The JWST Emission Line Survey (JELS): The sizes and merger fraction of star-forming galaxies during the Epoch of Reionization
H. M. O. Stephenson, J. P. Stott, C. A. Pirie, K. J. Duncan, D. J. McLeod, P. N. Best, M. Brinch, M. Clausen, R. K. Cochrane, J. S. Dunlop, S. R. Flury, J. E. G… 展开作者
H. M. O. Stephenson, J. P. Stott, C. A. Pirie, K. J. Duncan, D. J. McLeod, P. N. Best, M. Brinch, M. Clausen, R. K. Cochrane, J. S. Dunlop, S. R. Flury, J. E. Geach, C. L. Hale, E. Ibar, Zefeng Li, J. Matthee, R. J. McLure, L. Ossa-Fuentes, A. L. Patrick, D. Sobral, A. M. Swinbank
备注：
21 pages, 11 figures. This paper has been resubmitted to MNRAS after one round of minor referee comments
We used observations from the JWST Emission Line Survey (JELS) to measure the half-light radii ($r_{e}$) of 23 H$α$-emitting star-forming (SF) galaxies at $z=6.1$ in the PRIMER/COSMOS field. Galaxy sizes were measured in JWST Near-infrared Camera observations in rest-frame H$α$ (tracing recent star formation) with the F466N and F470N narrowband filters from JELS, and compared against rest-$R$-band, $V$-band (tracing established stellar populations) and near-ultraviolet sizes. We find a size-stellar mass ($r_{e}-M_{*}$) relationship with a slope that is consistent with literature values at lower redshifts, though offset to lower sizes. We observe a large scatter in $r_{e}$ at low stellar mass ($M_{*}<10^{8.4}$ M$_{\odot}$) which we believe is the result of bursty star formation histories (SFHs) of SF galaxies at the Epoch of Reionization (EoR). We find that the stellar and ionised gas components are similar in size at $z=6.1$. The evidence of already-established stellar components in these H$α$ emitters (HAEs) indicates previous episodes of star formation have occurred. As such, following other JELS studies finding our HAEs are undergoing a current burst of star formation, we believe our results indicate that SF galaxies at the end of the EoR have already experienced a bursty SFH. From our $r_{e}-M_{*}$ relationship, we find $r_{e, \text{F444W}}=0.76\pm0.46$ kpc for fixed stellar mass $M_{*}=10^{9.25}$ M$_{\odot}$, which is in agreement with other observations and simulations of star forming galaxies in the literature. We find a close-pair (major) merger fraction of ($f_{\text{maj. merger}}=0.44\pm0.22$) $f_{\text{merger}}=0.43\pm0.11$ for galaxy separations $d\lesssim25$ kpc, which is in agreement with other $z\approx6$ studies.
The JWST Emission Line Survey (JELS): A narrow-band determination of the H$α$ Luminosity Function and Cosmic Star Formation into the Epoch of Reionization
Institute for Astronomy, University of Edinburgh（爱丁堡大学天体物理研究所）；Astrophysics, Department of Physics, University of Oxford（牛津大学物理系天体物理学）
The JWST Emission Line Survey (JELS): Multi-wavelength properties of Paschen line-emitters at Cosmic Noon
Instituto de Física y Astronomía, Universidad de Valparaíso（瓦尔帕莱索大学物理与天文学研究所）；Millennium Nucleus for Galaxies (MINGAL)（银河系千年核）；Institute for Astronomy, University of Edinburgh（爱丁堡大学天文研究所）；Jodrell Bank Centre for Astrophysics, University of Manchester（曼彻斯特大学乔德雷尔银行天体物理学中心）；Institute of Science and Technology Austria (IS（奥地利科学与理工学院）
Breaking Through the Cosmic Fog: JWST/NIRSpec Constraints on Ionizing Photon Escape in Reionization-Era Galaxies
University of Geneva（日内瓦大学）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；Cosmic Dawn Center (DAWN)（宇宙黎明中心（DAWN））；Max Planck Institut für Astrophysik（马克斯·普朗克天体物理研究所）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；The University of Texas at Austin（德克萨斯大学奥斯汀分校）
Next generation telescopes such as the James Webb Space Telescope (JWST) and the Nancy Grace Roman Space Telescope (NGRST) will enable us to study the first billion years of our Universe in unprecedented detail. In this work we use the ASTRAEUS (semi-numerical rAdiative tranSfer coupling of galaxy formaTion and Reionization in N-body dArk mattEr simUlationS) framework, that couples galaxy formation and reionization (for a wide range of reionization feedback models), to estimate the cosmic variance expected in the UV Luminosity Function (UV LF) and the Stellar Mass Function (SMF) in JWST survey…
Reionization driven by the few: the ionizing budget of galaxies at z=5-10 from JWST/NIRSpec
University of Geneva（日内瓦大学）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；Department of Astronomy, The University of Texas at Austin（德克萨斯大学奥斯汀分校天文学系）；Universidad de Chile（智利大学）
We conduct a comprehensive study on dropout galaxy candidates at $z\sim9-16$ using the first 90 arcmin$^2$ JWST/NIRCam images taken by the early release observations (ERO) and early release science (ERS) programs. With the JWST simulation images, we find that a number of foreground interlopers are selected with a weak photo-$z$ determination ($Δχ^2>4$). We thus carefully apply a secure photo-$z$ selection criterion ($Δχ^2>9$) and conventional color criteria with confirmations of the ERO NIRSpec spectroscopic redshifts, and obtain a total of 23 dropout galaxies at $z\sim9-16$, including two can…
Towards Reconciling Reionization with JWST: The Role of Bright Galaxies and Strong Feedback
University of Maryland, College Park（马里兰大学帕克分校）；Space Telescope Science Institute（太空望远镜科学研究所）；University of Zurich（苏黎世大学）；University of Edinburgh（爱丁堡大学）；University of the Western Cape（西开普大学）；New Mexico State University（新墨西哥州立大学）；University of Copenhagen（哥本哈根大学）；Technical University of Denmark（丹麦技术大学）
Recent observations of galaxies at $z \gtrsim 7$, along with the low value of the electron scattering optical depth measured by the Planck mission, make galaxies plausible as dominant sources of ionizing photons during the epoch of reionization. However, scenarios of galaxy-driven reionization hinge on the assumption that the average escape fraction of ionizing photons is significantly higher for galaxies in the reionization epoch than in the local Universe. The NIRSpec instrument on the James Webb Space Telescope (JWST) will enable spectroscopic observations of large samples of reionization-e…
The scheduled launch of James Webb Space Telescope (JWST) in late 2021 marks a new start for studies of galaxy formation at high redshift z>~6 during the era of Cosmic Reionization. JWST can capture sensitive, high-resolution images and multi-object spectroscopy in the infrared that will transform our view of galaxy formation during the first billion years of cosmic history. This review summarizes our current knowledge of the role of galaxies in reionizing intergalactic hydrogen ahead of JWST, achieved through observations with Hubble Space Telescope and ground-based facilities including Keck,…
The Early Release Observations (EROs) of JWST beautifully demonstrate the promise of JWST in characterizing the universe at cosmic dawn. We analyze the ERO spectra of three $z \sim 8$ galaxies to determine their metallicities, gas temperatures and ionization. These galaxies offer the first opportunity to understand the physical properties of epoch-of-reionization galaxies through detailed rest-optical emission line spectroscopy. We show that these objects have metal abundances $12+\log[O/H] \approx 6.9 - 8.2$, based on both the $T_e$ method and on a recent calibration of the $R_{23}$ metallici…
Probing the Cosmic Reionization History with JWST: Gunn-Peterson and Ly$α$ Damping Wing Absorption at $4.5 < z < 13$
The University of Tokyo（东京大学）；National Astronomical Observatory of Japan（日本国立天文台）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo（东京大学宇宙物理数学研究所（WPI））
Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA): The core of the highest redshift galaxy overdensity at $z = 7.88$ confirmed by NIRSpec/JWST
Direct T_e-based Metallicities of z=2-9 Galaxies with JWST/NIRSpec: Empirical Metallicity Calibrations Applicable from Reionization to Cosmic Noon
University of Kentucky（肯塔基大学）；University of California, Davis（加州大学戴维斯分校）；University of California, Los Angeles（加州大学洛杉矶分校）；University of Arizona（亚利桑那大学）；University of California, Riverside（加州大学河滨分校）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）
Galaxies forming in low-mass halos are thought to be primarily responsible for reionizing the Universe during the first billion years after the Big Bang. Yet, these halos are extremely inefficient at forming stars in the nearby Universe. In this work, we address this apparent tension, and ask whether a physically motivated model of galaxy formation that reproduces the observed abundance of faint galaxies in the nearby Universe is also consistent with available observational constraints on the reionization history. By interfacing the Santa Cruz semi-analytic model for galaxy formation with an a…
Star cluster formation in the early universe and their contribution to reionization remains to date largely unconstrained. Here we present JWST/NIRCam imaging of the most highly magnified galaxy known at z ~ 6, the Sunrise arc. We identify six young massive star clusters (YMCs) with measured radii spanning ~ 20 pc down to ~ 1 pc (corrected for lensing magnification), estimated stellar masses of ~ $10^{(6-7)}$ Msun, and with ages 1-30 Myr based on SED fitting to photometry measured in 8 filters extending to rest-frame 7000A. The resulting stellar mass surface densities are higher than 1000 Msun…
Resolving dust and Lyα emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS
University of Ljubljana（卢布尔雅那大学）；University of California Davis（加州大学戴维斯分校）；Arizona State University（亚利桑那州立大学）；University of Groningen（格罗宁根大学）；INAF - Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Saint Mary’s University（圣玛丽大学）；Space Telescope Science Institute（太空望远镜科学研究所）
From THESAN-ZOOM to JWST: Predicting ionizing photon escape and the rise of UV-bright reionization sources
University of Cambridge（剑桥大学）；The University of Texas at Dallas（德克萨斯大学达拉斯分校）；York University（约克大学）；The University of Tokyo（东京大学）；Leibniz-Institut für Astrophysik Potsdam（波茨坦阿纳西斯天文台）；Massachusetts Institute of Technology（麻省理工学院）
The $z \gtrsim 9$ galaxy UV luminosity function from the JWST Advanced Deep Extragalactic Survey: insights into early galaxy evolution and reionization
University of Arizona（亚利桑那大学）；University of California, Berkeley（加州大学伯克利分校）；University of California, Santa Cruz（加州大学圣克鲁兹分校）；University of Texas, Austin（德克萨斯大学奥斯汀分校）；University of Copenhagen（哥本哈根大学）；European Space Agency（欧洲空间局）
UV slopes of Starforming Galaxies in Strong Lensing fields at the Epoch of Reionization with JWST
University of Ljubljana（卢布尔雅那大学）；University of California Davis（加州大学戴维斯分校）；Dunlap Institute for Astronomy and Astrophysics（邓普天文学与天体物理研究所）；York University（约克大学）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Kavli Institute for Cosmology, University of Cambridge（剑桥大学卡弗里宇宙学研究所）；Cavendish Laboratory - Astrophysics Group, University of Cambridge（剑桥大学卡文迪许实验室天体物理组）
The reionization of cosmic hydrogen marks a critical juncture in the history of structure formation in the universe. Here we present a new formulation of the standard reionization equation for the evolution of the volume-averaged HII fraction that is more consistent with the accepted conceptual model of inhomogeneous intergalactic absorption. The revised equation retains the basic terminology and simplicity of the classic calculation but explicitly accounts for the presence of the optically thick "Lyman-limit systems" that are known to determine the mean free path of ionizing radiation after o…
The James Webb Space Telescope will provide deep imaging and spectroscopy for sources at redshifts above 6, covering the Epoch of Reionization (EoR, 6 < z < 10). The Mid-IR instrument (MIRI) integral field spectrograph (MRS) will be the only instrument on board JWST able to observe the brightest optical emission lines H$α$ and [OIII]0.5007$μ$m at redshifts above 7 and 9, respectively. This paper presents a study of the H$α$ fluxes predicted by FIRSTLIGHT cosmological simulations for galaxies at redshifts of 6.5 to 10.5, and its detectability with MIRI. Deep (40 ks) spectroscopic integrations w…
Deep JWST spectroscopy of galaxies in a candidate ionized bubble at $z = 8.7$: probing reionization at pMpc scales with Ly$α$ emission
University of Cambridge（剑桥大学）；University of Arizona（亚利桑那大学）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；University of Vienna（维也纳大学）
Active galactic nuclei (AGN) forming in the early universe are thought to be the primary source of hard ionizing photons contributing to the reionization of intergalactic helium. However, the number density and spectral properties of high-redshift AGN remain largely unconstrained. In this work, we make use of physically-informed models calibrated with a wide variety of available observations to provide estimates for the role of AGN throughout the Epoch of Reionization. We present AGN luminosity functions in various bands between z = 2 to 7 predicted by the well-established Santa Cruz semi-anal…
JWST ASPIRE: How Did Galaxies Complete Reionization? Evidence for Excess IGM Transmission around ${\rm [O\,{\scriptstyle III}]}$ Emitters during Reionization
The James Webb Space Telescope (JWST) NIRSpec instrument will allow rest-frame ultraviolet/optical spectroscopy of galaxies in the epoch of reionization (EoR). Some galaxies may exhibit significant leakage of hydrogen-ionizing photons into the intergalactic medium, resulting in faint nebular emission lines. We present a machine learning framework for identifying cases of very high hydrogen-ionizing photon escape from galaxies based on the data quality expected from potential NIRSpec observations of EoR galaxies in lensed fields. We train our algorithm on mock samples of JWST/NIRSpec data for g…
Lyman-alpha emission at the end of reionization: line strengths and profiles from MMT and JWST observations at z~5-6
Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理与空间研究所）；Departement d’Astronomie, University of Geneva（日内瓦大学天文学系）；Kavli Institute for Cosmology, University of Cambridge（剑桥大学卡弗里宇宙学研究所）；Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）
Star-forming galaxies can exhibit strong morphological differences between the rest-frame far-UV and optical, reflecting inhomogeneities in star-formation and dust attenuation. We exploit deep, high resolution NIRCAM 7-band observations to take a first look at the morphology of galaxies in the epoch of reionization ($z>7$), and its variation in the rest-frame wavelength range between Lyman $α$ and 6000-4000Å, at $z=7-12$. We find no dramatic variations in morphology with wavelength -- of the kind that would have overturned anything we have learned from the Hubble Space Telescope. No significan…
The ultraviolet (UV) continuum slope ($β~$where$~f_λ\proptoλ^β$) of galaxies is sensitive to a variety of properties, from the metallicity and age of the stellar population to dust attenuation throughout the galaxy. Considerable attention has focused on identifying reionization-era galaxies with very blue UV slopes ($β<-3$). Not only do such systems provide a signpost of low-metallicity stars, but they also identify galaxies likely to leak ionizing photons from their HII regions as such blue UV slopes require the reddening effect of nebular continuum to be diminished. In this paper we present …
