<i>HUBBLE SPACE TELESCOPE</i>EMISSION LINE GALAXIES AT<i>z</i>∼ 2: THE Lyα ESCAPE FRACTION

Ciardullo, Robin; Zeimann, Gregory R.; Grönwall, C.; Gebhardt, Henry S. Grasshorn; Schneider, Donald P.; Hagen, Alex; Malz, Alex I.; Blanc, Guillermo A.; Hill, Gary J.; Drory, Niv; Gawiser, Eric

doi:10.1088/0004-637x/796/1/64

Cited by 34 publications

(47 citation statements)

References 84 publications

(156 reference statements)

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“…For the three objects that have relatively small errors, COSMOS-08501, COSMOS-41547, and SXDS-C-16564, the mean and median Lyα escape fractions are f Lyα esc = 0.68 ± 0.30 and 0.68 ± 0.30, respectively. These values are much higher than the average Lyα escape fraction of z ∼ 2 galaxies, f Lyα esc ∼ 2 − 5% (Hayes et al 2010;Steidel et al 2011;Ciardullo et al 2014;Oteo et al 2015;Matthee et al 2016), and even higher than the average value of z ∼ 2 LAEs, f Lyα esc ∼ 10 − 37% 2 The outflowing ISM also facilitates the Lyα escape due to the reduced number of scattering (e.g., Kunth et al 1998;Atek et al 2008; Rivera-Thorsen et al 2015). (Steidel et al 2011;Nakajima et al 2012;Kusakabe et al 2015;Trainor et al 2015;Erb et al 2016).…”

Section: Coarse Estimates Of the Lyα Escape Fractionmentioning

confidence: 98%

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

Hashimoto

Ouchi

Shimasaku

et al. 2016

Mon. Not. R. Astron. Soc.

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We present physical properties of spectroscopically confirmed Lyα emitters (LAEs) with very large rest-frame Lyα equivalent widths EW 0 (Lyα). Although the definition of large EW 0 (Lyα) LAEs is usually difficult due to limited statistical and systematic uncertainties, we identify six LAEs selected from ∼ 3000 LAEs at z ∼ 2 with reliable measurements of EW 0 (Lyα) ≃ 200−400Å given by careful continuum determinations with our deep photometric and spectroscopic data. These large EW 0 (Lyα) LAEs do not have signatures of AGN, but notably small stellar masses of M * = 10 7−8 M ⊙ and high specific star-formation rates (star formation rate per unit galaxy stellar mass) of ∼ 100 Gyr −1 . These LAEs are characterized by the median values of L(Lyα) = 3.7 × 10 42 erg s −1 and M UV = −18.0 as well as the blue UV continuum slope of β = −2.5 ± 0.2 and the low dust extinction E(B − V ) * = 0.02 +0.04 −0.02 , which indicate a high median Lyα escape fraction of f Lyα esc = 0.68 ± 0.30. This large f Lyα esc value is explained by the low Hi column density in the ISM that is consistent with FWHM of the Lyα line, FWHM(Lyα) = 212 ± 32 km s −1 , significantly narrower than those of small EW 0 (Lyα) LAEs. Based on the stellar evolution models, our observational constraints of the large EW 0 (Lyα), the small β, and the rest-frame Heii equivalent width imply that at least a half of our large EW 0 (Lyα) LAEs would have young stellar ages of 20 Myr and very low metallicities of Z < 0.02Z ⊙ regardless of the star-formation history.

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Section: Coarse Estimates Of the Lyα Escape Fractionmentioning

confidence: 98%

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

Hashimoto

Ouchi

Shimasaku

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The WFC3 grism spectrum of J123642+621331 was also analyzed by Ciardullo et al (2014), who derived z=2.018, and in the 3D-HST catalog of Momcheva et al (2016), who derived =  z 2.012 0.002 (68% confidence).…”

Section: A Revised Redshift and Spectral Energy Distributionmentioning

confidence: 99%

The GOODS-N Jansky VLA 10 GHz Pilot Survey: Sizes of Star-forming μJY Radio Sources

Murphy

Momjian

Condon

et al. 2017

ApJ

140

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“…Observations of star-forming galaxies at low redshift usually indicate a much lower escape fraction. For example, by measuring the ratio of Lyα to Hβ line emission, Ciardullo et al (2014) derived an escape fraction of 4.4 E-mail: Yuxiang.L.Qin@gmail.com † E-mail: swyithe@unimelb.edu.au per cent while Matthee et al (2016) measured a median escape fraction of 1.6 per cent using stacking of Hα-selected galaxies. Moreover, some theoretical works also suggest a low fesc, * (Gnedin et al 2007;Hassan et al 2016;Sun & Furlanetto 2016).…”

Section: Introductionmentioning

confidence: 99%

Dark-ages reionization and galaxy formation simulation – X. The small contribution of quasars to reionization

Qin

Mutch

Poole

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Motivated by recent measurements of the number density of faint AGN at high redshift, we investigate the contribution of quasars to reionization by tracking the growth of central supermassive black holes in an update of the Meraxes semi-analytic model. The model is calibrated against the observed stellar mass function at z ∼ 0.6 − 7, the black hole mass function at z 0.5, the global ionizing emissivity at z ∼ 2 − 5 and the Thomson scattering optical depth. The model reproduces a Magorrian relation in agreement with observations at z < 0.5 and predicts a decreasing black hole mass towards higher redshifts at fixed total stellar mass. With the implementation of an opening angle of 80 deg for quasar radiation, corresponding to an observable fraction of ∼23.4 per cent due to obscuration by dust, the model is able to reproduce the observed quasar luminosity function at z ∼ 0.6 − 6. The stellar light from galaxies hosting faint AGN contributes a significant or dominant fraction of the UV flux. At high redshift, the model is consistent with the bright end quasar luminosity function and suggests that the recent faint z ∼ 4 AGN sample compiled by Giallongo et al. (2015) includes a significant fraction of stellar light. Direct application of this luminosity function to the calculation of AGN ionizing emissivity consequently overestimates the number of ionizing photons produced by quasars by a factor of 3 at z ∼ 6. We conclude that quasars are unlikely to make a significant contribution to reionization.

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HUBBLE SPACE TELESCOPEEMISSION LINE GALAXIES ATz∼ 2: THE Lyα ESCAPE FRACTION

Cited by 34 publications

References 84 publications

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

The GOODS-N Jansky VLA 10 GHz Pilot Survey: Sizes of Star-forming μJY Radio Sources

Dark-ages reionization and galaxy formation simulation – X. The small contribution of quasars to reionization

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HUBBLE SPACE TELESCOPEEMISSION LINE GALAXIES ATz∼ 2: THE Lyα ESCAPE FRACTION

Cited by 34 publications

References 84 publications

Lyα emitters with very large Lyα equivalent widths, EW0(Lyα) ≃ 200–400 Å, atz∼ 2

Lyα emitters with very large Lyα equivalent widths, EW0(Lyα) ≃ 200–400 Å, atz∼ 2

The GOODS-N Jansky VLA 10 GHz Pilot Survey: Sizes of Star-forming μJY Radio Sources

Dark-ages reionization and galaxy formation simulation – X. The small contribution of quasars to reionization

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Product

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Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2

Lyα emitters with very large Lyα equivalent widths, EW₀(Lyα) ≃ 200–400 Å, atz∼ 2