A HIGH FRACTION OF Lyα EMITTERS AMONG GALAXIES WITH EXTREME EMISSION LINE RATIOS AT z ∼ 2*

Erb, Dawn K.; Pettini, Max; Steidel, Charles C.; Strom, Allison L.; Rudie, Gwen C.; Trainor, Ryan F.; Shapley, Alice E.; Reddy, Naveen A.

doi:10.3847/0004-637x/830/1/52

Cited by 78 publications

(112 citation statements)

References 60 publications

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“…Lam et al (2019) spectroscopic sample is based on MUSE Deep (Inami et al 2017) and MUSE Wide (Urrutia et al 2019) surveys, where spectroscopic redshifts of galaxies at z > 4 are primarily determined through Lyman-α. Nakajima et al (2016) sample also consists of Lyman-α emitters and Lyman break galaxies, thus introduce a strong sample selection bias (e.g Erb et al 2016).…”

Section: Selection Effects In High-z ξIon Estimatesmentioning

confidence: 99%

Reconstructing the Observed Ionizing Photon Production Efficiency at z ∼ 2 Using Stellar Population Models

Nanayakkara

Brinchmann

Glazebrook

et al. 2020

ApJ

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The ionizing photon production efficiency, ξ ion , is a critical parameter that provides a number of physical constraints to the nature of the early Universe, including the contribution of galaxies to the timely completion of the reionization of the Universe. Here we use KECK/MOSFIRE and ZFOURGE multi-band photometric data to explore the ξ ion of a population of galaxies at z ∼ 2 with log 10 (M * /M ) ∼ 9.0 − 11.5. Our 130 Hα detections show a median log 10 (ξ ion [Hz/erg]) of 24.8 ± 0.5 when dust corrected using a Calzetti et al. (2000) dust prescription. Our values are typical of mass/magnitude selected ξ ion values observed in the z ∼ 2 Universe. Using BPASSv2.2.1 and Starburst99 stellar population models with simple parametric star-formation-histories (SFH), we find that even with models that account for effects of stellar evolution with binaries/stellar rotation, model galaxies at log 10 (ξ ion [Hz/erg]) 25.0 have low Hα equivalent widths (EW) and redder colors compared to our z ∼ 2 observed sample. We find that introducing star-bursts to the SFHs resolve the tension with the models, however, due to the rapid time evolution of ξ ion , Hα EWs, and rest-frame optical colors, our Monte Carlo simulations of star-bursts show that random distribution of star-bursts in evolutionary time of galaxies are unlikely to explain the observed distribution. Thus, either our observed sample is specially selected based on their past SFH or stellar models require additional mechanisms to reproduce the observed high UV luminosity of galaxies for a given production rate of hydrogen ionizing photons.

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Section: Selection Effects In High-z ξIon Estimatesmentioning

confidence: 99%

Reconstructing the Observed Ionizing Photon Production Efficiency at z ∼ 2 Using Stellar Population Models

Nanayakkara

Brinchmann

Glazebrook

et al. 2020

ApJ

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“…Beside (Erb et al 2016;Henry et al 2015). Despite that, the Lyα emission in ID14 is deficient (see Section 4), independently from the adopted aperture shape.…”

Section: Spectral Featuresmentioning

confidence: 99%

Magnifying the Early Episodes of Star Formation: Super Star Clusters at Cosmological Distances*

Vanzella

Castellano

Meneghetti

et al. 2017

ApJ

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Magnifying the Early Episodes of Star FormationVanzella, E.; Castellano, M.; Meneghetti, M.; Mercurio, A.; Caminha, G. B.; Cupani, G.; Calura, F.; Christensen, L.; Merlin, E.; Rosati, P. IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document VersionPublisher's PDF, also known as Version of record Publication date: 2017Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Vanzella, E., Castellano, M., Meneghetti, M., Mercurio, A., Caminha, G. B., Cupani, G., ... Tozzi, P. (2017 AbstractWe study the spectrophotometric properties of a highly magnified ( 40 70 m  -) pair of stellar systems identified at z=3.2222 behind the Hubble Frontier Field galaxy cluster MACSJ0416. Five multiple images (out of six) have been spectroscopically confirmed by means of VLT/MUSE and VLT/X-Shooter observations. Each image includes two faint (m 30.6 UV  ), young ( 100  Myr), low-mass ( 10 7 < M  ), low-metallicity (12+Log(O/H);7.7, or 1/10 solar), and compact (30 pc effective radius) stellar systems separated by 300  pc after correcting for lensing amplification. We measured several rest-frame ultraviolet and optical narrow ( 25 v  s kms −1 ) high-ionization lines. These features may be the signature of very hot (T 50,000 > K) stars within dense stellar clusters, whose dynamical mass is likely dominated by the stellar component. Remarkably, the ultraviolet metal lines are not accompanied by Lyα emission (e.g., C IV/Lyα 15 > ), despite the fact that the Lyα line flux is expected to be 150 times brighter (inferred from the Hβ flux). A spatially offset, strongly magnified ( 50 m > ) Lyα emission with a spatial extent 7.6  kpc 2 is instead identified 2kpc away from the system. The origin of such a faint emission could be the result of fluorescent Lyα induced by a transverse leakage of ionizing radiation emerging from the stellar systems and/or may be associated with an underlying and barely detected object (with m 34 UV > de-lensed). This is the first confirmed metal-line emitter at such low-luminosity and redshift without Lyα emission-suggesting that, at least in some cases, a non-uniform covering factor of the neutral gas might hamper the Lyα detection.

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“…One of the eleven SFGs is COSMOS 12805 (Section 2). The other 10 SFGs are taken form the literature: 7 gravitationally lensed galaxies (Fosbury et al 2003;Villar-Martín et al 2004;Yuan & Kewley 2009;Christensen et al 2012bChristensen et al , 2012aBayliss et al 2014;Pettini et al 2010;James et al 2014;Stark et al 2014) and 3 BX galaxies obtained by KBSS (Steidel et al 2014;Erb et al 2016 The nebular line fluxes of the eleven galaxies and the S16-stack are summarized in Table 3 for forbidden and semiforbidden lines and in Table 4 for Balmer lines. The fluxes are normalized to Hβ in Tables 3 and 4.…”

Section: Samplementioning

confidence: 99%

Evolution of N/O abundance ratios and ionization parameters from z ∼ 0 to 2 investigated by the direct temperature method

Kojima

Ouchi

Nakajima

et al. 2017

Publications of the Astronomical Society of Japan

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We present N/O abundance ratios, ionization parameters q ion , and oxygen abundance O/H for a total of 41 galaxies (11 individual galaxies and a 30-galaxy stack) including Lyα emitters and Lyman break galaxies at z ∼ 2, and investigate galaxy evolution from z ∼ 0 to 2 in conjunction with 208,529 local SDSS galaxies and 9 green pea galaxies (GPs). In contrast with most of the recent studies, we obtain the N/O ratio, q ion , and O/H measurements by direct T e methods with [O III] λ4363 and O III] λ1665 lines. Based on these reliable measurements, we find that there exist z ∼ 2 galaxies with an excess of N/O falling beyond the local average of N/O-O/H relation, while the majority of the z ∼ 2 galaxies have the N/O ratios nearly comparable with z ∼ 0 galaxies in the N/O-stellar mass relation. Our galaxies place the upper limit of N/O ratio log(N/O) ≤ −1.26 on average, suggesting that the N/O ratio evolves, if at all, by < 0.17 dex. Exploiting our reliable measurements free from the N/O-q ion -O/H degeneracies, we identify, for the first time, that z ∼ 2 galaxies with offsets in the BPT diagram indicate either 1) only an N/O excess, 2) only a q ion excess, or 3) both N/O and q ion excesses. We argue that the BPT offsets at z ∼ 2 are not made by one of 1)-3) galaxy populations alone, but the composite of 1)-3) populations. We confirm that these 1)-3) populations also exist at z ∼ 0, such as GPs and SDSS low-mass and high-SFR galaxies (LMHSs).

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A HIGH FRACTION OF Lyα EMITTERS AMONG GALAXIES WITH EXTREME EMISSION LINE RATIOS AT z ∼ 2*

Cited by 78 publications

References 60 publications

Reconstructing the Observed Ionizing Photon Production Efficiency at z ∼ 2 Using Stellar Population Models

Reconstructing the Observed Ionizing Photon Production Efficiency at z ∼ 2 Using Stellar Population Models

Magnifying the Early Episodes of Star Formation: Super Star Clusters at Cosmological Distances*

Evolution of N/O abundance ratios and ionization parameters from z ∼ 0 to 2 investigated by the direct temperature method

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