TY - JOUR
T1 - CLASSY V
T2 - The Impact of Aperture Effects on the Inferred Nebular Properties of Local Star-forming Galaxies
AU - Arellano-Córdova, Karla Z.
AU - Mingozzi, Matilde
AU - Berg, Danielle A.
AU - James, Bethan L.
AU - Rogers, Noah S.J.
AU - Aloisi, Alessandra
AU - Amorín, Ricardo O.
AU - Brinchmann, Jarle
AU - Charlot, Stéphane
AU - Chisholm, John
AU - Heckman, Timothy
AU - Dubón, Stefany Fabian
AU - Hayes, Matthew
AU - Hernandez, Svea
AU - Jones, Tucker
AU - Kumari, Nimisha
AU - Leitherer, Claus
AU - Martin, Crystal L.
AU - Nanayakkara, Themiya
AU - Pogge, Richard W.
AU - Sanders, Ryan
AU - Senchyna, Peter
AU - Skillman, Evan D.
AU - Stark, Dan P.
AU - Wofford, Aida
AU - Xu, Xinfeng
N1 - Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - Strong nebular emission lines are an important diagnostic tool for tracing the evolution of star-forming galaxies across cosmic time. However, different observational setups can affect these lines, and the derivation of the physical nebular properties. We analyze 12 local star-forming galaxies from the COS Legacy Spectroscopy SurveY (CLASSY) to assess the impact of using different aperture combinations on the determination of the physical conditions and gas-phase metallicity. We compare optical spectra observed with the Sloan Digital Sky Survey Data Release aperture, which has a 3″ diameter similar to COS, IFU, and long-slit spectra, including new LBT/MODS observations of five CLASSY galaxies. We calculate the reddening, electron densities and temperatures, metallicities, star formation rates, and equivalent widths (EWs). We find that measurements of the electron densities and temperatures, and metallicity remained roughly constant with aperture size, indicating that the gas conditions are relatively uniform for this sample. However, using IFU observations of three galaxies, we find that the E(B - V) values derived from the Balmer ratios decrease (by up to 53%) with increasing aperture size. The values change most significantly in the center of the galaxies, and level out near the COS aperture diameter of 2.″5. We examine the relative contributions from the gas and stars using the Hα and [O iii] λ5007 EWs as a function of aperture light fraction, but find little to no variations within a given galaxy. These results imply that the optical spectra provide nebular properties appropriate for the far-UV CLASSY spectra, even when narrow 1.″0 long-slit observations are used.
AB - Strong nebular emission lines are an important diagnostic tool for tracing the evolution of star-forming galaxies across cosmic time. However, different observational setups can affect these lines, and the derivation of the physical nebular properties. We analyze 12 local star-forming galaxies from the COS Legacy Spectroscopy SurveY (CLASSY) to assess the impact of using different aperture combinations on the determination of the physical conditions and gas-phase metallicity. We compare optical spectra observed with the Sloan Digital Sky Survey Data Release aperture, which has a 3″ diameter similar to COS, IFU, and long-slit spectra, including new LBT/MODS observations of five CLASSY galaxies. We calculate the reddening, electron densities and temperatures, metallicities, star formation rates, and equivalent widths (EWs). We find that measurements of the electron densities and temperatures, and metallicity remained roughly constant with aperture size, indicating that the gas conditions are relatively uniform for this sample. However, using IFU observations of three galaxies, we find that the E(B - V) values derived from the Balmer ratios decrease (by up to 53%) with increasing aperture size. The values change most significantly in the center of the galaxies, and level out near the COS aperture diameter of 2.″5. We examine the relative contributions from the gas and stars using the Hα and [O iii] λ5007 EWs as a function of aperture light fraction, but find little to no variations within a given galaxy. These results imply that the optical spectra provide nebular properties appropriate for the far-UV CLASSY spectra, even when narrow 1.″0 long-slit observations are used.
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U2 - 10.3847/1538-4357/ac7854
DO - 10.3847/1538-4357/ac7854
M3 - Article
AN - SCOPUS:85136633691
SN - 0004-637X
VL - 935
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 74
ER -