Construction of the damped <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>Ly</mml:mi> <mml:mi>α</mml:mi> </mml:mrow> </mml:math> absorber catalog for DESI DR2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mrow> <mml:mrow> <mml:mi>Ly</mml:mi> <mml:mi>α</mml:mi> </mml:mrow> </mml:mrow> </mml:mrow> </mml:math> BAO
A. Brodzeller, Molly Wolfson, D. Martínez Santos, Ming-Feng Ho, T. Tan, Matthew M. Pieri, Andrei Cuceu, M. Karim, J. Aguilar, S. P. Ahlen, Abhijeet Anand, U. Andrade, E. Armengaud, Alejandro Avilés, S. Bailey, A. Bault, D. Bianchi, D. Brooks, Rebecca Canning, L.M. Jara Casas, M. Charles, E. Chaussidon, J. Chaves-Montero, D. Chebat, T. Claybaugh, K. S. Dawson, Roger de Belsunce, Axel de la Macorra, Arnaud de Mattia, Arjun Dey, Biprateep Dey, P. Doel, Mitali J. Doshi, Willem Elbers, Simone Ferraro, Andreu Font-Ribera, J. E. Forero-Romero, C. García-Quintero, Lehman H. Garrison, E. Gaztañaga, Satya Gontcho A Gontcho, Alma X. González‐Morales, D. Green, G. Gutiérrez, J. Guy, ChangHoon Hahn, M. Herbold, H. K. Herrera-Alcantar, K. Honscheid, Cullan Howlett, Dragan Huterer, Mustapha Ishak, S. Juneau, R. Kehoe, Theodore Kisner, Anthony Kremin, O. Lahav, C. Lamman, Martin Landriau, J.M. Le Goff, L. Le Guillou, Alexie Leauthaud, M. E. Levi, Qinxun Li, Marc Manera, Paul Martini, Aaron Meisner, J. Mena-Fernández, R. Miquel, John Moustakas, A. Muñoz-Gutiérrez, Adam D. Myers, S. Nadathur, L. Napolitano, H. E. Noriega, E. Paillas, N. Palanque‐Delabrouille, Will J. Percival, Claire Poppett, F. Prada, Ignasi Pérez-Ràfols, C. Ramírez-Pérez, C. Ravoux, J. Rohlf, G. Rossi, E. Sánchez, David J. Schlegel, M. Schubnell, Francesco Sinigaglia, David Sprayberry, G. Tarlé, Paul A. Taylor, W. Turner, Michael Walther, B. A. Weaver, Christophe Yèche, Rongpu Zhou, Hu Zou, Siwei Zou
Abstract
We present the Damped <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mi>Ly</a:mi> <a:mi>α</a:mi> </a:mrow> </a:math> Toolkit for automated detection and characterization of damped <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mi>Ly</c:mi> <c:mi>α</c:mi> </c:mrow> </c:math> absorbers (DLAs) in quasar spectra. Our method uses quasar spectral templates with and without absorption from intervening DLAs to reconstruct observed quasar forest regions. The best-fitting model determines whether a DLA is present while estimating the redshift and column density. With an optimized quality cut on detection significance ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi mathvariant="normal">Δ</e:mi> <e:msubsup> <e:mi>χ</e:mi> <e:mi>r</e:mi> <e:mn>2</e:mn> </e:msubsup> <e:mo>></e:mo> <e:mn>0.03</e:mn> </e:math> ), the technique achieves an estimated 80% purity and 79% completeness when evaluated on simulated spectra with <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:mi mathvariant="normal">S</h:mi> <h:mo>/</h:mo> <h:mrow> <h:mi mathvariant="normal">N</h:mi> <h:mo stretchy="false">></h:mo> <h:mn>2</h:mn> </h:mrow> </h:math> that are free of broad absorption lines (BALs). We provide a catalog containing candidate DLAs from the DLA Toolkit detected in DESI DR1 quasar spectra, of which 21 719 were found in <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mi mathvariant="normal">S</m:mi> <m:mo>/</m:mo> <m:mrow> <m:mi mathvariant="normal">N</m:mi> <m:mo stretchy="false">></m:mo> <m:mn>2</m:mn> </m:mrow> </m:math> spectra with predicted <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"> <r:mrow> <r:msub> <r:mrow> <r:mi>log</r:mi> </r:mrow> <r:mn>10</r:mn> </r:msub> <r:mo stretchy="false">(</r:mo> <r:msub> <r:mrow> <r:mi>N</r:mi> </r:mrow> <r:mrow> <r:mi mathvariant="monospace">HI</r:mi> </r:mrow> </r:msub> <r:mo stretchy="false">)</r:mo> <r:mo>></r:mo> <r:mn>20.3</r:mn> </r:mrow> </r:math> and detection significance <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"> <w:mi mathvariant="normal">Δ</w:mi> <w:msubsup> <w:mi>χ</w:mi> <w:mi>r</w:mi> <w:mn>2</w:mn> </w:msubsup> <w:mo>></w:mo> <w:mn>0.03</w:mn> </w:math> . We compare the Damped <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"> <z:mrow> <z:mi>Ly</z:mi> <z:mi>α</z:mi> </z:mrow> </z:math> Toolkit to two alternative DLA finders based on a convolutional neural network and Gaussian process models. We present a strategy for combining these three techniques to produce a high-fidelity DLA catalog from DESI DR2 for the <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"> <bb:mrow> <bb:mi>Ly</bb:mi> <bb:mi>α</bb:mi> </bb:mrow> </bb:math> forest baryon acoustic oscillation measurement. The combined catalog contains 41 152 candidate DLAs with <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"> <db:mrow> <db:msub> <db:mrow> <db:mi>log</db:mi> </db:mrow> <db:mn>10</db:mn> </db:msub> <db:mo stretchy="false">(</db:mo> <db:msub> <db:mrow> <db:mi>N</db:mi> </db:mrow> <db:mrow> <db:mi mathvariant="monospace">HI</db:mi> </db:mrow> </db:msub> <db:mo stretchy="false">)</db:mo> <db:mo>></db:mo> <db:mn>20.3</db:mn> </db:mrow> </db:math> from quasar spectra with <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" display="inline"> <ib:mi mathvariant="normal">S</ib:mi> <ib:mo>/</ib:mo> <ib:mrow> <ib:mi mathvariant="normal">N</ib:mi> <ib:mo stretchy="false">></ib:mo> <ib:mn>2</ib:mn> </ib:mrow> </ib:math> . We estimate this sample to be approximately 85% pure and 79% complete when BAL quasars are excluded.