VALES

VIII. Weak ionized gas outflows in star-forming galaxies at z ∼ 0.15 traced with VLT/MUSE

¹ Centro de Astronomía (CITEVA), Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile
e-mail: guilherme.couto@uantof.cl
² Chinese Academy of Sciences South America Center for Astronomy, China-Chile Joint Center for Astronomy, Camino El Observatorio 1515, Las Condes, Santiago, Chile
³ Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile
⁴ CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026, PR China
⁵ School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, PR China
⁶ Boltzmann, BV, Belgium
⁷ CePIA, Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile

Received: 7 June 2021
Accepted: 4 August 2021

Abstract

We characterize the ionized gas outflows in 15 low-redshift star-forming galaxies, a Valparaíso ALMA/APEX Line Emission Survey (VALES) subsample, using MUSE integral field spectroscopy and GAMA photometric broadband data. We measure the emission-line spectra by fitting a double-component profile, with the second and broader component related to the outflowing gas. This interpretation is in agreement with the correlation between the observed star-formation rate (SFR) surface density (Σ_SFR) and the second-component velocity dispersion (σ_2nd), expected when tracing the feedback component. By modeling the broadband spectra with spectral energy distribution fitting and obtaining the star-formation histories of the sample, we observe a small decrease in SFR between 100 and 10 Myr in galaxies when the outflow Hα luminosity contribution is increased, indicating that the feedback somewhat inhibits the star formation within these timescales. The observed emission-line ratios are best reproduced by photoionization models when compared to shock ionization, indicating that radiation from the young stellar population is dominant and seems to be a consequence of a continuous star-formation activity instead of a “bursty” event. The outflow properties, such as the mass outflow rate (∼0.1 M_⊙ yr⁻¹), the outflow kinetic power (∼5.2 × 10⁻⁴%L_bol), and the mass loading factor (∼0.12), point toward a scenario where the measured feedback is not strong and has a low impact on the evolution of galaxies in general.