Steven P. Ahlen

Cosmological Constraints from Full-scale Clustering and Galaxy–Galaxy Lensing with DESI DR1

Abstract We present constraints on cosmic structure growth from the analysis of galaxy clustering and galaxy–galaxy lensing with galaxies from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. Our analysis includes four samples drawn from the Bright Galaxy Survey (B...

Joint Modeling of GD-1 and C-19 as Old Streams

Abstract DESI observational data for the GD-1 and C-19 streams are compared to stream simulations in an evolving multihalo potential of a Milky Way–like galaxy based on a cosmological Milky Way–like simulation. The number of subhalos decreases with time, and the subhalo-stream en...

The Composite Spectrum of QSO Absorption Line Systems in DESI DR2

Abstract We present details regarding a composite spectrum of quasar (QSO) absorption line systems. In this composite spectrum, we identify more than 70 absorption lines and observe oxygen and hydrogen emission features at a higher signal-to-noise ratio than any previous study. A...

The DESI Y1 RR Lyrae Catalog. I. Empirical Modeling of the Cyclic Variation of Spectroscopic Properties and a Chemodynamical Analysis of the Outer Halo

Abstract We present the catalog of RR Lyrae stars (RRLs) observed in the first year of operations of the Dark Energy Spectroscopic Instrument (DESI) survey. This catalog contains 6240 RRLs out to ∼120 kpc from the Galactic center and over 12,000 individual epochs with homogeneous...

The DESI Y1 RR Lyrae Catalog. II. The Metallicity Dependency of Pulsational Properties, the Shape of the RR Lyrae Instability Strip, and Metal Rich RR Lyrae

Abstract RR Lyrae stars (RRLs) are valuable probes of both Milky Way assembly and stellar-evolution physics. Using a sample 6240 RRLs obtained in the first year of the Dark Energy Spectroscopic Instrument (DESI) survey, we investigate the metallicity of RRLs and its correlation w...