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Evidence for Pop III-like stellar populations in the most luminous Lyman-α emitters at the epoch of re-ionisation: spectroscopic confirmation

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Evidence for Pop III-like stellar populations in the most luminous Lyman-α emitters at the epoch of re-ionisation : spectroscopic confirmation. / Sobral, David; Matthee, Jorryt; Darvish, Behnam; Schaerer, Daniel; Mobasher, Bahram; Röttgering, Huub J. A.; Da Graça Santos, Sergio; Hemmati, Shoubaneh.

In: The Astrophysical Journal, Vol. 808, No. 2, 139, 28.07.2015.

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Sobral, D., Matthee, J., Darvish, B., Schaerer, D., Mobasher, B., Röttgering, H. J. A., ... Hemmati, S. (2015). Evidence for Pop III-like stellar populations in the most luminous Lyman-α emitters at the epoch of re-ionisation: spectroscopic confirmation. The Astrophysical Journal, 808(2), [139]. https://doi.org/10.1088/0004-637X/808/2/139

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Sobral, David ; Matthee, Jorryt ; Darvish, Behnam ; Schaerer, Daniel ; Mobasher, Bahram ; Röttgering, Huub J. A. ; Da Graça Santos, Sergio ; Hemmati, Shoubaneh. / Evidence for Pop III-like stellar populations in the most luminous Lyman-α emitters at the epoch of re-ionisation : spectroscopic confirmation. In: The Astrophysical Journal. 2015 ; Vol. 808, No. 2.

Bibtex

@article{f42039be916c4ceea0a6ca55f4031466,
title = "Evidence for Pop III-like stellar populations in the most luminous Lyman-α emitters at the epoch of re-ionisation: spectroscopic confirmation",
abstract = "Faint Lyman-$\alpha$ (Ly$\alpha$) emitters become increasingly rarer towards the re-ionisation epoch (z~6-7). However, observations from a very large (~5deg$^2$) Ly$\alpha$ survey at z=6.6 (Matthee et al. 2015) show that this is not the case for the most luminous emitters. Here we present follow-up observations of the two most luminous z~6.6 Ly$\alpha$ candidates in the COSMOS field: `MASOSA' and `CR7'. We used X-SHOOTER, SINFONI and FORS2 (VLT), and DEIMOS (Keck), to confirm both candidates beyond any doubt. We find redshifts of z=6.541 and z=6.604 for MASOSA and CR7, respectively. MASOSA has a strong detection in Ly$\alpha$ with a line width of $386\pm30$ km/s (FWHM) and with high EW$_0$ (>200 \AA), but it is undetected in the continuum. CR7, with an observed Ly$\alpha$ luminosity of $10^{43.93\pm0.05}$erg/s is the most luminous Ly$\alpha$ emitter ever found at z>6. CR7 reveals a narrow Ly$\alpha$ line with $266\pm15$ km/s FWHM, being detected in the NIR (rest-frame UV, with $\beta=-2.3\pm0.1$) with an excess in $J$, and also strongly detected in IRAC/Spitzer. We detect a narrow HeII1640$\AA$ emission line ($6\sigma$) which explains the excess seen in the $J$ band photometry (EW$_0$~80 \AA). We find no other emission lines from the UV to the NIR in our X-SHOOTER spectra, nor any signatures of Wolf-Rayet (WR) stars. We find that CR7 is best explained by a combination of a PopIII-like population which dominates the rest-frame UV and the nebular emission, and a more normal stellar population which dominates the mass. HST/WFC3 observations show that the light is indeed spatially separated between a very blue component, coincident with Ly$\alpha$ and HeII emission, and two red components (~5 kpc away), which dominate the mass. Our findings are consistent with theoretical predictions of a PopIII wave, with PopIII star formation migrating away from the original sites of star formation.",
author = "David Sobral and Jorryt Matthee and Behnam Darvish and Daniel Schaerer and Bahram Mobasher and R{\"o}ttgering, {Huub J. A.} and {Da Gra{\cc}a Santos}, Sergio and Shoubaneh Hemmati",
year = "2015",
month = "7",
day = "28",
doi = "10.1088/0004-637X/808/2/139",
language = "English",
volume = "808",
journal = "The Astrophysical Journal",
issn = "0004-637X",
publisher = "Institute of Physics Publishing",
number = "2",

}

RIS

TY - JOUR

T1 - Evidence for Pop III-like stellar populations in the most luminous Lyman-α emitters at the epoch of re-ionisation

T2 - spectroscopic confirmation

AU - Sobral, David

AU - Matthee, Jorryt

AU - Darvish, Behnam

AU - Schaerer, Daniel

AU - Mobasher, Bahram

AU - Röttgering, Huub J. A.

AU - Da Graça Santos, Sergio

AU - Hemmati, Shoubaneh

PY - 2015/7/28

Y1 - 2015/7/28

N2 - Faint Lyman-$\alpha$ (Ly$\alpha$) emitters become increasingly rarer towards the re-ionisation epoch (z~6-7). However, observations from a very large (~5deg$^2$) Ly$\alpha$ survey at z=6.6 (Matthee et al. 2015) show that this is not the case for the most luminous emitters. Here we present follow-up observations of the two most luminous z~6.6 Ly$\alpha$ candidates in the COSMOS field: `MASOSA' and `CR7'. We used X-SHOOTER, SINFONI and FORS2 (VLT), and DEIMOS (Keck), to confirm both candidates beyond any doubt. We find redshifts of z=6.541 and z=6.604 for MASOSA and CR7, respectively. MASOSA has a strong detection in Ly$\alpha$ with a line width of $386\pm30$ km/s (FWHM) and with high EW$_0$ (>200 \AA), but it is undetected in the continuum. CR7, with an observed Ly$\alpha$ luminosity of $10^{43.93\pm0.05}$erg/s is the most luminous Ly$\alpha$ emitter ever found at z>6. CR7 reveals a narrow Ly$\alpha$ line with $266\pm15$ km/s FWHM, being detected in the NIR (rest-frame UV, with $\beta=-2.3\pm0.1$) with an excess in $J$, and also strongly detected in IRAC/Spitzer. We detect a narrow HeII1640$\AA$ emission line ($6\sigma$) which explains the excess seen in the $J$ band photometry (EW$_0$~80 \AA). We find no other emission lines from the UV to the NIR in our X-SHOOTER spectra, nor any signatures of Wolf-Rayet (WR) stars. We find that CR7 is best explained by a combination of a PopIII-like population which dominates the rest-frame UV and the nebular emission, and a more normal stellar population which dominates the mass. HST/WFC3 observations show that the light is indeed spatially separated between a very blue component, coincident with Ly$\alpha$ and HeII emission, and two red components (~5 kpc away), which dominate the mass. Our findings are consistent with theoretical predictions of a PopIII wave, with PopIII star formation migrating away from the original sites of star formation.

AB - Faint Lyman-$\alpha$ (Ly$\alpha$) emitters become increasingly rarer towards the re-ionisation epoch (z~6-7). However, observations from a very large (~5deg$^2$) Ly$\alpha$ survey at z=6.6 (Matthee et al. 2015) show that this is not the case for the most luminous emitters. Here we present follow-up observations of the two most luminous z~6.6 Ly$\alpha$ candidates in the COSMOS field: `MASOSA' and `CR7'. We used X-SHOOTER, SINFONI and FORS2 (VLT), and DEIMOS (Keck), to confirm both candidates beyond any doubt. We find redshifts of z=6.541 and z=6.604 for MASOSA and CR7, respectively. MASOSA has a strong detection in Ly$\alpha$ with a line width of $386\pm30$ km/s (FWHM) and with high EW$_0$ (>200 \AA), but it is undetected in the continuum. CR7, with an observed Ly$\alpha$ luminosity of $10^{43.93\pm0.05}$erg/s is the most luminous Ly$\alpha$ emitter ever found at z>6. CR7 reveals a narrow Ly$\alpha$ line with $266\pm15$ km/s FWHM, being detected in the NIR (rest-frame UV, with $\beta=-2.3\pm0.1$) with an excess in $J$, and also strongly detected in IRAC/Spitzer. We detect a narrow HeII1640$\AA$ emission line ($6\sigma$) which explains the excess seen in the $J$ band photometry (EW$_0$~80 \AA). We find no other emission lines from the UV to the NIR in our X-SHOOTER spectra, nor any signatures of Wolf-Rayet (WR) stars. We find that CR7 is best explained by a combination of a PopIII-like population which dominates the rest-frame UV and the nebular emission, and a more normal stellar population which dominates the mass. HST/WFC3 observations show that the light is indeed spatially separated between a very blue component, coincident with Ly$\alpha$ and HeII emission, and two red components (~5 kpc away), which dominate the mass. Our findings are consistent with theoretical predictions of a PopIII wave, with PopIII star formation migrating away from the original sites of star formation.

U2 - 10.1088/0004-637X/808/2/139

DO - 10.1088/0004-637X/808/2/139

M3 - Journal article

VL - 808

JO - The Astrophysical Journal

JF - The Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 139

ER -