Identification of the brightest Lyα emitters at z = 6.6 : Implications for the evolution of the luminosity function in the reionization era

By J. Matthee, D. Sobral, S. Santos, H. Rottgering, B. Darvish, B. Mobasher. 2015

140 citations recorded by the source corpus.

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 deg 2 . 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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8092e811d89e1fc11b086e7a881a425e26637da2

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Citations in the corpus

Systematic Identification of LAEs for Visible Exploration and Reionization Research Using Subaru HSC (SILVERRUSH). I. Program strategy and clustering properties of ∼2000 Lyα emitters at z = 6–7 over the 0.3–0.5 Gpc2 survey area (2017, background): “…to z ∼ 7 including the evolution of Lyα luminosity functions (LFs; Malhotra & Rhoads 2004; Kashikawa et al. 2006, 2011; Deharveng et al. 2008; Ouchi et al. 2008, 2010; Cowie et al. 2010; Hu et al. 2010; Konno et al. 2014; Matthee et al. 2015; Santos et al. 2016; Ota et al. 2017; Zheng et al. 2017).”
Conditions for Reionizing the Universe with a Low Galaxy Ionizing Photon Escape Fraction (2019, background): “…for a bright-end “bump” seen in multiple surveys, where the abundance of LAEs at log L43 erg s−1, most spectroscopically confirmed, is higher than expected from a Schechter function fit to lower luminosities (e.g., Matthee et al. 2015; Bagley et al. 2017; Hu et al. 2017; Zheng et al. 2017).”
Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionization (2016, background): “…rapid evolution of Lyα emitters at z > 6 (Ono et al. 2012; Caruana et al. 2014; Schenker et al. 2014; Pentericci et al. 2014; Tilvi et al. 2014; Matthee et al. 2015) suggest that reionisation may have ended later than previously thought (e.g., Chardin et al. 2015; Choudhury et al. 2015;…”
Hyper-Eddington accretion flows on to massive black holes (2015, background): “Recently, Matthee et al. (2015) found the brightest LAE called CR7.”
Titans of the early Universe: The Prato statement on the origin of the first supermassive black holes (2018, background): “The CR7 system was first identified as a Lyman-α emitter by Matthee et al. (2015) and spectroscopically confirmed by Sobral et al. (2015).”
Observational evidence for intermediate-mass black holes (2017, background): “The source, CR7, is found in the COSMOS field with a redshift z = 6.6 (Matthee et al. 2015) and is spatially extended (∼16 kpc; Sobral et al. 2015).”
Lyα EMISSION FROM A LUMINOUS z = 8.68 GALAXY: IMPLICATIONS FOR GALAXIES AS TRACERS OF COSMIC REIONIZATION (2015, background): “The second question is whether these rarer luminous sources (c.f. Matthee et al. 2015; Ouchi et al. 2013) are physically distinct from the fainter population.”
SILVERRUSH. IV. Lyα luminosity functions at z = 5.7 and 6.6 studied with ∼1300 Lyα emitters on the 14–21 deg2 sky (2017, methodology): “These survey areas are 70− 87 times larger than those of the Subaru Deep Field studies (Shimasaku et al. 2006; Kashikawa et al. 2011), 14− 21 times larger than those of the Subaru/XMM-Newton Deep Survey (Ouchi et al. 2008; Ouchi et al. 2010), and 2− 5 times larger than those of other subsequent stud”
Stellar population effects on the inferred photon density at reionization (2015, background): “…currently available set of deep field observational data, and assume these Schechter (1976) function parameterizations extend to lower luminosities, beyond current observable limits (although note that z > 6 Lyman-α emitting galaxies may deviate from such a Schecter function, Matthee et al. 2015).”
Lyman-α spectral properties of five newly discovered Lyman continuum emitters (2016, background): “However, for galaxies located in large ionized bubbles – as recently found by Castellano et al. (2016), and suggested by Matthee et al. (2015)– this may not be a problem.”
Lyα and C iii] emission in z = 7–9 Galaxies: accelerated reionization around luminous star-forming systems? (2016, background): “Evidence for luminosity-dependent evolution of LAEs at z > 6 has been suggested in previous Lyα fraction studies (e.g., Ono et al. 2012) and is also consistent with the lack of evolution at the bright end of the Lyα luminosity function over 5.7 < z < 6.6 (e.g., Matthee et al. 2015).”