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 The H i bias during the Epoch of Reionization

2019 ◽  
Vol 490 (4) ◽  
pp. 5739-5748 ◽  
Author(s):  
Wenxiao Xu ◽  
Yidong Xu ◽  
Bin Yue ◽  
Ilian T Iliev ◽  
Hy Trac ◽  
...  
Keyword(s):  
Late Stage ◽  
Intergalactic Medium ◽  
Early Stage ◽  
Neutral Hydrogen ◽  
Scale Dependence ◽  
Neutral Fraction ◽  
Matter Distribution ◽  
Absolute Value ◽  
Small Scales

ABSTRACT The neutral hydrogen (H i) and its 21 cm line are promising probes to the reionization process of the intergalactic medium (IGM). To use this probe effectively, it is imperative to have a good understanding on how the neutral hydrogen traces the underlying matter distribution. Here, we study this problem using seminumerical modelling by combining the H i in the IGM and the H i from haloes during the epoch of reionization (EoR), and investigate the evolution and the scale dependence of the neutral fraction bias as well as the 21 cm line bias. We find that the neutral fraction bias on large scales is negative during reionization, and its absolute value on large scales increases during the early stage of reionization and then decreases during the late stage. During the late stage of reionization, there is a transition scale at which the H i bias transits from negative on large scales to positive on small scales, and this scale increases as the reionization proceeds to the end.

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 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 An HI Survey of LSB galaxies selected from the APM Survey

1999 ◽  
Vol 171 ◽  
pp. 307-314 ◽  
Author(s):  
Stéphanie Côté ◽  
Tom Broadhurst ◽  
Jon Loveday ◽  
Shannon Kolind
Keyword(s):  
Total Mass ◽  
Surface Brightness ◽  
Luminosity Function ◽  
Neutral Hydrogen ◽  
Mass Function ◽  
Low Surface Brightness ◽  
Redshift Survey ◽  
First Time ◽  
Lsb Galaxies ◽  
Negligible Contribution

AbstractWe present preliminary results of a neutral hydrogen (HI) redshift survey to find Low Surface Brightness (LSB) galaxies in the very nearby universe. Our sample consists of all galaxies in the APM catalog (Maddox et al. 1990) with a mean surface brightness of μ ≥ 24 mag/arcsec2, down to a magnitude limit of bj ≤ 17. With the Parkes 64m radiotelescope 35 objects were detected at v < 4300 km s−1. The resulting luminosity function, HI mass function, and for the first time total mass function are presented. It is found that LSBs make a negligible contribution to the overall integrated luminosity, HI mass, and total mass contained in galaxies.

scholarly journals Adaptability of Ultrasonic Lamb Wave Touchscreen to the Variations in Touch Force and Touch Area

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1736
Author(s):  
Zengchong Yang ◽  
Xiucheng Liu ◽  
Bin Wu ◽  
Ren Liu
Keyword(s):  
Lamb Wave ◽  
Weight Coefficient ◽  
The Self ◽  
Reference Database ◽  
Learning Method ◽  
Improved Method ◽  
Large Area ◽  
Localization Model ◽  
Reference Databases ◽  
First Time

Previous studies on Lamb wave touchscreen (LWT) were carried out based on the assumption that the unknown touch had the consistent parameters with acoustic fingerprints in the reference database. The adaptability of LWT to the variations in touch force and touch area was investigated in this study for the first time. The automatic collection of the databases of acoustic fingerprints was realized with an experimental prototype of LWT employing three pairs of transmitter–receivers. The self-adaptive updated weight coefficient of the used transmitter–receiver pairs was employed to successfully improve the accuracy of the localization model established based on a learning method. The performance of the improved method in locating single- and two-touch actions with the reference database of different parameters was carefully evaluated. The robustness of the LWT to the variation of the touch force varied with the touch area. Moreover, it was feasible to locate touch actions of large area with reference databases of small touch areas as long as the unknown touch and the reference databases met the condition of equivalent averaged stress.

scholarly journals Direct detection of atomic dark matter in white dwarfs

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
David Curtin ◽  
Jack Setford
Keyword(s):  
Dark Matter ◽  
Energy Loss ◽  
Cooling Rate ◽  
White Dwarf ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Direct Detection ◽  
Matter Density ◽  
Mixing Parameter ◽  
First Time

Abstract Dark matter could have a dissipative asymmetric subcomponent in the form of atomic dark matter (aDM). This arises in many scenarios of dark complexity, and is a prediction of neutral naturalness, such as the Mirror Twin Higgs model. We show for the first time how White Dwarf cooling provides strong bounds on aDM. In the presence of a small kinetic mixing between the dark and SM photon, stars are expected to accumulate atomic dark matter in their cores, which then radiates away energy in the form of dark photons. In the case of white dwarfs, this energy loss can have a detectable impact on their cooling rate. We use measurements of the white dwarf luminosity function to tightly constrain the kinetic mixing parameter between the dark and visible photons, for DM masses in the range 10−5–105 GeV, down to values of ϵ ∼ 10−12. Using this method we can constrain scenarios in which aDM constitutes fractions as small as 10−3 of the total dark matter density. Our methods are highly complementary to other methods of probing aDM, especially in scenarios where the aDM is arranged in a dark disk, which can make direct detection extremely difficult but actually slightly enhances our cooling constraints.

What drives housing prices, rent and new construction in China

2017 ◽  
Vol 10 (5) ◽  
pp. 662-686
Author(s):  
Dimitrios Staikos ◽  
Wenjun Xue
Keyword(s):  
Real Estate ◽  
Empirical Test ◽  
Housing Prices ◽  
Panel Cointegration ◽  
Real Estate Market ◽  
Estimation Methods ◽  
Content Type ◽  
New Construction ◽  
Using Data ◽  
First Time

Purpose With this paper, the authors aim to investigate the drivers behind three of the most important aspects of the Chinese real estate market, housing prices, housing rent and new construction. At the same time, the authors perform a comprehensive empirical test of the popular 4-quadrant model by Wheaton and DiPasquale. Design/methodology/approach In this paper, the authors utilize panel cointegration estimation methods and data from 35 Chinese metropolitan areas. Findings The results indicate that the 4-quadrant model is well suited to explain the determinants of housing prices. However, the same is not true regarding housing rent and new construction suggesting a more complex theoretical framework may be required for a well-rounded explanation of real estate markets. Originality/value It is the first time that panel data are used to estimate rent and new construction for China. Also, it is the first time a comprehensive test of the Wheaton and DiPasquale 4-quadrant model is performed using data from China.

scholarly journals Dynamic Range Analysis of the Phase Generated Carrier Demodulation Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
M. J. Plotnikov ◽  
A. V. Kulikov ◽  
V. E. Strigalev ◽  
I. K. Meshkovsky
Keyword(s):  
Theoretical Analysis ◽  
Dynamic Range ◽  
Range Analysis ◽  
Upper Limit ◽  
Low Pass ◽  
Nonlinear Character ◽  
Simulation Results ◽  
Low Pass Filters ◽  
First Time ◽  
Phase Generated Carrier

The dependence of the dynamic range of the phase generated carrier (PGC) technique on low-pass filters passbands is investigated using a simulation model. A nonlinear character of this dependence, which could lead to dynamic range limitations or measurement uncertainty, is presented for the first time. A detailed theoretical analysis is provided to verify the simulation results and these results are consistent with performed calculations. The method for the calculation of low-pass filters passbands according to the required dynamic range upper limit is proposed.

Microstrip Gas Counters

2014 ◽  
pp. 31-51
Keyword(s):  
Glass Surface ◽  
Two Dimensional ◽  
Large Area ◽  
Proportional Chamber ◽  
Microelectronic Technology ◽  
Multiwire Proportional Chamber ◽  
Dimensional Version ◽  
A Chain ◽  
New Generation ◽  
First Time

In this chapter, the first micropattern gaseous detector, the microstrip gas counter, invented in 1988 by A. Oed, is presented. It consists of alternating anode and cathode strips with a pitch of less than 1 mm created on a glass surface. It can be considered a two-dimensional version of a multiwire proportional chamber. This was the first time microelectronic technology was applied to manufacturing of gaseous detectors. This pioneering work offers new possibilities for large area planar detectors with small gaps between the anode and the cathode electrodes (less than 0.1 mm). Initially, this detector suffered from several serious problems, such as charging up of the substrate, discharges which destroyed the thin anode strips, etc. However, by efforts of the international RD28 collaboration hosted by CERN, most of them were solved. Although nowadays this detector has very limited applications, its importance was that it triggered a chain of similar developments made by various groups, and these collective efforts finally led to the creation of a new generation of gaseous detectors-micropattern detectors.

scholarly journals Probing the thermal state of the intergalactic medium at z > 5 with the transmission spikes in high-resolution  Ly α forest spectra

2020 ◽  
Vol 494 (4) ◽  
pp. 5091-5109 ◽  
Author(s):  
Prakash Gaikwad ◽  
Michael Rauch ◽  
Martin G Haehnelt ◽  
Ewald Puchwein ◽  
James S Bolton ◽  
...  
Keyword(s):  
High Resolution ◽  
Radiative Transfer ◽  
Intergalactic Medium ◽  
Thermal State ◽  
Neutral Hydrogen ◽  
High Spectral Resolution ◽  
Profile Fitting ◽  
Density Relation ◽  
Width Distribution ◽  
Hydrodynamical Simulations

ABSTRACT We compare a sample of five high-resolution, high S/N  Ly α forest spectra of bright 6 &lt; z &lt; ∼6.5 QSOs aimed at spectrally resolving the last remaining transmission spikes at z &gt; 5 with those obtained from mock absorption spectra from the Sherwoodand Sherwood–Relics simulation suites of hydrodynamical simulations of the intergalactic medium (IGM). We use a profile-fitting procedure for the inverted transmitted flux, 1 − F, similar to the widely used Voigt profile fitting of the transmitted flux F at lower redshifts, to characterize the transmission spikes that probe predominately underdense regions of the IGM. We are able to reproduce the width and height distributions of the transmission spikes, both with optically thin simulations of the post-reionization Universe using a homogeneous UV background and full radiative transfer simulations of a late reionization model. We find that the width of the fitted components of the simulated transmission spikes is very sensitive to the instantaneous temperature of the reionized IGM. The internal structures of the spikes are more prominent in low temperature models of the IGM. The width distribution of the observed transmission spikes, which require high spectral resolution (≤ 8  km s−1) to be resolved, is reproduced for optically thin simulations with a temperature at mean density of T0 = (11 000 ± 1600, 10 500 ± 2100, 12 000 ± 2200) K at z = (5.4, 5.6, 5.8). This is weakly dependent on the slope of the temperature-density relation, which is favoured to be moderately steeper than isothermal. In the inhomogeneous, late reionization, full radiative transfer simulations where islands of neutral hydrogen persist to z ∼ 5.3, the width distribution of the observed transmission spikes is consistent with the range of T0 caused by spatial fluctuations in the temperature–density relation.

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