J-PAS: Exploring the connection between local environment and the triggering of bursty star formation in Extreme Emission Line Galaxies

Abstract

[Abridged]Extreme Emission Line Galaxies (EELGs) are compact, low-mass systems undergoing intense bursts of star formation, whose physical conditions resemble those of galaxies in the early Universe. We characterise the local environment of EELGs identified in the J-PAS survey to determine whether their extreme properties are associated with the presence of nearby companions, as expected if galaxy-galaxy interactions were the main trigger of the burst. We analyse 917 EELGs from the J-PAS internal data release at $0.03 \lesssim z \lesssim 0.9$ over $\sim$30 deg$^2$. We use the Pair Probability Function formalism, based on the full photometric redshift probability distributions, to identify companions within projected separations up to 200 kpc and velocity differences up to 500 km s$^{-1}$. Stellar masses, star formation rates, dust attenuation, and metallicity estimates were derived for the EELGs and their companions through SED fitting with CIGALE, and Monte Carlo simulations were used to correct for projection and completeness effects. The average pair fraction of the EELGs is $f_\mathrm{pair} = 0.162^{+0.048}_{-0.033}$, indicating that only $\sim$16% of the sample has detectable companions, a value lower than the observed average for other star-forming galaxies within the adopted limits. When detected within the sensitivity and stellar-mass completeness limits of J-PAS, companions tend to be more massive and to show higher SED-based metallicity estimates than the EELGs, suggesting that the latter are typically the low-mass components of asymmetric pairs. However, lower-mass companions below these limits may remain undetected. No statistically significant correlation is found between the equivalent widths of the [OIII]$λ$5007, H$β$, and H$α$ emission lines and the projected separation to the detected companions within the J-PAS limits.