LLM embeddings condition generative networks for LHC events, yielding faster convergence, higher quality, and generalization to unseen processes.
21 Centimeter Fluctuations from Cosmic Gas at High Redshifts
5 Pith papers cite this work. Polarity classification is still indexing.
5
Pith papers citing it
abstract
The relatively large Thomson optical depth, tau_e, inferred recently from the WMAP observations suggests that the Universe was reionized in a more complex manner than previously believed. However, the value of tau_e provides only an integral constraint on the history of reionization and, by itself, cannot be used to determine the nature of the sources responsible for this transition. Here, we show that the evolution of the ionization state of the intergalactic medium at high redshifts can be measured statistically using fluctuations in 21 centimeter radiation from neutral hydrogen. By analogy with the mathematical description of anisotropies in the cosmic microwave background, we develop a formalism to quantify the variations in 21 cm emission as a function of both frequency and angular scale. Prior to and following reionization, fluctuations in the 21 cm signal are mediated by density perturbations in the distribution of matter. Between these epochs, pockets of gas surrounding luminous objects become ionized, producing large HII regions. These ``bubbles'' of ionized material imprint features into the 21 cm power spectrum that make it possible to distinguish them from fluctuations produced by the density perturbations. The variation of the power spectrum with frequency can be used to infer the evolution of this process. As has been emphasized previously by others, the absolute 21 cm signal from neutral gas at high redshifts is undetectable owing to contamination by foreground sources. However, we argue that this source of noise can be suppressed by comparing maps closely spaced in frequency, i.e. redshift, so that 21 cm fluctuations from the IGM can be measured against a much brighter, but smoothly varying (in frequency) background.
citation-role summary
background 1
citation-polarity summary
verdicts
UNVERDICTED 5roles
background 1polarities
support 1representative citing papers
The paper calculates multifrequency angular power spectra of the 21 cm line for models with primordial magnetic fields of strength 4 nG and spectral indices -2.9 and -2.5, then estimates signal-to-noise ratios for uGMRT, MeerKAT and SKA1-MID.
Empirical three-parameter fit to f_esc(M_h,z) yields steep redshift evolution with population-averaged escape fraction rising from ~2% at z=5 to ~9% at z=12.
Forecasts show that future 21 cm surveys can deliver moderate constraints on the scale-dependent growth index and HI bias in viable f(R) models.
Neutrino invisible decays and a boomerang mechanism transferring particles between visible and dark sectors could resolve cosmological anomalies while predicting an observable effective magnetic moment.
citing papers explorer
-
One Generator, Any Process: LLM-Conditioning for the LHC
LLM embeddings condition generative networks for LHC events, yielding faster convergence, higher quality, and generalization to unseen processes.
-
Steep Redshift Evolution of the Ionizing Escape Fraction at $z = 5$--$12$: Empirical Constraints and Comparison with Simulations
Empirical three-parameter fit to f_esc(M_h,z) yields steep redshift evolution with population-averaged escape fraction rising from ~2% at z=5 to ~9% at z=12.
-
Constraining Scale-Dependent Growth in $f(R)$ Gravity with Future 21 cm Surveys
Forecasts show that future 21 cm surveys can deliver moderate constraints on the scale-dependent growth index and HI bias in viable f(R) models.
-
How neutrinos could help solving cosmological anomalies and tensions
Neutrino invisible decays and a boomerang mechanism transferring particles between visible and dark sectors could resolve cosmological anomalies while predicting an observable effective magnetic moment.