Intrinsic alignment demographics for next-generation lensing: Revealing galaxy property trends with DESI Y1 direct measurements

Abstract We present direct measurements of the intrinsic alignments (IA) of over 2 million spectroscopic galaxies using DESI Data Release 1 and imaging from four lensing surveys: DES, HSC, KiDS, and SDSS. In this uniquely data-rich regime, we take initial steps towards a more tailored IA modelling approach by building a library of IA measurements across colour, luminosity, stellar mass, and redshift. We map the dependence between galaxy type—in terms of rest-frame colour, strength of the 4000 Å; break, and specific star formation rate—and IA amplitude; the bluest galaxies have an alignment consistent with zero, across low (0.05 < z < 0.5) and high (0.8 < z < 1.55) redshifts. In order to construct cosmic shear samples that are minimally impacted by IA but maintain maximum sample size and statistical power, we map the dependence of alignment with colour purity. Red, quenched galaxies are strongly aligned and the amplitude of the signal increases with luminosity, which is tightly correlated with stellar mass in our catalogues. For DESI galaxies between 0 < z < 1.5, trends in luminosity and colour alone are sufficient to explain the alignments we measure—with no need for an explicit redshift dependence. In a companion paper (Jeffrey et al., in prep), we perform detailed modelling of the IA signals with significant detections, including model comparison. Finally, to direct efforts for future IA measurements, we juxtapose the colour-magnitude-redshift coverage of existing IA measurements against modern and future lensing surveys.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-09-06
DOI
https://doi.org/10.1093/mnras/stag1691
Citations
2
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
0.00

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article

Intrinsic alignment demographics for next-generation lensing: Revealing galaxy property trends with DESI Y1 direct measurements

D. Kirkby, Agne Semenaite, Rongpu Zhou, A. Lambert et al.
2 citations
Monthly Notices of the Royal Astronomical Society
Astronomy and Astrophysical Research
article

Intrinsic alignment demographics for next-generation lensing: Revealing galaxy property trends with DESI Y1 direct measurements

D. Kirkby, Agne Semenaite, Rongpu Zhou, A. Lambert, N. Palanque‐Delabrouille, S. Nadathur, Jeffrey A. Newman, Andreu Font-Ribera, Benjamin Joachimi, A. Amon, N Emas, A. Porredon, Laurent Le Guillou, Gustavo Niz, Shahab Joudaki, D. Bianchi, David J. Schlegel, Ignasi Pérez-Ràfols, Axel de la Macorra, B. A. Weaver, Alex Krolewski, Simone Ferraro, M. E. Levi, M. Landriau, Marc Manera, J. McCullough, Satya Gontcho A Gontcho, N Jeffrey, Ashley J. Ross, G. Tarlé, J. Aguilar, Sven Heydenreich, Jeffrey H. Silber, J. E. Forero-Romero, Steven P. Ahlen, Aaron Meisner, Theodore S. Kisner, Cullen H. Blake, W.J Percival, R. Kehoe, John Moustakas, Mustapha Ishak, E. Sanchez, Zexin Sun, C. Lamman, F. J. Castander, Hu Zou, R. Miquel, M. Schubnell, P. Doel, E. Gaztañaga, C. Saulder, K. Honscheid, J. DeRose, H. Hoekstra, D Brooks, T. Claybaugh, Francisco Prada, Jerome H. Siegel, O. Lahav, G. Gutiérrez, D. Sprayberry
article en
2 citations

Abstract

Abstract We present direct measurements of the intrinsic alignments (IA) of over 2 million spectroscopic galaxies using DESI Data Release 1 and imaging from four lensing surveys: DES, HSC, KiDS, and SDSS. In this uniquely data-rich regime, we take initial steps towards a more tailored IA modelling approach by building a library of IA measurements across colour, luminosity, stellar mass, and redshift. We map the dependence between galaxy type—in terms of rest-frame colour, strength of the 4000 Å; break, and specific star formation rate—and IA amplitude; the bluest galaxies have an alignment consistent with zero, across low (0.05 < z < 0.5) and high (0.8 < z < 1.55) redshifts. In order to construct cosmic shear samples that are minimally impacted by IA but maintain maximum sample size and statistical power, we map the dependence of alignment with colour purity. Red, quenched galaxies are strongly aligned and the amplitude of the signal increases with luminosity, which is tightly correlated with stellar mass in our catalogues. For DESI galaxies between 0 < z < 1.5, trends in luminosity and colour alone are sufficient to explain the alignments we measure—with no need for an explicit redshift dependence. In a companion paper (Jeffrey et al., in prep), we perform detailed modelling of the IA signals with significant detections, including model comparison. Finally, to direct efforts for future IA measurements, we juxtapose the colour-magnitude-redshift coverage of existing IA measurements against modern and future lensing surveys.

Monthly Notices of the Royal Astronomical Society
Boston University (US), Institució Catalana de Recerca i Estudis Avançats (ES), Universidad Complutense de Madrid (ES), Leiden University (NL), Universitat Autònoma de Barcelona (ES), Centre National de la Recherche Scientifique (FR), Universidad de Guanajuato (MX), Fermi National Accelerator Laboratory (US), Institute of Space Sciences (ES), Lawrence Berkeley National Laboratory (US), University of Waterloo (CA), State Street (United States) (US), Universidad de Los Andes (CO), The University of Texas at Dallas (US), University of Pittsburgh (US), Southern Methodist University (US), Perimeter Institute (CA), University of California, Santa Cruz (US), Institute for High Energy Physics (ES), University of Milan (IT), Brookhaven National Laboratory (US), Princeton University (US), University of California, Irvine (US), University of Cambridge (GB), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), University of Michigan (US), Brera Astronomical Observatory (IT), Sejong University (KR), Sorbonne Université (FR), Max Planck Institute for Extraterrestrial Physics (DE), Institut d'Estudis Espacials de Catalunya (ES), Laboratoire de Physique Nucléaire et de Hautes Énergies (FR), Center for Astrophysics Harvard & Smithsonian (US), CEA Paris-Saclay (FR), Institut National de Physique Nucléaire et de Physique des Particules (FR), Community Science and Data Center (US), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (IT), Centro de Investigación en Materiales Avanzados (MX), NSF NOIRLab (US), Universidad de Los Andes (BO), Instituto de Astrofísica de Andalucía (ES), National Astronomical Observatories (CN), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), University College London (GB), University of Virginia (US), The Ohio State University (US), Swinburne University of Technology (AU), University of Portsmouth (GB), Universidad Nacional Autónoma de México (MX), Siena College (US), University of California, Berkeley (US), Universitat Politècnica de Catalunya (ES), Tsinghua University (CN)
National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, UK Research and Innovation, Ministerio de Ciencia, Innovación y Universidades, Deutsche Forschungsgemeinschaft, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Università degli Studi di Padova, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Office of Science, Science and Technology Facilities Council, Agencia Estatal de Investigación, Division of Astronomical Sciences
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