THE FAINT-END SLOPE OF THE REDSHIFT 5.7 Lyα LUMINOSITY FUNCTION^,

Abstract

Using new Keck DEIMOS spectroscopy, we examine the origin of the steep number counts of ultrafaint emission-line galaxies recently reported by Dressler et al. (2011). We confirm six Lyα emitters (LAEs), three of which have significant asymmetric line profiles with prominent wings extending 300-400 km s −1 redward of the peak emission. With these six LAEs, we revise our previous estimate of the number of faint LAEs in the Dressler et al. survey. Combining these data with the density of bright LAEs in the Cosmic Origins Survey and Subaru Deep Field provides the best constraints to date on the redshift 5.7 LAE luminosity function (LF). Schechter function parameters, φ * = 4.5 × 10 −4 Mpc −3 , L * = 9.1 × 10 42 erg s −1 , and α = −1.70, are estimated using a maximum likelihood technique with a model for slit losses. To place this result in the context of the UV-selected galaxy population, we investigate how various parameterizations of the Lyα equivalent width distribution, along with the measured UV-continuum LF, affect shape and normalization of the Lyα LF. The nominal model, which uses z ∼ 6 equivalent widths from the literature, falls short of the observed space density of LAEs at the bright end, possibly indicating a need for higher equivalent widths. This parameterization of the equivalent width distribution implies that as many as 50% of our faintest LAEs should have M U V > −18.0, rendering them undetectable in even the deepest Hubble Space Telescope surveys at this redshift. Hence, ultra-deep emission-line surveys find some of the faintest galaxies ever observed at the end of the reionization epoch. Such faint galaxies likely enrich the intergalactic medium with metals and maintain its ionized state. Observations of these objects provide a glimpse of the building blocks of present-day galaxies at an early time. 7 We have added one object that was dropped from the sample in Paper II, bringing the number of LAE candidates from 104 to 105.8 Multiple emission lines can be present in the 134Å of search spectrum when we detect Hα and [N II] λ6583Å, or [O III] λλ4959, 5007Å. 9The photometric redshifts used in this paper are taken from the COSMOS Photometric Redshift Cat-11

SHARDS Frontier Fields: Physical Properties of a Low-mass Lyα Emitter at z = 5.75

“…These line widths are small compared to brighter LAEs at this redshift, but similar to the widths measured by Karman et al (2017) for faint LAEs at z 3 < < 6. This is consistent with a continuation of the correlation found at higher luminosities between the width and luminosity of Lyα (Hu et al 2010;Henry et al 2012).…”

MUSE observations of the lensing cluster Abell 1689

“…10. Distribution of lens-corrected Lyman-α luminosities for the 17 galaxies found behind A1689 at 3 ≤ z ≤ 7 (red squares), as compared to Bacon et al (2015) (blue diamonds), and to a compilation of representative samples of LAE from the literature (gray symbols): 2 z 3.8 (Blanc et al 2011) (HETDEX Pilot Survey), 2.7 z 3.8 (gray triangles) (Rauch et al 2008), z ∼ 4.9 (Shioya et al 2009), z ∼ 5.7 (Shimasaku et al 2006;Ouchi et al 2008;Henry et al 2012;Hu et al 2010), and z ∼ 6.5 (Ouchi et al 2010;Hu et al 2010;Kashikawa et al 2011). small number of sources, we did not introduce any correction for incompleteness at this stage, knowing that incompleteness is expected to affect in particular the faintest bins in Fig. 11.…”

The MUSE Hubble Ultra Deep Field Survey

“…(Rhoads et al 2000, Ouchi et al 2003, Hu et al 2004, Ouchi et al 2008, Yamada et al 2012, Matthee et al 2015, Konno et al 2016, Santos et al 2016 An alternative approach to LAE selection, was pioneered by Martin et al (2008), and subsequently exploited in Dressler et al (2011), Henry et al (2012) and Dressler et al (2015), combining a narrowband filter with 100 long slits -multislit narrowband spectroscopy. With this technique the authors found evidence for a very steep faint-end slope of the luminosity function, confirmed by each subsequent study, although they note that this is a sensitive function of the correction they make for foreground galaxies.…”

“…In agreement with van Breukelen et al (2005), Shimasaku et al (2006), andOuchi et al (2008) they found no evidence of evolution between the redshift bins within their errors. Due to the dynamic range of the study, Cassata et al (2011) fixed φ * and L * in their lowest two redshift bins and used the 1/V max estimator to measure α, finding shallower values of the faint-end slope than implied by the number counts of Rauch et al (2008) or Martin et al (2008), Dressler et al (2011, and Henry et al (2012. Similarly in the highest redshift bin they fixed the value of α, fitting only for φ * and L * , although interestingly they found the measured value of α increased from their lowest redshift bin to the next.…”