RT Journal Article
T1 MEGADES: MEGARA galaxy disc evolution survey-Ionised gas disgnosis
A1 Chamorro Cazorla, Mario
A1 Gil De Paz, Armando
A1 Castillo Morales, María África
A1 Camps Fariña, Artemi
A1 Gallego Maestro, Jesús
A1 Carrasco, E.
A1 Iglesias Páramo, J.
A1 Cedazo, R.
A1 García Vargas, M. L.
A1 Pascual Ramírez, Sergio
A1 Cardiel López, Nicolás
A1 Pérez-Calpena, A.
A1 Gómez Álvarez, P.
A1 Martínez Delgado, I.
A1 Catalán Torrecilla, Cristina
A1 Zamorano Calvo, Jaime
AB We present the ionised gas properties and metallicity gradients of the central area of a sample of 43 galaxies using observations obtained by the MEGADES survey. The technical capabilities of MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) provide us with relatively high spectral (R ∼ 6000) and spatial (0.62″) resolution observations that we used to study the properties of the ionised gas via various methods, including using the classic diagnostic BPT diagrams of its [N II] and [S II] variants. We explore how the diagrams vary as a function of both the radius and velocity dispersion of the Hα line. We also propose a new diagnostic diagram for assessing the relative contributions of active galactic nuclei (AGN), shocks, and H II regions in each spatial region as the ratio between the velocity dispersion of the [N II]λ6584 and Hα lines. A considerable number of regions, regardless of their galactocentric distance, have emission line spectra associated with shocks. This inference follows both from their line ratios, typically characterised by high [N II]λ6584/Hα and intermediate [O III]λ5007/Hβ, and from their position in our diagnostic diagram, where they lie between the areas associated with HII regions and with AGN. The better selection of HII-region-like emission allowed for a robust oxygen abundance determination using the N2 indicator, which we used to measure precise abundance gradients. Most galaxies show negligible metallicity gradients, especially the low-abundance (< 8.37 dex) fast rotators. The mean value of the slope of the metallicity gradients for this subset is 0.005 dex R_(e)^(−1), with a dispersion of 0.422 dex R_(e)^(−1). Above 8.37 dex the fast rotators consistently show slightly negative metallicity gradients, with a weak correlation between the slope and the y-intercept. The mean slope of these galaxies is −0.681 dex R_(e)^(−1), with a dispersion of 0.933 dex R_(e)^(−1). The overall mean value of the gradients for all galaxies in the MEGADES sample is −0.025 dex R_(e)^(−1), with a dispersion of 0.766 dex R_(e)^(−1). We discuss the possible implications of these results regarding the impact of galactic winds on the abundance gradients of galaxies.
PB EDP Sciences
SN 0004-6361
YR 2026
FD 2026
LK https://hdl.handle.net/20.500.14352/131218
UL https://hdl.handle.net/20.500.14352/131218
LA eng
NO Chamorro-Cazorla, M., de Paz, A. G., Castillo-Morales, A., Camps-Fariña, A., Gallego, J., Carrasco, E., ... & Zamorano, J. (2026). MEGADES: MEGARA galaxy disc evolution survey-Ionised gas diagnosis. Astronomy & Astrophysics, 705, A53.
NO © The Authors 2026.
NO Comunidad de Madrid
NO Ministerio de Ciencia, Innovación y Universidades (España)
NO Agencia Estatal de Investigación (España)
NO European Commission
NO National Aeronautics and Space Administration (US)
NO National Science Foundation (US)
DS Docta Complutense
RD 21 mar 2026