Star formation efficiency in nearby galaxies revealed with a new CO-to-H2 conversion factor prescription

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A90106%2F24%3A00617526" target="_blank" >RIV/67985815:90106/24:00617526 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.3847/1538-4357/ad10ae" target="_blank" >https://doi.org/10.3847/1538-4357/ad10ae</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/ad10ae" target="_blank" >10.3847/1538-4357/ad10ae</a>

Result language

angličtina

Original language name

Star formation efficiency in nearby galaxies revealed with a new CO-to-H2 conversion factor prescription

Original language description

Determining how the galactic environment, especially the high gas densities and complex dynamics in bar-fed galaxy centers, alters the star formation efficiency (SFE) of molecular gas is critical to understanding galaxy evolution. However, these same physical or dynamical effects also alter the emissivity properties of CO, leading to variations in the CO-to-H-2 conversion factor (alpha(CO)) that impact the assessment of the gas column densities and thus of the SFE. To address such issues, we investigate the dependence of alpha(CO) on the local CO velocity dispersion at 150 pc scales using a new set of dust-based alpha(CO) measurements and propose a new alpha(CO) prescription that accounts for CO emissivity variations across galaxies. Based on this prescription, we estimate the SFE in a sample of 65 galaxies from the PHANGS-Atacama Large Millimeter/submillimeter Array survey. We find increasing SFE toward high-surface-density regions like galaxy centers, while using a constant or metallicity-based alpha(CO) results in a more homogeneous SFE throughout the centers and disks. Our prescription further reveals a mean molecular gas depletion time of 700 Myr in the centers of barred galaxies, which is overall three to four times shorter than in nonbarred galaxy centers or the disks. Across the galaxy disks, the depletion time is consistently around 2-3 Gyr, regardless of the choice of alpha(CO) prescription. All together, our results suggest that the high level of star formation activity in barred centers is not simply due to an increased amount of molecular gas, but also to an enhanced SFE compared to nonbarred centers or disk regions.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

—

Continuities

—

Publication year

2024

Confidentiality

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

Name of the periodical

Astrophysical Journal

ISSN

0004-637X

e-ISSN

1538-4357

Volume of the periodical

961

Issue of the periodical within the volume

1

Country of publishing house

GB - UNITED KINGDOM

Number of pages

11

Pages from-to

42

UT code for WoS article

001142454100001

EID of the result in the Scopus database

2-s2.0-85184189358