Do spiral arms enhance star formation efficiency?

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A90106%2F24%3A00617541" target="_blank" >RIV/67985815:90106/24:00617541 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1051/0004-6361/202449733" target="_blank" >https://doi.org/10.1051/0004-6361/202449733</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202449733" target="_blank" >10.1051/0004-6361/202449733</a>

Result language

angličtina

Original language name

Do spiral arms enhance star formation efficiency?

Original language description

Spiral arms, as those of our own Milky Way, are some of the most spectacular features in disc galaxies. It has been argued that star formation should proceed more efficiently in spiral arms as a result of gas compression. Yet, observational studies have so far yielded contradictory results. Here, we examine arm/interarm surface density contrasts at similar to 100 pc resolution in 28 spiral galaxies from the PHANGS survey. We find that the arm/interarm contrast in stellar mass surface density (Sigma star) is very modest, typically a few tens of percent. This is much smaller than the contrasts measured for molecular gas (Sigma(mol)) or star formation rate (Sigma(SFR)) surface density, which typically reach a factor of similar to 2 3. However, Sigma(mol) and Sigma(SFR) contrasts show a significant correlation with the enhancement in Sigma star, suggesting that the small stellar contrast largely dictates the stronger accumulation of gas and star formation. All these contrasts increase for grand-design spirals compared to multi-armed and flocculent systems (and for galaxies with high stellar mass). The median star formation efficiency (SFE) of the molecular gas is 16% higher in spiral arms than in interarm regions, with a large scatter, and the contrast increases significantly (median SFE contrast 2.34) for regions of particularly enhanced stellar contrast (Sigma star contrast > 1.97). The molecular-to-atomic gas ratio (Sigma(mol)/Sigma(atom)) is higher in spiral arms, pointing to a transformation of atomic to molecular gas. As a consequence, the total gas contrast (Sigma(mol) + Sigma(atom)) slightly drops compared to Sigma(mol) (median 4% lower, working at similar to kpc resolution), while the SFE contrast increases when we include atomic gas (median 8% higher than for Sigma(mol)). The contrasts show important fluctuations with galactocentric radius. We confirm that our results are robust against a number of effects, such as spiral mask width, tracers, resolution, and binning. In conclusion, the boost in the SFE of molecular gas in spiral arms is generally modest or absent, except for locations with exceptionally large stellar contrasts.

Czech name

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Czech description

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Type

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

CEP classification

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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

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

687

Issue of the periodical within the volume

July

Country of publishing house

FR - FRANCE

Number of pages

26

Pages from-to

A293

UT code for WoS article

001275047000001

EID of the result in the Scopus database

2-s2.0-85199498536