Nearby eXtremely Metal Poor galaxies with MEGARA

The powerful combination of MEGARA LCB mode (Integral Field Unit with 623 fibers covering a Field Of View of 12.5“ x 11.3“ on sky and a spaxel size of 0.62”) and spectrograph (with R ~ 6000, 12000, 18000 for LR, MR and HR gratings, respectively) at GTC provides a unique opportunity to boost the research in eXtremely Metal Poor, XMPs, galaxies.

We are carrying out a program to study with an unprecedented spatial and spectral resolution nearby XMD galaxies for which only imaging or long-slit spectroscopy were available. The final goal of this program (currently we have data for 16 galaxies) is understanding the origin of their low-metallicity and evolutionary status.

We are performing spatially resolved kinematical studies of gas, with resolution Dv = 16 – 50 kms-1 , emission lines maps and consequently 2D distribution of electron density, electron temperature and oxygen abundance; and using these observations to infer clues on the physical properties of the stellar populations.

We use PopStar models + CLOUDY photoionization code to predict gas emission line spectra, resulting from the photoionization by the youngest clusters, which is then compared to MEGARA observations across entire galaxies. We have published, Carrasco et al. 2022,  MEGARA data on Leoncino galaxy (12 + log(O/H) = 7.02 ± 0.03), mapping the gas distribution with a resolution of 22pc; finding no evidence of recent gas infall or loss of metals due to outflows, and therefore proposing Leoncino to be a genuine XMD galaxy. We are in the process of publishing results on two more galaxies: SDSSJ0859+3923 (García-Vargas et al. in prep) and SDSSJ1640+2845 (Gil de Paz et al. in prep).