TY - JOUR

T1 - ALMACAL VIII

T2 - a pilot survey for untargeted extragalactic CO emission lines in deep ALMA calibration data

AU - Hamanowicz, Aleksandra

AU - Zwaan, Martin A.

AU - Peroux, Celine

AU - Lagos, Claudia del P.

AU - Klitsch, Anne

AU - Ivison, Rob J.

AU - Biggs, Andrew D.

AU - Szakacs, Roland

AU - Fresco, Alejandra

PY - 2023/2/1

Y1 - 2023/2/1

N2 - We present a pilot, untargeted extragalactic carbon monoxide (CO) emission-line survey using ALMACAL, a project utilizing ALMA calibration data for scientific purposes. In 33 deep (T-exp' > 40 min) ALMACAL fields, we report six CO emission-line detections above S/N > 4, one-third confirmed by MUSE observations. With this pilot survey, we probe a cosmologically significant volume of similar to 10(5) cMpc(3), widely distributed over many pointings in the southern sky, making the survey largely insusceptible to the effects of cosmic variance. We derive the redshift probability of the CO detections using probability functions from the SHARK semi-analytical model of galaxy formation. By assuming typical CO excitations for the detections, we put constraints on the cosmic molecular gas mass density evolution over the redshift range 0 < z < 1.5. The results of our pilot survey are consistent with the findings of other untargeted emission-line surveys and the theoretical model predictions and currently cannot rule out a non-evolving molecular gas mass density. Our study demonstrates the potential of using ALMA calibrator fields as a multi-sightline untargeted CO emission-line survey. Applying this approach to the full ALMACAL database will provide an accurate, free of cosmic variance, measurement of the molecular luminosity function as a function of redshift.

AB - We present a pilot, untargeted extragalactic carbon monoxide (CO) emission-line survey using ALMACAL, a project utilizing ALMA calibration data for scientific purposes. In 33 deep (T-exp' > 40 min) ALMACAL fields, we report six CO emission-line detections above S/N > 4, one-third confirmed by MUSE observations. With this pilot survey, we probe a cosmologically significant volume of similar to 10(5) cMpc(3), widely distributed over many pointings in the southern sky, making the survey largely insusceptible to the effects of cosmic variance. We derive the redshift probability of the CO detections using probability functions from the SHARK semi-analytical model of galaxy formation. By assuming typical CO excitations for the detections, we put constraints on the cosmic molecular gas mass density evolution over the redshift range 0 < z < 1.5. The results of our pilot survey are consistent with the findings of other untargeted emission-line surveys and the theoretical model predictions and currently cannot rule out a non-evolving molecular gas mass density. Our study demonstrates the potential of using ALMA calibrator fields as a multi-sightline untargeted CO emission-line survey. Applying this approach to the full ALMACAL database will provide an accurate, free of cosmic variance, measurement of the molecular luminosity function as a function of redshift.

KW - ISM: molecules

KW - galaxies: evolution

KW - galaxies: ISM

KW - galaxies: star formation.

KW - MOLECULAR GAS CONTENT

KW - SPECTROSCOPIC SURVEY

KW - STAR-FORMATION

KW - LUMINOSITY FUNCTIONS

KW - COSMIC EVOLUTION

KW - PHYSICAL-PROPERTIES

KW - INTERSTELLAR-MEDIUM

KW - GALAXY FORMATION

KW - HIGH-REDSHIFT

KW - BLIND SEARCH

U2 - 10.1093/mnras/stac3159

DO - 10.1093/mnras/stac3159

M3 - Journal article

VL - 519

SP - 34

EP - 49

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 1

ER -