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In the nonrelativistic many-electron approximation of the theory of photoionization of the atom in the formalism of secondary quantization and the theory of irreducible tensor operators, analytical structures for the quadrupole transition…

Atomic Physics · Physics 2025-04-14 Alexey N. Hopersky , Alexey M. Nadolinsky , Rustam V. Koneev , Julia N. Tolkunova

Using the CoDa II simulation, we study the Ly$\alpha$ transmissivity of the intergalactic medium (IGM) during reionization. At $z>6$, a typical galaxy without an active galactic nucleus fails to form a proximity zone around itself due to…

We investigate the storage of light in an atomic sample with a lambda-type coupling scheme driven by optical fields at variable two-photon detuning. In the presence of electromagnetically induced transparency (EIT), light is stored and…

Atomic Physics · Physics 2015-05-13 Leon Karpa , Gor Nikoghosyan , Frank Vewinger , Michael Fleischhauer , Martin Weitz

Non-local energy transfer between bound electronic states close to the ionisation threshold is employed for efficient state preparation in dilute atom systems from technological foundations to quantum computing. The generalisation to…

Atomic Physics · Physics 2024-05-06 Axel Molle , Jan Philipp Drennhaus , Viktoria Noel , Nikola Kolev , Annika Bande

Multiphoton ionization provides a clear window into the nature of electron correlations in the helium atom. In the present study, the final state energy range extends up to the region near the $N=2$ and $N=3$ ionization thresholds, where…

Atomic Physics · Physics 2021-03-10 Yimeng Wang , Chris H. Greene

Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources. We use cosmological…

Astrophysics · Physics 2009-11-10 Tiziana Di Matteo , Benedetta Ciardi , Francesco Miniati

Radiation transport plays a crucial role in star formation models, as certain questions within this field cannot be accurately addressed without taking it into account. Given the high complexity of the interstellar medium from which stars…

Instrumentation and Methods for Astrophysics · Physics 2024-03-11 Richard Wünsch

The mean free path of ionizing photons, $\lambda_{\rm mfp}$, is a critical parameter for modeling the intergalactic medium (IGM) both during and after reionization. We present direct measurements of $\lambda_{\rm mfp}$ from QSO spectra over…

We show that numerical simulations of reionization that resolve the Lyman Limit systems (and, thus, correctly count absorptions of ionizing photons) have converged to about 10% level for 5<z<6.2 and are in reasonable agreement (within 10%)…

Astrophysics · Physics 2010-11-11 Nickolay Y. Gnedin , Xiaohui Fan

We have studied the IGM reionization process in its full cosmological context including structure evolution and a realistic galaxy population. We have used a combination of high-resolution N-body simulations (to describe the dark matter and…

Astrophysics · Physics 2009-11-07 B. Ciardi , F. Stoehr , S. D. M. White

We develop a numerical solver for radiative transfer problems based on the weighted essentially nonoscillatory (WENO) scheme modified with anti-diffusive flux corrections, in order to solve the temperature and ionization profiles around a…

Astrophysics · Physics 2008-11-26 Jing-Mei Qiu , Long-Long Feng , Chi-Wang Shu , Li-Zhi Fang

We present a novel generalization of the two-stream method of radiative transfer, which allows for the accurate treatment of radiative transfer in the presence of strong infrared scattering by aerosols. We prove that this generalization…

Earth and Planetary Astrophysics · Physics 2017-10-04 Kevin Heng , Daniel Kitzmann

We present a detailed comparison of three different simulations of the epoch of reionization (EoR). The radiative transfer simulation (${\rm C}^2$-RAY) among them is our benchmark. Radiative transfer codes can produce realistic results, but…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-07 Suman Majumdar , Garrelt Mellema , Kanan K. Datta , Hannes Jensen , T. Roy Choudhury , Somnath Bharadwaj , Martina M. Friedrich

Neutrino-matter interactions play an important role in the post-merger evolution of neutron star-neutron star and black hole-neutron star mergers. Most notably, they determine the properties of the bright optical/infrared transients…

High Energy Astrophysical Phenomena · Physics 2018-09-19 Francois Foucart , Matthew D. Duez , Lawerence E. Kidder , Ronny Nguyen , Harald P. Pfeiffer , Mark A. Scheel

We use cosmological simulations to explore the large-scale effects of reionization. Since reionization is a process that involves a large dynamic range - from galaxies to rare bright quasars - we need to be able to cover a significant…

Astrophysics · Physics 2008-11-26 Katharina Kohler , Nickolay Y. Gnedin , Andrew J. S. Hamilton

The reduced speed of light approximation (RSLA) has been employed to speed up radiative transfer simulations of reionization by a factor of $\gtrsim 5-10$. However, it has been shown to cause significant errors in the HI-ionizing background…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-20 Christopher Cain

Axions that couple to electromagnetism are produced in the early Universe by, among other channels, freeze-in via the Primakoff process. For sufficiently large axion masses, the same coupling causes the axions to decay into two photons,…

High Energy Physics - Phenomenology · Physics 2025-10-24 Ziwen Yin , Hanyu Cheng , Eleonora Di Valentino , Naomi Gendler , David J. E. Marsh , Luca Visinelli

Scattering hinders the passage of light through random media and consequently limits the usefulness of optical techniques for sensing and imaging. Thus, methods for increasing the transmission of light through such random media are of…

Optics · Physics 2014-06-23 Curtis Jin , Raj Rao Nadakuditi , Eric Michielssen , Stephen Rand

We use the photon flux and absorption tracer algorithm presented in Katz et al.~2018, to characterise the contribution of haloes of different mass and stars of different age and metallicity to the reionization of the Universe. We employ a…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-05 Harley Katz , Taysun Kimm , Martin G. Haehnelt , Debora Sijacki , Joakim Rosdahl , Jeremy Blaizot

Quantum simulation offers a route to study open-system molecular dynamics in non-perturbative regimes by programming the interactions among electronic, vibrational, and environmental degrees of freedom on similar energy scales. Trapped-ion…

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