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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Identification of the brightest Lyα emitters at z = 6.6
T2 - Implications for the evolution of the luminosity function in the reionization era
AU - Matthee, Jorryt
AU - Sobral, David
AU - Da Graça Santos, Sergio
AU - Röttgering, Huub
AU - Darvish, Behnam
AU - Mobasher, Bahram
PY - 2015/7/21
Y1 - 2015/7/21
N2 - Using wide-field narrow-band surveys, we provide a new measurement of the z = 6.6 Lymanα emitter (LAE) luminosity function (LF), which constraints the bright end for the first time. We use a combination of archival narrow-band NB921 data in UDS and new NB921 measurements in SA22 and COSMOS/UltraVISTA, all observed with the Subaru telescope, with a total area of ~5 deg2. We exclude lower redshift interlopers by using broad-band optical and near-infrared photometry and also exclude three supernovae with data split over multiple epochs. Combining the UDS and COSMOS samples, we find no evolution of the bright end of the Lyα LF between z = 5.7 and 6.6, which is supported by spectroscopic follow-up, and conclude that sources with Himiko-like luminosity are not as rare as previously thought, with number densities of ~1.5 × 10-5 Mpc-3. Combined with our wide-field SA22 measurements, our results indicate a non-Schechter-like bright end of the LF at z = 6.6 and a different evolution of observed faint and bright LAEs, overcoming cosmic variance. This differential evolution is also seen in the spectroscopic follow-up of UV-selected galaxies and is now also confirmed for LAEs, and we argue that it may be an effect of reionization. Using a toy model, we show that such differential evolution of the LF is expected, since brighter sources are able to ionize their surroundings earlier, such that Lyα photons are able to escape. Our targets are excellent candidates for detailed follow-up studies and provide the possibility to give a unique view on the earliest stages in the formation of galaxies and reionization process.
AB - Using wide-field narrow-band surveys, we provide a new measurement of the z = 6.6 Lymanα emitter (LAE) luminosity function (LF), which constraints the bright end for the first time. We use a combination of archival narrow-band NB921 data in UDS and new NB921 measurements in SA22 and COSMOS/UltraVISTA, all observed with the Subaru telescope, with a total area of ~5 deg2. We exclude lower redshift interlopers by using broad-band optical and near-infrared photometry and also exclude three supernovae with data split over multiple epochs. Combining the UDS and COSMOS samples, we find no evolution of the bright end of the Lyα LF between z = 5.7 and 6.6, which is supported by spectroscopic follow-up, and conclude that sources with Himiko-like luminosity are not as rare as previously thought, with number densities of ~1.5 × 10-5 Mpc-3. Combined with our wide-field SA22 measurements, our results indicate a non-Schechter-like bright end of the LF at z = 6.6 and a different evolution of observed faint and bright LAEs, overcoming cosmic variance. This differential evolution is also seen in the spectroscopic follow-up of UV-selected galaxies and is now also confirmed for LAEs, and we argue that it may be an effect of reionization. Using a toy model, we show that such differential evolution of the LF is expected, since brighter sources are able to ionize their surroundings earlier, such that Lyα photons are able to escape. Our targets are excellent candidates for detailed follow-up studies and provide the possibility to give a unique view on the earliest stages in the formation of galaxies and reionization process.
KW - Cosmology: observations
KW - Dark ages, reionization, first stars
KW - Galaxies: evolution
KW - Galaxies: high-redshift
U2 - 10.1093/mnras/stv947
DO - 10.1093/mnras/stv947
M3 - Journal article
AN - SCOPUS:84938223883
VL - 451
SP - 400
EP - 417
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 1
ER -