GOODS-ALMA: 1.1 mm galaxy survey

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 Floc’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.; Lagache, G.; Leiton, R.; Lin, L.; Magdis, G.; Messias, H.; Motohara, K.; Mullaney, J.; Okumura, K.; Papovich, C.; Pforr, J.; Rujopakarn, W.; Sargent, M.; Shu, X.; Zhou, L.

Abstract

Aims. We present a 69 arcmin2 ALMA survey at 1.1 mm, GOODS-ALMA, matching the deepest HST-WFC3 H-band part of the GOODS-South field. Methods. We tapered the 0″24 original image with a homogeneous and circular synthesized beam of 0″60 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 1.1 mm in the 0″60 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 × 1011 M⊙. 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.

Citation

Franco, M., Elbaz, D., Béthermin, M., Magnelli, B., Schreiber, C., Ciesla, L., …Zhou, L. (2018). GOODS-ALMA: 1.1 mm galaxy survey. Astronomy & Astrophysics, 620, Article A152. https://doi.org/10.1051/0004-6361/201832928

• Journal Article Type: Article
• Acceptance Date: Jul 30, 2018
• Online Publication Date: Dec 11, 2018
• Publication Date: Dec 11, 2018
• Deposit Date: Jan 4, 2019
• Publicly Available Date: Jan 4, 2019
• Journal: Astronomy and astrophysics.
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 620
• Article Number: A152
• DOI: https://doi.org/10.1051/0004-6361/201832928