GOODS-ALMA: 1.1 mm galaxy survey - I. Source catalogue and optically dark galaxies

Franco, M, Elbaz, D, Béthermin, M, Magnelli, B, Schreiber, C, Ciesla, L, Dickinson, M, Nagar, N, Silverman, J, Daddi, E, Alexander, D M, Wang, T, Pannella, M, Le Foc'h, E, Pope, A, Giavalisco, M, Maury, A J, Bournaud, F, Chary, R, Demarco, R, Ferguson, H, Finkelstein, S L, Inami, H, Iono, D, Juneau, S, Legache, G, Leiton, R, Lin, L, Magdis, G, Messias, H, Motohara, K, Mullaney, J, Okumura, K, Papovich, C, Pforr, J, Rujopakarn, W, Sargent, Mark, Shu, X and Zhou, L (2018) GOODS-ALMA: 1.1 mm galaxy survey - I. Source catalogue and optically dark galaxies. Astronomy & Astrophysics. ISSN 0004-6361

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Aims. We present a 69 arcmin2 ALMA survey at 1.1mm, GOODS–ALMA, matching the deepest HST–WFC3 H-band part of the GOODS–South field.

Methods. We tapered the 00024 original image with a homogeneous and circular synthesized beam of 00060 to reduce the number of independent beams – thus reducing the number of purely statistical spurious detections – and optimize the sensitivity to point sources. We extracted a catalog of galaxies purely selected by ALMA and identified sources with and without HST counterparts down to a 5σ limiting depth of H=28.2 AB (HST/WFC3 F160W).

Results. ALMA detects 20 sources brighter than 0.7 mJy at 1.1mm in the 00060 tapered mosaic (rms sensitivity σ ' 0.18 mJy.beam−1 ) with a purity greater than 80%. Among these detections, we identify three sources with no HST nor Spitzer-IRAC counterpart, consistent with the expected number of spurious galaxies from the analysis of the inverted image; their definitive status will require additional investigation. We detect additional three sources with HST counterparts either at high significance in the higher resolution map, or with different detection-algorithm parameters ensuring a purity greater than 80%. Hence we identify in total 20 robust detections.

Conclusions. Our wide contiguous survey allows us to push further in redshift the blind detection of massive galaxies with ALMA with a median redshift of z = 2.92 and a median stellar mass of M? = 1.1 × 1011M. Our sample includes 20% HST–dark galaxies (4 out of 20), all detected in the mid-infrared with Spitzer–IRAC. The near-infrared based photometric redshifts of two of them (z∼4.3 and 4.8) suggest that these sources have redshifts z > 4. At least 40% of the ALMA sources host an X-ray AGN, compared to ∼14% for other galaxies of similar mass and redshift. The wide area of our ALMA survey provides lower values at the bright end of number counts than single-dish telescopes affected by confusion.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Mark Sargent
Date Deposited: 23 Aug 2018 13:29
Last Modified: 03 Dec 2018 11:23

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