J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe

Context. Over the past decades, several studies have discovered a population of galaxies that undergo very strong star formation events. They are called extreme emission line galaxies (EELGs). <BR /> Aims: We exploit the capabilities of the Javalambre Photometric Local Universe Survey (J-PLUS), a wide-field multifilter survey, with which 2000 square degrees of the northern sky are already observed. We use it to identify EELGs at low redshift by their [OIII]5007 emission line. We intend to provide a more complete, deep, and less biased sample of local EELGs. <BR /> Methods: We selected objects with an excess of flux in the J-PLUS medium-band J0515 filter, which covers the [OIII] line at z &lt; 0.06. We removed contaminants (stars and higher-redshift systems) using J-PLUS and WISE infrared photometry, with SDSS spectra as a benchmark. We performed spectral energy distribution fitting to estimate the physical properties of the galaxies: line fluxes, equivalent widths (EWs), masses, stellar population ages, and so on. <BR /> Results: We identify 466 EELGs at z &lt; 0.06 with [OIII] EW over 300 Å and an r-band magnitude below 20, of which 411 were previously unknown. Most show compact morphologies, low stellar masses (log(M<SUB>⋆</SUB>/<SUB>M</SUB><SUB>⊙</SUB>) ∼ 8.13<SUB>−0.58</SUB><SUP>+0.61</SUP>), low dust extinction (E(<SUB>B−V</SUB>) ∼ 0.1<SUB>−0.1</SUB><SUP>+0.2</SUP>), and very young bursts of star formation (3.0<SUB>−2.0</SUB><SUP>+2.7</SUP> Myr). Our method is up to ∼20 times more efficient in detecting EELGs per Mpc<SUP>3</SUP> than broadband surveys, and it is as complete as magnitude-limited spectroscopic surveys (but reaches fainter objects). The sample is not directly biased against strong Hα emitters, in contrast with works using broadband surveys. <BR /> Conclusions: We demonstrate that J-PLUS can identify a large sample of previously unknown EELGs showing unique properties following a clear selection process. A fraction of the EELGs are probably similar to the first galaxies in the Universe, but they are at a much lower redshift, which makes them ideal targets for follow-up studies. <P />Full Tables 3 and 4 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/668/A60">https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/668/A60</A>