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We present an analysis combining the simultaneous measurement of intergalactic absorption by hydrogen (H I), helium (He II) and oxygen (O VI) in UV and optical quasar spectra. The combination of the H I and He II Lyman-alpha forests through…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-04 Sean Morrison , Matthew M. Pieri , David Syphers , Tae-Sun Kim

This study focuses on assessing smartphone camera characteristics for developing an economic smartphone-based Particle Image Velocimetry (PIV) system. In the investigation, flow around a cylinder was visualized using two…

Image and Video Processing · Electrical Eng. & Systems 2020-09-29 Vishesh Kashyap , Sushrut Kumar , Nehal Amit Jajal , Mrudang Mathur , Raj Kumar Singh

We report on the design and performance of a velocity map imaging (VMI) spectrometer optimized for experiments using high-intensity extreme ultraviolet (XUV) sources such as laser-driven high-order harmonic generation (HHG) sources and…

{We explored the {softness parameter} in the infrared, whose main purpose is the characterisation of the hardness of the incident ionising radiation in emission-line nebulae. This parameter is obtained from the combination of mid-infrared…

We use Keck HIRES spectra of three intermediate redshift QSOs to study the physical state and kinematics of the individual components of CIV selected heavy element absorption systems. Fewer than 8 % of all CIV lines with column densities…

Astrophysics · Physics 2009-10-28 M. Rauch , W. L. W. Sargent , D. S. Womble , T. A. Barlow

We revisit the proximity effect produced by QSOs at redshifts 2.1-3.3 applying the FLO approach (Saitta et al. 2008) to a sample of ~6300 Ly-alpha lines fitted in 21 high resolution, high signal-to-noise spectra. This new technique allows…

Astrophysics · Physics 2015-05-13 V. D'Odorico , M. Bruscoli , F. Saitta , F. Fontanot , M. Viel , S. Cristiani , P. Monaco

The accuracy of deformable image registration (DIR) has a significant dosimetric impact in radiation treatment planning. We evaluated accuracy of various DIR algorithms using variations of the deformation point and volume. The reference…

We use high quality echelle spectra of 24 QSOs to provide a calibrated measurement of the total amount of Lyman-alpha forest absorption (DA) over the redshift range 2.2 < z < 3.2. Our measurement of DA excludes absorption from metal lines…

We present constraints on the baryonic matter density parameter, $\Omega_b$, within the framework of the $\Lambda$CDM model. Our analysis utilizes observational data on the effective optical depth from high-redshift quasars. To parameterize…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-31 Wen-Fei Liu , Yuan-Bo Xie , Zhi-E Liu , Jin Qin , Kang Jiao , Dong-Yao Zhao , Tong-Jie Zhang

The Caldeira-Leggett model provides a compact characterization of a thermal environment in terms of a spectral density function. This simplicity has led to a variety of numerically exact quantum methods for reduced density matrix…

Chemical Physics · Physics 2019-03-27 Fabian Gottwald , Sergei D. Ivanov , Oliver Kühn

We use high signal-to-noise ratio, high-resolution VLT-UVES data of Q J0643-5041 amounting to a total of more than 23 hours exposure time and fit the neutral hydrogen, metals and H2 absorption features with multiple-component Voigt…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-09 D. Albornoz Vásquez , H. Rahmani , P. Noterdaeme , P. Petitjean , R. Srianand , C. Ledoux

We simulate the Lya forest in a standard CDM universe using a 2-level hierarchical grid code to evolve the dark and baryonic matter components self-consistently. We solve the time-dependent ionization equations for hydrogen and helium,…

Astrophysics · Physics 2009-10-28 Yu Zhang , Peter Anninos , Michael L. Norman , Avery Meiksin

We analyze the physical conditions of the outflow seen in QSO 2359-1241 (NVSS J235953-124148), based on high resolution spectroscopic VLT observations. This object was previously studied using Keck/HIRES data. The main improvement over the…

Astrophysics · Physics 2009-11-13 Kirk Korista , Manuel Bautista , Nahum Arav , Maxwell Moe , Elisa Costantini , Chris Benn

I apply the well controlled Hydro-PM approximation of Gnedin & Hui to model the column density distribution of the Lyman-alpha forest for 25 different flat cosmological scenarios, including variants of the standard CDM, tilted CDM, CDM with…

Astrophysics · Physics 2009-10-30 Nickolay Y. Gnedin

Column density distribution functions of CIV with 12.05 < log (N) < 14.35 and SiIV with 11.70 < log (N) < 13.93 have been obtained using 81 CIV absorbers and 35 SiIV absorbers redward of the Ly alpha forest in the lines of sight to seven…

Astrophysics · Physics 2009-10-30 Antoinette Songaila

Using radiative transfer calculations and cosmological simulations of structure formation, we study constraints that can be placed on the nature of the cosmic ultraviolet (UV) background in the redshift interval 2.5< z <5. Our approach…

Astrophysics · Physics 2007-05-23 Aaron Sokasian , Tom Abel , Lars E. Hernquist

The remarkable efficiency of the UVES spectrograph at the VLT has made it possible to push high-resolution, high-S/N ground observations of the Ly-a forest down to z~1.5, gaining new insight into the physical conditions of the intergalactic…

Astrophysics · Physics 2009-11-07 S. Cristiani , S. Bianchi , S. D'Odorico , T. -S. Kim

We present 40 fully hydrodynamical numerical simulations of the intergalactic gas that gives rise to the Ly-alpha forest. We make artificial spectra from each and measure three output parameters: the mean flux, a measure of the most common…

LIRGs and ULIRGs are much more numerous at higher redshifts than locally, dominating the star-formation rate density at redshifts ~1 - 2. Therefore, they are important objects in order to understand how galaxies form and evolve through…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Javier Rodriguez Zaurin , Santiago Arribas , Ana Monreal Ibero , Luis Colina , Almudena Alonso Herrero , Julia Alfonso Garzon

We present results of the first survey of high-redshift (<z> ~ 2.3) OVI absorption systems along parallel lines of sight toward two lensed QSOs. After a careful and well-defined search, we find ten intervening OVI systems. Within the…

Astrophysics · Physics 2009-11-13 S. Lopez , S. Ellison , S. D'Odorico , T. -S. Kim
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