The Lyman-a forest from LBGs: first 3D correlation measurement with DESI and prospects for cosmology
The Lyman-a (Lya) forest is a key tracer of large-scale structure at redshifts z > 2, traditionally studied using the spectra of luminous but relatively rare quasars. In this work, we explore the viability of using the fainter yet significantly more abundant Lyman Break Galaxies (LBGs) as alterna...
| Autores: | , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:dnet:upcommonspor::fb88a7bbf320ced285a842aaa7969cfd |
| Acceso en línea: | https://hdl.handle.net/2117/461454 https://dx.doi.org/10.1088/1475-7516/2025/12/053 |
| Access Level: | acceso abierto |
| Palabra clave: | Baryon acoustic oscillations Dark energy experiments High redshift galaxies Lyman alpha forest Àrees temàtiques de la UPC::Física::Astronomia i astrofísica |
| Sumario: | The Lyman-a (Lya) forest is a key tracer of large-scale structure at redshifts z > 2, traditionally studied using the spectra of luminous but relatively rare quasars. In this work, we explore the viability of using the fainter yet significantly more abundant Lyman Break Galaxies (LBGs) as alternative background sources for Lya forest studies. We analyze 4,151 Lya forest skewers extracted from LBG spectra obtained in the DESI pilot surveys conducted in the COSMOS and XMM-LSS fields. From this dataset, we present the first measurement of the Lya forest auto-correlation function derived exclusively from LBG spectra, probing comoving separations up to 48 h-1 Mpc at an effective redshift of zeff = 2.70. The measured LBG Lya forest auto-correlation is consistent with that derived from DESI DR2 quasar Lya forest spectra at a comparable redshift, validating the use of LBGs as reliable background sources for Lya forest analyses. In addition, we measure the cross-correlation between the LBG Lya forest and the positions of 13,362 galaxies, demonstrating that this observable serves as a sensitive diagnostic for assessing the precision and accuracy of galaxy redshift estimates, and for identifying and correcting systematic offsets. Finally, using both synthetic LBG spectra and Fisher matrix forecasts, we show that a future wide-area survey covering ~5,000 deg2, targeting 1,000 LBGs per square degree at signal-to-noise levels comparable to our sample, could enable LBG-based Lya forest baryon acoustic oscillation (BAO) measurements with expected uncertainties of saISO = 0.4% (isotropic) and saAP = 1.3% (Alcock-Paczynski). This performance is further enhanced when combining the BAO analysis with a Lya forest Full Shape (FS) approach, yielding a predicted uncertainty of saISOFS = 0.6%. These results open a new avenue for precision cosmology at high redshift using the Lya forest in dense LBG samples. |
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