DEEP LBT/LUCI SPECTROSCOPY OF AN Ly alpha EMITTER CANDIDATE AT z similar or equal to 7.7

作者：Jiang Linhua^*; Bian Fuyan; Fan Xiaohui; Krug Hannah B; McGreer Ian D; Stark Daniel P; Clement Benjamin; Egami Eiichi

来源：Astrophysical Journal Letters, 2013, 771(1): L6.

DOI：10.1088/2041-8205/771/1/L6

• cosmology: observations
• galaxies: evolution
• galaxies: high-redshift

We present deep spectroscopic observations of an Lya emitter (LAE) candidate at z similar or equal to 7.7 using the infrared spectrograph LUCI on the 2 x 8.4 m Large Binocular Telescope (LBT). The candidate is the brightest among the four z similar or equal to 7.7 LAE candidates found in a narrowband imaging survey by Krug et al. Our spectroscopic data include a total of 7.5 hr of integration with LBT/ LUCI and are deep enough to significantly (3.2 sigma-4.9 sigma) detect the Ly alpha emission line of this candidate based on its Ly alpha flux 1.2 x 10(-17) erg s(-1) cm(-2) estimated from the narrowband photometry. However, we do not find any convincing signal at the expected position of its Lya emission line, suggesting that this source is not an LAE at z similar or equal to 7.7. The non-detection in this work, together with the previous studies of z similar to 7.7 LAEs, puts a strong constraint on the bright-end Lya luminosity LF) at z similar to 7.7. We find a rapid evolution of the Lya LF from z similar or equal to 6.5 to 7.7: the upper limit of the z similar or equal to 7.7 LF is more than five times lower than the z similar or equal to 6.5 LF at the bright end (f >= 1.0 x 10-17 erg s(-1) cm(-2) or L >= 6.9 x 10(42) erg s(-1)). This is likely caused by an increasing neutral fraction in the intergalactic medium that substantially attenuates Lya emission at z similar or equal to 7.7.

• 出版日期2013-7-1