Search for [C II] emission in z = 6.5-11 star-forming galaxies

We present the search for the [C II] emission line in three z > 6.5 Lyα emitters (LAEs) and one J-dropout galaxy using the Combined Array for Research in Millimeter-wave Astronomy and the Plateau de Bure Interferometer. We observed three bright z 6.5-7 LAEs discovered in the Subaru Deep Field (SDF) and the multiple imaged lensed z 11 galaxy candidate found behind the galaxy cluster MACSJ0647.7+7015. For the LAEs IOK-1 (z = 6.965), SDF J132415.7+273058 (z = 6.541), and SDF J132408.3+271543 (z = 6.554) we find upper limits for the [C II] line luminosity of <2.05, <4.52, and <10.56 × 10 ⁸ L _⊙, respectively. We find upper limits to the far-IR (FIR) luminosity of the galaxies using a spectral energy distribution template of the local galaxy NGC 6946 and taking into account the effects of the cosmic microwave background on the millimeter observations. For IOK-1, SDF J132415.7+273058, and SDF J132408.3+271543 we find upper limits for the FIR luminosity of <2.33, 3.79, and 7.72 × 10¹¹ L _⊙, respectively. For the lensed galaxy MACS0647-JD, one of the highest-redshift galaxy candidates to date with , we put an upper limit in the [C II] emission of <1.36 × 10⁸ × (μ/15) ^-1 L _⊙ and an upper limit in the FIR luminosity of <6.1 × 10¹⁰ × (μ/15)^-1 L _⊙ (where μ is the magnification factor). We explore the different conditions relevant for the search for [C II] emission in high-redshift galaxies as well as the difficulties for future observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Cerro Chajnantor Atacama Telescope (CCAT).