We investigate the presence of ionised gas outflows in a sample of 141main-sequence star-forming galaxies at $1.2<2.6$ from the KLEVER (KMOS LensedEmission Lines and VElocity Review) survey. Our sample covers an exceptionallywide range of stellar masses, $8.1<\log(M_\star/M_{\odot})<11.3$, pushingoutflow studies into the dwarf regime thanks to gravitationally lensed objects.We stack optical rest-frame emission lines (H$\beta$, [OIII], H$\alpha$ and[NII]) in different mass bins and seek for tracers of gas outflows by using anovel, physically motivated method that improves over the widely used,simplistic double Gaussian fitting. We compare the observed emission lines withthe expectations from a rotating disc (disc+bulge for the most massivegalaxies) model, whereby significant deviations are interpreted as a signatureof outflows. We find clear evidence for outflows in the most massive,$\log(M_\star/M_{\odot}) >10.8$, AGN-dominated galaxies, suggesting that AGNsmay be the primary drivers of these gas flows. Surprisingly, at$\log(M_\star/M_{\odot})\leq 9.6$, the observed line profiles are fullyconsistent with a rotating disc model, indicating that ionised gas outflows indwarf galaxies might play a negligible role even during the peak of cosmicstar-formation activity. Finally, we find that the observed mass loading factorscales with stellar mass as expected from the TNG50 cosmological simulation,but the ionised gas mass accounts for only 2$\%$ of the predicted value. Thissuggests that either the bulk of the outflowing mass is in other gaseous phasesor the current feedback models implemented in cosmological simulations need tobe revised.
Being KLEVER at cosmic noon: ionised gas outflows are inconspicuous in low-mass star-forming galaxies but prominent in massive AGN hosts
MERCURIO AMATA;
2022-01-01
Abstract
We investigate the presence of ionised gas outflows in a sample of 141main-sequence star-forming galaxies at $1.2<2.6$ from the KLEVER (KMOS LensedEmission Lines and VElocity Review) survey. Our sample covers an exceptionallywide range of stellar masses, $8.1<\log(M_\star/M_{\odot})<11.3$, pushingoutflow studies into the dwarf regime thanks to gravitationally lensed objects.We stack optical rest-frame emission lines (H$\beta$, [OIII], H$\alpha$ and[NII]) in different mass bins and seek for tracers of gas outflows by using anovel, physically motivated method that improves over the widely used,simplistic double Gaussian fitting. We compare the observed emission lines withthe expectations from a rotating disc (disc+bulge for the most massivegalaxies) model, whereby significant deviations are interpreted as a signatureof outflows. We find clear evidence for outflows in the most massive,$\log(M_\star/M_{\odot}) >10.8$, AGN-dominated galaxies, suggesting that AGNsmay be the primary drivers of these gas flows. Surprisingly, at$\log(M_\star/M_{\odot})\leq 9.6$, the observed line profiles are fullyconsistent with a rotating disc model, indicating that ionised gas outflows indwarf galaxies might play a negligible role even during the peak of cosmicstar-formation activity. Finally, we find that the observed mass loading factorscales with stellar mass as expected from the TNG50 cosmological simulation,but the ionised gas mass accounts for only 2$\%$ of the predicted value. Thissuggests that either the bulk of the outflowing mass is in other gaseous phasesor the current feedback models implemented in cosmological simulations need tobe revised.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
