University of Hertfordshire

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

Research output: Contribution to journalArticlepeer-review

• D. Elbaz
• M. Béthermin
• B. Magnelli
• C. Schreiber
• L. Ciesla
• M. Dickinson
• N. Nagar
• J. Silverman
• D. M. Alexander
• T. Wang
• M. Pannella
• E. Le Floc'h
• A. Pope
• M. Giavalisco
• A. J. Maury
• F. Bournaud
• R. Chary
• R. Demarco
• H. Ferguson
• S. L. Finkelstein
• H. Inami
• D. Iono
• S. Juneau
• G. Lagache
• R. Leiton
• L. Lin
• G. Magdis
• H. Messias
• K. Motohara
• J. Mullaney
• K. Okumura
• C. Papovich
• J. Pforr
• W. Rujopakarn
• M. Sargent
• X. Shu
• L. Zhou
Original language English A152 26 Astronomy & Astrophysics 620 11 Dec 2018 https://doi.org/10.1051/0004-6361/201832928 E-pub ahead of print - 11 Dec 2018

Abstract

We present a 69 arcmin$^2$ ALMA survey at 1.1mm, GOODS-ALMA, matching the deepest HST-WFC3 H-band part of the GOODS-South field. We taper 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 extract a catalogue of galaxies purely selected by ALMA and identify sources with and without HST counterparts down to a 5$\sigma$ limiting depth of H=28.2 AB (HST/WFC3 F160W). ALMA detects 20 sources brighter than 0.7 mJy in the 0"60 tapered mosaic (rms sensitivity =0.18 mJy/beam) 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. An additional three sources with HST counterparts are detected 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. 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$_{\star}$ = 1.1 $\times 10^{11}$M$_\odot$. Our sample includes 20% HST-dark galaxies (4 out of 20), all detected in the mid-infrared with IRAC. The near-infrared based photometric redshifts of two of them $z\sim$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

ID: 24855436