The ALMA Spectroscopic Survey in the HUDF: Deep 1.2 mm Continuum Number Counts

Jorge González-López*, Mladen Novak, Roberto Decarli, Fabian Walter, Manuel Aravena, Chris Carilli, Leindert Boogaard, Gergö Popping, Axel Weiss, Roberto J. Assef, Franz Erik Bauer, Rychard Bouwens, Paulo C. Cortes, Pierre Cox, Emanuele Daddi, Elisabete Da Cunha, Tanio Díaz-Santos, Rob Ivison, Benjamin Magnelli, Dominik RiechersIan Smail, Paul Van Der Werf, Jeff Wagg

*Corresponding author for this work

    Research output: Contribution to journalReview articlepeer-review

    55 Citations (Scopus)


    We present the results from the 1.2 mm continuum image obtained as part of the Atacama Large Millimeter/ submillimeter Array Spectroscopic Survey in the Hubble Ultra Deep Field. The 1.2 mm continuum image has a size of 2.9 (4.2) arcmin2 within a primary beam response of 50% (10%) and an rms value of 9.3 mJy beam-1. We detect 35 sources at high significance (Fidelity .0.5); 32 have well-characterized near-infrared Hubble Space Telescope counterparts. We estimate the 1.2 mm number counts to flux levels of 30 mJy in two different ways: we first use the detected sources to constrain the number counts and find a significant flattening of the counts below Sv-0.1 mJy. In a second approach, we constrain the number counts using a probability of deflection statistics (P(D)) analysis. For this latter approach, we describe new methods to accurately measure the noise in interferometric imaging (employing jackknifing in the cube and in the visibility plane). This independent measurement confirms the flattening of the number counts. Our analysis of the differential number counts shows that we are detecting 93% (100% if we include the lower fidelity detections) of the total continuum dust emission associated with galaxies in the Hubble Ultra Deep Field. The ancillary data allow us to study the dependence of the 1.2 mm number counts on redshift (z=0?4), galaxy dust mass (Mdust = 10-10 M? 7 9 ), stellar mass (M = 109-1012M? ), and star formation rate (SFR = 1-1000 M? yr-1). In an accompanying paper we show that the number counts are crucial to constrain galaxy evolution models and the understanding of star-forming galaxies at high redshift.

    Original languageEnglish
    Article number91
    JournalAstrophysical Journal
    Issue number1
    Publication statusPublished - 1 Jul 2020


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