Lyα Emitters at <i>z</i> = 5.7 in the Subaru Deep Field

Shimasaku, Kazuhiro; Kashikawa, Nobunari; Doi, Mamoru; Ly, Chun; Malkan, Matthew A.; Matsuda, Yoshihisa; Ouchi, Masami; Hayashino, T.; Iye, Masanori; Motohara, Kentaro; Murayama, Takashi; Nagao, Tohru; Ohta, Kouji; Okamura, S.; Sasaki, Toshiyuki; Shioya, Yasuhiro; Taniguchi, Yoshiaki

doi:10.1093/pasj/58.2.313

Cited by 291 publications

(476 citation statements)

References 62 publications

(79 reference statements)

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“…At higher redshift (z 4), emitters with EWs larger than 240 Å have been predicted (Schaerer 2003;Tumlison et al 2003) and observed (Malhotra & Rhoads 2002;Shimasaku et al 2006;Stanway et al 2007). These large EWs supposedly cannot be explained by a normal initial mass function but have been proposed to be signs of Population III stars.…”

Section: Equivalent Width Distributionmentioning

confidence: 85%

“…Objects with large equivalent widths (EWs) are thus selected by comparing the colours in the narrow-band image and complementary broad-band images. Spectroscopically confirmed Lyα emitters now include several hundreds of sources at redshifts z ∼ 3 (e.g., Møller & Warren 1993;Cowie & Hu 1998;Steidel et al 2000;Fynbo et al 2001Fynbo et al , 2003aMatsuda et al 2005;Venemans et al 2007;Nilsson et al 2007;Ouchi et al 2008), z ∼ 4.5 (Finkelstein et al 2007), z ∼ 5.7 (Malhotra et al 2005;Shimasaku et al 2006;Tapken et al 2006) and z ∼ 6.5 (Taniguchi et al 2005;Kashikawa et al 2006). However, in the low redshift range, between z ≈ 1.6 corresponding to the atmospheric cut-off in the UV and z ∼ 3, little progress has been made.…”

Section: Introductionmentioning

confidence: 99%

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

Nilsson¹,

Tapken²,

Møller

et al. 2009

A&A

155

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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Section: Equivalent Width Distributionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

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

Nilsson¹,

Tapken²,

Møller

et al. 2009

A&A

155

237

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show abstract

“…An independent test of the determined AGN fraction is to calculate the LAE volume density by dividing a known AGN volume density by the LAE AGN fraction. For this test, we used the AGN comoving volume densities as determined observationally by Bongiorno et al (2007) and theoretically by Hopkins et al (2007), and we compared them with comoving LAE volume densities from eighteen different publications (Steidel et al 2000;Stiavelli et al 2001;Dawson et al 2004;Hayashino et al 2004;Shimasaku et al 2006;Nilsson et al 2007;Gronwall et al 2007;Venemans et al 2007;Murayama et al 2007;Prescott et al 2008;Deharveng et al 2008;Ouchi et al 2008;Grove et al 2009;Shioya et al 2009;Guaita et al 2010;Bongiovanni et al 2010;Yuma et al 2010). In Fig.…”

Section: Agn and Lae Volume Density Evolutionmentioning

confidence: 99%

Lyman-αemitters as tracers of the transitioning Universe

Nilsson

Møller²

2011

A&A

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Of all the many ways of detecting high-redshift galaxies, the selection of objects by their redshifted Lyα emission has become one of the most successful. But what types of galaxies are selected in this way? Until recently, Lyα emitters were understood to be small star-forming galaxies, the possible building-blocks of larger galaxies. But with increased number of observations of Lyα emitters at lower redshifts, a new picture emerges. Lyα emitters display strong evolution in their properties from higher to lower redshift. It has previously been shown that the fraction of ultra-luminous infrared galaxies (ULIRGs) among the Lyα emitters increases dramatically between redshifts three and two. Here, the fraction of AGN among the LAEs is shown to follow a similar evolutionary path. We argue that Lyα emitters are not a homogeneous class of objects and that the objects selected with this method reflect the general star forming and active galaxy populations at that redshift. Lyα emitters should thus be excellent tracers of galaxy evolution in future simulations and modelling.

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“…More interestingly, it has been theoretically predicted that galaxies hosting zero-metallicity stars (or Population III stars, hereafter PopIII) should show huge Lyα equivalent widths that could reach up to EW 0 ∼ 1000 Å (e.g., Schaerer 2002Schaerer , 2003Tumlinson et al 2003;Scannapieco et al 2003). Therefore, the frequency distribution of the Lyα equivalent width in high-z galaxies and its evolution with redshift are important for understanding the early stages of galaxy evolution (e.g., Shimasaku et al 2006;Ando et al 2006). …”

Section: Introductionmentioning

confidence: 99%

High-redshift Ly$\mathsf{\alpha}$ emitters with a large equivalent width

Nagao

Murayama

Maiolino

et al. 2007

A&A

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We report new follow-up spectroscopy of i -dropout galaxies with an NB921-band depression found in the Subaru Deep Field. The NB921-depressed i -dropout selection method is expected to select galaxies with large equivalent-width Lyα emission over a wide redshift range, 6.0 < ∼ z < ∼ 6.5. Two of four observed targets show a strong emission line with a clear asymmetric profile, identified as Lyα emitters at z = 6.11 and 6.00. Their rest-frame equivalent widths are 153 Å and 114 Å, which are lower limits on the intrinsic equivalent widths. Through our spectroscopic observations (including previous ones) of NB921-depressed i -dropout galaxies, we identified 5 galaxies in total with a rest-frame equivalent width larger than 100 Å at 6.0 < ∼ z < ∼ 6.5 out of 8 photometric candidates, which suggests that the NB921-depressed i -dropout selection method is possibly an efficient way to search for Lyα emitters with a large Lyα equivalent width, in a wider redshift range than with usual narrow-band excess techniques. By combining these findings with our previous observational results, we infer that the fraction of broad-band selected galaxies having a rest-frame equivalent width larger than 100 Å is significantly higher at z ∼ 6 (the cosmic age of ∼1 Gyr) than that at z ∼ 3 (∼2 Gyr), being consistent with the idea that the typical stellar population of galaxies is significantly younger at z ∼ 6 than that at z ∼ 3. The NB921-depressed i -dropout galaxies may be interesting candidates for hosts of massive, zero-metallicity Population III stars.

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Lyα Emitters at z = 5.7 in the Subaru Deep Field

Cited by 291 publications

References 62 publications

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

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

Lyman-αemitters as tracers of the transitioning Universe

High-redshift Ly$\mathsf{\alpha}$ emitters with a large equivalent width

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