Star Formation Rate Indicators in the Sloan Digital Sky Survey

By Andrew M. Hopkins, C. Miller, Robert Nichol, Andrew J. Connolly, Mariangela Bernardi, P. Gomez, T. Goto, Christy A. Tremonti, J. Brinkmann, Željko Ivezic´ and 7 more. 2003

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The Sloan Digital Sky Survey (SDSS) first data release provides a database of ≈106,000 unique galaxies in the main galaxy sample with measured spectra. A sample of star-forming (SF) galaxies are identified from among the 3079 of these having 1.4 GHz luminosities from FIRST, by using optical spectral diagnostics. Using 1.4 GHz luminosities as a reference star formation rate (SFR) estimator insensitive to obscuration effects, the SFRs derived from the measured SDSS Hα, [O II], and u-band luminosities, as well as far-infrared luminosities from IRAS, are compared. It is established that straightforward corrections for obscuration and aperture effects reliably bring the SDSS emission line and photometric SFR estimates into agreement with those at 1.4 GHz, although considerable scatter (≈60%) remains in the relations. It thus appears feasible to perform detailed investigations of star formation for large and varied samples of SF galaxies through the available spectroscopic and photometric measurements from the SDSS. We provide herein exact prescriptions for determining the SFR for SDSS galaxies. The expected strong correlation between [O II] and Hα line fluxes for SF galaxies is seen, but with a median line flux ratio F/FHα = 0.23, about a factor of 2 smaller than that found in the sample of Kennicutt. This correlation, used in deriving the [O II] SFRs, is consistent with the luminosity-dependent relation found by Jansen and coworkers. The median obscuration for the SDSS SF systems is found to be AHα = 1.2 mag, while for the radio-detected sample the median obscuration is notably higher, 1.6 mag, and with a broader distribution.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Galaxy Zoo: a sample of blue early-type galaxies at low redshift (2009, methodology): “In order to determine whether this aperture correction is appropriate, we compare with independent tracers of the total SFR: the IR SFR from theIRASobservations and the SFR from theu-band light (Hopkins et al. 2003), corrected for extinction using the Balmer decrement.”
Optical Star Formation Rate Indicators (2005, unknown): “However, the U-band luminosity also depends on the recent star formation history of the galaxy, and its sensitivity as a SFR indicator may be compromised by evolved (k100Myr) stellar populations (Kennicutt 1998; Cram et al. 1998; Hopkins et al. 2003).”
Aperture Effects on Star Formation Rate, Metallicity, and Reddening (2005, methodology): “The potential implications of these biases are discussed by several authors (Gómez et al. 2003; Pérez-González et al. 2003; Hopkins et al. 2003; Nakamura et al. 2003).”
Minor Galaxy Interactions: Star Formation Rates and Galaxy Properties (2007, methodology): “We use the Hopkins et al. (2003) prescription for calculating the H star formation rate based on the SDSS observed H flux.”
Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity (2008, background): “Unfortunately, we do not presently have an accurate handle on the dust corrections, which are likely to be at least luminosity-dependent (Hopkins et al. 2001, 2003; Sullivan et al. 2001; Pérez-González et al. 2003; Afonso et al. 2003; Reddy et al. 2006).”
Semi-empirical analysis of Sloan Digital Sky Survey galaxies – II. The bimodality of the galaxy population revisited (2005, background): “This may be somewhat problematic because this kind of correction is performed just in this type of galaxies (e.g. Hopkins et al. 2003).”
The C4 Clustering Algorithm: Clusters of Galaxies in the Sloan Digital Sky Survey (2005, background): “For example, the u–band is an excellent measurement of recent star–formation in galaxies (see Hopkins et al. 2003), and is below the D4000 feature.”
The SAMI Galaxy Survey: shocks and outflows in a normal star-forming galaxy (2014, background): “This is not surprising given that the systematic uncertainties involved in different SFR calibrations (e.g., Hopkins et al. 2003), and the fact that the different indicators trace star-formation of different timescales; how- Star (PSF) PSF model Residuals ever, an order of magnitude difference is…”
On the Normalization of the Cosmic Star Formation History (2006, background): “More significantly, though, for individual galaxies there can be large differences, up to an order of magnitude, in the SFRs inferred through different indicators (e.g. Hopkins et al. 2003), although on average for large samples there is a high level of consistency.”
K-Corrections and Filter Transformations in the Ultraviolet, Optical, and Near-Infrared (2006, methodology): “Our results roughly scale as those of Hopkins et al. (2003) do, but with lower star formation rates by a factor of 5 or so.”
Galaxy And Mass Assembly (GAMA): Spectroscopic analysis (2013, methodology): “Due to the2′′ fibre diameter, emission from a galaxy that is larger than this on the sky will not be measured within the fibre (e.g., Hopkins et al. 2003; Brinchmann et al. 2004).”
Galaxy Zoo: the properties of merging galaxies in the nearby Universe – local environments, colours, masses, star formation rates and AGN activity (2009, result): “Similar studies since then have strongly confirmed that mergers-induce star formation (see §1; Hopkins et al. 2003), though the idea that AGN are significantly induced by mergers remains tentative (Ellison et al. 2008).”
Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function (2011, methodology): “High SFR galaxies are subjected to greater dust obscuration than lower luminosity objects (Hopkins et al. 2001, 2003; Afonso et al. 2003; Pérez-González et al. 2003).”
Physical properties and environments of nearby galaxies (2009, background): “A variety of both direct and indirect techniques have been developed to measure the globally averaged star-formation rates (SFRs) of galaxies, as reviewed in detail by Kennicutt (1998b) (see also Hopkins et al. 2003; Moustakas, Kennicutt & Tremonti 2006; Calzetti 2008).”
On the Evolution of Star-forming Galaxies (2004, methodology): “When applying a common obscuration correction, AH ¼ 1:0 mag is assumed for emission-line measurements, often found as the average obscuration to H emission in samples of local galaxies (e.g., Kennicutt 1992; Hopkins et al. 2003b).”
The Environmental Dependence of Galaxy Properties in the Local Universe: Dependences on Luminosity, Local Density, and System Richness (2004, methodology): “There are several formulae in the literature to convert Hα flux to SFRs (e.g., Kennicutt 1998; Hopkins, Connolly, Haarsma, & Cram 2001; Charlot & Longhetti 2001; Hopkins et al. 2003).”
The physical properties of star-forming galaxies in the low-redshift universe (2003, background): “This shows a peak around 1.0 mag of extinction in Hα, in good agreement with other determinations (e.g. Kennicutt 1983; Sullivan et al. 2000; Hopkins et al. 2003; Nakamura et al. 2003, C02).”
Predicting dust extinction from the stellar mass of a galaxy (2010, methodology): “This is effectively the same correction as is discussed by Hopkins et al. (2003), who use the ratio of total and fibre-based r-band magnitudes to correct the detected Hα emission of SDSS galaxies.”
GASP. I. Gas Stripping Phenomena in Galaxies with MUSE (2017, methodology): “Using the calibration from Hopkins et al. (2003), the 1.4 GHz flux would yield an SFR of about -M12 yr 1, which is a factor of 2 higher than the SFR measured from Hα (see Section 7.5).”
Star formation at z=1.47 from HiZELS: an Hα+[O ii] double-blind study* (2011, methodology): “…emit strongly in the ultraviolet (UV), and although this is often significantly absorbed, it is then re-emitted through a variety of processes, resulting in detectable signatures such as strong emission lines or thermal infrared emission from heated dust (see discussion in Hopkins et al. 2003).”