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 Yeche, Eric Aubourg, Julian Bautista, Dmitry Bizyaev, Michael Blomqvist, Adam S. Bolton, Arnaud Borde, Howard BrewingtonNicolas G. Busca, Rupert A. C. Croft, Timothee 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-Escude, 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, Anze Slosar, David N. Spergel, Nao Suzuki, Matteo Viel, Benjamin A. Weaver

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We present the BOSS Lyman-α (Lyα) Forest Sample from SDSS Data Release 9, comprising 54,468 quasar spectra with z qso > 2.15 suitable for Lyα forest analysis. This data set probes the intergalactic medium with absorption redshifts 2.0 < z α < 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
Pages (from-to)69
JournalThe Astronomical Journal
Issue number3
Early online date6 Feb 2013
Publication statusPublished - 1 Mar 2013


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