Detalles de publicación

PP 020045

Gas fractions and depletion times in galaxies with different degrees of interaction

Díaz-García, Simón; Knapen, Johan H.
IAC & ULL
We study the atomic gas content and the central stellar mass concentration for a sample of almost 1500 nearby galaxies to investigate the nature of starbursts and the influence of galaxy-galaxy interactions on star formation. We use the catalogue on interacting and merging galaxies in the S4G survey of Knapen et al. (2014) along with archival HI gas masses, stellar masses (M∗), and SFRs (from IRAS far-IR fluxes), and calculate depletion times (τ) and gas fractions. We trace the central stellar mass concentration from the inner slope of the stellar component of the rotation curves, dRv∗(0). Starbursts - defined as galaxies with a factor >4 enhanced SFR relative to a control sample (±0.2 dex in stellar mass, ±1 in T-type, non-interacting) - are mainly early-type (T≲5) massive spiral galaxies (M∗≳1010M⊙), not necessarily interacting. For a given stellar mass bin, starbursts are characterised by lower gas depletion times, similar gas fractions, and larger central stellar mass concentrations than non-starburst galaxies. The global distributions of gas fraction and gas depletion time are not statistically different for interacting and non-interacting galaxies. However, in the case of currently merging galaxies, the median gas depletion time is a factor of 0.4±0.2 that of control sample galaxies, and their star formation rates are a factor of 1.9±0.5 enhanced, even though the median gas fraction is similar. Starbursts present long-lasting star formation in the circumnuclear regions that causes an enhancement of the central stellar density at z≈0 in both interacting and non-interacting systems. Starbursts have low gas depletion timescales, yet similar gas fractions as normal main-sequence galaxies. Galaxy mergers cause a moderate enhancement of the star formation efficiency (Abridged).

 
Aceptado para publicación en A&A | Enviado el 2020-03-02 | Proyecto 3I2407