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

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 Angstrom break, and specific star formation rate -- and IA amplitude; the bluest galaxies have an alignment consistent with zero, across low ($0.05. Authors: Siegel, J. [Princeton U.]; McCullough, J. [Princeton U.]; Amon, A. [Princeton U.; Cambridge U., Inst. of Astron.]; Lamman, C. [Harvard-Smithsonian Ctr. Astrophys.]; Jeffrey, N. [University Coll. London]. DOE Contract: 89243024CSC000002