Panchromatic Photometry of Low-redshift, Massive Galaxies Selected from SDSS Stripe 82

Abstract

The broadband spectral energy distribution of a galaxy encodes valuable information on its stellar mass, star formation rate (SFR), dust content, and possible fractional energy contribution from nonstellar sources. We present a comprehensive catalog of panchromatic photometry, covering 17 bands from the far-ultraviolet to 500 μm, for 2685 low-redshift (z = 0.01–0.11), massive (M * > 1010 M ⊙) galaxies selected from the Stripe 82 region of the Sloan Digital Sky Survey, one of the largest areas with relatively deep, uniform observations over a wide range of wavelengths. Taking advantage of the deep optical coadded images, we develop a hybrid approach for matched-aperture photometry of the multiband data. We derive robust uncertainties and upper limits for undetected galaxies, deblend interacting/merging galaxies and sources in crowded regions, and treat contamination by foreground stars. We perform spectral energy distribution fitting to derive the stellar mass, SFR, and dust mass, critically assessing the influence of flux upper limits for undetected photometric bands and applying corrections for systematic uncertainties based on extensive mock tests. Comparison of our measurements with those of commonly used published catalogs reveals good agreement for the stellar masses. While the SFRs of galaxies on the star-forming main sequence show reasonable consistency, galaxies in and below the green valley show considerable disagreement between different sets of measurements. Our analysis suggests that one should incorporate the most accurate and inclusive photometry into the spectral energy distribution analysis, and that care should be exercised in interpreting the SFRs of galaxies with moderate to weak star formation activity.

The Subtle Effects of Mergers on Star Formation in Nearby Galaxies

“…We make use of the local galaxies in the SDSS Stripe 82 region that are covered by the Herschel Stripe 82 Survey (HerS; Viero et al 2014) with the SPIRE instrument (Griffin et al 2010) on board Herschel (Pilbratt et al 2010). The parent sample comes from the catalog produced by Li et al (2023), which is defined by the redshift range of z = 0.01-0.11 and a stellar mass cut of M * 10 10 M e , using values from the GALEX-SDSS-WISE Legacy Catalog 2 (GSWLC-2; Salim et al 2018). The lower limit on redshift excludes very nearby galaxies, which can have unreliable distances based on redshift, the overall narrow redshift range ensures negligible cosmic evolution in global galaxy properties, and the stellar mass cut yields a sample with high completeness.…”

“…While the primary galaxy must be a member of our parent sample and have M * 10 10 M e , the secondary galaxy is allowed to be less massive than this stellar mass limit in order to better explore the effect of minor mergers, although we do not consider galaxy pairs with stellar mass ratios of f 0.01 M < * to minimize confusion with bright galactic substructures. Stellar mass ratios are evaluated by taking into account the 3σ uncertainty of M * , which is ∼0.15 dex (Li et al 2023). The following analysis involves 174 merging galaxies and a control sample of 2244 isolated galaxies.…”

“…CIGALE gives the Bayesian probability distribution for the model parameters. We consider flux upper limits in calculating the likelihoods of the SED models, and we use mock tests to correct the physical parameters for systematic biases that may arise from photometry of low signal-to-noise ratio (see details in Section 4.4 of Li et al 2023). We exclude a minority of galaxies that have reduced χ 2 > 10 in the SED fits, which typically stem from sources that are decomposed poorly by GALFITM in some near-infrared bands.…”

“…Following Shangguan et al (2018), we add 0.23 dex to δ GDR to account for the empirical difference between dust-converted gas masses and direct gas observations. The total uncertainty of the gas masses, ∼0.45 dex, stems from the scatter of 0.15 dex in δ GDR propagated from the scatter of the stellar mass-metallicity relation and the typical uncertainty of 0.42 dex for M d (Li et al 2023), which principally relates to uncertainties of the dust temperature and absorption coefficient. Dust radiation is very sensitive to temperature; even a tiny change in temperature can induce a large variation in dust mass (Lv et al 2018).…”

“…In this paper, we investigate the effect of tidal interactions on the star formation activity and gas content of galaxies, by comparing the SFR, M gas , and specific SFR (sSFR ≡ SFR/M * ) and SFE (SFE ≡ SFR/M gas ) of mergers with non-mergers, where both populations are drawn from a large sample of nearby galaxies selected from the Stripe 82 region (Annis et al 2014) of the Sloan Digital Sky Survey (SDSS; York et al 2000), whose panchromatic, far-ultraviolet (FUV) to farinfrared (FIR) spectral energy distribution (SED) and physical parameters have been analyzed uniformly in the companion work of Li et al (2023). Section 2 introduces the parent sample, the selection criteria for the merger subsample, as well as the derivation of the physical parameters studied in this work.…”