The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Nature of the Faintest Dusty Star-forming Galaxies

Abstract

ervenD wnuel nd foogrdD veindert nd q¡ onzlezEv¡ opezD torge nd herliD oerto nd lterD pin nd grilliD ghris vF nd milD sn nd eissD exel nd essefD oerto tF nd fuerD prnz irik nd fouwensD yhrd tF nd gortesD ulo gF nd goxD ierre nd d gunhD ilisete nd hddiD imnuele nd h¡ %zEntosD nio nd snmiD rne nd svisonD o nd xovkD wlden nd oppingD qerg¤ o nd iehersD hominik nd vn der erfD ul nd ggD te' @PHPHA 9he evwe petrosopi urvey in the rule ltr heep pield X the nture of the fintest dusty strEforming glxiesF9D estrophysil journlFD WHI @IAF pF UWF

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: CO Excitation and Atomic Carbon in Star-forming Galaxies at z = 1–3

“…The absolute flux calibration is expected to be reliable at the ∼10% level. (Aravena et al 2020;González-López et al 2020).…”

“…For five of these sources we also detect the continuum at 3 mm (González-López et al 2019). From the Band 6 data we detect 35 sources in 1.2 mm dust continuum at high significance, 32 of which show counterparts in the optical/near-IR imaging (Aravena et al 2020;González-López et al 2020). We conduct a search for emission lines in the Band 6 cube following the same approach as for the Band 3 data.…”

“…Notably, we did not find any highsignificance lines in sources not already detected in the dust continuum. The Band 6 continuum sources furthermore encompass all Band 3 CO emitters (Aravena et al 2020), with four exceptions: the first two are the lowest mass and SFR source of the main sample (3mm.11) and the faintest source in CO (ASPECS-LP-MP.3mm.02). The third is 3mm.16, which does however have a dust-continuum counterpart in the supplementary catalog of 26 sources at lower significance (the "Faint" sample), which were selected based on the presence of a optical/near-IR counterpart (González-López et al 2020).…”

“…Furthermore, we include 5σ upper limits of 50 μJy and 20 μJy in the case of a non-detection at 1.2 mm and 3 mm, respectively. The fits for the full dust-continuum sample (including the sources not detected in CO) are presented in Aravena et al (2020). Following Aravena et al (2020), we conservatively fold in an additional 0.1 dex to the error bars to account for underestimated and systematic uncertainties.…”

“…The coverage of ASPECS (Band 3 and Band 6) provides simultaneous constraints on multiple lines from CO, [ ] C I for most sources, depending on the redshift (as well as any other species in the frequency range). Furthermore, the multiple tunings scanning through the entire ALMA frequency bands give a high continuum sensitivity, providing a deep (9.3 μJy beam −1 , Section 2.1), contiguous continuum map at 1.2 mm in the Hubble Ultra Deep Field (HUDF; Aravena et al 2020;González-López et al 2020). Using earlier data from the ASPECS-Pilot program on a smaller area of the sky, Decarli et al (2016b) studied a sample of seven galaxies at z=1-3 (a subset of the sources studied in this paper), finding that the CO excitation conditions were overall lower than those typically found in starbursts, SMGs, and QSO environments. This paper studies the CO excitation, atomic carbon emission and ISM conditions in a flux-limited sample of 22 CO and/or dust-continuum detected galaxies at z=1-3 from the ASPECS Large Program (LP), supplemented by follow-up CO(1-0) observations from VLASPECS (Riechers et al 2020).…”