DESI DR1 Ly$$α$$ forest: 3D full-shape analysis and cosmological constraints

Journal Article · Thu Sep 18 04:00:00 EDT 2025 · No journal information

OSTI ID:2997659

Cuceu, Andrei ^[1]; Herrera-Alcantar, Hiram K. ^[2]; Gordon, Calum ^[3]; Ramírez-Pérez, César ^[3]; Armengaud, E. ^[4]; Font-Ribera, A. ^[3]; Guy, J. ^[5]; Joachimi, B. ^[6]; Martini, P. ^[7]; Nadathur, S. ^[8]; Pérez-Ràfols, I. ^[9]; Rich, J. ^[10]; Aguilar, J. ^[5]; Ahlen, S. ^[11]; Anand, A. ^[5]; Bailey, S. ^[5]; Bault, A. ^[5]; Bianchi, D. ^[12]; Brodzeller, A. ^[5]; Brooks, D. ^[6] ; Chaves-Montero, J. ^[3]; Claybaugh, T. ^[5]; Dawson, K. S. ^[13]; de la Macorra, A. ^[14]; Della Costa, J. ^[15]; Doel, P. ^[6]; Ferraro, S. ^[16]; Forero-Romero, J. E. ^[17]; Gaztañaga, E. ^[18]; Gontcho A. Gontcho, S. ^[19]; Gonzalez-Morales, A. X. ^[20]; Green, D. ^[5]; Gutierrez, G. ^[21]; Hahn, C. ^[22]; Herbold, M. ^[23]; Honscheid, K. ^[24]; Iršič, V. ^[25]; Ishak, M. ^[26]; Joyce, R. ^[27]; Karaçaylı, N. G. ^[7]; Kirkby, D. ^[28]; Kisner, T. ^[5]; Kremin, A. ^[5]; Lahav, O. ^[6]; Lambert, A. ^[5]; Lamman, C. ^[23]; Landriau, M. ^[5]; Le Goff, J. M. ^[4]; Le Guillou, L. ^[29]; Levi, M. E. ^[5]; Manera, M. ^[30]; Meisner, A. ^[27]; Miquel, R. ^[31]; Moustakas, J. ^[32]; Muñoz-Gutiérrez, A. ^[14]; Newman, J. A. ^[33]; Niz, G. ^[34]; Palanque-Delabrouille, N. ^[35]; Percival, W. J. ^[36]; Pieri, Matthew M. ^[37]; Poppett, C. ^[38]; Prada, F. ^[39]; Ravoux, C. ^[40]; Rossi, G. ^[41]; Sanchez, E. ^[42]; Schlegel, D. ^[5]; Schubnell, M. ^[43]; Seo, H. ^[44]; Silber, J. ^[5]; Sinigaglia, F. ^[45]; Sprayberry, D. ^[27]; Tan, T. ^[4]; Tarlé, G. ^[43]; Walther, M. ^[46]; Weaver, B. A. ^[27]; Yèche, C. ^[4]; Zhou, R. ^[5]; Zou, H. ^[47]

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1. LBL, Berkeley; Chicago U., KICP
2. Paris, Inst. Astrophys.; IRFU, Saclay
3. Barcelona, IFAE
4. IRFU, Saclay
5. LBL, Berkeley
6. University Coll. London
7. Chicago U., KICP; Ohio State U., Dept. Astron.; Ohio State U.
8. Portsmouth U., ICG
9. Barcelona, Polytechnic U.
10. IRFU, Saclay; LPNHE, Paris
11. Boston U.
12. Milan U.; Brera Observ.
13. Utah U.
14. UNAM, Mexico
15. San Diego State U.; Natl. Solar Observ., Tucson
16. LBL, Berkeley; UC, Berkeley, Math. Dept.
17. Andes U., Bogota
18. Barcelona, IEEC; Portsmouth U., ICG; ICE, Bellaterra
19. LBL, Berkeley; Virginia U.
20. Guanajuato U.
21. Fermilab
22. Arizona U., Astron. Dept. - Steward Observ.
23. Ohio State U.
24. Chicago U., KICP; Ohio State U.
25. IFPU, Trieste; SISSA, Trieste; Hertfordshire U.; Cambridge U., Inst. of Astron.
26. U. Texas, Dallas
27. Natl. Solar Observ., Tucson
28. UC, Irvine
29. LPNHE, Paris
30. Barcelona, IFAE; Barcelona, Autonoma U.
31. ICREA, Barcelona; Barcelona, IFAE
32. Siena Coll., Loudonville
33. Pittsburgh U.
34. Guanajuato U.; Mexico U., ICN
35. IRFU, Saclay; LBL, Berkeley
36. Waterloo U.; Perimeter Inst. Theor. Phys.
37. Marseille, Lab. Astrophys.
38. LBL, Berkeley; UC, Berkeley, Space Sci. Dept.; UC, Berkeley, Math. Dept.
39. Granada U., Theor. Phys. Astrophys.
40. LPC, Clermont-Ferrand
41. Sejong U.
42. Madrid, CIEMAT
43. Michigan U.; KEK, Tsukuba; Hiroshima Shudo U.
44. Ohio U., Athens
45. Laguna U., Tenerife; IAC, La Laguna
46. Munich, Tech. U., Universe; Munich U.
47. Beijing Observ.

We perform an analysis of the full shapes of Lyman-$$α$$ (Ly$$α$$) forest correlation functions measured from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). Our analysis focuses on measuring the Alcock-Paczynski (AP) effect and the cosmic growth rate times the amplitude of matter fluctuations in spheres of $$8$$$h^{-1}\text{Mpc}$$, $$fσ_8$$. We validate our measurements using two different sets of mocks, a series of data splits, and a large set of analysis variations, which were first performed blinded. Our analysis constrains the ratio $$D_M/D_H(z_\mathrm{eff})=4.525\pm0.071$$, where $$D_H=c/H(z)$$ is the Hubble distance, $$D_M$$ is the transverse comoving distance, and the effective redshift is $$z_\mathrm{eff}=2.33$$. This is a factor of $2.4$ tighter than the Baryon Acoustic Oscillation (BAO) constraint from the same data. When combining with Ly$$α$$ BAO constraints from DESI DR2, we obtain the ratios $$D_H(z_\mathrm{eff})/r_d=8.646\pm0.077$$ and $$D_M(z_\mathrm{eff})/r_d=38.90\pm0.38$$, where $$r_d$$ is the sound horizon at the drag epoch. We also measure $$fσ_8(z_\mathrm{eff}) = 0.37\; ^{+0.055}_{-0.065} \,(\mathrm{stat})\, \pm 0.033 \,(\mathrm{sys})$$, but we do not use it for cosmological inference due to difficulties in its validation with mocks. In $$Λ$$CDM, our measurements are consistent with both cosmic microwave background (CMB) and galaxy clustering constraints. Using a nucleosynthesis prior but no CMB anisotropy information, we measure the Hubble constant to be $$H_0 = 68.3\pm 1.6\;\,{\rm km\,s^{-1}\,Mpc^{-1}}$$ within $$Λ$$CDM. Finally, we show that Ly$$α$$ forest AP measurements can help improve constraints on the dark energy equation of state, and are expected to play an important role in upcoming DESI analyses.

• Research Organization: LPNHE, Paris; IFPU, Trieste; IAC, La Laguna; ICE, Bellaterra; Barcelona, Polytechnic U.; Mexico U., ICN; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); SISSA, Trieste; Boston U.; Natl. Solar Observ., Tucson; Brera Observ.; UC, Irvine; UC, Berkeley, Math. Dept.; Beijing Observ.; Hiroshima Shudo U.; University Coll. London; San Diego State U.; Virginia U.; Utah U.; Milan U.; Andes U., Bogota; Pittsburgh U.; Sejong U.; Ohio U., Athens; Siena Coll., Loudonville; Barcelona, IFAE; Granada U., Theor. Phys. Astrophys.; Munich, Tech. U., Universe; Marseille, Lab. Astrophys.; Michigan U.; Ohio State U., Dept. Astron.; Guanajuato U.; KEK, Tsukuba; Waterloo U.; LPC, Clermont-Ferrand; Ohio State U.; Perimeter Inst. Theor. Phys.; ICREA, Barcelona; UNAM, Mexico; Barcelona, Autonoma U.; Arizona U., Astron. Dept. - Steward Observ.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); U. Texas, Dallas; Laguna U., Tenerife; UC, Berkeley, Space Sci. Dept.; Munich U.; Cambridge U., Inst. of Astron.; Chicago U., KICP; Barcelona, IEEC; Hertfordshire U.; Madrid, CIEMAT; Paris, Inst. Astrophys.; IRFU, Saclay; Portsmouth U., ICG
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: 89243024CSC000002
• OSTI ID: 2997659
• Report Number(s): FERMILAB-PUB-25-0693-PPD; oai:inspirehep.net:2971559; arXiv:2509.15308
• Journal Information: No journal information, Journal Name: No journal information
• Country of Publication: United States
• Language: English