GASP XXXII. Measuring the diffuse ionized gas fraction in ram-pressure stripped galaxies

Abstract

The diffuse ionized gas (DIG) is an important component of the interstellar medium and it can be affected by many physical processes in galaxies. Measuring its distribution and contribution in emission allows us to properly study both its ionization and star formation in galaxies. Here, we measure for the first time the DIG emission in 38 gas-stripped galaxies in local clusters drawn from the GAs Stripping Phenomena in galaxies with MUSE survey (GASP). These galaxies are at different stages of stripping. We also compare the DIG properties to those of 33 normal galaxies from the same survey. To estimate the DIG fraction (C${}_{DIG}$) and derive its maps, we combine attenuation corrected H$\alpha$ surface brightness with $[\mathrm{SII}]/H\alpha$ line ratio. Our results indicate that we cannot use neither a single H$\alpha$ or $[\mathrm{SII}]/H\alpha$ value, nor a threshold in equivalent width of H$\alpha$ emission line to separate spaxels dominated by DIG and non-DIG emission. Assuming a constant surface brightness of the DIG across galaxies underestimates C${}_{DIG}$. Contrasting stripped and non-stripped galaxies, we find no clear differences in C${}_{DIG}$. The DIG emission contributes between 20\% and 90\% of the total integrated flux, and does not correlate with the galactic stellar mass and star-formation rate (SFR). The C${}_{DIG}$ anti-correlates with the specific SFR, which may indicate an older ($>10^8$ yr) stellar population as ionizing source of the DIG. The DIG fraction shows anti-correlations with the SFR surface density, which could be used for a robust estimation of integrated C${}_{DIG}$ in galaxies.

This article is currently in press for the ApJ. 28 pages of which the main text is 21 pages, 17 figures of which 11 are in the main text, 2 tables, Appendix on the end (with 6 figures)

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Cited by in corpus (16)

• Environmental dependence of the molecular cloud lifecycle in 54 main sequence galaxies
• GASP XXXIII. The ability of spatially resolved data to distinguish among the different physical mechanisms affecting galaxies in low-density environments
• GASP XXXIV: Unfolding the thermal side of ram pressure stripping in the jellyfish galaxy JO201
• GASP and MaNGA surveys shed light on the enigma of the gas metallicity gradients in disk galaxies
• The diffuse ionized gas (DIG) in star-forming galaxies: the influence of aperture effects on local HII regions
• The Gas-Star Formation Cycle in Nearby Star-forming Galaxies II. Resolved Distributions of CO and H$\alpha$ Emission for 49 PHANGS Galaxies
• Observing ram pressure at work in intermediate redshift clusters with MUSE: the case of Abell 2744and Abell 370
• GASP XXXV: Characteristics of the diffuse ionised gas in gas-stripped galaxies
• UV and H$\alpha$ HST observations of 6 GASP jellyfish galaxies
• HST imaging of star-forming clumps in 6 GASP ram-pressure stripped galaxies
• The MUSE view of ram pressure stripped galaxies in clusters: the GASP sample
• Ultraviolet imaging observations of three jellyfish galaxies: Star formation suppression in the centre and ongoing star formation in stripped tails
• Star formation at different stages of ram-pressure stripping as observed through far-ultraviolet imaging of 13 GASP galaxies
• Clump formation in ram-pressure stripped galaxies: evidence from mass function
• Mechanisms Affecting Galaxies Nearby and Environmental Trends (MAGNET)
• ESO 137-002: a large spiral undergoing edge-on ram-pressure stripping with little star formation in the tail