J-PLUS: measuring ${\rm H}\alpha$ emission line fluxes in the nearby universe

TL;DR

This paper validates a method to accurately measure H-alpha emission line fluxes from J-PLUS photometric data, enabling large-scale studies of star formation in the nearby universe using multi-band imaging.

Contribution

It introduces and validates a photometric technique to extract H-alpha fluxes from J-PLUS survey data, demonstrating high agreement with spectroscopic measurements.

Findings

Photometric H-alpha fluxes agree with spectroscopic data within 25%.

The method enables reliable star formation rate measurements over large sky areas.

Application to galaxy pairs shows localized star formation enhancements.

Abstract

In the present paper we aim to validate a methodology designed to extract the Halpha emission line flux from J-PLUS photometric data. J-PLUS is a multi narrow-band filter survey carried out with the 2 deg2 field of view T80Cam camera, mounted on the JAST/T80 telescope in the OAJ, Teruel, Spain. The information of the twelve J-PLUS bands, including the J0660 narrow-band filter located at rest-frame Halpha, is used over 42 deg2 to extract de-reddened and [NII] decontaminated Halpha emission line fluxes of 46 star-forming regions with previous SDSS and/or CALIFA spectroscopic information. The agreement of the inferred J-PLUS photometric Halpha fluxes and those obtained with spectroscopic data is remarkable, with a median comparison ratio R = 1.05 +- 0.25. This demonstrates that it is possible to retrieve reliable Halpha emission line fluxes from J-PLUS photometric data. With an expected area of thousands of square degrees upon completion, the J-PLUS dataset will allow the study of several star formation science cases in the nearby universe, as the spatially resolved star formation rate of nearby galaxies at z < 0.015, and how it is influenced by the environment, morphology or nuclear activity. As an illustrative example, the close pair of interacting galaxies NGC3994 and NGC3995 is analyzed, finding an enhancement of the star formation rate not only in the center, but also in outer parts of the disk of NGC3994.