An investigation of the star-forming main sequence considering the nebular continuum emission at low-z

Journal Article · Wed Dec 21 00:00:00 EST 2022 · Astronomy and Astrophysics

DOI:https://doi.org/10.1051/0004-6361/202244390· OSTI ID:2425101

Miranda, Henrique ^[1]; Pappalardo, Ciro ^[1]; Papaderos, Polychronis ^[2]; Afonso, José ^[1]; Matute, Israel ^[1]; Lobo, Catarina ^[3]; Paulino-Afonso, Ana ^[3]; Carvajal, Rodrigo ^[1]; Lorenzoni, Silvio ^[1]; Santos, Duarte ^[1]

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1. Universidade de Lisboa (Portugal)
2. Universidade de Lisboa (Portugal); Universidade do Porto (Portugal)
3. Universidade do Porto (Portugal)

Galaxy evolution has been studied by interpreting the spectral energy distribution of galaxies using spectral synthesis codes. This method has been crucial in discovering different pillars of modern galaxy evolution theories. However, this analysis was mostly carried out using spectral synthesis codes that are purely stellar, that is, they assume that the nebular contribution to the total continuum is negligible. The code FADO is the first publicly available population spectral synthesis tool that treats the contribution from ionised gas to the observed emission self-consistently. This is expected to have a particularly strong effect in star-forming (SF) galaxies. We study the impact of the nebular contribution on the determination of the star formation rate (SFR), stellar mass, and consequent effect on the star-forming main sequence (SFMS) at low redshift. We applied FADO to the spectral database of the SDSS to derive the physical properties of galaxies. As a comparison, we used the data in the MPA-JHU catalogue, which contains the properties of SDSS galaxies derived without the nebular contribution. We selected a sample of SF galaxies with Hα and Hβ flux measurements, and we corrected the fluxes for the nebular extinction through the Balmer decrement. We then calculated the Hα luminosity to estimate the SFR. Then, by combining the stellar mass and SFR estimates from FADO and MPA-JHU, the SFMS was obtained. The Hα flux estimates are similar between FADO and MPA-JHU. Because the Hα flux was used as tracer of the SFR, FADO and MPA-JHU agree in their SFR. The stellar mass estimates are slightly higher for FADO than for MPA-JHU on average. However, considering the uncertainties, the differences are negligible. With similar SFR and stellar mass estimates, the derived SFMS is also similar between FADO and MPA-JHU. Our results show that for SDSS normal SF galaxies, the additional modelling of the nebular contribution does not affect the retrieved fluxes and consequentially also does not influence SFR estimators based on the extinction-corrected Hα luminosity. For the stellar masses, the results point to the same conclusion. These results are a consequence of the fact that the vast majority of normal SF galaxies in the SDSS have a low nebular contribution. However, the obtained agreement might only hold for local SF galaxies, but higher-redshift galaxies might show different physical properties when FADO is used. This would then be an effect of the expected increased nebular contribution.

• Research Organization: US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Sloan Digital Sky Survey (SDSS)
• Sponsoring Organization: Fundação para a Ciência e a Tecnologia (FCT); USDOE
• OSTI ID: 2425101
• Journal Information: Astronomy and Astrophysics, Journal Name: Astronomy and Astrophysics Vol. 669; ISSN 0004-6361
• Publisher: EDP Sciences
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Astronomy & Astrophysics
galaxies: evolution
galaxies: fundamental parameters
galaxies: star formation
galaxies: stellar content
methods: numerical
techniques: spectroscopic