Constraining Resolved Extragalactic R21 Variation with Well-calibrated ALMA Observations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A90106%2F25%3A00646702" target="_blank" >RIV/67985815:90106/25:00646702 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.3847/1538-4357/addf4c" target="_blank" >https://doi.org/10.3847/1538-4357/addf4c</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/addf4c" target="_blank" >10.3847/1538-4357/addf4c</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Constraining Resolved Extragalactic R21 Variation with Well-calibrated ALMA Observations

Popis výsledku v původním jazyce

CO(1-0) and CO(2-1) are commonly used as bulk molecular gas tracers. The CO line ratios (especially CO(2-1)/ CO(1-0)-R21) vary within and among galaxies, yet previous studies on R21 and alike often rely on measurements constructed by combining data from facilities with substantial relative calibration uncertainties that have the same order as physical line ratio variations. Hence, robustly determining systematic R21 variations is challenging. Here, we compare CO(1-0) and CO(2-1) mapping data from ALMA for 14 nearby galaxies, at a common physical resolution of 1.7 kpc. Our data set includes new ALMA (7 m+TP) CO(1-0) maps of 12 galaxies. We investigate R21 variation to understand its dependence on global galaxy properties, kiloparsec-scale environmental factors, and its correlation with star formation rate (SFR) surface density and metallicity. We find that the galaxy-to-galaxy scatter is 0.05 dex. This is lower than previous studies, which reported over 0.1 dex variation, likely reflecting significant flux calibration uncertainties in single-dish surveys. Within individual galaxies, R21 has a typical mean value of similar to 0.64 and 0.1 dex variation, with an increase to similar to 0.75 toward galactic centers. We find strong correlations between R21 and various galactic parameters, particularly SFR surface density, which shows a power-law slope of 0.10-0.11 depending on the adopted binning/fitting methods. Our findings suggest that, for studies covering main-sequence galaxy samples, assuming a fixed R21 = 0.64 does not significantly bias kiloparsec-scale molecular gas mass estimates from CO(2-1). Instead, systematic uncertainties from flux calibration and the CO-to-H2 conversion factor account for more systematic scatter of CO-derived molecular gas properties

Název v anglickém jazyce

Constraining Resolved Extragalactic R21 Variation with Well-calibrated ALMA Observations

Popis výsledku anglicky

CO(1-0) and CO(2-1) are commonly used as bulk molecular gas tracers. The CO line ratios (especially CO(2-1)/ CO(1-0)-R21) vary within and among galaxies, yet previous studies on R21 and alike often rely on measurements constructed by combining data from facilities with substantial relative calibration uncertainties that have the same order as physical line ratio variations. Hence, robustly determining systematic R21 variations is challenging. Here, we compare CO(1-0) and CO(2-1) mapping data from ALMA for 14 nearby galaxies, at a common physical resolution of 1.7 kpc. Our data set includes new ALMA (7 m+TP) CO(1-0) maps of 12 galaxies. We investigate R21 variation to understand its dependence on global galaxy properties, kiloparsec-scale environmental factors, and its correlation with star formation rate (SFR) surface density and metallicity. We find that the galaxy-to-galaxy scatter is 0.05 dex. This is lower than previous studies, which reported over 0.1 dex variation, likely reflecting significant flux calibration uncertainties in single-dish surveys. Within individual galaxies, R21 has a typical mean value of similar to 0.64 and 0.1 dex variation, with an increase to similar to 0.75 toward galactic centers. We find strong correlations between R21 and various galactic parameters, particularly SFR surface density, which shows a power-law slope of 0.10-0.11 depending on the adopted binning/fitting methods. Our findings suggest that, for studies covering main-sequence galaxy samples, assuming a fixed R21 = 0.64 does not significantly bias kiloparsec-scale molecular gas mass estimates from CO(2-1). Instead, systematic uncertainties from flux calibration and the CO-to-H2 conversion factor account for more systematic scatter of CO-derived molecular gas properties

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

—

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astrophysical Journal

ISSN

0004-637X

e-ISSN

1538-4357

Svazek periodika

988

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

23

Strana od-do

162

Kód UT WoS článku

001533803800001

EID výsledku v databázi Scopus

2-s2.0-105011296233