J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe
Abstract
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).
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.
Methods: We selected objects with an excess of flux in the J-PLUS medium-band J0515 filter, which covers the [OIII] line at z < 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.
Results: We identify 466 EELGs at z < 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⋆/M⊙) ∼ 8.13−0.58+0.61), low dust extinction (E(B−V) ∼ 0.1−0.1+0.2), and very young bursts of star formation (3.0−2.0+2.7 Myr). Our method is up to ∼20 times more efficient in detecting EELGs per Mpc3 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.
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.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- December 2022
- DOI:
- 10.1051/0004-6361/202142898
- arXiv:
- arXiv:2112.06938
- Bibcode:
- 2022A&A...668A..60L
- Keywords:
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- galaxies: starburst;
- galaxies: star formation;
- galaxies: dwarf;
- galaxies: photometry;
- galaxies: ISM;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 22 pages, 22 figures. Submitted to Astronomy &