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We use the large spectroscopic data set of the MOSFIRE Deep Evolution Field survey to investigate the kinematics and energetics of ionised gas outflows. Using a sample of 598 star-forming galaxies at redshift 1.4 < $z$ < 3.8, we decompose $\rm{H}\alpha$ and [OIII] emission lines into narrow and broad components, finding significant detections of broad components in 10% of the sample. The ionised outflow velocity from individual galaxies appears independent of galaxy properties, such as stellar mass, star-formation rate (SFR), and star-formation-rate surface density ($\Sigma_{\rm SFR}$). Adopting a simple outflow model, we estimate the mass-, energy- and momentum-loading factors of the ionised outflows, finding modest values with averages of 0.33, 0.04, and 0.22, respectively. The larger momentum- than energy-loading factors, for the adopted physical parameters, imply that these ionised outflows are primarily momentum-driven. We further find a marginal correlation (2.5$\sigma$) between the mass-loading factor and stellar mass in agreement with predictions by simulations, scaling as $\eta_{m}$ $\propto M_{\star}^{-0.45}$. This shallow scaling relation is consistent with these ionised outflows being driven by a combination of mechanical energy generated by supernovae explosions and radiation pressure acting on dusty material. In a majority of galaxies, the outflowing material does not appear to have sufficient velocity to escape the gravitational potential of their host, likely recycling back at later times. Together, these results suggest that the ionised outflows traced by nebular emission lines are negligible, with the bulk of mass and energy carried out in other gaseous phases., Comment: 17 pages, 9 figures, Submitted to Monthly Notices of the Royal Astronomical Society

The exceptional spectra of the most luminous $z>10$ sources observed so far have challenged our understanding of early galaxy evolution, requiring a new observational benchmark for meaningful interpretation. As such, we construct spectroscopic templates representative of high-redshift, star-forming populations, using 482 confirmed sources at $z=5.0-12.9$ with JWST/NIRSpec prism observations, and report on their average properties. We find $z=5-11$ galaxies are dominated by blue UV continuum slopes ($\beta=-2.3$ to $-2.7$) and inverse Balmer jumps, characteristic of dust-poor and young systems, with a shift towards bluer slopes and younger ages with redshift. The evolution is mirrored by ubiquitous CIII] detections across all redshifts (EW$_{0}=5-14$ \r{A}), which increase in strength towards early times. Rest-frame optical lines reveal elevated ratios ($O32=7-31$, $R23=5-8$, and $Ne3O2=1-2$) and subsolar metallicities (log O/H$=7.3-7.9$), typical of ionization conditions and metallicities rarely observed in $z\sim0$ populations. Within our sample, we identify 57 Ly$\alpha$-emitters which we stack and compare to a matched sample of non-emitters. The former are characterized by more extreme ionizing conditions with enhanced CIII], CIV, and HeII+[OIII] line emission, younger stellar populations from inverse Balmer jumps, and a more pristine ISM seen through bluer UV slopes and elevated rest-frame optical line ratios. The novel comparison illustrates important intrinsic differences between the two populations, with implications for Ly$\alpha$ visibility. The spectral templates derived here represent a new observational benchmark with which to interpret high-redshift sources, lifting our constraints on their global properties to unprecedented heights and extending out to the earliest of cosmic times., Comment: Submitted to ApJ. 33 pages (24 pages for main body), 13 figures, 6 tables. All composite spectra available online or upon request. Comments welcome!

While the shape of the Ly$\alpha$ profile is viewed as one of the best tracers of ionizing-photon escape fraction ($f_{esc}$) within low redshift (z~0.3) surveys of the Lyman continuum, this connection remains untested at high redshift. Here, we combine deep, rest-UV Keck/LRIS spectra of 80 objects from the Keck Lyman Continuum Spectroscopic Survey with rest-optical Keck/MOSFIRE spectroscopy in order to examine potential correlations between Ly$\alpha$ profile shape and the escape of ionizing radiation within z~3 star-forming galaxies. We measure the velocity separation between double-peaked Ly$\alpha$ emission structure (v$_{\rm sep}$), between red-side Ly$\alpha$ emission peaks and systemic (v$_{\rm Ly\alpha,red}$), and between red-side emission peaks and low-ionization interstellar absorption lines (v$_{\rm Ly\alpha-LIS}$). We find that the IGM-corrected ratio of ionizing to non-ionizing flux density is significantly higher in KLCS objects with lower v$_{\rm Ly\alpha,red}$. We find no significant trend between measures of ionizing-photon escape and v$_{\rm Ly\alpha-LIS}$. We compare our results to measurements of z~0.3 "Green Peas" from the literature and find that KLCS objects have larger v$_{\rm sep}$ at fixed v$_{\rm Ly\alpha,red}$, larger $f_{esc}$ at fixed v$_{\rm Ly\alpha,red}$, and higher v$_{\rm Ly\alpha,red}$ overall than z~0.3 analogs. We conclude that the Ly$\alpha$ profile shapes of our high-redshift sources are fundamentally different, and that measurements of profile shape such as v$_{\rm Ly\alpha,red}$ map on to $f_{esc}$ in different ways. We caution against building reionization-era $f_{esc}$ diagnostics based purely on Ly$\alpha$ profiles of low-redshift dwarf galaxies. Tracing v$_{\rm sep}$, v$_{\rm Ly\alpha,red}$, and $f_{esc}$ in a larger sample of z~3 galaxies will reveal how these variables may be connected for galaxies at the epoch of reionization., Comment: 22 pages, 7 figures, submitted to ApJ

The Technology Immersion Pilot (TIP), created by the Texas Legislature in 2003, was based on the assumption that the use of technology in Texas public schools could be achieved more effectively by "immersing" schools in technology rather than by introducing technology resources, such as hardware, software, digital content, and educator training, in a cyclical fashion over time. The Texas Education Agency (TEA) invested more than $20 million in federal Title II, Part D monies to fund Technology Immersion projects at high-need middle schools through a competitive grant process. Concurrently, a research study partially funded by a federal Evaluating State Educational Technology Programs grant has investigated whether student achievement improved over time through exposure to Technology Immersion. The Texas Center for Educational Research (TCER) was TEA's partner for a four-year evaluation of the implementation and effectiveness of the Technology Immersion model. The study addressed five major research questions: (1) What was the effect of Technology Immersion on teachers and teaching?; (2) What was the effect of Technology Immersion on students and learning?; (3) What was the effect of Technology Immersion on students' academic achievement?; (4) How well was Technology Immersion implemented; and (5) What was the relationship between implementation and student academic outcomes? The fourth-year evaluation provides final conclusions about the effects of Technology Immersion on schools, teachers, and students. This report combines information gathered during the fourth project year (2007-08) with data from the first-through-third implementation years (2004-05 through 2006-07). The study's quasi-experimental research design has allowed inferences about the causal effects of Technology Immersion through comparisons between 21 treatment schools and 21 control schools. Like previous years, outcomes represented the effects of Technology Immersion for schools that generally reached less than full implementation. Major findings from the fourth year are described. A final section discusses the quality of Technology Immersion implementation, prospects for sustainability of the model, and implications for educational policy. Appended are: (1) Theoretical Framework for technology Immersion--Literature Review; (2) Characteristics of Participating Schools; (3) Survey Items and Scale Reliabilities; (4) Measurement of Implementation Fidelity; and (5) Technical Appendix--Hierarchical Linear Modeling (HLM). Individual chapters contain footnotes. (Contains 26 tables and 73 figures.)

The Technology Immersion Pilot (TIP), created by the Texas Legislature in 2003, set forth a vision for technology immersion in public schools. Senate Bill 396 called for the Texas Education Agency (TEA) to establish a pilot project to "immerse" schools in technology by providing a wireless mobile computing device for each teacher and student, technology-based learning resources, training for teachers to integrate technology into the classroom, and support for effective technology use. In response to this non-funded legislative mandate, the TEA has used more than $20 million in federal Title II, Part D monies to fund "technology immersion" projects for high-need middle schools through a competitive grant process. Concurrently, a research study, partially funded by a federal Evaluating State Educational Technology Programs grant, is evaluating whether student achievement improves over time as a result of exposure to technology immersion. The Texas Center for Educational Research (TCER)--a non-profit research organization in Austin--is the TEA's primary partner for this four-year evaluation that began in the 2004-05 school year and will continue through 2007-08. The overarching purpose of the study is to scientifically investigate the effectiveness of technology immersion in increasing middle school students' achievement in core academic subjects as measured by the Texas Assessment of Knowledge and Skills (TAKS). The evaluation also examines the relationships that exist among contextual conditions, technology immersion, intervening factors (school, teacher, and student), and student achievement. The research design is quasi-experimental with middle schools assigned to either treatment or control groups. This report concentrates on information gathered during the 2006-07 school year, but analyses also include data from the first (2004-05) and second (2005-06) project years. The research includes 42 grades 6 to 8 middle schools drawn from rural, suburban, and urban locations in Texas. Schools are divided equally between the treatment group (21) and control group (21). The middle schools are typically small (402 students, on average); however, enrollments vary widely (from 83 to 1,447 students). While schools are mainly concentrated in small or very small Texas districts (less than 3,000 students), about a third of schools are in very large districts (10,000 or more students). Some of the findings include: (1) In the third year, immersion teachers continued to grow in technology proficiency and in their use of technology for professional productivity at significantly faster rates than control teachers; (2) Technology immersion significantly increased students' technology proficiency and reduced the proficiency gap between economically advantaged and disadvantaged students; (3) Technology immersion had no statistically significant effect on students' TAKS reading achievement; and (4) Although the overall level of implementation increased between the second and third project years, just a quarter of schools reached substantial levels of technology immersion. Appended are: (1) Theoretical Framework for Technology Immersion--Literature Review; (2) Characteristics of Participating Schools; (3) Survey Items and Scale Reliabilities; (4) Measurement of Implementation Fidelity; (5) Technical Appendix--Hierarchical Linear Modeling (HLM); and (6) Effects of Technology Immersion on Schools. Individual chapters contain footnotes. (Contains 25 figures, 82 tables and 1 exhibit.)

The Technology Immersion Pilot (TIP) sets forth a vision for technology immersion in Texas public schools. The Texas Education Agency (TEA) originally directed more than $14.5 million in federal Title II, Part D monies toward funding a wireless learning environment for high-need middle schools through a competitive grant process. A concurrent research project funded by a federal Evaluating State Educational Technology Programs grant is evaluating whether student achievement improves over time as a result of exposure to technology immersion. The Texas Center for Educational Research (TCER)--a non-profit research organization in Austin--is the TEA's primary partner in this four-year endeavor. The overarching purpose of the study is to scientifically investigate the effectiveness of technology immersion in increasing middle school students' achievement in core academic subjects as measured by the Texas Assessment of Knowledge and Skills (TAKS). Technology immersion encompasses multiple components, including a laptop computer for every middle school student and teacher, wireless access throughout the campus, online curricular and assessment resources, professional development and ongoing pedagogical support for curricular integration of technology resources, and technical support to maintain an immersed campus. The evaluation employs a quasi-experimental research design, and in the first year, included 22 experimental and 22 control schools. In the project's second year, however, the research design was modified when two middle schools in one district (one experimental and one control) were lost due to damage caused by Hurricane Rita on the Texas Gulf coast. Thus, second-year results (for the 2005-06 school year) are for the remaining 21 treatment and 21 control schools. A re-analysis of baseline data for the new sample revealed that school and student characteristics generally were unchanged and differences between comparison groups remained statistically insignificant. In the second year, researchers examined the nature of project implementation at the immersion sites. Additionally, they gauged the effects of technology immersion on teacher and student mediating variables as well as the effects of immersion on students' reading, mathematics, and writing achievement. Some of the second-year findings include: (1) Immersion teachers grew in technology proficiency and in their use of technology for professional productivity at significantly faster rates than control teachers; (2) Technology immersion had no statistically significant effect on Cohort 1, seventh graders' achievement in reading, mathematics, or writing; and (3) Most of the middle schools struggled in the second year to implement the prescribed components of technology immersion. Appended are: (1) Theoretical Framework for Technology Immersion--Literature Review; (2) Survey Items and Scale Reliabilities; (3) Measuring Implementation Fidelity; (4) Effects of Technology Immersion on Schools; and (5) Technical Appendix--Hierarchical Linear Modeling (HLM). Individual chapters contain footnotes. (Contains 17 figures and 63 tables.)

This study supports efforts by the U.S. Department of Education, Office of Special Education Programs (OSEP) to foster greater state accountability and establish data-driven planning and self-assessment processes that help states and schools to address provisions of the recently enacted Individuals with Disabilities Education Improvement Act (IDEA) of 2004. In response to state-level requirements, the Texas Education Agency (TEA) asked Region 4 Education Service Center (ESC) to facilitate the second statewide study of special education professionals personnel needs. This study, which was authorized in December 2004, augments the initial "Statewide Study of Special Education Professionals' Personnel Needs" conducted by the Texas Center for Educational Research (TCER) and published in September 2001. The current study was designed to identify existing shortages in special education teacher and other professional positions, to investigate the various issues that appear to influence turnover in these positions, and to identify effective approaches to retention. Report sections are organized around findings for the study's major research questions. Key findings are summarized for Texas single districts and SSAs. "Section 2, Method" gives a description of the instrument development and validation process, the four surveys used in the study, and the data collection procedures. The authors also discuss the generalizability of the study to public schools statewide. "Section 3, Special Education Personnel Staffing Needs" provides information on special education positions and critical shortage areas, and special education personnel turnover. This section specifically addresses the special education personnel needs in Texas public schools. "Section 4, Hiring Special Education Personnel" provides information on recruitment strategies and barriers to hiring qualified special education personnel. "Section 5, Retaining Special Education Personnel" provides information on retention strategies and barriers to retaining qualified special education personnel. "Section 6, Special Education Teachers" provides information on teacher workload and teaching arrangements, teaching experience and preparation of special education teachers, perceptions of the work environment, and intentions to remain in the job. "Section 7, Other Special Education Professionals" provides information on special education professionals workload and service arrangements, certifications attained by special education professionals, perceptions of the work environment, and intentions to remain in the job. "Section 8, Professional Development Needs of Special Education Personnel" provides information on administrators' perceptions of the degree to which their staff required professional development. This section also identifies the professional development areas in which special education teachers and other professionals had completed training as well as the areas in which they desired additional training. "Section 9, Special Education Staffing in Charter Schools" provides information on the special education staffing levels in charter schools, and the recruitment, staffing, and retention strategies utilized by these schools. "Section 10, Policy Implications and Recommendations" discusses the implications of the results of the current study, and recommendations for addressing recruitment, staffing, and retention issues relative to special education personnel. (Contains 103 tables and 7 figures.) [For "Texas Study of Personnel Needs in Special Education. Executive Summary," see ED538138.]

The Texas Education Agency's (TEA's) state GEAR UP project--Texans Getting Academically Prepared (TGAP)--has provided interconnected activities supporting early awareness of and preparation for higher education among low-income and minority students, their families, and schools in six South Texas school districts. Over its six years, the state grant was guided by three goals for (a) building educator and student capacity for successful participation in challenging college preparatory programs, (b) increasing student and family awareness of opportunities for college and financial aid assistance, and (c) providing meaningful incentives and support for high student achievement from the business community. The TGAP evaluation assessed progress toward the three overarching TGAP goals. Researchers explored (a) how TGAP influenced the capacity of districts, schools, educators, parents, and students to support students' participation in higher education; (b) the extent to which student and parent awareness of college opportunities, including financial aid and assistance, increased; and (c) the academic outcomes for schools and their students. The findings also offer insight into program implementation and sustainability. Researchers combined qualitative and quantitative data collection approaches with rich and varied sources of data. These included annual, on-site interviews (with teachers, students, counselors, and university faculty fellows), classroom observations in Advanced Placement (AP) and Pre-AP classrooms, document and product reviews, interviews with project partners, teacher and student surveys, and demographic and performance data. The methodological approach relied on triangulation to examine patterns in both project implementation and academic outcomes. Appended are: (1) TGAP Goals; (2) Site Visit Interview Protocols; (3) Classroom Observation Instrument; (4) Faculty Fellows Interview Instruments; (5) Student Survey; (6) Teacher Survey; (7) Parent/Guardian Surveys; (8) Data Detail; (9) Methodological Detail; and (10) TAKS Objective Scores. Individual sections contain footnotes. (Contains 163 tables and 36 figures.) [For "Texans Getting Academically Prepared (TGAP): Year Six Evaluation Report, September 2004-August 2005. Executive Summary," see ED539928.]

In October 1999, the Texas Education Agency (TEA) received a GEAR UP state grant. TEA's project, Texans Getting Academically Prepared (TGAP), was originally a five-year grant. However, additional federal funding extended the project for a sixth year. TGAP begins at the middle-school level to prepare low-income and minority students for higher education opportunities. Targeting six South Texas school districts, TGAP includes interconnected activities supporting early awareness of and preparation for higher education among students, their families, and schools. This evaluation examines the fifth year of a six-year TGAP project. TGAP was initiated in the 1999-2000 school year, continued through its fifth school year in 2003-04, and as a result of additional federal grant funds, will conclude at the end of the 2004-05 school year. The evaluation assesses progress toward three overarching TGAP goals: "building capacity, increasing student and family awareness, and gaining business and community support." Specifically, the evaluation explores how TGAP builds the capacity of districts, schools, educators, parents, and students to support students' participation in higher education; and the extent to which student and parent awareness of college opportunities, including financial aid and assistance, increases. In addition, the evaluation assesses academic outcomes for schools and their students, and offers insight into program implementation and sustainability. Appended are: (1) TGAP Goals; (2) Site Visit Interview Protocols; (3) Classroom Observation Instrument; (4) Faculty Fellows Interview Instruments; (5) Student Survey; (6) Teacher Survey; (7) Parent/Guardian Surveys; (8) Data Detail; (9) Methodological Detail; and (10) TAKS Objective Scores. Individual sections contain footnotes. (Contains 167 tables and 34 figures.)

The Texas Study of Students at Risk (TxSSAR) is a comprehensive evaluation examining the effectiveness of three state-level programs with the common goal of helping students at risk of failure to achieve academically. The study comprises investigations of the Optional Extended Year Program (OEYP), the Texas After School Initiative (TASI), and the Ninth Grade Success Initiative (NGSI), and case studies of districts that received NGSI grants. The evaluation covers a four-year period between the 1999-2000 and 2002-03 school years. Appended are: (1) Theory of Change Model for the NGSI/TASI/OEYP Evaluation; (2) Estimating TASI and NGSI Student Participation; (3) TAAS Reading and Mathematics Passing Rates by Grade; and (4) Case Study Site Selection Indicators. (Contains 97 tables and 19 figures.) [For executive summary, "Texas Study of Students at Risk: Efficacy of Grants Supporting Academic Success from Elementary through High School," see ED538140.]

In the next decade, deep galaxy surveys from telescopes such as the James Webb Space Telescope and Roman Space Telescope will provide transformational data sets that will greatly enhance the understanding of galaxy formation during the epoch of reionization (EoR). In this work, we present the Deep Realistic Extragalactic Model (DREaM) for creating synthetic galaxy catalogs. Our model combines dark matter simulations, subhalo abundance matching and empirical models, and includes galaxy positions, morphologies, and spectral energy distributions. The resulting synthetic catalog extends to redshifts z ∼12, and galaxy masses log10(M/M⊙)=5 covering an area of 1 deg2 on the sky. We use DREaM to explore the science returns of a 1 deg2 Roman ultra-deep field (UDF), and to provide a resource for optimizing ultra-deep survey designs. We find that a Roman UDF to 30 m AB will potentially detect more than 106 M UV < - 17 galaxies, with more than 104 at redshifts z > 7, offering an unparalleled data set for constraining galaxy properties during the EoR. Our synthetic catalogs and simulated images are made publicly available to provide the community with a tool to prepare for upcoming data.

We use medium-resolution JWST/NIRSpec observations from the Cosmic Evolution Early Release Science Survey to place the first constraints on dust attenuation and star formation based on Paschen lines for a sizable sample of 63 galaxies at redshifts z = 1.0-3.1. Our analysis indicates strong correlations between the Balmer decrement, H alpha/H beta, and line ratios that include Paschen lines (i.e., Pa alpha/H beta, Pa beta/H beta, and the Paschen decrement, Pa alpha/Pa beta), suggesting that the former is sensitive to the overall dust obscuration toward H ii regions in high-redshift galaxies. The line ratios are used to derive nebular reddening, E(B - V)(neb), and star formation rates (SFRs). There is marginal evidence that the SFRs deduced from Paschen lines may exceed by approximate to 25% those derived from Balmer lines alone, suggesting the presence of star formation that is optically thick in Balmer lines, though deeper observations are needed to confirm this result. Using the Paschen-line constraints on the bolometric SFRs, we reevaluate the relationship between dust obscuration and UV spectral slope, and find a reddening of the UV continuum that, on average, follows the SMC extinction curve. This analysis highlights the need for deeper spectroscopy of more representative samples to evaluate nebular dust attenuation and bolometric SFRs in high-redshift galaxies, and their relationship to the reddening of the UV continuum.

We present a joint analysis of the galaxy S04590 at z = 8.496 based on NIRSpec, NIRCam, and NIRISS observations obtained as part of the Early Release Observations program of the James Webb Space Telescope (JWST) and the far-infrared [C ii] 158 mu m emission line detected by dedicated Atacama Large Millimeter/submillimeter Array (ALMA) observations. We determine the physical properties of S04590 from modeling of the spectral energy distribution (SED) and through the redshifted optical nebular emission lines detected with JWST/NIRSpec. The best-fit SED model reveals a low-mass (M-? = 10(7.2)-10(8) M-?) galaxy with a low oxygen abundance of derived from the strong nebular and auroral emission lines. Assuming that [C ii] effectively traces the interstellar medium, we estimate the total gas mass of the galaxy to be M-gas = (8.0 +/- 4.0) x 10(8) M-? based on the luminosity and spatial extent of [C ii]. This yields an exceptionally high gas fraction, f(gas) = M-gas/(M-gas + M-?) ? 90%, though one still consistent with the range expected for low metallicity. We further derive the metal mass of the galaxy based on the gas mass and gas-phase metallicity, which we find to be consistent with the expected metal production from Type II supernovae. Finally, we make the first constraints on the dust-to-gas (DTG) and dust-to-metal (DTM) ratios of galaxies in the epoch of reionization at z ? 6, showing overall low mass ratios of logDTG < -3.8 and logDTM < -0.5, though they are consistent with established scaling relations and in particular with those of the local metal-poor galaxy I Zwicky 18. Our analysis highlights the synergy between ALMA and JWST in characterizing the gas, metal, and stellar content of the first generation of galaxies.

While star-forming galaxies are likely the dominant force behind cosmic reionization, the relative contributions of different galaxy populations remains uncertain. Understanding how ionizing photons are produced and subsequently escape from these galaxies in the early Universe is crucial for reducing such uncertainties in existing models. In this dissertation, I conduct four observational studies of star-forming galaxies at z~3-5 to build a more complete picture of ionizing-photon production and escape. These works utilize observations of the rest-UV portion of the electromagnetic spectrum to examine the interplay between massive stars, neutral gas, and dust in star-forming galaxies. These studies are conducted at the highest redshifts feasible for this type of analysis by avoiding complete attenuation of relevant observational signals from the neutral intergalactic medium. I present the redshift evolution of rest-UV spectral features out to z~5 using a data set from the DEIMOS 10K Survey, alongside comparisons to similar analyses performed at z~2-4. I find a relationship between Lya emission line strength and low-ionization absorption line strength and conclude that the neutral-gas covering fraction of a galaxy simultaneously modulates the two. The redshift evolution of this relation indicates that the ionizing photon production efficiency xi_ion of this z~5 sample is elevated as compared to z~2-4 samples. I examine the effects of foreground contamination in direct measurements of the Lyman continuum (LyC) at z~3 using data from the Keck Lyman Continuum (KLCS) Survey and novel Hubble Space Telescope imaging. After the removal of contamination, I measure an average escape fraction of ionizing radiation of f_esc=0.06+-0.01 at z~3, and present 13 confirmed, individual LyC leakers. Using this cleaned KLCS sample, I measure trends between f_esc and different galaxy properties in order to elucidate which galaxy populations contribute most strongly to the ionizing emissiv

The ratios of strong rest-frame optical emission lines are the dominant indicator of metallicities in high-redshift galaxies. Since typical strong-line based metallicity indicators are calibrated on auroral lines at $z=0$, their applicability for galaxies in the distant Universe is unclear. In this paper, we make use of mock emission line data from cosmological simulations to investigate the calibration of rest-frame optical emission lines as metallicity indicators at high redshift. Our model, which couples the SIMBA cosmological galaxy formation simulation with cloudy photoionization calculations, includes contributions from HII regions, post-AGB stars and Diffuse Ionized Gas (DIG). We find mild redshift evolution in the 12 indicators that we study, which implies that the dominant physical properties that evolve in our simulations do have a discernible impact on the metallicity calibrations at high redshifts. When comparing our calibrations with high redshift auroral line observations from James Webb Space Telescope we find a slight offset between our model results and the observations and find that a higher ionization parameter at high redshifts can be one of the possible explanations. We explore the physics that drives the shapes of strong-line metallicity relationships and propose calibrations for hitherto unexplored low-metallicity regimes. Finally, we study the contribution of DIG to total line fluxes. We find that the contribution of DIG increases with metallicity at z $\sim$ 0 for singly ionized oxygen and sulfur lines and can be as high as 70% making it crucial to include their contribution when modeling nebular emission., Comment: 28 pages, 6 figures, typo corrected: in polynomial fits, x represents metallicity and y represents the line ratio

With the remarkable sensitivity and resolution of JWST in the infrared, measuring rest-optical kinematics of galaxies at $z>5$ has become possible for the first time. This study pilots a new method for measuring galaxy dynamics for highly multiplexed, unbiased samples by combining FRESCO NIRCam grism spectroscopy and JADES medium-band imaging. Here we present one of the first JWST kinematic measurements for a galaxy at $z>5$. We find a significant velocity gradient, which, if interpreted as rotation yields $V_{rot} = 240\pm50$km/s and we hence refer to this galaxy as Twister-z5. With a rest-frame optical effective radius of $r_e=2.25$kpc, the high rotation velocity in this galaxy is not due to a compact size as may be expected in the early universe but rather a high total mass, ${\rm log(M}_{dyn}/{\rm M}_\odot)=11.0\pm0.2$. This is a factor of roughly 4x higher than the stellar mass within the effective radius. We also observe that the radial H$\alpha$ equivalent width profile and the specific star formation rate map from resolved stellar population modeling is centrally depressed by a factor of $\sim1.5$ from the center to $r_e$. Combined with the morphology of the line-emitting gas in comparison to the continuum, this centrally suppressed star formation is consistent with a star-forming disk surrounding a bulge growing inside-out. While large, rapidly rotating disks are common to z~2, the existence of one after only 1Gyr of cosmic time, shown for the first time in ionized gas, adds to the growing evidence that some galaxies matured earlier than expected in the history of the universe., Comment: Fig. 3 shows the main result

The recent UNCOVER survey with the James Webb Space Telescope (JWST) exploits the nearby cluster Abell 2744 to create the deepest view of our universe to date by leveraging strong gravitational lensing. In this work, we perform photometric fitting of more than 50,000 robustly detected sources out to $z \sim 15$. We show the redshift evolution of stellar ages, star formation rates, and rest-frame colors across the full range of $0.2 \lesssim z \lesssim 15$. The galaxy properties are inferred using the Prospector Bayesian inference framework using informative Prospector-$\beta$ priors on masses and star formation histories to produce joint redshift and stellar population posteriors, and additionally lensing magnification is performed on-the-fly to ensure consistency with the scale-dependent priors. We show that this approach produces excellent photometric redshifts with $\sigma_{\rm NMAD} \sim 0.03$, of a similar quality to the established photometric redshift code EAzY. In line with the open-source scientific objective of the Treasury survey, we publicly release the stellar population catalog with this paper, derived from the photometric catalog adapting aperture sizes based on source profiles. This release includes posterior moments, maximum-likelihood spectra, star-formation histories, and full posterior distributions, offering a rich data set to explore the processes governing galaxy formation and evolution over a parameter space now accessible by JWST., Comment: Corrected typos: Eq.1 should've been (1-kappa)^2, and the lens maps are normalized to D_ds/D_s=1. These errors were only in the writing; no data products or results were affected. The SPS catalogs are accessible via the UNCOVER survey webpage: https://jwst-uncover.github.io/DR2.html#SPSCatalogs, with a copy deposited to Zenodo: https://doi.org/10.5281/zenodo.8401181

Over the past decade, the existence of a substantial population of optically invisible, massive galaxies at $z\gtrsim3$ has been implied from mid-infrared to millimeter observations. With the unprecedented sensitivity of the JWST, such extremely massive galaxy candidates have immediately been identified even at $z>7$, in much larger numbers than expected. These discoveries raised a hot debate. If confirmed, early, high-mass galaxies challenge the current models of galaxy formation. However, the lack of spectroscopic confirmations leads to uncertain stellar mass ($M_{\star}$) estimates, and the possible presence of active galactic nuclei (AGN) adds further uncertainty. Here, we present the first sample of 36 dust-obscured galaxies with robust spectroscopic redshifts at $z_{\rm spec}=5-9$ from the JWST FRESCO survey. The three most extreme sources at $z\sim5-6$ ($\sim$1 billion years after the Big Bang) are so massive (log$M_{\star}/M_{\odot}$ $\gtrsim11.0$) that they would require, on average, about 50% of the baryons in their halos to be converted into stars -- two to three times higher than even the most efficient galaxies at later times. The extended emission of these galaxies suggests limited contribution by AGN. This population of ultra-massive galaxies accounts for 20% of the total cosmic star formation rate density at $z\sim5-6$, suggesting a substantial proportion of extremely efficient star formation in the early Universe., Comment: Submitted to Nature. 22 pages, 4 main figures, 7 supplementary figures, 3 supplementary tables. Comments are welcome

We report the detection of a 13$\sigma$ H$\alpha$ emission line from HDF850.1 at $z=5.188\pm0.001$ using the FRESCO NIRCam F444W grism observations. Detection of H$\alpha$ in HDF850.1 is noteworthy, given its high far-IR luminosity, substantial dust obscuration, and the historical challenges in deriving its redshift. HDF850.1 shows a clear detection in the F444W imaging data, distributed between a northern and southern component, mirroring that seen in [CII] from the Plateau de Bure Interferometer. Modeling the SED of each component separately, we find that the northern component has a higher mass, star formation rate (SFR), and dust extinction than the southern component. The observed H$\alpha$ emission appears to arise entirely from the less-obscured southern component and shows a similar $\Delta$v$\sim$+130 km/s velocity offset to that seen for [CII] relative to the source systemic redshift. Leveraging H$\alpha$-derived redshifts from FRESCO observations, we find that HDF850.1 is forming in one of the richest environments identified to date at $z>5$, with 100 $z=5.17-5.20$ galaxies distributed across 10 structures and a $\sim$(15 cMpc)$^3$ volume. Based on the evolution of analogous structures in cosmological simulations, the $z=5.17-5.20$ structures seem likely to collapse into a single $>$10$^{14}$ $M_{\odot}$ cluster by $z\sim0$. Comparing galaxy properties forming within this overdensity with those outside, we find the masses, SFRs, and $UV$ luminosities inside the overdensity to be clearly higher. The prominence of H$\alpha$ line emission from HDF850.1 and other known highly-obscured $z>5$ galaxies illustrates the potential of NIRCam-grism programs to map both the early build-up of IR-luminous galaxies and overdense structures., Comment: Submitted to MNRAS. 20 pages, 10 figures and 8 tables (including appendices)

The chemical enrichment of dust and metals are vital processes in constraining the star formation history of the universe. Previously, the dust masses of high-redshift star-forming galaxies have been determined through their far-infrared continuum, however, equivalent, and potentially simpler, approaches to determining the metal masses have yet to be explored at $z\gtrsim 2$. Here, we present a new method of inferring the metal mass in the interstellar medium (ISM) of galaxies out to $z\approx 8$, using the far-infrared [CII]$-158\mu$m emission line as a proxy. We calibrated the [CII]-to-$M_{\rm Z,ISM}$ conversion factor based on a benchmark observational sample at $z\approx 0$, in addition to gamma-ray burst sightlines at $z>2$ and cosmological hydrodynamical simulations of galaxies at $z\approx 0$ and $z\approx 6$. We found a universal scaling across redshifts of $\log (M_{\rm Z,ISM}/M_\odot) = \log (L_{\rm [CII]}/L_\odot) - 0.45,$ with a 0.4 dex scatter, which is constant over more than two orders of magnitude in metallicity. We applied this scaling to recent surveys for [CII] in galaxies at $z\gtrsim 2$ and determined the fraction of metals retained in the gas-phase ISM, $M_{\rm Z,ISM} / M_\star$, as a function of redshift showing that an increasing fraction of metals reside in the ISM of galaxies at higher redshifts. We place further constraints on the cosmic metal mass density in the ISM ($\Omega_{\rm Z,ISM}$) at $z\approx 5$ and $\approx 7$, yielding $\Omega_{\rm Z,ISM} = 6.6^{+13}_{-4.3}\times 10^{-7}\,M_\odot\, {\rm Mpc}^{-3}$ ($z\approx 5$) and $\Omega_{\rm Z,ISM} = 2.0^{+3.5}_{-1.3}\times 10^{-7}\,M_\odot\, {\rm Mpc}^{-3}$ ($z\approx 7$). These results are consistent with the expected metal yields from the integrated star formation history at the respective redshifts. This suggests that the majority of metals produced at $z\gtrsim 5$ are confined to the ISM of galaxies., Comment: Accepted in A&A, abstract abridged

We investigate the production efficiency of ionizing photons ($\xi_{ion}^*$) of 1174 galaxies with secure redshift at z=2-5 from the VANDELS survey to determine the relation between ionizing emission and physical properties of bright and massive sources. We constrain $\xi_{ion}^*$ and galaxy physical parameters by means of spectro-photometric fits performed with the BEAGLE code. The analysis exploits the multi-band photometry in the VANDELS fields, and the measurement of UV rest-frame emission lines (CIII]$\lambda 1909$, HeII$\lambda 1640$, OIII]$\lambda 1666$) from deep VIMOS spectra. We find no clear evolution of $\xi_{ion}^*$ with redshift within the probed range. The ionizing efficiency slightly increases at fainter $M_{UV}$, and bluer UV slopes, but these trends are less evident when restricting the analysis to a complete subsample at log(M$_{star}$/M$_{\odot}$)$>$9.5. We find a significant trend of increasing $\xi_{ion}^*$ with increasing EW(Ly$\alpha$), with an average log($\xi_{ion}^*$/Hz erg$^{-1}$)$>$25 at EW$>$50\AA, and a higher ionizing efficiency for high-EW CIII]$\lambda 1909$ and OIII]$\lambda 1666$ emitters. The most significant correlations are found with respect to stellar mass, specific star-formation rate (sSFR) and SFR surface density ($\Sigma_{SFR}$). The relation between $\xi_{ion}^*$ and sSFR shows a monotonic increase from log($\xi_{ion}^*$/Hz erg$^{-1}$) $\sim$24.5 at log(sSFR)$\sim$-9.5$yr^{-1}$ to $\sim$25.5 at log(sSFR)$\sim$-7.5$yr^{-1}$, a low scatter and little dependence on mass. The objects above the main-sequence of star-formation consistently have higher-than-average $\xi_{ion}^*$. A clear increase of $\xi_{ion}^*$ with $\Sigma_{SFR}$ is also found, with log($\xi_{ion}^*$/Hz erg$^{-1}$)$>$25 for objects at $\Sigma_{SFR}>$10 M$_{\odot}/yr/kpc^2$.(Abridged), Comment: 11 pages, 9 figures, accepted for publication in A&A

We present a study of the connection between the escape fraction of Lyman-alpha (Ly$\alpha$) and Lyman-continuum (LyC) photons within a sample of N=152 star-forming galaxies selected from the VANDELS survey at $3.85

We report on the discovery of cool gas inflows towards three star-forming galaxies at $\left\sim$ 2.30. Analysis of Keck Low-Resolution Imaging Spectrometer spectroscopy reveals redshifted low-ionisation interstellar (LIS) metal absorption lines with centroid velocities of 60 - 130 km $\rm{s}^{-1}$. These inflows represent some of the most robust detections of inflowing gas into isolated, star-forming galaxies at high redshift. Our analysis suggests that the inflows are due to recycling metal-enriched gas from previous ejections. Comparisons between the galaxies with inflows and a larger parent sample of 131 objects indicate that galaxies with detected inflows may have higher specific star-formation rates (sSFR) and star-formation-rate surface densities. However, when additional galaxies without robustly detected inflows based on centroid velocity but whose LIS absorption line profiles indicate large red-wing velocities are considered, galaxies with inflows do not show unique properties relative to those lacking inflows. Additionally, we calculate the covering fraction of cool inflowing gas as a function of red-wing inflow velocity, finding an enhancement in high sSFR binned galaxies, likely due to an increase in the amount of recycling gas. Together, these results suggest that the low detection rate of galaxies with cool inflows is primarily related to the viewing angle rather than the physical properties of the galaxies., Comment: 10 pages, 7 figures, accepted for publication in MNRAS

Using deep near-infrared Keck/MOSFIRE observations, we analyze the rest-optical spectra of eight star-forming galaxies in the COSMOS and GOODS-N fields. We reach integration times of $\sim$10 hours in the deepest bands, pushing the limits on current ground-based observational capabilities. The targets fall into two redshift bins -- 5 galaxies at $z \sim 1.7$ and 3 at $z \sim 2.5$ -- and were selected as likely to yield significant auroral-line detections. Even with long integration times, detection of the auroral lines remains challenging. We stack the spectra together into subsets based on redshift, improving the signal-to-noise ratio on the [O III] $\lambda 4364$ auroral emission line and, in turn, enabling a direct measurement of the oxygen abundance for each stack. We compare these measurements to commonly-employed strong-line ratios alongside measurements from the literature. We find that the stacks fall within the distribution of $z>1$ literature measurements, but a larger sample size is needed to robustly constrain the relationships between strong-line ratios and oxygen abundance at high redshift. We additionally report detections of [O I] $\lambda6302$ for nine individual galaxies and composite spectra of 21 targets in the MOSFIRE pointings. We plot their line ratios on the [O III] $\lambda 5008$/H$\beta$ vs. [O I] $\lambda 6302$/H$\alpha$ diagnostic BPT diagram, comparing our targets to local galaxies and H II regions. We find that the [O I]/H$\alpha$ ratios in our sample of galaxies are consistent with being produced in gas ionized by $\alpha$-enhanced massive stars, as has been previously inferred for rapidly-forming galaxies at early cosmic times., Comment: 18 pages, 6 figures, submitted to ApJ

We investigate dust attenuation and its dependence on viewing angle for 308 star-forming galaxies at $1.3\leq z\leq2.6$ from the MOSFIRE Deep Evolution Field (MOSDEF) survey. We divide galaxies with a detected H$\alpha$ emission line and coverage of H$\beta$ into eight groups by stellar mass, star formation rate (SFR), and inclination (i.e., axis ratio), then stack their spectra. From each stack, we measure Balmer decrement and gas-phase metallicity, then we compute median \AV and UV continuum spectral slope ($\beta$). First, we find that none of the dust properties (Balmer decrement, \AV, $\beta$) vary with axis ratio. Second, both stellar and nebular attenuation increase with increasing galaxy mass, showing little residual dependence on SFR or metallicity. Third, nebular emission is more attenuated than stellar emission, and this difference grows even larger at higher galaxy masses and SFRs. Based on these results, we propose a three-component dust model where attenuation predominantly occurs in star-forming regions and large, dusty star-forming clumps, with minimal attenuation in the diffuse ISM. In this model, nebular attenuation primarily originates in clumps, while stellar attenuation is dominated by star-forming regions. Clumps become larger and more common with increasing galaxy mass, creating the above mass trends. Finally, we argue that a fixed metal yield naturally leads to mass regulating dust attenuation. Infall of low-metallicity gas increases SFR and lowers metallicity, but leaves dust column density mostly unchanged. We quantify this idea using the Kennicutt-Schmidt and fundamental metallicity relations, showing that galaxy mass is indeed the primary driver of dust attenuation., Comment: 19 pages, 13 figures, accepted for publication in ApJ

We present the JWST Cycle 1 53.8hr medium program FRESCO, short for "First Reionization Epoch Spectroscopically Complete Observations". FRESCO covers 62 arcmin$^2$ in each of the two GOODS/CANDELS fields for a total area of 124 arcmin$^2$ exploiting JWST's powerful new grism spectroscopic capabilities at near-infrared wavelengths. By obtaining ~2 hr deep NIRCam/grism observations with the F444W filter, FRESCO yields unprecedented spectra at R~1600 covering 3.8 to 5.0 $\mu$m for most galaxies in the NIRCam field-of-view. This setup enables emission line measurements over most of cosmic history, from strong PAH lines at z~0.2-0.5, to Pa$\alpha$ and Pa$\beta$ at z~1-3, HeI and [SIII] at z~2.5-4.5, H$\alpha$ and [NII] at z~5-6.5, up to [OIII] and H$\beta$ for z~7-9 galaxies, and possibly even [OII] at z~10-12. FRESCO's grism observations provide total line fluxes for accurately estimating galaxy stellar masses and calibrating slit-loss corrections of NIRSpec/MSA spectra in the same field. Additionally, FRESCO results in a mosaic of F182M, F210M, and F444W imaging in the same fields to a depth of ~28.2 mag (5 $\sigma$ in 0.32" diameter apertures). Together with this publication, the v1 imaging mosaics are released as high-level science products via MAST. Here, we describe the overall survey design and the key science goals that can be addressed with FRESCO. We also highlight several, early science results, including: spectroscopic redshifts of Lyman break galaxies that were identified almost 20 years ago, the discovery of broad-line active galactic nuclei at z>4, and resolved Pa$\alpha$ maps of galaxies at z~1.4. These results demonstrate the enormous power for serendipitous discovery of NIRCam/grism observations., Comment: 12 pages, 11 figures; MNRAS in press; for more information on the survey and data releases, see http://jwst-fresco.astro.unige.ch/ and https://archive.stsci.edu/hlsp/fresco

We report detections of the [OIII]$\lambda$4364 auroral emission line for 16 galaxies at z=2.1-8.7, measured from JWST/NIRSpec observations obtained as part of the Cosmic Evolution Early Release Science (CEERS) survey program. We combine this CEERS sample with 9 objects from the literature at z=4-9 with auroral-line detections from JWST/NIRSpec and 21 galaxies at z=1.4-3.7 with auroral-line detections from ground-based spectroscopy. We derive electron temperature T_e and direct-method oxygen abundances for the combined sample of 46 star-forming galaxies at z=1.4-8.7. We use these measurements to construct the first high-redshift empirical T_e-based metallicity calibrations for the strong-line ratios [OIII]/H$\beta$, [OII]/H$\beta$, R23=([OIII]+[OII])/H$\beta$, [OIII]/[OII], and [NeIII]/[OII]. These new calibrations are valid over 12+log(O/H)=7.0-8.4 and can be applied to samples of star-forming galaxies at z=2-9, leading to an improvement in the accuracy of metallicity determinations at Cosmic Noon and in the Epoch of Reionization. The high-redshift strong-line relations are offset from calibrations based on typical $z\sim0$ galaxies or HII regions, reflecting the known evolution of ionization conditions between $z\sim0$ and $z\sim2$. Deep spectroscopic programs with JWST/NIRSpec promise to improve statistics at the low and high ends of the metallicity range covered by the current sample, as well as improve the detection rate of [NII]$\lambda$6585 to allow the future assessment of N-based indicators. These new high-redshift calibrations will enable accurate characterizations of metallicity scaling relations at high redshift, improving our understanding of feedback and baryon cycling in the early universe., Comment: 22 pages, 7 figures, 3 tables, submitted to ApJ

We analyze the rest-optical emission-line ratios of star-forming galaxies at 2.7<=z<6.5 drawn from the Cosmic Evolution Early Release Science (CEERS) Survey, and their relationships with stellar mass (M_*). Our analysis includes both line ratios based on the [NII]6583 feature -- [NII]6583/Ha, ([OIII]5007/Hb)/([NII]6583/Ha) (O3N2), and [NII]6583/[OII]3727 -- and those those featuring alpha elements -- [OIII]5007/Hb, [OIII]5007/[OII]3727 (O_32), ([OIII]4959,5007+[OII]3727)/Hb (R_23), and [NeIII]3869/[OII]3727. Given the typical flux levels of [NII]6583 and [NeIII]3869, which are undetected in the majority of individual CEERS galaxies at 2.7<=z<6.5, we construct composite spectra in bins of M_* and redshift. Using these composite spectra, we compare the relationships between emission-line ratios and M_* at 2.7<=z<6.5 with those observed at lower redshift. While there is significant evolution towards higher excitation (e.g., higher [OIII]5007/Hb, O_32, O3N2), and weaker nitrogen emission (e.g., lower [NII]6583/Ha and [NII]6583/[OII]3727) between z~0 and z~3, we find in most cases that there is no significant evolution in the relationship between line ratio and M_* beyond z~3. The [NeIII]3869/[OII]3727 ratio is anomalous in showing evidence for significant elevation at 4.0<=z<6.5 at fixed mass, relative to z~3.3. Collectively, however, our empirical results suggest that there is no significant evolution in the mass-metallicity relationship at 2.7<=z<6.5. Representative galaxy samples and metallicity calibrations based on existing and upcoming JWST/NIRSpec observations will be required to translate these empirical scaling relations into ones tracing chemical enrichment and gas cycling, and distinguish among the descriptions of star-formation feedback in simulations of galaxy formation at z>3., Comment: 10 pages, 4 figures, ApJL, in press

We conduct a statistical analysis of the factors responsible for the variation in the ionization parameter (U) of high-redshift star-forming galaxies based on medium resolution JWST/NIRSpec observations obtained by the Cosmic Evolution Early Release Science (CEERS) survey. The sample consists of 48 galaxies with spectroscopic redshifts z=2.7-6.3 which are largely representative of typical star-forming galaxies at these redshifts. The [SII] 6718, 6733 doublet is used to estimate electron densities (n_e), and dust-corrected Ha luminosities are used to compute total ionizing photon rates (Q). Using composite spectra of galaxies in bins of [OIII]/[OII] (i.e., O32) as a proxy for U, we determine that galaxies with higher O32 have ~ 500 cm^-3 that are at least a factor of ~5 larger than that of lower-O32 galaxies. We do not find a significant difference in between low- and high-O32 galaxies. Photoionization modeling of all available strong rest-frame optical emission lines is used to simultaneously constrain U and oxygen abundance (Z_neb). We find a large spread in log U of ~1.5 dex at a fixed Z_neb. On the other hand, the data indicate a highly significant correlation between U and star-formation-rate surface density (Sigma_SFR) which appears to be redshift invariant at z~1.6-6.3, and possibly up to z~9.5. We consider several avenues through which metallicity and Sigma_SFR (or gas density) may influence U, including variations in n_e and Q that are tied to metallicity and gas density, internal dust extinction of ionizing photons, and the effects of gas density on the volume filling fraction of dense clumps in HII regions and the escape fraction of ionizing photons. Based on these considerations, we conclude that gas density may play a more central role than metallicity in modulating U at these redshifts., Comment: 16 pages, 13 figures, 4 tables

We selected 35 low-mass SFGs (7.91000\r{A} and EW(CIII])>5\r{A}, closely resembling those now seen in EoR galaxies with JWST. We find low gas-phase metallicities 12+log(O/H)~7.5-8.5 and C/O abundances from 23%-128% solar, with no apparent increasing trend with metallicity. From our [OIII]4959,5007 profile modeling, we find that 65% of our sample shows an outflow component, which is shifted relative to the ionized gas systemic velocity, with mean $v_{max}$~280 km/s which correlates with the $\Sigma_{SFR}$. We find that the mass-loading factor $\mu$ of our sample is typically lower than in more massive galaxies from literature but higher than in typical local dwarf galaxies. In the stellar mass range covered, we find that $\mu$ increases with $\Sigma_{SFR}$ thus suggesting that for a given stellar mass, denser starbursts in low-mass galaxies produce stronger outflows. Our results complement the picture drawn by similar studies at lower redshift, suggesting that the removal of ionized gas in low-mass SFGs driven by stellar feedback is regulated by their stellar mass and by the strength and concentration of their star formation, i.e. $\Sigma_{\rm SFR}$., Comment: Accepted for publication in A&A. We updated the manuscript following referee's suggestions. We updated the estimations of C/O by not including CIV flux since it is not detected in most of our sample. No major changes in our results compared with previous version

We use the large spectroscopic dataset of the MOSFIRE Deep Evolution Field (MOSDEF) survey to investigate some of the key factors responsible for the elevated ionization parameters (U) inferred for high-redshift galaxies, focusing in particular on the role of star-formation-rate surface density (Sigma_SFR). Using a sample of 317 galaxies with spectroscopic redshifts z~1.9-3.7, we construct composite rest-frame optical spectra in bins of Sigma_SFR and infer electron densities, n_e, using the ratio of the [OII] 3727, 3730 doublet. Our analysis suggests a significant (~3 sigma) correlation between n_e and Sigma_SFR. We further find significant correlations between U and Sigma_SFR for composite spectra of a subsample of 113 galaxies, and for a smaller sample of 25 individual galaxies with inferences of U. The increase in n_e -- and possibly also the volume filling factor of dense clumps in HII regions -- with Sigma_SFR appear to be important factors in explaining the relationship between U and Sigma_SFR. Further, the increase in n_e and SFR with redshift at a fixed stellar mass can account for most of the redshift evolution of U. These results suggest that the gas density, which sets n_e and the overall level of star-formation activity, may play a more important role than metallicity evolution in explaining the elevated ionization parameters of high-redshift galaxies., Comment: 11 pages, 9 figures, 1 table, submitted to ApJ

In November 2022, the James Webb Space Telescope (JWST) returned deep near-infrared images of Abell 2744 -- a powerful lensing cluster capable of magnifying distant, incipient galaxies beyond it. Together with the existing Hubble Space Telescope (HST) imaging, this publicly available dataset opens a fundamentally new discovery space to understand the remaining mysteries of the formation and evolution of galaxies across cosmic time. In this work, we detect and measure some 60,000 objects across the 49 arcmin$^2$ JWST footprint down to a $5\,\sigma$ limiting magnitude of $\sim$30 mag in 0.32" apertures. Photometry is performed using circular apertures on images matched to the point spread function of the reddest NIRCam broad band, F444W, and cleaned of bright cluster galaxies and the related intra-cluster light. To give an impression of the photometric performance, we measure photometric redshifts and achieve a $\sigma_{\rm NMAD}\approx0.03$ based on known, but relatively small, spectroscopic samples. With this paper, we publicly release our HST and JWST PSF-matched photometric catalog with optimally assigned aperture sizes for easy use, along with single aperture catalogs, photometric redshifts, rest-frame colors, and individual magnification estimates. These catalogs will set the stage for efficient and deep spectroscopic follow-up of some of the first JWST-selected samples in Summer 2023., Comment: 28 pages, 19 figures, resubmitted to ApJS following significant data product improvements. Comments welcome. Catalogs can be accessed at https://jwst-uncover.github.io/DR2.html#PhotometricCatalogs

We use medium resolution JWST/NIRSpec observations from the Cosmic Evolution Early Release Science (CEERS) Survey to place the first constraints on dust attenuation and star formation based on the Paschen lines for a sizable sample of 63 galaxies at redshifts z=1.0-3.1. Our analysis indicates strong correlations between the Balmer decrement, Ha/Hb, and line ratios that include the Paschen lines (i.e., Paa/Hb, Pab/Hb, and the Paschen decrement, Paa/Pab), suggesting that the former is sensitive to the overall dust obscuration towards HII regions in high-redshift galaxies. The line ratios are used to derive the nebular reddening, E(B-V)neb, and star-formation rates (SFRs). There is marginal evidence that SFRs deduced from the Paschen lines may exceed by ~25% those derived from the Balmer lines alone, suggesting the presence of star formation that is optically thick in the Balmer lines, though deeper observations are needed to confirm this result. Using the Paschen-line constraints on bolometric SFRs, we reevaluate the relationship between dust obscuration and UV spectral slope, and find a reddening of the UV continuum that, on average, follows the SMC extinction curve. This analysis highlights the need for deeper spectroscopy of more representative samples to evaluate nebular dust attenuation and bolometric SFRs in high-redshift galaxies, and their relationship to the reddening of the UV continuum., Comment: 9 pages, 8 figures, 1 table

We utilize medium-resolution JWST/NIRSpec observations of 164 galaxies at $z=2.0-9.3$ from the Cosmic Evolution Early Release Science (CEERS) survey to investigate the evolution of the excitation and ionization properties of galaxies at high redshifts. Our results represent the first statistical constraints on the evolution of the [OIII]/H$\beta$ vs. [NII]/H$\alpha$, [SII]/H$\alpha$, and [OI]/H$\alpha$ ``BPT'' diagrams at $z>2.7$, and the first analysis of the O32 vs. R23 diagram at $z>4$ with a large sample. We divide the sample into five redshift bins containing 30-40 galaxies each. The subsamples at $z\sim2.3$, $z\sim3.3$, and $z\sim4.5$ are representative of the main-sequence star-forming galaxy population at these redshifts, while the $z\sim5.6$ and $z\sim7.5$ samples are likely biased toward high specific star-formation rate due to selection effects. Using composite spectra, we find that each subsample at $z=2.0-6.5$ falls on the same excitation sequence in the [NII] and [SII] BPT diagrams and the O32-R23 diagram on average, offset from the sequences followed by $z=0$ HII regions in the same diagrams. The direction of these offsets are consistent with high-redshift star-forming galaxies uniformly having harder ionizing spectra than typical local galaxies at fixed nebular metallicity. The similarity of the average line ratios suggests that the ionization conditions of the interstellar medium do not strongly evolve between $z\sim2$ and $z\sim6$. Overall, the rest-optical line ratios suggest the $z=2.7-9.3$ CEERS/NIRSpec galaxies at log($M_*/M_{\odot})\sim7.5-10$ have high degrees of ionization and moderately low oxygen abundances ($\sim0.1-0.3~Z_{\odot}$), but are not extremely metal poor ($<0.1~Z_{\odot}$) even at $z>6.5$., Comment: 15 pages, 6 figures, submitted to ApJ

We present an analysis of the star-formation rates (SFRs) and dust attenuation properties of star-forming galaxies at $2.7\leq z<6.5$ drawn from the Cosmic Evolution Early Release Science (CEERS) Survey. Our analysis is based on {\it JWST}/NIRSpec Micro-Shutter Assembly (MSA) $R\sim1000$ spectroscopic observations covering approximately $1-5$$\mu$m. Our primary rest-frame optical spectroscopic measurements are H$\alpha$/H$\beta$ Balmer decrements, which we use as an indicator of nebular dust attenuation. In turn, we use Balmer decrements to obtain dust-corrected H$\alpha$-based SFRs (i.e., SFR(H$\alpha$)). We construct the relationship between SFR(H$\alpha$) and stellar mass ($M_*$) in three bins of redshift ($2.7\leq z< 4.0$, $4.0\leq z< 5.0$, and $5.0\leq z<6.5$), which represents the first time the star-forming main sequence has been traced at these redshifts using direct spectroscopic measurements of Balmer emission as a proxy for SFR. In tracing the relationship between SFR(H$\alpha$) and $M_*$ back to such early times ($z>3$), it is essential to use a conversion factor between H$\alpha$ and SFR that accounts for the subsolar metallicity prevalent among distant galaxies. We also use measured Balmer decrements to investigate the relationship between dust attenuation and stellar mass out to $z\sim6$. The lack of significant redshift evolution in attenuation at fixed stellar mass, previously confirmed using Balmer decrements out to $z\sim2.3$, appears to hold out to $z\sim 6.5$. Given the rapidly evolving gas, dust, and metal content of star-forming galaxies at fixed mass, this lack of significant evolution in attenuation provides an ongoing challenge to explain., Comment: 9 pages, 4 figures, ApJ, in press

High-redshift Lyman break galaxies (LBGs) are efficiently selected in deep images using as few as three broadband filters, and have been shown to have multiple intrinsic and small- to large-scale environmental properties related to Lyman-alpha. In this paper we demonstrate a statistical relationship between net Lyman-alpha equivalent width (net Lya EW) and the optical broadband photometric properties of LBGs at z~2. We show that LBGs with the strongest net Lya EW in absorption (aLBGs) and strongest net Lya EW in emission (eLBGs) separate into overlapping but discrete distributions in $(U_n-R)$ colour and $R$-band magnitude space, and use this segregation behaviour to determine photometric criteria by which sub-samples with a desired Lya spectral type can be selected using data from as few as three broadband optical filters. We propose application of our result to current and future large-area and all-sky photometric surveys that will select hundreds of millions of LBGs across many hundreds to thousands of Mpc, and for which spectroscopic follow-up to obtain Lya spectral information is prohibitive. To this end, we use spectrophotometry of composite spectra derived from a sample of 798 LBGs divided into quartiles on the basis of net Lya EW to calculate criteria for the selection of Lya absorbing and Lya emitting populations of z~3 LBGs using $ugri$ broadband photometric data from the Vera Rubin Observatory Legacy Survey of Space and Time (LSST)., Comment: Published in Publications of the Astronomical Society of Australia 16 pages, 6 figures, 8 tables

We aim to quantify the relation between the dust-to-gas (DTG) mass ratio and gas-phase metallicity of $z=$2.1-2.5 luminous galaxies and contrast this high-redshift relation against analogous constraints at $z=$0. We present a sample of 10 star-forming main-sequence galaxies in the redshift range $2.1

We present observations of CO(3-2) in 13 main-sequence $z=2.0-2.5$ star-forming galaxies at $\log(M_*/M_{\odot})=10.2-10.6$ that span a wide range in metallicity (O/H) based on rest-optical spectroscopy. We find that CO(3-2)/SFR decreases with decreasing metallicity, implying that the CO luminosity per unit gas mass is lower in low-metallicity galaxies at $z\sim2$. We constrain the CO-to-H$_2$ conversion factor ($\alpha_{\text{CO}}$) and find that $\alpha_{\text{CO}}$ inversely correlates with metallicity at $z\sim2$. We derive molecular gas masses ($M_{\text{mol}}$) and characterize the relations among $M_*$, SFR, $M_{\text{mol}}$, and metallicity. At $z\sim2$, $M_{\text{mol}}$ increases and molecular gas fraction ($M_{\text{mol}}$/$M_*$) decrease with increasing $M_*$, with a significant secondary dependence on SFR. Galaxies at $z\sim2$ lie on a near-linear molecular KS law that is well-described by a constant depletion time of 700 Myr. We find that the scatter about the mean SFR-$M_*$, O/H-$M_*$, and $M_{\text{mol}}$-$M_*$ relations is correlated such that, at fixed $M_*$, $z\sim2$ galaxies with larger $M_{\text{mol}}$ have higher SFR and lower O/H. We thus confirm the existence of a fundamental metallicity relation at $z\sim2$ where O/H is inversely correlated with both SFR and $M_{\text{mol}}$ at fixed $M_*$. These results suggest that the scatter of the $z\sim2$ star-forming main sequence, mass-metallicity relation, and $M_{\text{mol}}$-$M_*$ relation are primarily driven by stochastic variations in gas inflow rates. We place constraints on the mass loading of galactic outflows and perform a metal budget analysis, finding that massive $z\sim2$ star-forming galaxies retain only 30% of metals produced, implying that a large mass of metals resides in the circumgalactic medium., Comment: 35 pages, 17 figures, submitted to ApJ

We investigate the conditions that facilitate galactic-scale outflows using a sample of 155 typical star-forming galaxies at $z$~2 drawn from the MOSFIRE Deep Evolution Field (MOSDEF) survey. The sample includes deep rest-frame UV spectroscopy from the Keck Low-Resolution Imaging Spectrometer (LRIS), which provides spectral coverage of several low-ionisation interstellar (LIS) metal absorption lines and Ly$\alpha$ emission. Outflow velocities are calculated from the centroids of the LIS absorption and/or Ly$\alpha$ emission, as well as the highest-velocity component of the outflow from the blue wings of the LIS absorption lines. Outflow velocities are found to be marginally correlated or independent of galaxy properties, such as star-formation rate (SFR) and star-formation rate surface density ($\Sigma_{\rm SFR}$). Outflow velocity scales with SFR as a power-law with index 0.24, which suggests that the outflows may be primarily driven by mechanical energy generated by supernovae explosions, as opposed to radiation pressure acting on dusty material. On the other hand, outflow velocity and $\Sigma_{\rm SFR}$ are not significantly correlated, which may be due to the limited dynamic range of $\Sigma_{\rm SFR}$ probed by our sample. The relationship between outflow velocity and $\Sigma_{\rm SFR}$ normalised by stellar mass ($\Sigma_{\rm sSFR}$), as a proxy for gravitational potential, suggests that strong outflows (e.g., > 200 km s$^{-1}$) appear ubiquitous above a threshold of log($\Sigma_{\rm sSFR}/\rm{yr}^{-1}\ \rm{kpc}^{-2}$) ~ -11.3, and that above this threshold, outflow velocity uncouples from $\Sigma_{\rm sSFR}$. These results highlight the need for higher resolution spectroscopic data and spatially resolved imaging to test the driving mechanisms of outflows predicted by theory., Comment: 15 pages, 5 figures, Submitted to Monthly Notices of the Royal Astronomical Society

We present results from ALMA 1.2mm continuum observations of a sample of 27 star-forming galaxies at z=2.1-2.5 from the MOSFIRE Deep Evolution Field (MOSDEF) survey. These galaxies have gas-phase metallicity and star-formation rate measurements from Hb, [OIII], Ha, and [NII]. Using stacks of Spitzer, Herschel, and ALMA photometry (rest-frame ~ 8-400$\mu$m), we examine the IR SED of high-redshift subsolar metallicity (~0.5 $Z_{\odot}$) LIRGs. We find that the data agree well with an average SED template of higher luminosity local low-metallicity dwarf galaxies (reduced $\chi^2$ of 1.8). When compared with the commonly used templates for solar-metallicity local galaxies or high-redshift LIRGs and ULIRGs, even in the most favorable case (with reduced $\chi^2$ of 2.8), the templates are rejected at >98% confidence level. The broader and hotter IR SED of both the local dwarfs and high-redshift subsolar metallicity galaxies may result from different grain properties, a clumpy dust geometry, or a harder/more intense ionizing radiation field that heats the dust to higher temperatures. The obscured SFR indicated by the FIR emission of the subsolar metallicity galaxies is only ~ 60% of the total SFR, which is considerably lower than that of the local LIRGs with ~ 96-97% obscured fractions. Due to the evolving IR SED shape, the local LIRG templates fit to mid-IR data can overestimate the Rayleigh-Jeans tail measurements at z~2 by a factor of 2-20, and these templates underestimate IR luminosities if fit to the observed ALMA fluxes by >0.4dex. At a given stellar mass or metallicity, dust masses at z~2.3 are an order of magnitude higher than those at z~0. Given the predicted molecular gas mass fractions, the observed z~2.3 dust-to-stellar mass ratios suggest lower dust-to-molecular gas masses than in local galaxies at the same metallicity., Comment: Accepted for publication in ApJ. 29 pages, 2 appendices, 10 figures, 3 tables