at comparable mass. Our pilot study using the new JWST F200W filter showcases the efficiency of searching UDGs at cosmological distances, with 1/30 of the exposure time of the previous deep observing campaign with HST. Further studies with JWST focusing on spatially-resolved properties of individual sources will provide insight into their origin., Comment: Accepted for publication in MNRAS, 10 pages, 7 figures, 2 tables

We determine the bright end of the rest-frame UV luminosity function at $z=8-10$ by selecting bright $z\gtrsim 8$ photometric candidates from the largest systematic compilation of HST (pure-)parallel observations to date, the Super-Brightest-of-Reionizing-Galaxies (SuperBoRG) data set. The data set includes $\sim300$ independent sightlines distributed across the sky with WFC3 observations, totalling $800-1300$ arcmin$^2$ (depending on redshift). We identify 31 $z\gtrsim8$ candidates via colour selection and photo-$z$ analysis with observed magnitude ($24.1< H_{160}, Submitted to MNRAS on 4 May 2022. 11 pages, 9 figures

We present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on the James Webb Space Telescope (JWST) as part of the GLASS-JWST Early Release Science program. We select 388 sources at redshifts \(0.8 < z < 5.4\) and use the seven 0.9--5\micron\ NIRCam filters to generate rest-frame $gri$ composite color images, and conduct visual morphological classification. Compared to HST-based work we find a higher incidence of disks and bulges than expected at $z>1.5$, revealed by rest frame optical imaging. We detect 123 clear disks (58 at $z>1.5$) of which 76 have bulges. No evolution of bulge fraction with redshift is evident: 61\% at \(z 10^{9.5}\, {\rm M}_{\odot}\) (\(N=41\)) but only 52\% at \(M < 10^{9.5}\, {\rm M}_{\odot}\) (\(N=82\)). We supplement visual morphologies with non-parametric measurements of Gini and Asymmetry coefficients in the rest-frame $i$-band. Our sources are more asymmetric than local galaxies, with slightly higher Gini values. When compared to high-z rest-frame ultraviolet measurements with Hubble Space Telescope, JWST shows more regular morphological types such as disks, bulges and spiral arms at $z>1.5$, with smoother (i.e. lower Gini) and more symmetrical light distributions., Accepted for publication in ApJ Letters

The formation of the first generation of quasars and galaxies has been one of the top priority subjects in astronomy today. Such objects in the early universe play the key role in the cosmic (re-)ionization history, and thus their identification is of critical interest. In this contribution, we present results from SuperBoRG, a project compiling all data taken with HST pure-parallel surveys in the past decade. From ~300 independent sightlines (~0.3deg2 in total area), we identified a number of luminous candidates at 88.

The formation of the first generation of quasars and galaxies has been one of the top priority subjects in astronomy today. Such objects in the early universe play the key role in the cosmic (re-)ionization history, and thus their identification is of critical interest. In this contribution, we present results from SuperBoRG, a project compiling all data taken with HST pure-parallel surveys in the past decade. From ~300 independent sightlines (~0.3deg2 in total area), we identified a number of luminous candidates at 88.

We present the Super Eight galaxies - a set of very luminous, high-redshift ($7.1, 21 pages, 17 figures, accepted for publication in ApJ

The CIII] and CIV rest-frame UV emission lines are powerful probes of the ionizations states of galaxies. They have furthermore been suggested as alternatives for spectroscopic redshift confirmation of objects at the epoch of reionization ($z>6$), where the most frequently used redshift indicator, Ly$��$, is attenuated by the high fraction of neutral hydrogen in the inter-galactic medium. However, currently only very few confirmations of carbon UV lines at these high redshifts exist, making it challenging to quantify these claims. Here, we present the detection of CIV$����$1548,1551�� in \HST\ slitless grism spectroscopy obtained by GLASS of a Ly$��$ emitter at $z=6.11$ multiply imaged by the massive foreground galaxy cluster RXJ2248. The CIV emission is detected at the 3--5$��$ level in two images of the source, with marginal detection in two other images. We do not detect significant CIII]$����$1907,1909�� emission implying an equivalent width EW$_\textrm{CIII]}0.7$ (2$��$). Combined with limits on the rest-frame UV flux from the HeII$��$1640�� emission line and the OIII]$����$1661,1666�� doublet, we put constraints on the metallicity and the ionization state of the galaxy. The estimated line ratios and equivalent widths do not support a scenario where an AGN is responsible for ionizing the carbon atoms. SED fits including nebular emission lines imply a source with a mass of log(M/M$_\odot)\sim9$, SFR of around 10M$_\odot$/yr, and a young stellar population $, Update after replying to referee report from ApJ

Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3 < z < 0.7. We use 85 foreground and background galaxies in the same redshift range as a field sample. The samples are well matched in stellar mass (108-1011 M⊙) and star formation rate (0.5-50 M⊙ yr-1). We visually classify galaxies in terms of broad band morphology, H? morphology, and likely physical process acting on the galaxy. Most H? emitters have a spiral morphology (41% ± 8% in clusters, 51% ± 8% in the field), followed by mergers/interactions (28% ± 8%, 31% ±7%, respectively) and early-type galaxies (remarkably as high as 29% ±8% in clusters and 15% ± 6% in the field). A diversity of H? morphologies is detected, suggesting a diversity of physical processes. In clusters, 30% ± 8% of the galaxies present a regular morphology, mostly consistent with star formation diffused uniformly across the stellar population (mostly in the disk component, when present). The second most common morphology (28% ±8%) is asymmetric/jellyfish, consistent with rampressure stripping or other non-gravitational processes in 18% ± 8% of the cases. Ram-pressure stripping appears significantly less prominent in the field (2% ± 2%), where the most common morphology/mechanism appears to be consistent with minor gas-rich mergers or clump accretion. This work demonstrates that while environmentspecific mechanisms affect galaxy evolution at this redshift, they are diverse and their effects are subtle. A full understanding of this complexity requires larger samples and detailed and spatially resolved physical models.

Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3< z, ApJ in press (22 pages, 21 figures)

Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3\lt z\lt 0.7. We use 85 foreground and background galaxies in the same redshift range as a field sample. The samples are well matched in stellar mass (108-1011 {M}☉ ) and star formation rate (0.5-50 {M}☉ {{yr}}-1). We visually classify galaxies in terms of broad band morphology, Hα morphology, and likely physical process acting on the galaxy. Most Hα emitters have a spiral morphology (41% ± 8% in clusters, 51% ± 8% in the field), followed by mergers/interactions (28% ± 8%, 31% ± 7%, respectively) and early-type galaxies (remarkably as high as 29% ± 8% in clusters and 15% ± 6% in the field). A diversity of Hα morphologies is detected, suggesting a diversity of physical processes. In clusters, 30% ± 8% of the galaxies present a regular morphology, mostly consistent with star formation diffused uniformly across the stellar population (mostly in the disk component, when present). The second most common morphology (28% ± 8%) is asymmetric/jellyfish, consistent with ram-pressure stripping or other non-gravitational processes in 18% ± 8% of the cases. Ram-pressure stripping appears significantly less prominent in the field (2% ± 2%), where the most common morphology/mechanism appears to be consistent with minor gas-rich mergers or clump accretion. This work demonstrates that while environment-specific mechanisms affect galaxy evolution at this redshift, they are diverse and their effects are subtle. A full understanding of this complexity requires larger samples and detailed and spatially resolved physical models.

Using the deepest data yet obtained, we find no evidence preferring compaction-triggered quenching---where rapid increases in galaxy density truncate star formation---over a null hypothesis in which galaxies age at constant surface density ($\Sigma_e\equiv M_*/2\pi r_{e}^{2}$). Results from two fully empirical analyses and one quenching-free model calculation support this claim at all $z\leq3$: (1) Qualitatively, galaxies' mean $U-V$ colors at $6.5\lesssim\log\Sigma_e/{\rm M_\odot}\,{\rm kpc}^{-2}\lesssim10$ have reddened at rates/times correlated with $\Sigma_e$, implying that there is no density threshold at which galaxies turn red but that $\Sigma_e$ sets the pace of maturation; (2) Quantitatively, the abundance of $\log M_*/{\rm M_\odot}\geq9.4$ red galaxies never exceeds that of the total population a quenching time earlier at any $\Sigma_e$, implying that galaxies need not transit from low to high densities before quenching; (3) Applying $d\log r_{e}/dt =1/2\,d\log M_*/dt$ to a suite of lognormal star formation histories reproduces the evolution of the size--mass relation at $\log M_*\geq10$. All results are consistent with evolutionary rates being set ab initio by global densities, with denser objects evolving faster than less-dense ones towards a terminal quiescence induced by gas depletion or other $\sim$Hubble-timescale phenomena. Unless stellar ages demand otherwise, observed $\Sigma_e$ thresholds need not bear any physical relation to quenching beyond this intrinsic density--formation epoch correlation, adding to Lilly & Carollo's arguments to that effect., Comment: 11 pages, 9 figures; Accepted to ApJ. This version replaces "How Strong is the Evidence for Density-Triggered Quenching?" (posted August 2016) to reflect revisions during refereeing. All results are unchanged, but the text now includes modeling, data, and appendices not present in the original manuscript. A movie of the size--mass evolution (Figure 4) is available upon request

Using the HST/WFC3 and ACS multi-band imaging data taken in CANDELS and 3D-HST, we study the general properties and the diversity of the progenitors of the Milky Way (MWs) and local massive galaxy (MGs) at 0.5 < z < 3.0, based on a constant cumulative number density analysis. After careful data reduction and stacking analysis, we conduct a radially resolved pixel SED fitting to obtain the radial distributions of the stellar mass and rest-frame colors. The stellar mass of MWs increases in self-similar way, irrespective of the radial distance, while that of MGs grows in inside-out way where they obtain ~ 75% of the total mass at outer (> 2.5 kpc) radius since z ~ 2. Although the radial mass profiles evolve in distinct ways, the formation and quenching of the central dense region (or bulge) ahead of the outer disk formation are found to be common for both systems. The sudden reddening of bulge at z ~ 1.6 and z ~ 2.4 for MWs and MGs, respectively, suggests the formation of bulge and would give a clue to the different gas accretion histories and quenching. A new approach to evaluate the morphological diversity is conducted by using the average surface density profile and its dispersion. The variety of the radial mass profiles for MGs peaks at higher redshift (z > 2.8), and then rapidly converges to more uniform shape at z < 1.5, while that for MWs remains in the outer region over the redshift. Compared with the observed star formation rates and color profiles, the evolution of variety is consistently explained by the star formation activities., Accepted for publication in The Astrophysical Journal

We analyze the recent released HST/WFC3 IR images in the GOODS-N region to study the formation and evolution of Quiescent galaxies (QGs). After examining the reliability with artificial galaxies, we obtain the morphological parameters with S'ersic profile of 299 QGs and 1,083 star-forming galaxies (SFGs) at z ~ 0.5-3.0, finding the evolution of re and n of massive (M* > 10^10.5 Msun) QGs while weaker evolution of SFGs and less massive (M* < 10^10.5 Msun) QGs. The regression of the size evolution of massive QGs follows re \propto (1 + z)-{\alpha}re with {\alpha}re = 1.06 \pm 0.19 (a factor of ~ 2.2 increase from z ~ 2.5 to ~ 0.5), which is consistent with the general picture of the significant size growth. For the further understanding of the evolution scenario, we study the evolution of S'ersic index, n, and find that of massive QGs to significantly evolve as n \propto (1 + z)-{\alpha}n with {\alpha}n = 0.74 \pm 0.23 (n ~ 1 at z ~ 2.5 to n ~ 4 at z ~ 0.5), while those of the other populations are unchanged (n ~ 1) over the redshift range. The results in the present study are consistent with both of observation and numerical simulations, where gas-poor minor merger is believed to be the main evolution scenario. By taking account of the connection with less massive QGs and SFGs, we discuss the formation and evolution of the massive QGs over "Cosmic High Noon", or the peak of star-formation in the universe., Comment: 20 pages, 21 figures, ApJ, accepted

"Electric energy storage devices, such as lithium ion rechargeable batteries and electrochemical capacitors, are used in various equipments. They are going to be used more in various systems, for examples, electric vehicles, but for these applications better performances, such as higher power density and better rate characteristics, are strongly required. In the present thesis, new materials for these electric energy storage devices were investigated.For two materials, manganese vanadate and carbon-coated metallic tin, their synthesis procedures were established by referring to their characteristics in structure and performance for the anode of lithium ion rechargeable batteries.Manganese vanadate MnV2O6 is one of the candidates for anode materials of lithium ion rechargeable batteries, which might be possible to replace graphite (Chapter 2). Crystalline powders of anhydrous MnV2O6 were successfully synthesized at a temperature below 200℃ under autogenous hydrothermal condition and by coprecipitation method. MnV2O6 powders, which were synthesized using a high concentration solutions, more than 0.1 mol/L, gave relatively high reversible capacity as 600 mAh/g and interesting cyclic performance, reversible capacity increasing to more than initial charge capacity after 3rd or 4th cycle of charge-discharge. The powders showing this interesting performance were characterized by strong 110 diffraction peak relative to other peaks and by thin rod-like morphology. The Oxidation state of anhydrous MnV2O6 synthesized was investigated by different techniques, such as XPS, XAFS, TEM, etc.Carbon-coated metallic tin powders were prepared through the heat treatment of the powder mixtures of poly(vinyl alcohol) (PVA) as a carbon precursor, SnO2 as a Sn precursor and MgO in different mass ratios in N2 gas flow (Chapter 3). SnO2 was reduced to metal, which wetted with the surface of MgO particles and so could not flow to coagulate. After carbonization of PVA, MgO was dissolved out using 1 M HCl. The carbon-coated Sn powders was found to give a high capacity as 500 mAh/g and a stable cyclic performance as an anode of lithium ion rechargeable batteries, though they showed relatively large irreversible capacity at the first cycle of charge-discharge. The reasons for this good performance for the anode of lithium ion rechargeable batteries were a small particle size of Sn, which was possible by the existence of MgO particles during carbonization process, the inhibition of coagulation of small Sn particles during charge-discharge cycles because they are coated by carbon, and the existence of spaces neighboring to Sn metal particle in carbon shells, which could absorb a large volume expansion of Sn particle due to Li alloying during charging.Two materials, mesoporous carbons and carbon-coated metal carbides, were developed for the electrode of electrochemical capacitors for electric energy storage, by establishing the synthesis procedures and measuring their structural and electrochemical characteristics.Electric double layer formation on large surface area of activated carbons has been employed for capacitors. In the present work, novel process for the synthesis of porous carbons, rich in mesopores, from thermoplastic precursors was newly developed (Chapter 4). BET surface area of the carbons synthesized through this process reached to 2000 m2/g, even though no activation process was employed.The mixtures of MgO precursor (MgO, magnesium acetate and magnesium citrate) and thermoplastic carbon precursor (PVA, poly(ethylene terephtarate) PET and hydroxyl propyl cellulose HPC) were carbonized at 700-1000 ℃ in inert atmosphere. After carbonization, carbon was isolated by dissolution of MgO formed from its precursors using diluted acid. MgO particles formed from magnesium acetate and citrate were very fine and left a large amount of mesopores with a sharp distribution in size of around 1O and 5 nm, respectively. The mesoporous carbons synthesized gave relatively high capacity, as about 300 F/g, and excellent rate characteristics in 1 M H2S04 electrolyie. Mesopores in the electrode carbons were shown to have an important role for their rate performance.The mixtures of HPC with K2W04 and K2M004 were found to give carbon-coated tungsten carbide WC and molybdenum carbide M02C after heat treatment at 1OOO and 850 ℃, respectively (Chapter 5). Cyclic voltammogram for these carbon-coated metal carbides showed a clear box-shaped curve even in the first cycle, which was known to be characteristic for electric double layer capacitor, no redox peak being observed. The capacity was about 21O F/g, which suggested the overlap of redox capacity due to either tungsten or molybdenum hydroxide, which was formed during the first cycle of charge-discharge, to the capacity due to the formation of electric double layers on porous carbons. Carbon coating kept carbide particles small, as 30 to 100 nm, which made the transformation of carbides to hydroxides possible in the first charge-discharge cycle, and inhibited the coagulation of metal hydroxide particles during cycles of charge-discharge. Carbon-coated metal carbides thus prepared have very high capacitance based on the volume of electrode film, 500 ～ 700 F/cm3, which is much higher than about 140 F/cm3 for carbon electrode.In the present thesis, MnV206 and carbon-coated Sn fine particles were developed for anode materials of lithium ion rechargeable batteries, and also mesoporous carbons and carbon-coated WC and M02C were developed for electrode materials of electrochemical capacitors. These materials showed either larger electric energy storage and/or better charge-discharge performance than the conventional materials. These materials are believed to contribute the future development of electric energy storage devices. The process for the preparation of porous carbons from thermoplastic precursors is expected to be developed as a novel process for the production of activated carbons.", 蓄電デバイスは、小型電子機器に限らず様々な電源として、需要が非常に高く、新規開発や改質が早急に望まれている。このような中で、リチウムイオンニ次電池には、高容量、長寿命、高効率化が強く求められ、電極の開発、改質は非常に重要な課題として取り上げられている。また、二次電池に並んで、電気化学キャパシタが近年様々な用途に期待され、高容量化、レート特性の改良などが強く求められている。いずれのデバイスに対しても国内外で多数の報告がなされている中、未だ現状に変わる次の主流となる材料が決まらないという事実がある。これには、工業的な問題やコスト、プロセスなどいろいろな課題が存在することが大きい。そこで本研究では、電極材料のより簡便でかつ経済性の高い合成方法を開発し、それらデバイスのより高性能化に寄与することを目的とした。 複合酸化物であるMnV206は、リチウムイオンニ次電池負極材の一つとして期待されている材料である。本研究では、エネルギーコストが低く、装置が簡便な水熱法および共沈法により200℃以下という低温で、その無水物を直接合成することに成功した。得られた試料は10回目のサイクル時においても600mAh/gと比較的良好な容量が確認された。さらに0.1mol/L以上の濃度条件下で合成した試料は、3回目もしくは4回目のサイクル時に一且減少した充放電容量が初期容量近くまで回復するというサイクル特異性を見出だした。このサイクル特異性を引き起こす試料は、いずれもX線による110回折線のピーク強度が他の回折線に比べて強く出ていることが共通して確認された。その構造について各種の手法（XPS，XAFS，TEM）による解析を行った。 金属スズは、理論容量が990mAh/gと非常に高く，リチウムイオンニ次電池の負極材として注目されている。しかし、Li吸蔵時の体積膨張やサイクル寿命に限度があることなどの欠点によりそのままでは使用が難しいとされてきた。本研究では、炭素被覆した微粒子金属スズを作成することによって、リチウムイオンニ次電池の高容量および高性能化が可能であることを示した。熱可塑性樹脂をSnO2およびMgOと混合した後、不活性ガス気流中で900℃に加熱、炭素化し、MgOを希酸により溶解、除去した。SnO2は、熱処理によって金属スズに還元され、混在するMgOとの親和性から凝集が妨げられ、30から100nmの微粒子に保たれる。その電極性能は、500mAh/gとグラファイト電極より優れ、リチウム挿入による金属スズの体積膨張は、MgOの溶解後に残った空隙によって吸収されていると考えられる。 電池と並び蓄電デバイスとして、キャパシタが存在する。高比表面積を有する活性炭を電極とした電気二重層を利用したキャパシタが様々な用途に期待さている。この高表面積を持つ活性炭を作る工程は非常に複雑であり環境に与える影響も大きい。本研究では、MgO上へ炭素被覆した後、そのMgOを取り除くことで、多孔質炭素を調製する新しい活性炭の製造方法を開発することに成功した。この方法は、活性炭製造では通常では用いられない熱可塑性樹脂を使用するため、様々な樹脂を選択できる利点がある。また、得られた炭素の表面積は2000m2/g以上と非常に高く、表面積および細孔構造は、炭素前駆体およびMgO前駆体そしてそれらの混合比を選択することにより簡単に制御可能であることを見出した。特に、従来の方法では直接的には作成しにくいメソ孔を作ることができることが特徴的である。この多孔質炭素をキャパシタ電極に用いた場合300F/gと非常に高い容量が得られ、高速充放電時にも損失が少ないという利点を有することを明らかにした。 さらに、熱可塑性炭素前駆体であるヒドロキシプロピルセルロース（HPC）とK2WO4またはK2MOO4の水溶液混合物から作ったゲルを800～1100℃の温度に1時間、不活性ガス中で熱処理することによって、炭素被覆タングステン（WC）またはモリブデンカーバイド（MO2C）を作成した。このカーバイドをキャパシタの電極活物質に用い、CV測定を行ったところ、電気二重層キャパシタ特有のボックス型の挙動を描き、その容量は210F/gを示した。これは、1000m2/gを超えるような高純度活性炭の電気容量と比較しても遜色のない容量である。現在まで、金属カーバイドをキャパシタ電極に用いたという報告例はない。一方、市販のWCでは、このような容量や挙動は得られず、炭素被覆されているためカーバイドが微粒に保たれていることが有利に働いていると考えられる。これらの炭素被覆カーバイドは、電極フィルムの体積あたりの容量としては500～700F/cm3となり、炭素電極の約140F/cm3に比べると極めて高い値を示した。 以上のように、本研究では、電気エネルギー貯蔵のためのデバイスであるリチウムイオンニ次電池の負極材としてのMnV206および炭素被覆金属スズ微粒子、キャパシタの電極材としてのメソポーラス炭素、炭素被覆タングステンおよびモリブデンカーバイドの調製方法を開発した。作製した材料は、いずれも従来のものよりも高い性能（高い貯蔵容量および優れたレート特性）を示し、それぞれのエネルギー貯蔵デバイスの高性能化に対して貢献できると考えられる。また、本研究で開発した熱可塑性炭素前駆体を原料とする多孔炭の製造法は、全く画期的な方法であり、今後活性炭の新しい製造法としての展開が期待できる

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