Aravena, M.M.AravenaDECARLI, ROBERTOROBERTODECARLIWalter, F.F.WalterBouwens, R.R.BouwensOesch, P. A.P. A.OeschCarilli, C. L.C. L.CarilliBauer, F. E.F. E.BauerDa Cunha, E.E.Da CunhaDaddi, E.E.DaddiGónzalez-López, J.J.Gónzalez-LópezIvison, R. J.R. J.IvisonRiechers, D. A.D. A.RiechersSmail, I.I.SmailSwinbank, A. M.A. M.SwinbankWeiss, A.A.WeissAnguita, T.T.AnguitaBacon, R.R.BaconBell, E.E.BellBertoldi, F.F.BertoldiCortes, P.P.CortesCox, P.P.CoxHodge, J.J.HodgeIbar, E.E.IbarInami, H.H.InamiInfante, L.L.InfanteKarim, A.A.KarimMagnelli, B.B.MagnelliOta, K.K.OtaPopping, G.G.Poppingvan der Werf, P.P.van der WerfWagg, J.J.WaggFudamoto, Y.Y.Fudamoto2020-06-292020-06-2920160004-637Xhttp://hdl.handle.net/20.500.12386/26259We present a search for [C II] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212-272 GHz, encompass approximately the range of 6 < z < 8 for [C II] line emission and reach a limiting luminosity of L <SUB>[C II]</SUB> ∼ (1.6-2.5) × 10<SUP>8</SUP> L <SUB>☉</SUB>. We identify 14 [C II] line emitting candidates in this redshift range with significances >4.5σ, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C II] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C II] candidates results in a tentative detection with S <SUB>1.2 mm</SUB> = 14 ± 5 μJy. This implies a dust-obscured star-formation rate (SFR) of (3 ± 1) M <SUB>☉</SUB> yr<SUP>-1</SUP>. We find that the two highest-SFR objects have candidate [C II] lines with luminosities that are consistent with the low-redshift L <SUB>[C II]</SUB> versus SFR relation. The other candidates have significantly higher [C II] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C II] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C II] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe.STAMPAenArticle10.3847/1538-4357/833/1/712-s2.0-85006375111https://iopscience.iop.org/article/10.3847/1538-4357/833/1/712016ApJ...833...71AFIS/05 - ASTRONOMIA E ASTROFISICA