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Observational Requirements for Lyman-alpha Forest Tomographic Mapping of Large-Scale Structure at z ~ 2
Cosmology and Nongalactic Astrophysics · Submitted 5 Sep 2013
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim Assuming ~ 250 h^{-1} Mpc is probed along the line-of-sight, 1 deg^2 of survey area would cover a comoving volume of ~ 10^6 h^{-3} Mpc^3 at <z>=2.3, enabling efficient mapping of large volumes with 8-10m telescopes.
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The abstract, sentence by sentence
The z > 2 Lyman-alpha (Lya) forest traces the underlying dark-matter distribution on large scales and, given sufficient sightlines, can be used to create 3D maps of large-scale structure. We examine the observational requirements to construct such maps and estimate the signal-to-noise as a function of exposure time and sightline density. Sightline densities at z = 2.25 are n_los = [360, 1200,3300] deg^{-2} at limiting magnitudes of g =[24.0, 24.5,25.0], resulting in transverse sightline separations of d_perp = [3.6, 1.9, 1.2] h^{-1} Mpc, which roughly sets the reconstruction scale. We simulate these reconstructions using mock spectra with realistic noise properties, and find that spectra with S/N = 4 per angstrom can be used to generate maps that clearly trace the underlying dark-matter at overdensities of rho/<rho> ~ 1. For the VLT/VIMOS spectrograph, exposure times t_exp = [4, 6, 10] hrs are sufficient for maps with spatial resolution epsilon_3d = [5.0, 3.2, 2.3] h^{-1} Mpc. Assuming ~ 250 h^{-1} Mpc is probed along the line-of-sight, 1 deg^2 of survey area would cover a comoving volume of ~ 10^6 h^{-3} Mpc^3 at <z>=2.3, enabling efficient mapping of large volumes with 8-10m telescopes. These maps could be used to study galaxy environments, detect proto-clusters, and study the topology of large-scale structure at high-z.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The z > 2 Lyman-alpha (Lya) forest traces the underlying dark-matter distribution on large scales and, given sufficient sightlines, can be used to create 3D maps of large-scale structure. | background 1.00 | 0.07 | 0.09 | asserted 0.74 |
| s1 | We examine the observational requirements to construct such maps and estimate the signal-to-noise as a function of exposure time and sightline density. | contribution 0.98 | 0.90 | 0.05 | asserted 0.87 |
| s2 | Sightline densities at z = 2.25 are n_los = [360, 1200,3300] deg^{-2} at limiting magnitudes of g =[24.0, 24.5,25.0], resulting in transverse sightline separations of d_perp = [3.6, 1.9, 1.2] h^{-1} Mpc, which roughly sets the reconstruction scale. | result 0.80 | 0.66 | 0.12 | asserted 0.92 |
| s3 | We simulate these reconstructions using mock spectra with realistic noise properties, and find that spectra with S/N = 4 per angstrom can be used to generate maps that clearly trace the underlying dark-matter at overdensities of rho/<rho> ~ 1. | result 0.99 | 0.96 | 0.30 | asserted 0.99 |
| s4 | For the VLT/VIMOS spectrograph, exposure times t_exp = [4, 6, 10] hrs are sufficient for maps with spatial resolution epsilon_3d = [5.0, 3.2, 2.3] h^{-1} Mpc. | result 0.98 | 0.84 | 0.13 | asserted 0.97 |
| s5 | Assuming ~ 250 h^{-1} Mpc is probed along the line-of-sight, 1 deg^2 of survey area would cover a comoving volume of ~ 10^6 h^{-3} Mpc^3 at <z>=2.3, enabling efficient mapping of large volumes with 8-10m telescopes. | interpretation 0.53 | 0.61 | 0.15 | asserted 0.66 |
| s6 | These maps could be used to study galaxy environments, detect proto-clusters, and study the topology of large-scale structure at high-z. | interpretation 0.60 | 0.09 | 0.14 | hedged possibility 1.00 |
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The paper
Original abstract
The z > 2 Lyman-alpha (Lya) forest traces the underlying dark-matter distribution on large scales and, given sufficient sightlines, can be used to create 3D maps of large-scale structure. We examine the observational requirements to construct such maps and estimate the signal-to-noise as a function of exposure time and sightline density. Sightline densities at z = 2.25 are n_los = [360, 1200,3300] deg^{-2} at limiting magnitudes of g =[24.0, 24.5,25.0], resulting in transverse sightline separations of d_perp = [3.6, 1.9, 1.2] h^{-1} Mpc, which roughly sets the reconstruction scale. We simulate these reconstructions using mock spectra with realistic noise properties, and find that spectra with S/N = 4 per angstrom can be used to generate maps that clearly trace the underlying dark-matter at overdensities of rho/<rho> ~ 1. For the VLT/VIMOS spectrograph, exposure times t_exp = [4, 6, 10] hrs are sufficient for maps with spatial resolution epsilon_3d = [5.0, 3.2, 2.3] h^{-1} Mpc. Assuming ~ 250 h^{-1} Mpc is probed along the line-of-sight, 1 deg^2 of survey area would cover a comoving volume of ~ 10^6 h^{-3} Mpc^3 at <z>=2.3, enabling efficient mapping of large volumes with 8-10m telescopes. These maps could be used to study galaxy environments, detect proto-clusters, and study the topology of large-scale structure at high-z.
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References
How the literature uses it
5 arXiv papers cite this in 6 sentences
Papers citing it · 3 sentences without a confident label
Uses its method or tool 1 paper
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A simple implementation of this method, adapted to forest datasets, was developed by CLAMATO [ref] ; and our work uses the same public code, [ <https://github.com/caseywstark/dachshund>].
A tomographic map of the large-scale matter distribution using the eBOSS Stripe 82 Ly-$\alpha$ forest · Tomographic map-making algorithm · 1.00
Cites it as background 2 papers
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Lyman-$α$ absorption observed in spectra of distant quasars is now widely used to: (i) calculate 3D correlation functions to study Baryon Acoustic Oscillations (BAO) [ref] ; (ii) measure the line-of-sight one-dimensional flux power spectrum ($P_1D$) to constrain the amplitude and shape of the matter power spectrum at high redshifts [ref] , and thus to yield tight constraints on neutrino masses [ref] and dark matter models [ref] , to mention some applications; (iii) study the evolution of the intergalactic medium (IGM) through techniques such as the tomography of the Lyman-$α$ forest [ref] .
Synthetic spectra for Lyman-$\alpha$ forest analysis in the Dark Energy Spectroscopic Instrument · Introduction · 0.92
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Other background sources, such as Lyman-break galaxies, are also being investigated for a dense mapping of the Lyman-$α$ forest [ref] .
New approach for precise computation of Lyman-alpha forest power spectrum with hydrodynamical simulations · Introduction · 0.97
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