Michael Romano

Narodowe Centrum Badań Jądrowych

Sesja VII: Kosmologia i ewolucja galaktyk

Czwartek 14.09.2023 16:24 – 16:36

abstrakt:
Galactic feedback plays a fundamental role in the framework of galaxy formation and evolution. Dwarf galaxies are particularly affected by such feedback that can produce strong winds able to transport significant amount of gas, metals and dust into the circumgalactic (or even intergalactic) medium, drastically affecting their growth. We investigate the physical properties of galactic outflows in a sample of 29 local low-metallicity dwarf galaxies drawn from the Dwarf Galaxy Survey. We make use of Herschel/PACS archival data to detect atomic outflows in the broad wings of observed [CII] 158 um line profiles. We find evidence of outflowing gas in 1/3 of the sample, and in the average galaxy population through line stacking. The outflow rates of our sources are comparable to their star-formation rates, implying mass-loading factors (i.e., outflow efficiencies) of the order of unity. Outflow velocities are larger than the velocities required from gas to escape away from the galaxies with, on average, ~40% of gas carried out into their intergalactic medium. Moreover, their energetics suggest that our outflows are consistent with momentum-driven winds powered by the radiation pressure of young stellar populations on dust grains, in agreement with observations of local starbursts.

These results highlight the importance of feedback in the baryon cycle of low-mass sources. Indeed, galactic outflows powered by star formation are able to bring a significant amount of gas and dust out of the dark matter halos of dwarf galaxies, enriching their surroundings and shaping their star-formation histories. Our constraints on the mass-loading factors will be used as input for chemical evolution models attempting to reproduce the physical processes ruling the evolution of these galaxies across cosmic time.