As the James Webb Space Telescope approaches scientific operation, there is much interest in exploring the redshift range beyond that accessible with Hubble Space Telescope imaging. Currently, the only means to gauge the presence of such early galaxies is to age-date the stellar population of systems in the reionisation era. As a significant fraction of $z\simeq7-8$ galaxies are inferred from Spitzer photometry to have extremely intense [OIII] emission lines, it is commonly believed these are genuinely young systems that formed at redshifts $z<10$, consistent with a claimed rapid rise in the star formation density at that time. Here we study a spectroscopically-confirmed sample of extreme [OIII] emitters at $z=1.3-3.7$, using both dynamical masses estimated from [OIII] line widths and rest-frame UV to near-infrared photometry to illustrate the dangers of assuming such systems are genuinely young. For the most extreme of our intermediate redshift line emitters, we find dynamical masses $10-100$ times that associated with a young stellar population mass, which are difficult to explain solely by the presence of additional dark matter or gaseous reservoirs. Adopting nonparametric star formation histories, we show how the near-infrared photometry of a subset of our sample reveals an underlying old ($>100$ Myr) population whose stellar mass is $\simeq40$ times that associated with the starburst responsible for the extreme line emission. Without adequate rest-frame near-infrared photometry we argue it may be premature to conclude that extreme line emitters in the reionisation era are low mass systems that formed at redshifts below $z\simeq10$.
We have found a sample of extreme emission-line galaxies (EELGs) with strong [OIII]$λ$5007 emission at z $\sim$ 0.5. Using broadband photometric selection and requiring small uncertainties in photometry, we searched the 14th Data Release (DR14) of the Sloan Digital Sky Survey (SDSS) and found 2658 candidates with strong i-band excess (i - z $\leqslant$ r - i - 0.7). We further obtained 649 SDSS spectra of these objects, and visually identified 22 [OIII] emitters lying at 0.40 $<$ z $<$ 0.63. Having constructed their UV-IR spectral energy distributions (SED) we found that they have fairly blue …
Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) detected far-infrared emission lines such as the [OIII] 88 μm line from galaxies at $z \sim 7 - 9$. Far-infrared lines can be used to probe the structure and kinematics of such high-redshift galaxies as well as to accurately determine their spectroscopic redshifts. We use a cosmological simulation of galaxy formation to study the physical properties of [OIII] 88 μm emitters. In a comoving volume of 50 $h^{-1}$ Mpc on a side, we locate 34 galaxies with stellar masses greater than $10^8\ {\rm M_\odot}$ at $z = 9$, a…
Recent work has suggested extreme [OIII] emitting star-forming galaxies are important to reionization. Relatedly, [OIII]/[OII] has been put forward as an indirect estimator of the Lyman Continuum (LyC) escape fraction ($f_{esc}$) at $z\gtrsim4.5$ when the opaque IGM renders LyC photons unobservable. Using deep archival U-band (VLT/VIMOS) imaging of a recently confirmed overdensity at $z\sim3.5$ we calculate tight constraints on $f_{esc}$ for a sample (N=73) dominated by extreme [OIII] emitters. We find no Lyman Continuum signal ($f_{esc}^{rel} < 6.3^{+0.7}_{-0.7} \%$ at $1σ$) in a deep U-band …
We make use of \textit{JWST} medium and broad-band NIRCam imaging, along with ultra-deep MIRI $5.6 \rm μm$ imaging, in the Hubble eXtreme Deep Field (XDF) to identify prominent line emitters at $z\simeq 7-8$. Out of a total of 58 galaxies at $z\simeq 7-8$, we find 18 robust candidates ($\simeq$31\%) for (H$β$ + [OIII]) emitters, based on their enhanced fluxes in the F430M and F444W filters, with EW$_{0}$(H$β$ +[OIII]) $\simeq 87 - 2100$ Å. Among these emitters, 16 lie in the MIRI coverage area and 12 exhibit a clear flux excess at $5.6 \, \rm μm$, indicating the simultaneous presence of a prom…
Strong [OIII]$+$H$β$ emitters dominated the ionizing budget at $z\sim7$
Astrophysics Science Division, Goddard Space Flight Center（天体物理学科学部，戈达德太空飞行中心）；The Catholic University of America（美国天主教大学）；Center for Research and Exploration in Space Science and Technology, NASA/GSFC（NASA/戈达德太空飞行中心空间科学与技术研究与探索中心）
Galaxies in the reionization-era have been shown to have prominent [OIII]+H$β$ emission. Little is known about the gas conditions and radiation field of this population, making it challenging to interpret the spectra emerging at $z\gtrsim6$. Motivated by this shortcoming, we have initiated a large MMT spectroscopic survey identifying rest-frame optical emission lines in 227 intense [OIII] emitting galaxies at $1.3<z<2.4$. This sample complements the MOSDEF and KBSS surveys, extending to much lower stellar masses ($10^7-10^8 M_\odot$) and larger specific star formation rates ($5-300$ Gyr$^{-1}$…
We study statistics of the 21-cm signal from the epoch of reionization. We propose to use [OIII] line emitting galaxies to cross-correlate with the 21-cm signal from $z = 7 - 10$. To this aim, we employ simulations of reionization obtained post-processing the high-resolution cosmological hydrodynamic simulation Massive Black-II with the three-dimensional (3D) radiative transfer code CRASH to follow the propagation of ionizing photons from a variety of sources. We show that, during the early phases of reionization, the 21-cm signal is positively correlated with the spatial distribution of the […
Deep spectroscopy of galaxies in the reionization-era has revealed intense CIII] and CIV line emission (EW $>15-20$ Å). In order to interpret the nebular emission emerging at $z>6$, we have begun targeting rest-frame UV emission lines in galaxies with large specific star formation rates (sSFRs) at $1.3<z<3.7$. We find that CIII] reaches the EWs seen at $z>6$ only in large sSFR galaxies with [OIII]+H$β$ EW $>1500$ Å. In contrast to previous studies, we find that many galaxies with intense [OIII] have weak CIII] emission (EW $=5-8$ Å), suggesting that the radiation field associated with young st…
We present our measurements of the H$α$, [OIII], and [OII] luminosity functions as part of the Lyman Alpha Galaxies at Epoch of Reionization (LAGER) survey using our samples of 1577 $z = 0.47$ H$α$-, 3933 $z = 0.93$ [OIII]-, and 5367 $z = 1.59$ [OII]-selected emission line galaxies in a single 3 deg$^2$ CTIO/Blanco DECam pointing of the COSMOS field. Our observations reach 5$σ$ depths of $8.2\times10^{-18}$ erg s$^{-1}$ cm$^{-2}$ and comoving volumes of $(1-7)\times10^{5}$ Mpc$^3$ making our survey one of the deepest narrowband surveys. We measure the observed luminosity functions and find bes…
JWST ASPIRE: How Did Galaxies Complete Reionization? Evidence for Excess IGM Transmission around ${\rm [O\,{\scriptstyle III}]}$ Emitters during Reionization
Using a large sample of sub-L$_*$ galaxies, with similar UV magnitudes, M$_{\rm UV}\simeq -19$ at $z\simeq6$, extracted from the FirstLight simulations, we show the diversity of galaxies at the end of the reionization epoch. We find a factor $\sim$40 variation in the specific star-formation rate (sSFR). This drives a $\sim$1 dex range in equivalent width of the [OIII]$λ$5007 line. Variations in nebular metallicity and ionization parameter within HII regions lead to a scatter in the equivalent widths and [OIII]/H$α$ line ratio at a fixed sSFR. [OIII]-bright emitters ([OIII]/H$α$>1) have higher …
We present a study of the [OIII]5007/[OII]3727 (O32) ratios of star-forming galaxies drawn from MUSE data spanning a redshift range 0.28<z<0.85. Recently discovered Lyman continuum (LyC) emitters have extremely high oxygen line ratios: O32>4. Here we aim to understand the properties and the occurrences of galaxies with such high line ratios. Combining data from several MUSE GTO programmes, we select a population of star-forming galaxies with bright emission lines, from which we draw 406 galaxies for our analysis based on their position in the z-dependent star formation rate (SFR) - stellar mas…
Over the past decades, several studies have discovered a population of galaxies undergoing very strong star formation events, called extreme emission line galaxies (EELGs). In this work, we exploit the capabilities of the Javalambre Photometric Local Universe Survey (J-PLUS), a wide field multifilter survey, with 2000 square degrees observed. We use it to identify EELGs at low redshift by their [OIII]5007 emission line. We intend to provide with a more complete, deep, and less biased sample of local EELGs. We select objects with an excess of flux in the J-PLUS mediumband $J0515$ filter, which …
We assemble a sample of 17 low metallicity (7.45 < log(O/H)+12 < 8.12) galaxies with z < 0.1 found spectroscopically, without photometric pre-selection, in early data from the Hobby Eberly Telescope Dark Energy Experiment (HETDEX). Star forming galaxies that occupy the lowest mass and metallicity end of the mass-metallicity relation tend to be under sampled in continuum-based surveys as their spectra are typically dominated by emission from newly forming stars. We search for galaxies with high [OIII]$λ$5007 / [OII]$λ$3727, implying highly ionized nebular emission often indicative of low metall…
We assemble an unbiased sample of 29 galaxies with [O II] $λ3727$ and/or [O III] $λ5007$ detections at $z < 0.15$ from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Pilot Survey (HPS). HPS finds galaxies without pre-selection based on their detected emission lines via integral field spectroscopy. Sixteen of these objects were followed up with the second-generation, low resolution spectrograph (LRS2) on the upgraded Hobby-Eberly Telescope. Oxygen abundances were then derived via strong emission lines using a Bayesian approach. We find most of the galaxies fall along the mass-metall…
The gas metallicity of galaxies is often estimated using strong emission lines such as the optical lines of [OIII] and [OII]. The most common measure is "R23", defined as ([OII]$λ$$λ$3726, 3729 + [OIII]$λ$$λ$4959,5007)/H$β$. Most calibrations for these strong-line metallicity indicators are for continuum selected galaxies. We report a new empirical calibration of R23 for extreme emission-line galaxies using a large sample of about 800 star-forming green pea galaxies with reliable T$_e$-based gas-phase metallicity measurements. This sample is assembled from Sloan Digital Sky Survey (SDSS) Data …
We report the discovery of a double-peaked Lyman-$α$ (Ly$α$) emitter (LAE) at $z=3.2177\pm0.0001$ in VLT/MUSE data. The galaxy is strongly lensed by the galaxy cluster RXC~J0018.5+1626 recently observed in the RELICS survey, and the double-peaked Ly$α$ emission is clearly detected in the two counter images in the MUSE field-of-view. We measure a relatively high Ly$α$ rest-frame equivalent width (EW) of $\mathrm{EW}_{\mathrm{Ly}α,0}=(63\pm2)\,\mathring{\mathrm{A}}$. Additional near-infrared (NIR) spectroscopy allows us to measure the H$β$, [OIII]$\lambda4959\,\mathring{\mathrm{A}}$ and [OIII]$\…
We present a search for extreme emission line galaxies (EELGs) at z<1 in the COSMOS and North Ecliptic Pole (NEP) fields with imaging from Subaru/Hyper Suprime-Cam (HSC) and a combination of new and existing spectroscopy. We select EELGs on the basis of substantial excess flux in the z broadband, which is sensitive to H$α$ at 0.3<z<0.42 and [OIII]$λ$5007 at 0.7<z<0.86. We identify 10,470 galaxies with z excesses in the COSMOS dataset and 91,385 in the NEP field. We cross-reference the COSMOS EELG sample with the zCOSMOS and DEIMOS 10k spectral catalogs, finding 1395 spectroscopic matches. We m…
The new era of Lyman alpha emitters (LAEs): Typical star formation histories of LAEs in the ILLUSTRIS simulation
Universidad Central de Chile（智利中央大学）；Universidad de La Serena（拉塞雷纳大学）；Universidad Andrés Bello（安德烈斯贝洛大学）；Rutgers, the State University of New Jersey（新泽西州立罗格斯大学）；Institute for Advanced Study, Princeton（普林斯顿高等研究院）；Purdue University（普渡大学）
MIDIS: Strong H$β$+[OIII] Line Emitters at $z \geq 9$
Space Telescope Science Institute（太空望远镜科学研究所）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU-Space, Technical University of Denmark（丹麦技术大学空间科学与技术学院）；Department of Astronomy, Stockholm University（斯德哥尔摩大学天文学系）；Centro de Astrobiología, CSIC-INTA（西班牙国家航空航天技术研究院与西班牙高等科学研究理事会天文生物中心）；Max Planck Institut für Astronomie（马克斯·普朗克天文学研究所）；Centre for Extragalactic Astronomy, Department of Physics, Durham University（杜伦大学物理系河外星系研究中心）
We present constraints on the physical properties (including stellar mass, age, and star formation rate) of 207 $6\lesssim z \lesssim8$ galaxy candidates from the Reionization Lensing Cluster Survey (RELICS) and companion Spitzer-RELICS surveys. We measure photometry using T-PHOT and perform spectral energy distribution fitting using EA$z$Y and BAGPIPES. Of the 207 candidates for which we could successfully measure Spitzer fluxes, 23 were demoted to likely low redshift ($z<4$). Among the remaining high redshift candidates, we find intrinsic stellar masses between $1\times10^6\rm{M_{\odot}}$ an…
JADES: Detecting [OIII]$λ4363$ Emitters and Testing Strong Line Calibrations in the High-$z$ Universe with Ultra-deep JWST/NIRSpec Spectroscopy up to $z \sim 9.5$
The Multiphase CGM in the Epoch of Reionization: CII and CIV absorbers around [OIII] Emitters
University of Trieste（的里雅斯特大学）；INAF - Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；IFPU - Institute for Fundamental Physics of the Universe（宇宙基础物理研究所）；Dipartimento di Fisica “Enrico Fermi”, Università di Pisa（比萨大学恩里科·费米物理系）；IUCAA（印度联合大学天体物理中心）；Università degli Studi di Milano-Bicocca（米兰比可卡大学）；Max-Planck-Institut für Ex
We discuss the rest-frame ultraviolet emission line spectra of a large (~100) sample of low luminosity redshift z~3.1 Lyman alpha emitters (LAEs) drawn from a Subaru imaging survey in the SSA22 survey field. Our earlier work based on smaller samples indicated that such sources have high [OIII]/[OII] line ratios possibly arising from a hard ionising spectrum that may be typical of similar sources in the reionisation era. With optical spectra secured from VLT/VIMOS, we re-examine the nature of the ionising radiation in a larger sample using the strength of the high ionisation diagnostic emission…
We discuss the rest-frame optical emission line spectra of a large (~50) sample of z=3.1 Lyman alpha emitters (LAEs) whose physical properties suggest such sources are promising analogs of galaxies in the reionization era. Reliable Lyman continuum escape fractions have now been determined for a large sample of such LAEs from the Lyman Continuum Escape Survey (LACES) undertaken via deep HST imaging in the SSA22 survey area reported in Fletcher et al. (2019). Using new measures of [OII] emission secured from Keck MOSFIRE spectra we re-examine, for a larger sample, earlier claims that Lyman conti…
The [OIII] 88 $μ$m fine structure emission line has been detected into the Epoch of Reionization (EoR) from star-forming galaxies at redshifts $6 < z \lesssim 9$ with ALMA. These measurements provide valuable information regarding the properties of the interstellar medium (ISM) in the highest redshift galaxies discovered thus far. The [OIII] 88 $μ$m line observations leave, however, a degeneracy between the gas density and metallicity in these systems. Here we quantify the prospects for breaking this degeneracy using future ALMA observations of the [\oiii] 52 $μ$m line. Among the current set o…
We present a catalog of 208 $0.3 < z < 2.1$ Emission Line Galaxies (ELG) selected from 1D slitless spectroscopy obtained using Hubble's WFC3 G102 grism, as part of the Faint Infrared Grism Survey (FIGS). We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra, and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission line fluxes and errors, redshifts, and equivalent widths (EW) for H$α$ $\lambda6563$, [OIII]$λ\lambda4959,5007$, …
