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1. The Galaxy–Halo Connection of DESI Luminous Red Galaxies with Subhalo Abundance Matching

   https://doi.org/10.3847/1538-4357/ace76e  

   Berti, Angela M; Dawson, Kyle S; Dominguez, Wilber (August 2023, The Astrophysical Journal)

   Abstract We use subhalo abundance and age distribution matching to create magnitude-limited mock galaxy catalogs atz∼ 0.43, 0.52, and 0.63 withz-band and 3.4μmW1-band absolute magnitudes andr−zandr−W1 colors. From these magnitude-limited mocks, we select mock luminous red galaxy (LRG) samples according to the (r−z)-based (optical) and (r−W1)-based (infrared) selection criteria for the LRG sample of the Dark Energy Spectroscopic Instrument (DESI) survey. Our models reproduce the number densities, luminosity functions, color distributions, and projected clustering of the DESI Legacy Surveys that are the basis for DESI LRG target selection. We predict the halo occupation statistics of both optical and IR DESI LRGs at fixed cosmology and assess the differences between the two LRG samples. We find that IR-based SHAM modeling represents the differences between the optical and IR LRG populations better than using thezband and that age distribution matching overpredicts the clustering of LRGs, implying that galaxy color is uncorrelated with halo age in the LRG regime. Both the optical and IR DESI LRG target selections exclude some of the most luminous galaxies that would appear to be LRGs based on their position on the red sequence in optical color–magnitude space. Both selections also yield populations with a nontrivial LRG–halo connection that does not reach unity for the most massive halos. We find that the IR selection achieves greater completeness (≳90%) than the optical selection across all redshift bins studied. 

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2. Galaxy Clustering in the Mira-Titan Universe. I. Emulators for the Redshift Space Galaxy Correlation Function and Galaxy–Galaxy Lensing

   https://doi.org/10.3847/1538-4357/acd92f  

   Kwan, Juliana; Saito, Shun; Leauthaud, Alexie; Heitmann, Katrin; Habib, Salman; Frontiere, Nicholas; Guo, Hong; Huang, Song; Pope, Adrian; Rodriguéz-Torres, Sergio (July 2023, The Astrophysical Journal)

   Abstract We construct accurate emulators for the projected and redshift space galaxy correlation functions and excess surface density as measured by galaxy–galaxy lensing, based on halo occupation distribution modeling. Using the complete Mira-Titan suite of 111N-body simulations, our emulators vary over eight cosmological parameters and include the effects of neutrino mass and dynamical dark energy. We demonstrate that our emulators are sufficiently accurate for the analysis of the Baryon Oscillation Spectroscopic Survey DR12 CMASS galaxy sample over the range 0.5 ≤r≤ 50h⁻¹Mpc. Furthermore, we show that our emulators are capable of recovering unbiased cosmological constraints from realistic mock catalogs over the same range. Our mock catalog tests show the efficacy of combining small-scale galaxy–galaxy lensing with redshift space clustering and that we can constrain the growth rate andσ₈to 7% and 4.5%, respectively, for a CMASS-like sample using only the measurements covered by our emulator. With the inclusion of a cosmic microwave background prior onH₀, this reduces to a 2% measurement of the growth rate. 

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3. An Intensity Mapping Constraint on the CO-galaxy Cross-power Spectrum at Redshift ∼3

   https://doi.org/10.3847/1538-4357/ac4888  

   Keenan, Ryan P.; Keating, Garrett K.; Marrone, Daniel P. (March 2022, The Astrophysical Journal)

   Abstract The abundance of cold molecular gas plays a crucial role in models of galaxy evolution. While deep spectroscopic surveys of CO emission lines have been a primary tool for measuring this abundance, the difficulty of these observations has motivated alternative approaches to studying molecular gas content. One technique, line intensity mapping, seeks to constrain the average molecular gas properties of large samples of individually undetectable galaxies through the CO brightness power spectrum. Here we present constraints on the cross-power spectrum between CO intensity maps and optical galaxy catalogs. This cross-measurement allows us to check for systematic problems in CO intensity mapping data, and validate the data analysis used for the auto-power spectrum measurement of the CO Power Spectrum Survey. We place a 2σupper limit on the band-averaged CO-galaxy cross-power ofP_×< 540μK h⁻³Mpc³. Our measurement favors a nonzero 〈T_CO〉 at around 90% confidence and gives an upper limit on the mean molecular gas density atz∼ 2.6 of 7.7 × 10⁸M_⊙Mpc⁻³. We forecast the expected cross-power spectrum by applying a number of literature prescriptions for the CO luminosity–halo mass relation to a suite of mock light cones. Under the most optimistic forecasts, the cross-spectrum could be detected with only moderate extensions of the data used here, while more conservative models could be detected with a factor of 10 increase in sensitivity. Ongoing CO intensity mapping experiments will target fields allowing for extensive cross-correlation analysis and should reach the sensitivity required to detect the cross-spectrum signal. 

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4. DESI Emission-line Galaxies: Clustering Dependence on Stellar Mass and [O II ] Luminosity

   https://doi.org/10.3847/1538-4357/ae0036  

   Hagen, T; Dawson, K S; Zheng, Z; Aguilar, J; Ahlen, S; BenZvi, S; Bianchi, D; Brooks, D; Castander, F J; Claybaugh, T; et al (October 2025, The Astrophysical Journal)

   Abstract We measure the projected two-point correlation functions of emission-line galaxies (ELGs) from the Dark Energy Spectroscopic Instrument One-Percent Survey and model their dependence on stellar mass and [OII] luminosity. We select ∼180,000 ELGs with redshifts of 0.8 < z < 1.6, and define 27 samples according to cuts in redshift and both galaxy properties. Following a framework that describes the conditional [OII] luminosity–stellar mass distribution as a function of halo mass, we simultaneously model the clustering measurements of all samples at fixed redshift. Based on the modeling result, most ELGs in our samples are classified as central galaxies, residing in halos of a narrow mass range with a typical median of ∼10^12.2−12.4h⁻¹M_⊙. We observe a weak dependence of clustering amplitude on stellar mass, which is reflected in the model constraints and is likely a consequence of the 0.5 dex measurement uncertainty in the stellar mass estimates. The model shows a trend between galaxy bias and [OII] luminosity at high redshift (1.2 < z < 1.6) that is otherwise absent at lower redshifts. 

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5. ODIN: Clustering Analysis of 14,000 Ly α -emitting Galaxies at z = 2.4, 3.1, and 4.5

   https://doi.org/10.3847/2041-8213/adec82  

   Herrera, Danisbel; Gawiser, Eric; Benda, Barbara; Firestone, Nicole M; Ramakrishnan, Vandana; Moon, Byeongha; Lee, Kyoung-Soo; Park, Changbom; Valdes, Francisco; Yang, Yujin; et al (July 2025, The Astrophysical Journal Letters)

   Abstract Lyαemitters (LAEs) are star-forming galaxies that efficiently probe the spatial distribution of galaxies in the high-redshift Universe. The spatial clustering of LAEs reflects the properties of their individual host dark matter halos, allowing us to study the evolution of the galaxy–halo connection. We analyze the clustering of 5233, 5220, and 3706 LAEs atz= 2.4, 3.1, and 4.5, respectively, in the 9 deg²COSMOS field from the One-hundred-deg²DECam Imaging in Narrowbands survey. After correcting for redshift-space distortions, LAE contamination rates, and the integral constraint, the observed angular correlation functions imply linear galaxy bias factors ofb= $1.72_{-0.27}^{+0.26},2.01_{-0.29}^{+0.26},$and $2.95_{-0.46}^{+0.40}$forz= 2.4, 3.1, and 4.5, respectively. The median dark matter halo masses inferred from these measurements are $\log (M_h/M_{\odot })$= $11.44_{-0.28}^{+0.30},11.13_{-0.26}^{+0.26},\mathrm{and}10.85_{-0.24}^{+0.24}$for the three samples, respectively. The analysis also reveals that LAEs occupy roughly 3%–7% of the halos whose clustering strength matches that of the LAEs. 

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