A galaxy at a redshift z = 6.96

Iye, Masanori; Ota, Kazuaki; Kashikawa, Nobunari; Furusawa, Hisanori; Hashimoto, Tetsuya; Hattori, Takashi; Matsuda, Yoshihisa; Morokuma, Tomoki; Ouchi, Masami; Shimasaku, Kazuhiro

doi:10.1038/nature05104

Cited by 339 publications

(466 citation statements)

References 28 publications

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“…26 -0. 24 . The lensing-corrected UV luminosity is ~1.8×10 10 L ⊙ , resulting in a star-formation rate estimate of 2.7±0.3 M ⊙ yr -1 based on the UV emission and uncorrected for dust extinction, for a Chabrier initial mass function 11 .…”

mentioning

confidence: 99%

A dusty, normal galaxy in the epoch of reionization

Watson

Christensen

Knudsen

et al. 2015

Nature

390

409

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Candidates for the modest galaxies that formed most of the stars in the early universe, at redshifts z > 7, have been found in large numbers with extremely deep restframe-UV imaging 1 . But it has proved difficult for existing spectrographs to characterise them in the UV 2,3,4 . The detailed properties of these galaxies could be measured from dust and cool gas emission at far-infrared wavelengths if the galaxies have become sufficiently enriched in dust and metals. So far, however, the most distant UV-selected galaxy detected in dust emission is only at z = 3.2 5 , and recent results have cast doubt on whether dust and molecules can be found in typical galaxies at this early epoch 6,7,8 . Here we report thermal dust emission from an archetypal early universe starforming galaxy, A1689-zD1. We detect its stellar continuum in spectroscopy and determine its redshift to be z = 7.5±0.2 from a spectroscopic detection of the Lyα break. A1689-zD1 is representative of the star-forming population during reionisation 9 , with a total star-formation rate of about 12 M ⊙ yr -1 . The galaxy is highly evolved: it has a large stellar mass, and is heavily enriched in dust, with a dust-to-gas ratio close to that of the Milky Way. Dusty, evolved galaxies are thus present among the fainter star-forming population at z > 7, in spite of the very short time since they first appeared.As part of a programme to investigate galaxies at z > 7 with the X-shooter spectrograph on the Very Large Telescope, we observed the candidate high-redshift galaxy, A1689-zD1, behind the lensing galaxy cluster, Abell 1689 (Fig. 1). The source was originally identified 10 as a candidate z > 7 system from deep imaging with the Hubble and Spitzer Space Telescopes. Suggested to be at z = 7.6±0.4 from photometry fitting, it is gravitationally magnified by a factor of 9.3 by the galaxy cluster 10 , and though intrinsically faint, because of the gravitational amplification, is one of the brightest candidate z > 7 galaxies known. The X-shooter observations were carried out on several nights between March 2010 and March 2012 with a total time of 16 hours on target.The galaxy continuum is detected and can be seen in the binned spectrum (Fig. 2). The Lya cutoff is at 1035±24 nm and defines the redshift, z = 7.5±0.2. It is thus one of the most distant galaxies known to date to be confirmed via spectroscopy, and the only galaxy at z > 7 where the redshift is determined from spectroscopy of its stellar continuum. The spectral slope is blue; using a power-law fit, F λ ∝ λ -β , β = 2.0 ± 0.1. The flux break is sharp, and greater than a factor of ten in depth. In addition, no line emission is detected, ruling out a different redshift solution for the galaxy. Line emission is excluded to lensing-corrected depths of 3×10 -19 erg cm -2 s -1 (3σ) in the absence of sky emission lines, making this by far the deepest intrinsic spectrum published of a reionization era object, highlighting the difficulty of obtaining UV redshifts for objects at this epoch that are not strongly domin...

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mentioning

confidence: 99%

A dusty, normal galaxy in the epoch of reionization

Watson

Christensen

Knudsen

et al. 2015

Nature

390

409

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“…Hu et al 2002;Kurk et al 2004;Stern et al 2005;Murayama et al 2007). In particular, Taniguchi et al (2005) report the detection of 9 spectroscopically confirmed LAE at redshifts of z ∼ 6.6 in the Subaru Deep Field (currently, the published LAE redshift record holder is at z = 6.98, Iye et al 2006). The mere presence of Lyman alpha emission in these sources provides strong evidence that they are undergoing bursts of star formation: the star formation rates of individual objects are ∼10 M yr −1 (based on their FUV luminosities) and their redshifts place them well within the end of cosmic reionization.…”

Section: Introduction: the Highest Redshift Galaxiesmentioning

confidence: 99%

Detecting the most distant (z>7) objects with ALMA

Walter

Carilli

2007

Astrophys Space Sci

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Detecting and studying objects at the highest redshifts, out to the end of Cosmic Reionization at z > 7, is clearly a key science goal of ALMA. ALMA will in principle be able to detect objects in this redshift range both from high-J (J > 7) CO transitions and emission from ionized carbon, [CII], which is one of the main cooling lines of the ISM. ALMA will even be able to resolve this emission for individual targets, which will be one of the few ways to determine dynamical masses for systems in the Epoch of Reionization. We discuss some of the current problems regarding the detection and characterization of objects at high redshifts and how ALMA will eliminate most (but not all) of them.

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“…Although Lyα emitters are among the most distant galaxies with spectroscopically confirmed redshifts (see Iye et al 2006;Ota et al 2008), few have been found at z > ∼ 7 (see e.g. Cuby et al 2007;Stark et al 2007b;Willis et al 2008;Hibon et al 2009;Sobral et al 2009).…”

Section: Introductionmentioning

confidence: 99%

On the physical properties ofz≈6–8 galaxies

Schaerer

Barros

2010

A&A

186

219

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Aims. We analyse the spectral energy distributions (SEDs) of the most distant galaxies discovered with the Hubble Space telescope and from the COSMOS survey and determine their physical properties, such as stellar age and mass, dust attenuation, and star-formation rate. Methods. We use our SED fitting tool including the effects of nebular emission to analyse three samples of z ∼ 6−8 galaxies with observed magnitudes J AB ∼ 23 to 29. Our models cover a wide parameter space. Results. We find that the physical parameters of most galaxies cover a wide range of acceptable values. Stellar ages, in particular, are not strongly constrained, even for objects detected longward of the Balmer break. As already pointed out earlier, the effects of nebular lines significantly affect the age determinations of star-forming galaxies at z ∼ 6−8. We find no need for stellar populations with extreme metallicities or other non-standard assumptions (IMF, escape fraction) to explain the observed properties of faint z-dropout galaxies. Albeit with large uncertainties, our fit results show indications of dust attenuation in some of the z ≈ 6−8 galaxies, which have best-fit values of A V up to ∼1. Furthermore, we find a possible trend of increasing dust attenuation with galaxy mass, and a relatively large scatter in specific star-formation rates, SFR/M . Conclusions. The physical parameters of very high-z galaxies may be more uncertain than indicated by previous studies. Dust attenuation seems also to be present in some z ≈ 6−8 galaxies, and may be correlated with galaxy mass, as is also the case for SFR.

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A galaxy at a redshift z = 6.96

Cited by 339 publications

References 28 publications

A dusty, normal galaxy in the epoch of reionization

A dusty, normal galaxy in the epoch of reionization

Detecting the most distant (z>7) objects with ALMA

On the physical properties ofz≈6–8 galaxies

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