The Ages and Masses of Lyα Galaxies at<i>z</i>∼ 4.5

Finkelstein, Steven L.; Rhoads, James E.; Malhotra, Sangeeta; Pirzkal, Norbert; Wang, Junxian

doi:10.1086/513462

Cited by 138 publications

(202 citation statements)

References 52 publications

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“…At even higher redshift, Pirzkal et al (2007) showed that a sample of 4 < z < 5.7 Lyα emitters had very young ages of a few Myr and small stellar masses, in the range 10 6 −10 8 M . These results agreed well with those of Finkelstein et al (2007), who studied almost 100 Lyα emitters at z = 4.5. Finkelstein et al (2008) reported, studying a different sample, finding very dusty, massive galaxies with A 1200 as high as 4.5 mag and masses as high as several ×10 10 M , at z = 4.5.…”

Section: Datesupporting

confidence: 92%

“…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

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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Section: Datesupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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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“…At the redshift of the burst, the Ly-α luminosity is 4.3×10 42 erg s −1 . This value is in the range of luminosities of other LAEs identified by dedicated surveys at z ∼ 4.5 (Finkelstein et al 2007;Shioya et al 2009;Wang et al 2009). In particular, Shioya et al (2009), in a survey of z ∼ 4.8 LAEs in the COSMOS two square degree field, computed the Ly-α luminosity function of these objects, measuring L = 8 +17 −4 × 10 42 erg s −1 .…”

Section: Grb Hostmentioning

confidence: 52%

The afterglow and host galaxy of GRB 090205: evidence of a Ly-αemitter at z = 4.65

D’Avanzo

Perri²,

Fugazza

et al. 2010

A&A

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Context. Gamma-ray bursts (GRBs) have proven to be detectable to distances much larger than any other astrophysical object, providing the most effective way, complementing ordinary surveys of studying the high redshift universe. Aims. We present the results of an observational campaign devoted to the study of the high-z GRB 090205. Methods. We carried out optical/NIR spectroscopy and imaging of GRB 090205 with the ESO-VLT starting from hours after the event to several days later to detect the host galaxy. We compared the results obtained from our optical/NIR observations with the available Swift high-energy data of this burst. Results. Our observational campaign led to the detection of the optical afterglow and host galaxy of GRB 090205 and to the first measure of its redshift, z = 4.65. As in other high-z GRBs, GRB 090205 has a short duration in the rest frame with T 90,rf = 1.6 s, which suggests that it might belong to the short GRB class. The X-ray afterglow of GRB 090205 has a complex and interesting behavior with a possible rebrightening at 500-1000 s from the trigger time and late flaring activity. Photometric observations of the GRB 090205 host galaxy imply that it is a starburst galaxy with a stellar population younger than ∼150 Myr. Moreover, the metallicity of Z > 0.27 Z derived from the GRB afterglow spectrum is among the highest derived from GRB afterglow measurement at high-z, suggesting that the burst occurred in a rather enriched environment. Finally, a detailed analysis of the afterglow spectrum shows the existence of a line corresponding to Lyman-α emission at the redshift of the burst. GRB 090205 is thus hosted by a typical Lyman-α emitter (LAE) at z = 4.65. This makes the host galaxy of GRB 090205 the farthest GRB host galaxy, spectroscopically confirmed, detected to date.

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“…By now, several hundreds of Lyα emitters (LAEs) have been detected through narrow-band imaging at z = 0.3−7.7 (e.g. Møller & Warren 1993;Fynbo et al 2003;Gronwall et al 2007;Venemans et al 2007;Nilsson et al 2007;Finkelstein et al 2007;Ouchi et al 2008;Grove et al 2009;Hibon et al 2010). Lyα emission may be generated by three main mechanisms: i) the ionising flux of O and B stars indicative of star formation; ii) the ionising flux of an energetic UV source, e.g.…”

Section: Introductionmentioning

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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The Ages and Masses of Lyα Galaxies atz∼ 4.5

Cited by 138 publications

References 52 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

The afterglow and host galaxy of GRB 090205: evidence of a Ly-αemitter at z = 4.65

Lyman-αemitters as tracers of the transitioning Universe

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