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The properties of the Lyman-$\alpha$ absorptions observed in the spectra of QSOs are reviewed: the distribution of column densities and Doppler widths, the redshift evolution, the ``inverse effect'', the clustering. By interpreting the…

Astrophysics · Physics 2007-05-23 S. Cristiani

The angular positions of quasars are deflected by the gravitational lensing effect of foreground matter. The Lyman-alpha forest seen in the spectra of these quasars is therefore also lensed. We propose that the signature of weak…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-21 Rupert A. C. Croft , Alessandro Romeo , R. Benton Metcalf

We investigate the amount of primordial information that can be reconstructed from spectroscopic galaxy surveys, as well as what sets the noise in reconstruction at low wavenumbers, by studying a simplified universe in which galaxies are…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-23 Matthew McQuinn

The impact of cosmic reionization on the Ly$\alpha$ forest power spectrum has recently been shown to be significant even at low redshifts ($z \sim 2$). This memory of reionization survives cosmological time scales because high-entropy…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-14 Paulo Montero-Camacho , Yi Mao

We present a novel method for reconstructing weak lensing mass or convergence maps as a probe to study non-Gaussianities in the cosmic density field. While previous surveys have relied on a flat-sky approximation, the forthcoming stage IV…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-03 Vanshika Kansal

We compare the low redshift (z ~ 0.1) Lyman-alpha forest from hydrodynamical simulations with data from the Cosmic Origin Spectrograph (COS). We find tension between the observed number of lines with b-parameters in the range 25-45 km/s and…

Astrophysics of Galaxies · Physics 2017-04-19 M. Viel , M. G. Haehnelt , J. S. Bolton , T. -S. Kim , E. Puchwein , F. Nasir , B. P. Wakker

Lyman limit systems (LLSs) are dense hydrogen clouds with high enough HI column densities to absorb Lyman continuum photons emitted from distant quasars. Their high column densities imply an origin in dense environments; however, the…

Astrophysics of Galaxies · Physics 2024-03-04 Jiawen Fan , Hanjue Zhu , Camille Avestruz , Nickolay Y. Gnedin

The Lyman $\alpha$ (Ly$\alpha$) line from high-redshift galaxies is a powerful probe of the Epoch of Reionization (EoR). Neutral hydrogen in the intergalactic medium (IGM) can significantly attenuate the emergent Ly$\alpha$ line, even in…

Astrophysics of Galaxies · Physics 2026-02-17 Samuel Gagnon-Hartman , Andrei Mesinger , Ivan Nikolić , Eleonora Parlanti , Giacomo Venturi

Spectrum map construction, which is crucial in cognitive radio (CR) system, visualizes the invisible space of the electromagnetic spectrum for spectrum-resource management and allocation. Traditional reconstruction methods are generally for…

Signal Processing · Electrical Eng. & Systems 2024-03-14 Wang Jie , Lin Zhipeng , Zhu Qiuming , Wu Qihui , Lan Tianxu , Zhao Yi , Bai Yunpeng , Zhong Weizhi

We combine parallax distances to nearby O stars with parsec-scale resolution three-dimensional dust maps of the local region of the Milky Way (within 1.25 kpc of the Sun) to simulate the transfer of Lyman continuum photons through the…

Recognising individual trees within remotely sensed imagery has important applications in forest ecology and management. Several algorithms for tree delineation have been suggested, mostly based on locating local maxima or inverted basins…

Computer Vision and Pattern Recognition · Computer Science 2017-01-25 Juheon Lee , David Coomes , Carola-Bibiane Schonlieb , Xiaohao Cai , Jan Lellmann , Michele Dalponte , Yadvinder Malhi , Nathalie Butt , Mike Morecroft

Determining when and how the first galaxies reionized the intergalactic medium (IGM) promises to shed light on both the nature of the first objects and the cosmic history of baryons. Towards this goal, quasar absorption lines play a unique…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-16 George D. Becker , James S. Bolton , Adam Lidz

We present a method to recover the shape and amplitude of the power spectrum of mass fluctuations, P(k), from observations of the high redshift \lya forest. The method is motivated by the physical picture of the \lya forest that has emerged…

Astrophysics · Physics 2009-10-30 Rupert A. C. Croft , David H. Weinberg , Neal Katz , Lars Hernquist

We present a direct approach to nonparametrically reconstruct the linear density field from an observed nonlinear map. We solve for the unique displacement potential consistent with the nonlinear density and positive definite coordinate…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-25 Hong-Ming Zhu , Yu Yu , Ue-Li Pen , Xuelei Chen , Hao-Ran Yu

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Kyle S. Dawson , David J. Schlegel , Christopher P. Ahn , Scott F. Anderson , Éric Aubourg , Stephen Bailey , Robert H. Barkhouser , Julian E. Bautista , Alessandra Beifiori , Andreas A. Berlind , Vaishali Bhardwaj , Dmitry Bizyaev , Cullen H. Blake , Michael R. Blanton , Michael Blomqvist , Adam S. Bolton , Arnaud Borde , Jo Bovy , W. N. Brandt , Howard Brewington , Jon Brinkmann , Peter J. Brown , Joel R. Brownstein , Kevin Bundy , N. G. Busca , William Carithers , Aurelio R. Carnero , Michael A. Carr , Yanmei Chen , Johan Comparat , Natalia Connolly , Frances Cope , Rupert A. C. Croft , Antonio J. Cuesta , Luiz N. da Costa , James R. A. Davenport , Timothée Delubac , Roland de Putter , Saurav Dhital , Anne Ealet , Garrett L. Ebelke , Daniel J. Eisenstein , S. Escoffier , Xiaohui Fan , N. Filiz Ak , Hayley Finley , Andreu Font-Ribera , R. Génova-Santos , James E. Gunn , Hong Guo , Daryl Haggard , Patrick B. Hall , Jean-Christophe Hamilton , Ben Harris , David W. Harris , Shirley Ho , David W. Hogg , Diana Holder , Klaus Honscheid , Joe Huehnerhoff , Beatrice Jordan , Wendell P. Jordan , Guinevere Kauffmann , Eyal A. Kazin , David Kirkby , Mark A. Klaene , Jean-Paul Kneib , Jean-Marc Le Goff , Khee-Gan Lee , Daniel C. Long , Craig P. Loomis , Britt Lundgren , Robert H. Lupton , Marcio A. G. Maia , Martin Makler , Elena Malanushenko , Viktor Malanushenko , Rachel Mandelbaum , Marc Manera , Claudia Maraston , Daniel Margala , Karen L. Masters , Cameron K. McBride , Patrick McDonald , Ian D. McGreer , Richard McMahon , Olga Mena , Jordi Miralda-Escudé , Antonio D. Montero-Dorta , Francesco Montesano , Demitri Muna , Adam D. Myers , Tracy Naugle , Robert C. Nichol , Pasquier Noterdaeme , Sebastián E. Nuza , Matthew D. Olmstead , Audrey Oravetz , Daniel J. Oravetz , Russell Owen , Nikhil Padmanabhan , Nathalie Palanque-Delabrouille , Kaike Pan , John K. Parejko , Isabelle Pâris , Will J. Percival , Ismael Pérez-Fournon , Ignasi Pérez-Ràfols , Patrick Petitjean , Robert Pfaffenberger , Janine Pforr , Matthew M. Pieri , Francisco Prada , Adrian M. Price-Whelan , M. Jordan Raddick , Rafael Rebolo , James Rich , Gordon T. Richards , Constance M. Rockosi , Natalie A. Roe , Ashley J. Ross , Nicholas P. Ross , Graziano Rossi , J. A. Rubiño-Martin , Lado Samushia , Ariel G. Sánchez , Conor Sayres , Sarah J. Schmidt , Donald P. Schneider , C. G. Scóccola , Hee-Jong Seo , Alaina Shelden , Erin Sheldon , Yue Shen , Yiping Shu , Anže Slosar , Stephen A. Smee , Stephanie A. Snedden , Fritz Stauffer , Oliver Steele , Michael A. Strauss , Alina Streblyanska , Nao Suzuki , Molly E. C. Swanson , Tomer Tal , Masayuki Tanaka , Daniel Thomas , Jeremy L. Tinker , Rita Tojeiro , Christy A. Tremonti , M. Vargas Magana , Licia Verde , Matteo Viel , David A. Wake , Mike Watson , Benjamin A. Weaver , David H. Weinberg , Benjamin J. Weiner , Andrew A. West , Martin White , W. M. Wood-Vasey , Christophe Yeche , Idit Zehavi , Gong-Bo Zhao , Zheng Zheng

The amplitude of the ionizing background that pervades the intergalactic medium (IGM) at the end of the epoch of reionization provides a valuable constraint on the emissivity of the sources which reionized the Universe. While measurements…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-28 Frederick B. Davies , Joseph F. Hennawi , Anna-Christina Eilers , Zarija Lukić

LiDAR-based place recognition serves as a crucial enabler for long-term autonomy in robotics and autonomous driving systems. Yet, prevailing methodologies relying on handcrafted feature extraction face dual challenges: (1) Inconsistent…

Computer Vision and Pattern Recognition · Computer Science 2025-08-28 Xiaohui Jiang , Haijiang Zhu , Chade Li , Fulin Tang , Ning An

We present methods for interpolating between the 1-D flux power spectrum of the Lyman-$\alpha$ forest, as output by cosmological hydrodynamic simulations. Interpolation is necessary for cosmological parameter estimation due to the limited…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-25 Simeon Bird , Keir K. Rogers , Hiranya V. Peiris , Licia Verde , Andreu Font-Ribera , Andrew Pontzen

Most cosmic shear analyses to date have relied on summary statistics (e.g. $\xi_+$ and $\xi_-$). These types of analyses are necessarily sub-optimal, as the use of summary statistics is lossy. In this paper, we forward-model the convergence…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-29 Supranta Sarma Boruah , Eduardo Rozo , Pier Fiedorowicz