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We explore the effect of applying a non-linear transformation to the Lyman-$\alpha$ forest transmitted flux $F=e^{-\tau}$ and the ability of analytic models to predict the resulting clustering amplitude. Both the large-scale bias of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-10 Xinkang Wang , Andreu Font-Ribera , Uros Seljak

Recently, several fast algorithms have been proposed to decompose predicted value into Shapley values, enabling individualized feature contribution analysis in tree models. While such local decomposition offers valuable insights, it…

Machine Learning · Statistics 2025-05-28 Zhongli Jiang , Min Zhang , Dabao Zhang

The hydrogen Ly$\alpha$ forest is an important probe of the $z>2$ Universe that is otherwise challenging to observe with galaxy redshift surveys, but this technique has traditionally been limited to 1D studies in front of bright quasars.…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-22 Khee-Gan Lee

We present an effective field theory (EFT) approach to extract fundamental cosmological parameters from the Lyman-alpha forest flux fluctuations as an alternative to the standard simulation-based techniques. As a first application, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-21 Mikhail M. Ivanov , Michael W. Toomey , Naim Göksel Karaçaylı

We present here a new algorithm for the fast computation of N-point correlation functions in large astronomical data sets. The algorithm is based on kdtrees which are decorated with cached sufficient statistics thus allowing for orders of…

We review the methodology for measurements of two point functions of the cosmological observables, both power spectra and correlation functions. For pseudo-$C_\ell$ estimators, we will argue that the window weighted overdensity field can…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-27 Sukhdeep Singh

Motivated by the relative lack of neutral hydrogen around Lyman Break Galaxies deduced from recent observations, we investigate the properties of the Lyalpha forest around high redshift galaxies. The study is based on improved numerical SPH…

Astrophysics · Physics 2009-11-07 M. Bruscoli , A. Ferrara , S. Marri , R. Schneider , A. Maselli , E. Rollinde , B. Aracil

We present moderate resolution data for 39 QSOs at z $\approx$ 2 obtained at the Multiple Mirror Telescope. These data are combined with spectra of comparable resolution of 60 QSOs with redshifts greater than 1.7 found in the literature to…

Astrophysics · Physics 2009-10-31 J. Scott , J. Bechtold , A. Dobrzycki

A large fraction of the information collected by cosmological surveys is simply discarded to avoid lengthscales which are difficult to model theoretically. We introduce a new technique which enables the extraction of useful information from…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-08 Fergus Simpson , J. Berian James , Alan F. Heavens , Catherine Heymans

Large scale structure surveys promise to be the next leading probe of cosmological information. It is therefore crucial to reliably predict their observables. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 John Joseph M. Carrasco , Simon Foreman , Daniel Green , Leonardo Senatore

The Ly-alpha forest provides important constraints on the smoothness of the universe on large scales. We calculate the flux distribution along line-of-sight to quasars in a universe made of randomly distributed clumps, each of them with a…

Astrophysics · Physics 2009-10-31 Adi Nusser , Ofer Lahav

We present precision measurements of the bias parameters of the one-loop power spectrum model of the Lyman-alpha (Lya) forest, derived within the effective field theory of large-scale structure (EFT). We fit our model to the…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-26 Roger de Belsunce , Shi-Fan Chen , Mikhail M. Ivanov , Corentin Ravoux , Solene Chabanier , Jean Sexton , Zarija Lukic

We present predictions of the correlation between the Lyman-alpha forest absorption in quasar spectra and the mass within \sim 5 Mpc/h (comoving) of the line of sight, using fully hydrodynamic and hydro-PM numerical simulations of the cold…

Astrophysics · Physics 2009-11-07 Patrick McDonald , Jordi Miralda-Escudé , Renyue Cen

We investigate the possibility of detecting the 3D cross correlation power spectrum of the Ly-$\alpha$ forest and HI 21 cm signal from the post reionization epoch. The cross-correlation signal is directly dependent on the dark matter power…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-19 Tapomoy Guha Sarkar , Kanan K. Datta

By exploiting small-scale structure formation probed by Lyman-$\alpha$ forest observations, we study constraints on a model of dark matter from dark sector decay. We compute the phase space distribution of the dark matter and the linear…

High Energy Physics - Phenomenology · Physics 2026-03-30 Si-Yuan Zhao , Yi-Cheng Dai , Wei Liao , Yi-Song Lu

We investigate the effect of galactic winds on the Lyalpha forest in cosmological simulations of structure and galaxy formation. We combine high resolution N-body simulations of the evolution of the dark matter with a semi-analytic model…

Astrophysics · Physics 2009-09-25 Serena Bertone , Simon D. M. White

The two-point correlation function, $\xi$, of Lyman-alpha forest is found to be large, $\xi = 1.8^{+1.6}_{-1.2}$, > 90% confidence level, on the scale of 250-500 km/s for a sample of absorbers (0 < z < 1.3) assembled from HST Key Project…

Astrophysics · Physics 2009-10-28 Andrew Ulmer

The proximity effect of metal line absorption systems in spectra of high redshift quasars and quasar pairs is investigated through the distribution of \Lyalpha forests. No strong proximity effect is found down to 500 km/sec away from a…

Astrophysics · Physics 2007-05-23 Xiangdong Shi

We present constraints on the amplitude and shape of the matter power spectrum and the density of dark matter within the framework of a standard LambdaCDM model. We use a Markov Chain Monte Carlo approach to combine independent measurements…

Astrophysics · Physics 2008-11-26 J. Lesgourgues , M. Viel , M. G. Haehnelt , R. Massey

We present observations of the Lyman alpha forest towards B2 1225+317 taken at a resolution of 18 km/s. A clean sample of Lyman alpha forest lines is extracted after a careful profile fitting analysis and removal of absorption lines of…

Astrophysics · Physics 2015-06-24 Pushpa Khare , R. Srianand , D. G. York , R. Green , D. Welty , Ke-Liang Huang , J. Bechtold