A High Resolution Atlas of Composite SDSS Galaxy Spectra

Abstract

In this work we present an atlas of composite spectra of galaxies based on the data of the Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Galaxies are classified by colour, nuclear activity and star-formation activity to calculate average spectra of high signal-to-noise ratio and resolution (S/N = 132 - 4760 at {Dlambda = 1 A), using an algorithm that is robust against outliers. Besides composite spectra, we also compute the first five principal components of the distributions in each galaxy class to characterize the nature of variations of individual spectra around the averages. The continua of the composite spectra are fitted with BC03 stellar population synthesis models to extend the wavelength coverage beyond the coverage of the SDSS spectrographs. Common derived parameters of the composites are also calculated: integrated colours in the most popular filter systems, line strength measurements, and continuum absorption indices (including Lick indices). These derived parameters are compared with the distributions of parameters of individual galaxies and it is shown on many examples that the composites of the atlas cover much of the parameter space spanned by SDSS galaxies. By co-adding thousands of spectra, a total integration time of several months can be reached, which results in extremely low noise composites. The variations in redshift not only allow for extending the spectral coverage bluewards to the original wavelength limit of the SDSS spectrographs, but also make higher spectral resolution achievable. The composite spectrum atlas is available online at http://www.vo.elte.hu/compositeatlas.

References in corpus (4)

• The Host Galaxies and Classification of Active Galactic Nuclei
• PHAT: PHoto-z Accuracy Testing
• Reliable Eigenspectra for New Generation Surveys
• The nature of the SDSS galaxies in various classes based on morphology, colour and spectral features -- I. Optical properties

Cited by in corpus (27)

• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• Photometric redshifts for the SDSS Data Release 12
• Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at z~2
• An X-shooter composite of bright 1 < z < 2 quasars from UV to infrared
• The weirdest SDSS galaxies: results from an outlier detection algorithm
• Retired galaxies: not to be forgotten in the quest of the star formation -- AGN connection
• Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI). IV. Lensed quasar search in the HSC survey
• Spectral classification and composites of galaxies in LAMOST DR4
• The relationship between dust and [CI] at z=1 and beyond
• The VIMOS Public Extragalactic Redshift Survey (VIPERS): spectral classification through Principal Component Analysis
• Leveraging 3D-HST Grism Redshifts to Quantify Photometric Redshift Performance
• Serendipitous discovery of quadruply-imaged quasars: two diamonds
• Unsupervised classification of SDSS galaxy spectra
• The local universe in the era of large surveys. I. Spectral classification of S0 galaxies
• Reeling in the Whirlpool: the distance to M 51 clarified by Cepheids and the Type IIP SN 2005cs
• Discovery of an unusually compact lensed Lyman Break Galaxy from the Hyper Suprime-Cam Survey
• Sensitive Radio Survey of Obscured Quasar Candidates
• Objective Identification of Informative Wavelength Regions in Galaxy Spectra
• Single parameter galaxy classification: The Principal Curve through the multi-dimensional space of galaxy properties
• How dark are filaments in the cosmic web?
• The faint end of the 250 micron luminosity function at z < 0.5
• Lick-index entanglement and biased diagnostic of stellar populations in galaxies
• Stellar population analysis on the stacked spectra of double-peaked emission-line galaxies
• Precision age indicators that exploit chemically peculiar stars
• From VIPERS to SDSS: Unveiling galaxy spectra evolution over 9 Gyr through unsupervised machine-learning
• Chemically Peculiar Stars in Integrated Light Stellar Population Models and Local Group Galaxies