The boss lyα forest sample from sdss data release 9

Khee Gan Lee, Stephen Bailey, Leslie E. Bartsch, William Carithers, Kyle S. Dawson, David Kirkby, Britt Lundgren, Daniel Margala, Nathalie Palanque-Delabrouille, Matthew M. Pieri, David J. Schlegel, David H. Weinberg, Christophe Yèche, Éric Aubourg, Julian Bautista, Dmitry Bizyaev, Michael Blomqvist, Adam S. Bolton, Arnaud Borde, Howard BrewingtonNicolás G. Busca, Rupert A.C. Croft, Timothée Delubac, Garrett Ebelke, Daniel J. Eisenstein, Andreu Font-Ribera, Jian Ge, Jean Christophe Hamilton, Joseph F. Hennawi, Shirley Ho, Klaus Honscheid, Jean Marc Le Goff, Elena Malanushenko, Viktor Malanushenko, Jordi Miralda-Escudé, Adam D. Myers, Pasquier Noterdaeme, Daniel Oravetz, Kaike Pan, Isabelle Pâris, Patrick Petitjean, James Rich, Emmanuel Rollinde, Nicholas P. Ross, Graziano Rossi, Donald P. Schneider, Audrey Simmons, Stephanie Snedden, Anže Slosar, David N. Spergel, Nao Suzuki, Matteo Viel, Benjamin A. Weaver

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


We present the BOSS Lyman-α (Lyα) Forest Sample from SDSS Data Release 9, comprising 54,468 quasar spectra with zqso > 2.15 suitable for Lyα forest analysis. This data set probes the intergalactic medium with absorption redshifts 2.0 < zα < 5.7 over an area of 3275 deg2, and encompasses an approximate comoving volume of 20 h -3 Gpc3. With each spectrum, we have included several products designed to aid in Lyα forest analysis: improved sky masks that flag pixels where data may be unreliable, corrections for known biases in the pipeline estimated noise, masks for the cores of damped Lyα systems and corrections for their wings, and estimates of the unabsorbed continua so that the observed flux can be converted to a fractional transmission. The continua are derived using a principal component fit to the quasar spectrum redward of rest-frame Lyα (λ > 1216 Å), extrapolated into the forest region and normalized by a linear function to fit the expected evolution of the Lyα forest mean flux. The estimated continuum errors are ≲ 5% rms. We also discuss possible systematics arising from uncertain spectrophotometry and artifacts in the flux calibration; global corrections for the latter are provided. Our sample provides a convenient starting point for users to analyze clustering in BOSS Lyα forest data, and it provides a fiducial data set that can be used to compare results from different analyses of baryon acoustic oscillations in the Lyα forest. The full data set is available from the SDSS-III DR9 Web site.

Original languageEnglish (US)
Article number69
JournalAstronomical Journal
Issue number3
StatePublished - Mar 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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