scholarly journals Constraints on the End of Reionization from the Density Fields Surrounding Two Highly Opaque Quasar Sightlines

2021 ◽  
Vol 923 (1) ◽  
pp. 87
Author(s):  
Holly M. Christenson ◽  
George D. Becker ◽  
Steven R. Furlanetto ◽  
Frederick B. Davies ◽  
Matthew A. Malkan ◽  
...  
Keyword(s):  
Large Scale ◽  
Intergalactic Medium ◽  
Neutral Hydrogen ◽  
Large Fluctuations ◽  
First Time ◽  
The Relationship

Abstract The observed large-scale scatter in Lyα opacity of the intergalactic medium at z < 6 implies large fluctuations in the neutral hydrogen fraction that are unexpected long after reionization has ended. A number of models have emerged to explain these fluctuations that make testable predictions for the relationship between Lyα opacity and density. We present selections of z = 5.7 Lyα-emitting galaxies (LAEs) in the fields surrounding two highly opaque quasar sightlines with long Lyα troughs. The fields lie toward the z = 6.0 quasar ULAS J0148+0600, for which we reanalyze previously published results using improved photometric selection, and toward the z = 6.15 quasar SDSS J1250+3130, for which results are presented here for the first time. In both fields, we report a deficit of LAEs within 20 h −1 Mpc of the quasar. The association of highly opaque sightlines with galaxy underdensities in these two fields is consistent with models in which the scatter in Lyα opacity is driven by large-scale fluctuations in the ionizing UV background or by an ultra-late reionization that has not yet concluded at z = 5.7.

scholarly journals The neutral hydrogen distribution in large-scale haloes from 21-cm intensity maps

2020 ◽  
Vol 498 (4) ◽  
pp. 5916-5935
Author(s):  
Denis Tramonte ◽  
Yin-Zhe Ma
Keyword(s):  
Large Scale ◽  
Neutral Hydrogen ◽  
Principal Component ◽  
Theoretical Models ◽  
Mapping Data ◽  
Hydrogen Distribution ◽  
Intensity Mapping ◽  
Concentration Parameter ◽  
Functional Forms ◽  
First Time

ABSTRACT We detect the neutral hydrogen (H i) radial brightness temperature profile in large-scale haloes by stacking 48 430 galaxies selected from the 2dFGRS catalogue on to a set of 21-cm intensity maps obtained with the Parkes radio telescope, spanning a total area of ∼1300 deg2 on the sky and covering the redshift range 0.06 ≲ z ≲ 0.10. Maps are obtained by removing both 10 and 20 foreground modes in the principal component analysis. We perform the stack at the map level and extract the profile from a circularly symmetrized version of the halo emission. We detect the H i halo emission with the significance 12.5σ for the 10-mode and 13.5σ for the 20-mode removed maps at the profile peak. We jointly fit for the observed halo mass Mv and the normalization $c_{0,\rm H\, \small{I}}$ for the H i concentration parameter against the reconstructed profiles, using functional forms for the H i halo abundance proposed in the literature. We find $\log _{10}{(M_{\rm v}/\text{M}_{\odot })}= 16.1^{+0.1}_{-0.2}$, $c_{0,\rm H\, \small{I}}=3.5^{+0.7}_{-1.0}$ for the 10-mode and $\log _{10}{(M_{\rm v}/\text{M}_{\odot })}= 16.5^{+0.1}_{-0.2}$, $c_{0,\rm H\, \small{I}}=5.3^{+1.1}_{-1.7}$ for the 20-mode removed maps. These estimates show the detection of the integrated contribution from multiple galaxies located inside very massive haloes. We also consider subsamples of 13 979 central and 34 361 satellite 2dF galaxies separately, and obtain marginal differences suggesting satellite galaxies are H i-richer. This work shows for the first time the feasibility of testing theoretical models for the H i halo content directly on profiles extracted from 21-cm maps and opens future possibilities for exploiting upcoming H i intensity-mapping data.

scholarly journals SILVERRUSH. XI. Constraints on the Lyα Luminosity Function and Cosmic Reionization at z = 7.3 with Subaru/Hyper Suprime-Cam

2021 ◽  
Vol 923 (2) ◽  
pp. 229
Author(s):  
Hinako Goto ◽  
Kazuhiro Shimasaku ◽  
Satoshi Yamanaka ◽  
Rieko Momose ◽  
Makoto Ando ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Intergalactic Medium ◽  
Neutral Hydrogen ◽  
Neutral Fraction ◽  
Estimation Methods ◽  
Large Area ◽  
Upper Limit ◽  
Narrowband Imaging ◽  
First Time

Abstract The Lyα luminosity function (LF) of Lyα emitters (LAEs) has been used to constrain the neutral hydrogen fraction in the intergalactic medium (IGM) and thus the timeline of cosmic reionization. Here we present the results of a new narrowband imaging survey for z = 7.3 LAEs in a large area of ∼3 deg2 with Subaru/Hyper Suprime-Cam. No LAEs are detected down to L Lyα ≃ 1043.2 erg s−1 in an effective cosmic volume of ∼2 × 106 Mpc3, placing an upper limit on the bright part of the z = 7.3 Lyα LF for the first time and confirming a decrease in bright LAEs from z = 7.0. By comparing this upper limit with the Lyα LF in the case of fully ionized IGM, which is predicted using an observed z = 5.7 Lyα LF on the assumption that the intrinsic Lyα LF evolves in the same way as the UV LF, we obtain the relative IGM transmission T Ly α IGM ( 7.3 ) / T Ly α IGM ( 5.7 ) < 0.77 and then the volume-averaged neutral fraction x H I(7.3) > 0.28. Cosmic reionization is thus still ongoing at z = 7.3, consistent with results from other x H I estimation methods. A similar analysis using literature Lyα LFs finds that at z = 6.6 and 7.0, the observed Lyα LF agrees with the predicted one, consistent with full ionization.

scholarly journals Natal molecular cloud of SNR Kes 41. Complete characterisation

2018 ◽  
Vol 619 ◽  
pp. A108 ◽  
Author(s):  
L. Supan ◽  
G. Castelletti ◽  
A. D. Supanitsky ◽  
M. G. Burton ◽  
G. F. Wong ◽  
...  
Keyword(s):  
Large Scale ◽  
Galactic Plane ◽  
Line Emission ◽  
Neutral Hydrogen ◽  
Young Stellar Objects ◽  
Proton Density ◽  
Large Area ◽  
Stellar Objects ◽  
High Resolution Data ◽  
First Time

Using high-resolution data of the 12CO and 13CO (J = 1–0) line emission from the Mopra Southern Galactic Plane CO Survey in conjunction with neutral hydrogen observations from the Southern Galactic Plane Survey (SGPS) and mid-infrared Spitzer data, we have explored the large-scale environment of the supernova remnant Kes 41. On the basis of these data, we identified for the first time the parent cloud of Kes 41 in its whole extension and surveyed the HII regions, masers, and the population of massive young stellar objects in the cloud. The whole unveiled giant cloud, located at the kinematic distance of 12.0 ± 3.6 kpc, whose average total mass and size are ~10–30 × 105 M⊙ and ~ 26′, also shines in γ-rays, as revealed by the Large Area Telescope on board the Fermi satellite. We determined a high average proton density ~500–1000 cm−3 in the large molecular complex, of which protons from the neutral atomic and ionised gases comprise only ~15%.

scholarly journals Chasing the Tail of Cosmic Reionization with Dark Gap Statistics in the Lyα Forest over 5 < z < 6

2021 ◽  
Vol 923 (2) ◽  
pp. 223
Author(s):  
Yongda Zhu ◽  
George D. Becker ◽  
Sarah E. I. Bosman ◽  
Laura C. Keating ◽  
Holly M. Christenson ◽  
...  
Keyword(s):  
Large Scale ◽  
Intergalactic Medium ◽  
Neutral Hydrogen ◽  
Hydrodynamical Simulations

Abstract We present a new investigation of the intergalactic medium (IGM) near the end of reionization using “dark gaps” in the Lyα forest. Using spectra of 55 QSOs at z em > 5.5, including new data from the XQR-30 VLT Large Programme, we identify gaps in the Lyα forest where the transmission averaged over 1 comoving h −1 Mpc bins falls below 5%. Nine ultralong (L > 80 h −1 Mpc) dark gaps are identified at z < 6. In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than 30 h −1 Mpc, F 30, as a function of redshift. We measure F 30 ≃ 0.9, 0.6, and 0.15 at z = 6.0, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to z ≃5.3. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. Models wherein the IGM is essentially fully reionized that retain large-scale fluctuations in the ionizing UV background at z ≲6 are also potentially consistent with the data. Overall, our results suggest that signatures of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the IGM until at least z ≃ 5.3.

scholarly journals Variations in shape among observed Lyman-α spectra due to intergalactic absorption

2020 ◽  
Vol 642 ◽  
pp. L16
Author(s):  
C. Byrohl ◽  
M. Gronke
Keyword(s):  
Spectral Properties ◽  
Large Scale ◽  
Intergalactic Medium ◽  
Neutral Hydrogen ◽  
Small Scale ◽  
Ionization State ◽  
Future Studies ◽  
Small Scale Structure ◽  
Peak Asymmetry ◽  
The Impact

Lyman-α (Lyα) spectra provide insights into the small-scale structure and kinematics of neutral hydrogen (HI) within galaxies as well as the ionization state of the intergalactic medium (IGM). The former defines the intrinsic spectrum of a galaxy, which, in turn, is modified by the latter. These two effects are degenerate. Using the IllustrisTNG100 simulation, we studied the impact of the IGM on Lyα spectral shapes between z ∼ 0 and 5. We computed the distribution of the expected Lyα peaks and of the peak asymmetry for different intrinsic spectra, redshifts, and large-scale environments. We find that the averaged transmission curves that are commonly applied give a misleading perception of the observed spectral properties. We show that the distributions of peak counts and asymmetry can lift the degeneracy between the intrinsic spectrum and IGM absorption. For example, we expect a significant number of triple-peaked Lyα spectra (up to 30% at z ∼ 3) if the galaxies’ HI distribution become more porous at higher redshift, as predicted by cosmological simulations. We provide a public catalog of transmission curves for simulations and observations to allow for a more realistic IGM treatment in future studies.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

Affirmative Action and Leadership Attitudes in Brazilian Women Managers

2011 ◽  
Vol 10 (3) ◽  
pp. 139-143 ◽  
Author(s):  
Gazi Islam ◽  
Sarah E. S. Zilenovsky
Keyword(s):  
Affirmative Action ◽  
Latin American ◽  
Women Managers ◽  
Psychological Effects ◽  
Preferential Selection ◽  
Justice Perceptions ◽  
First Time ◽  
The Relationship

This note examines the relationship between affirmative action (AA) program perceptions and women’s self-ascribed capacity and desire to become leaders. We propose that women who believe that their organization implements a program of preferential selection toward women will experience negative psychological effects leading to lowered self-expectations for leadership, but that this effect will be moderated by their justice perceptions of AA programs. We test this proposition empirically for the first time with a Latin American female sample. Among Brazilian women managers, desire but not self-ascribed capacity to lead was reduced when they believed an AA policy was in place. Both desire’s and capacity’s relationships with belief in an AA policy were moderated by justice perceptions.

Scheming

2018 ◽  
Author(s):  
Seán Damer
Keyword(s):  
Social Class ◽  
Housing Policy ◽  
Large Scale ◽  
Class Structure ◽  
Local Council ◽  
Housing Scheme ◽  
Post War ◽  
First Time ◽  
The Voice ◽  
House Building

This book seeks to explain how the Corporation of Glasgow, in its large-scale council house-building programme in the inter- and post-war years, came to reproduce a hierarchical Victorian class structure. The three tiers of housing scheme which it constructed – Ordinary, Intermediate, and Slum-Clearance – effectively signified First, Second and Third Class. This came about because the Corporation uncritically reproduced the offensive and patriarchal attitudes of the Victorian bourgeoisie towards the working-class. The book shows how this worked out on the ground in Glasgow, and describes the attitudes of both authoritarian housing officials, and council tenants. This is the first time the voice of Glasgow’s council tenants has been heard. The conclusion is that local council housing policy was driven by unapologetic considerations of social class.

New ''Cold War''

2020 ◽  
pp. 27-34
Author(s):  
Vladimir Batiuk
Keyword(s):  
Cold War ◽  
Nuclear Weapons ◽  
Armed Conflict ◽  
Large Scale ◽  
Arms Race ◽  
Ideological Struggle ◽  
Nuclear Arms Race ◽  
The Cold War ◽  
The Relationship ◽  
Nuclear Arms

In this article, the ''Cold War'' is understood as a situation where the relationship between the leading States is determined by ideological confrontation and, at the same time, the presence of nuclear weapons precludes the development of this confrontation into a large-scale armed conflict. Such a situation has developed in the years 1945–1989, during the first Cold War. We see that something similar is repeated in our time-with all the new nuances in the ideological struggle and in the nuclear arms race.

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