Diagnosing the reionization of the universe: The absorption spectrum of the intergalactic medium and Lyman α clouds

1991 ◽  
Author(s):  
Mark L. Giroux ◽  
Paul R. Shapiro
Keyword(s):  
Absorption Spectrum ◽  
Intergalactic Medium ◽  
The Universe

scholarly journals The Dust Impact on the Intergalactic Medium

2004 ◽  
Vol 217 ◽  
pp. 114-115
Author(s):  
L. Montier ◽  
M. Giard
Keyword(s):  
Large Scale ◽  
Intergalactic Medium ◽  
High Redshift ◽  
Dust Emission ◽  
The Other ◽  
Heating And Cooling ◽  
Cooling Agent ◽  
Small Scales ◽  
The Impact ◽  
The Universe

Recent observations at low and high redshift seem to confirm the presence of dust at very low abundances in the InterGalactic Medium (IGM) and especially in the IntraCluster Medium (ICM). We have studied the impact of this dust on the IGM, in terms of heating and cooling. on one hand, with an analytical model of dust emission, we have proved that the dust can be considered as the dominant cooling agent of the ICM at large scale, when the temperature is greater than T = 107 K. on the other hand, with a strong UV Background and a low temperature (Te ≤ 105 K), dust grains become an efficient heating agent of the IGM. These two opposite effects may have played an important role regarding structure formation of the Universe at large and small scales.

scholarly journals Hydrodynamic Response of the Intergalactic Medium to Reionization. II. Physical Characteristics and Dynamics of Ionizing Photon Sinks

2021 ◽  
Vol 923 (2) ◽  
pp. 161
Author(s):  
Fahad Nasir ◽  
Christopher Cain ◽  
Anson D’Aloisio ◽  
Nakul Gangolli ◽  
Matthew McQuinn
Keyword(s):  
Intergalactic Medium ◽  
Mean Free Path ◽  
Small Scale ◽  
Hydrodynamic Simulations ◽  
Density Distributions ◽  
Ionization Fronts ◽  
Density Peaks ◽  
Hydrodynamic Response ◽  
The Mean ◽  
The Universe

Abstract Becker et al. measured the mean free path of Lyman-limit photons in the intergalactic medium (IGM) at z = 6. The short value suggests that absorptions may have played a prominent role in reionization. Here we study physical properties of ionizing photon sinks in the wake of ionization fronts (I-fronts) using radiative hydrodynamic simulations. We quantify the contributions of gaseous structures to the Lyman-limit opacity by tracking the column-density distributions in our simulations. Within Δt = 10 Myr of I-front passage, we find that self-shielding systems (N H I > 1017.2 cm−2) are comprised of two distinct populations: (1) overdensity Δ ∼ 50 structures in photoionization equilibrium with the ionizing background, and (2) Δ ≳ 100 density peaks with fully neutral cores. The self-shielding systems contribute more than half of the opacity at these times, but the IGM evolves considerably in Δt ∼ 100 Myr as structures are flattened by pressure smoothing and photoevaporation. By Δt = 300 Myr, they contribute ≲10% to the opacity in an average 1 Mpc3 patch of the universe. The percentage can be a factor of a few larger in overdense patches, where more self-shielding systems survive. We quantify the characteristic masses and sizes of self-shielding structures. Shortly after I-front passage, we find M = 104–108 M ⊙ and effective diameters d eff = 1–20 ckpc h −1. These scales increase as the gas relaxes. The picture herein presented may be different in dark matter models with suppressed small-scale power.

scholarly journals QSO Absorption Lines and Cosmology

1987 ◽  
Vol 124 ◽  
pp. 777-792 ◽  
Author(s):  
Wallace L. W. Sargent
Keyword(s):  
Physical Properties ◽  
Recent Work ◽  
Intergalactic Medium ◽  
Cosmological Evolution ◽  
Absorption Lines ◽  
Lyman Alpha ◽  
Different Types ◽  
Potential Applications ◽  
The Universe

The properties of the different types of QSO absorption systems are briefly summarized. An overview is given of the potential applications of absorption lines in cosmology. Recent work on the cosmological evolution of the different types of absorbers is discussed. The physical properties of the intergalactic medium are discussed in the light of recent work on the “Lyman alpha clouds”. The uses of the lines for studies of the evolution of clustering in the Universe are described. Recent puzzling results on common absorption in pairs of QSOs, particularly Q1037–2704 and Q1038–2712, are summarized.

scholarly journals Cosmic metal enrichment

2008 ◽  
Vol 4 (S255) ◽  
pp. 86-99
Author(s):  
Andrea Ferrara
Keyword(s):  
Intergalactic Medium ◽  
Heavy Elements ◽  
Metal Enrichment ◽  
Physical Cosmology ◽  
The Universe ◽  
Present Understanding

AbstractI review the present understanding of the process by which the universe has been enriched in the course of its history with heavy elements produced by stars and transported into the surrounding intergalactic medium. This process goes under the name of “cosmic metal enrichment” and presents some of the most challenging puzzles in present day physical cosmology. These are reviewed along with some proposed explanations that all together form a coherent working scenario.

scholarly journals Is the Bremer Deep Field reionized, at z ∼ 7?

2021 ◽  
Vol 503 (3) ◽  
pp. 4242-4249
Author(s):  
J M Rodríguez Espinosa ◽  
J M Mas-Hesse ◽  
R Calvi
Keyword(s):  
Production Efficiency ◽  
Intergalactic Medium ◽  
Evolutionary Model ◽  
Photon Production ◽  
Analytic Model ◽  
Star Forming ◽  
Lyman Continuum ◽  
The Universe

ABSTRACT We show herein that the population of star-forming galaxies in the Bremer Deep Field (BDF) has enough ionizing power to form two large ionized bubbles that could be in the process of merging into a large one with a volume of 14 000 cMpc3. The sources identified in the BDF have been completed with a set of expected low-luminosity sources at z ∼ 7. We have estimated the number of ionizing photons per second produced by the different star-forming galaxies in the BDF. This number has been compared with the number that would be required to ionize the bubbles around the two overdense regions. We have used, as reference, ionizing emissivities derived from the AMIGA (Analytic Model of Intergalactic-medium and Galaxies) cosmological evolutionary model. We find that even using the most conservative estimates, with a Lyman continuum escape fraction of 10${{\ \rm per\ cent}}$, the two regions we have defined within the BDF would be reionized. Assuming more realistic estimates of the ionizing photon production efficiency, both bubbles would be in the process of merging into a large reionized bubble, such as those that through percolation completed the reionization of the Universe by z = 6. The rather small values of the escape fraction required to reionize the BDF are compatible with the low fraction of faint Ly α emitters identified in the BDF. Finally, we confirm that the low-luminosity sources represent indeed the main contributors to the BDF ionizing photon production.

scholarly journals The intergalactic medium in the cosmic web

2014 ◽  
Vol 11 (S308) ◽  
pp. 364-367
Author(s):  
Nicolas Tejos
Keyword(s):  
Intergalactic Medium ◽  
Three Dimensional ◽  
Baryonic Matter ◽  
One Dimensional ◽  
Star Forming ◽  
Galaxy Surveys ◽  
Dimensional Distribution ◽  
Formation And Evolution ◽  
The Universe ◽  
Cross Matching

AbstractThe intergalactic medium (IGM) accounts for ≳ 90% of baryons at all epochs and yet its three dimensional distribution in the cosmic web remains mostly unknown. This is so because the only feasible way to observe the bulk of the IGM is through intervening absorption line systems in the spectra of bright background sources, which limits its characterization to being one-dimensional. Still, an averaged three dimensional picture can be obtained by combining and cross-matching multiple one-dimensional IGM information with three-dimensional galaxy surveys. Here, we present our recent and current efforts to map and characterize the IGM in the cosmic web using galaxies as tracers of the underlying mass distribution. In particular, we summarize our results on: (i) IGM around star-forming and non-star-forming galaxies; (ii) IGM within and around galaxy voids; and (iii) IGM in intercluster filaments. With these datasets, we can directly test the modern paradigm of structure formation and evolution of baryonic matter in the Universe.

scholarly journals Magnetizing the Cosmic Web during Reionization

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 124 ◽  
Author(s):  
Mathieu Langer ◽  
Jean-Baptiste Durrive
Keyword(s):  
Magnetic Fields ◽  
Standard Model ◽  
Intergalactic Medium ◽  
Classical Physics ◽  
The Standard Model ◽  
Magnetic Seeds ◽  
The Universe

Increasing evidence suggests that cosmological sheets, filaments, and voids may be substantially magnetized today. The origin of magnetic fields in the intergalactic medium (IGM) is, however, currently uncertain. It seems well known that non-standard extensions to the physics of the standard model can provide mechanisms susceptible of magnetizing the universe at large. Perhaps less well known is the fact that standard, classical physics of matter–radiation interactions actually possesses the same potential. We discuss a magnetogenesis mechanism based on the exchange of momentum between hard photons and electrons in an inhomogeneous IGM. Operating in the neighborhood of ionizing sources during the epoch of reionization, this mechanism is capable of generating magnetic seeds of relevant strengths over scales comparable to the distance between ionizing sources. In addition, summing up the contributions of all ionizing sources and taking into account the distribution of gas inhomogeneities, we show that this mechanism leaves the IGM, at the end of reionization, with a level of magnetization that might account, when amplification mechanisms take over, for the magnetic fields strengths in the current cosmic web.

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