CLEAR: Paschen-β Star Formation Rates and Dust Attenuation of Low-redshift Galaxies

Abstract

We use Paschen-β (Paβ; 1282 nm) observations from the Hubble Space Telescope G141 grism to study the star formation and dust-attenuation properties of a sample of 29 low-redshift (z < 0.287) galaxies in the CANDELS Lyα Emission at Reionization survey. We first compare the nebular attenuation from Paβ/Hα with the stellar attenuation inferred from the spectral energy distribution, finding that the galaxies in our sample are consistent with an average ratio of the continuum attenuation to the nebular gas of 0.44, but with a large amount of excess scatter beyond the observational uncertainties. Much of this scatter is linked to a large variation between the nebular dust attenuation as measured by (space-based) Paβ to (ground-based) Hα to that from (ground-based) Hα/Hβ. This implies there are important differences between attenuation measured from grism-based/wide-aperture Paβ fluxes and the ground-based/slit-measured Balmer decrement. We next compare star formation rates (SFRs) from Paβ to those from dust-corrected UV. We perform a survival analysis to infer a census of Paβ emission implied by both detections and nondetections. We find evidence that galaxies with lower stellar mass have more scatter in their ratio of Paβ to attenuation-corrected UV SFRs. When considering our Paβ detection limits, this observation supports the idea that lower-mass galaxies experience “burstier” star formation histories. Together, these results show that Paβ is a valuable tracer of a galaxy’s SFR, probing different timescales of star formation and potentially revealing star formation that is otherwise missed by UV and optical tracers.

CLEAR: The Ionization and Chemical-Enrichment Properties of Galaxies at 1.1 < z < 2.3

“…These will be described fully in the forthcoming paper on the data release (Simons et al, in prep. ) and have been discussed in other papers using these data (e.g., Estrada-Carpenter et al 2019, 2020Simons et al 2021;Jung et al 2021;Backhaus et al 2022;Cleri et al 2022;Matharu 2022).…”

CLEAR: The Evolution of Spatially Resolved Star Formation in Galaxies between 0.5 ≲ z ≲ 1.7 Using Hα Emission Line Maps

“…By virtue of being a spectroscopic survey in the well-studied GOODS-S and GOODS-N fields, the CLEAR data has high utility, especially when combined with the wealth of ancillary photometry spanning from the ultraviolet to the near-infrared (Skelton et al 2014) and WFC3/G141 grism spectroscopy from the 3D-HST survey (see Section 2.2). So far, it has allowed for studies on the ages, metallicities, and star formation histories of highredshift massive quiescent galaxies (Estrada-Carpenter et al 2019, the gas-phase metallicity gradients of star-forming galaxies between 0.6 < z < 2.6 (Simons et al 2021), emission line ratios at z ∼ 1.5 (Backhaus et al 2022), an exploration of Paschen-β as a star formation rate indicator in the local (z  0.3) universe (Cleri et al 2022), and the ionization and chemical enrichment properties of star-forming galaxies at 1.1  z  2.3 (Papovich et al 2022).…”

High-resolution Hubble Space Telescope Imaging Survey of Local Star-forming Galaxies. I. Spatially Resolved Obscured Star Formation with Hα and Paschen-β Recombination Lines

“…Calzetti et al (1996) find equivalent results with the Paβ/Brγ ratio on a sample of local starburst galaxies. The Balmer-to-Paschen decrement (Hα/Paβ) technique has been demonstrated for Local Group H II regions (Pang et al 2011;De Marchi & Panagia 2014), for a portion of the nearby starburst M83 (L13), and more recently employed at somewhat higher redshifts (Cleri et al 2022). However, to date this technique has not been used extensively for systematic study of the extinction properties of local galaxies, nor with the quality and high spatial resolution of the Hubble Space Telescope (HST).…”