The Physical Nature of Lyα-emitting Galaxies at
                    <i>z</i>
                     = 3.1

Gawiser, Eric; Dokkum, Pieter van; Grönwall, C.; Ciardullo, Robin; Blanc, Guillermo A.; Castander, F. J.; Feldmeier, John J.; Francke, Harold; Franx, Marijn; Haberzettl, L.; Herrera, David; Hickey, Thomas J.; Infante, L.; Lira, P.; Maza, J.; Quadri, Ryan; Richardson, Alexander; Schawinski, Kevin; Schirmer, M.; Taylor, Edward N.; Treister, Ezequiel; Urry, C. Megan; Virani, S.

doi:10.1086/504467

Cited by 278 publications

(445 citation statements)

References 49 publications

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“…Several physical possibilities have already been investigated to explain these high EW(Lyα), such as the presence of either population III stars or active galactic nuclei (AGNs) in the host galaxies. But none of them have proven to be consistent with the observations (Dawson et al 2004;Wang et al 2004;Gawiser et al 2006). Another possibility is that the high EW(Lyα) values found are due to the combined effect of IGM absorption (lowering the continuum on the blue side of Lyα at high z) and observational errors biasing the average EW(Lyα) to higher values (Hayes & Östlin 2006).…”

Section: Introductionmentioning

confidence: 85%

Lymanαline and continuum radiative transfer in a clumpy interstellar medium

Duval

Schaerer

Östlin

et al. 2014

A&A

108

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Aims. Studying the effects of an inhomogeneous interstellar medium (ISM) on the strength and the shape of the Lyman alpha (Lyα) line in starburst galaxies. Methods. Using our 3D Monte Carlo Lyα radiation transfer code, we study the radiative transfer of Lyα, UV and optical continuum photons in homogeneous and clumpy shells of neutral hydrogen and dust surrounding a central source. Our simulations predict the Lyα and continuum escape fraction, the Lyα equivalent width EW(Lyα), and the Lyα line profile, and their dependence on the geometry of the gas distribution and the main input physical parameters. Results. The ISM clumpiness is found to have a strong impact on the Lyα line radiative transfer, entailing a strong dependence of the emergent features of the Lyα line (escape fraction, EW(Lyα)) on the ISM morphology. Although a clumpy and dusty ISM appears more transparent to radiation (both line and continuum) compared to an equivalent homogeneous ISM of equal dust optical depth, we find that the Lyα photons are, in general, still more attenuated than UV continuum radiation. As a consequence, the observed equivalent width of the Lyα line (EW obs (Lyα)) is lower than the intrinsic one (EWint(Lyα)) for nearly all clumpy ISM configurations considered. There are, however, special conditions under which Lyα photons escape more easily than the continuum, resulting in an enhanced EW obs (Lyα). The requirement for this to happen is that the ISM is almost static (galactic outflows ≤ 200 km s −1 ), extremely clumpy (with density contrasts > 10 7 in HI between clumps and the interclump medium), and very dusty (E(B-V) > 0.30). When these conditions are fulfilled the emergent Lyα line profile generally shows no velocity shift and little asymmetry. Otherwise the Lyα line profile is very similar to that expected for homogeneous media. Conclusions. Given the asymmetry and velocity shifts generally observed in star-forming galaxies with Lyα emission, we therefore conclude that clumping is unlikely to significantly enhance their relative Lyα/UV transmission.

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Section: Introductionmentioning

confidence: 85%

Lymanαline and continuum radiative transfer in a clumpy interstellar medium

Duval

Schaerer

Östlin

et al. 2014

A&A

108

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“…The SEDs of the candidates have characteristics that are atypical of higher redshift LAE SEDs. It has previously been reported that LAEs have SEDs that are in many cases blue (Gawiser et al 2006(Gawiser et al , 2007Pirzkal et al 2007). Only two other surveys reported detections of red SEDs in several LAEs (Stiavelli et al 2001;Lai et al 2008), although one extremely red object was found by Nilsson et al (2007).…”

Section: Photometrymentioning

confidence: 99%

“…At z ∼ 3, Gawiser et al (2006) inferred stellar masses of a few ×10 8 M , almost no dust extinction, and ages of the order of 100 Myr. In a follow-up paper, Gawiser et al (2007) studied a stacked sample of 52 Lyα emitters without Spitzer detections and confirmed their results of young ages and that no dust appears to be present in these systems, although they inferred slightly higher masses.…”

Section: Introductionmentioning

confidence: 96%

Evolution in the properties of Lyman-αemitters from redshiftsz~ 3 toz ~ 2

Nilsson¹,

Tapken²,

Møller

et al. 2009

A&A

156

237

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Context. Narrow-band surveys to detect Lyα emitters are powerful tools for identifying high, and very high, redshift galaxies. Although samples are increasing at redshifts z = 3−6, the nature of these galaxies is still poorly known. The number of galaxies detected at redshifts below z ∼ 3 are also small. Aims. We study the properties of z = 2.25 Lyα emitters and compare them with those of z > 3 Lyα emitters.Methods. We present narrow-band imaging made with the MPG/ESO 2.2m telescope and the WFI (Wide Field Imager) detector. Using this data, we have searched for emission-line objects. We find 170 candidate typical Lyα emitters and 17 candidates that we regard as high UV-transmission Lyα emitters. We have derived the magnitudes of these objects in 8 photometric bands from u * to K s , and studied whether they have X-ray and/or radio counterparts. Results. We demonstrate that there has been significant evolution in the properties of Lyα emitters between redshift z ∼ 3 and z = 2.25. The spread in spectral energy distributions (SEDs) at the lower redshift is larger and we detect a significant AGN contribution in the sample. The distribution of the equivalent widths is narrower than at z ∼ 3, with only a few candidates with rest-frame equivalent width above the predicted limit of 240 Å. The star formation rates derived from the Lyα emission compared to those derived from the UV emission are lower by on average a factor of ∼1.8, indicative of a significant absorption by dust. Conclusions. Lyα emitters at redshift z = 2.25 may be more evolved than Lyα emitters at higher redshift. The red SEDs imply more massive, older and/or dustier galaxies at lower redshift than observed at higher redshifts. The decrease in equivalent widths and star formation rates indicate more quiescent galaxies, with in general less star formation than in higher redshift galaxies. At z = 2.25, AGN appear to be more abundant and also to contribute more to the Lyα emitting population.

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“…Steidel et al 1996Steidel et al , 2003Cooke et al 2006;Bielby et al 2011) and Lyα emission (e.g. Cowie & Hu 1998;Ouchi et al 2003;Gawiser et al 2006). However, to follow the galaxy population into the redshift range 1 z 2.5, near-infrared observations are essential as all spectral features move out of visible bands.…”

Section: Introductionmentioning

confidence: 99%

The WIRCam Deep Survey

Bielby

Hudelot

McCracken

et al. 2012

A&A

173

208

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We present a new near-infrared imaging survey in the four CFHTLS deep fields: the WIRCam Deep Survey or "WIRDS". WIRDS comprises extremely deep, high quality (FWHM ∼ 0.6 ) J, H, and K s imaging covering a total effective area of 2.1 deg 2 and reaching AB 50% completeness limits of ≈24.5. We combine our images with the CFHTLS to create a unique eight-band ugrizJHK S photometric catalogues in the four CFHTLS deep fields; these four separate fields allow us to make a robust estimate of the effect of cosmic variance for all our measurements. We use these catalogues in combination with ≈9800 spectroscopic redshifts to estimate precise photometric redshifts (σ Δz/(1+z) 0.03 at i < 25), galaxy types, star-formation rates and stellar masses for a unique sample of ≈1.8 million galaxies. Our JHK s number counts are consistent with previous studies. We apply the "BzK" selection to our gzK filter set and find that the star forming BzK selection successfully selects 76% of star-forming galaxies in the redshift range 1.4 < z < 2.5 in our photometric catalogue, based on our photometric redshift measurement. Similarly the passive BzK selection returns 52% of the passive 1.4 < z < 2.5 population identified in the photometric catalogue. We present the mass functions of the total galaxy population as a function of redshift up to z = 2 and present fits using double Schechter functions. A mass-dependent evolution of the mass function is seen with the numbers of galaxies with masses of M 10 10.75 still evolving at z 1, but galaxies of higher mass reaching their present day numbers by z ∼ 0.8−1. This is consistent with the present picture of downsizing in galaxy evolution. We compare our results with the predictions of the GALFORM semi-analytical galaxy formation model and find that the simulations provide a relatively successful fit to the observed mass functions at intermediate masses (i.e. 10 log (M/M ) 11). However, as is common with semi-analytical predictions of the mass function, the GALFORM results under-predict the mass function at low masses (i.e. log (M/M ) 10), whilst the fit as a whole degrades beyond redshifts of z ∼ 1.2. All photometric catalogues and images are made publicly available from TERAPIX and CADC.

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The Physical Nature of Lyα-emitting Galaxies at z = 3.1

Cited by 278 publications

References 49 publications

Lymanαline and continuum radiative transfer in a clumpy interstellar medium

Lymanαline and continuum radiative transfer in a clumpy interstellar medium

Evolution in the properties of Lyman-αemitters from redshiftsz~ 3 toz ~ 2

The WIRCam Deep Survey

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