scholarly journals Testing the scale-dependent hemispherical asymmetry with the 21-cm power spectrum from the epoch of reionization

2019 ◽  
Vol 487 (4) ◽  
pp. 5564-5571 ◽  
Author(s):  
Botao Li ◽  
Zhaoting Chen ◽  
Yi-Fu Cai ◽  
Yi Mao
Keyword(s):  
Power Spectrum ◽  
High Redshift ◽  
Phase 2 ◽  
Microwave Background ◽  
Power Asymmetry ◽  
Inflation Model ◽  
Asymmetric Power ◽  
Asymmetry Amplitude ◽  
Order Of Magnitude ◽  
Statistical Isotropy

Abstract Hemispherical power asymmetry has emerged as a new challenge to cosmology in early Universe. While the cosmic microwave background (CMB) measurements indicated the asymmetry amplitude A ≃ 0.07 at the CMB scale $k_{\rm CMB}\simeq 0.0045\, {\rm Mpc}^{-1}$, the high-redshift quasar observations found no significant deviation from statistical isotropy. This conflict can be reconciled in some scale-dependent asymmetry models. We put forwards a new parametrization of scale-dependent asymmetric power spectrum, inspired by a multispeed inflation model. The 21-cm power spectrum from the epoch of reionization can be used to constrain the scale-dependent hemispherical asymmetry. We demonstrate that an optimum, multifrequency observation by the Square Kilometre Array (SKA) Phase 2 can impose a constraint on the amplitude of the power asymmetry anomaly at the level of ΔA ≃ 0.2 at $0.056 \lesssim k_{\rm 21cm} \lesssim 0.15 \, {\rm Mpc}^{-1}$. This limit may be further improved by an order of magnitude as ΔA ≃ 0.01 with a cosmic variance limited experiment such as the Omniscope.

scholarly journals NATURAL INFLATION, PLANCK SCALE PHYSICS AND OSCILLATING PRIMORDIAL SPECTRUM

2005 ◽  
Vol 14 (08) ◽  
pp. 1347-1364 ◽  
Author(s):  
XIULIAN WANG ◽  
BO FENG ◽  
MINGZHE LI ◽  
XUE-LEI CHEN ◽  
XINMIN ZHANG
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
High Frequency ◽  
Large Scale ◽  
Planck Scale ◽  
Microwave Background ◽  
Precision Data ◽  
Inflation Model ◽  
High Precision Data ◽  
Planck Scale Physics

In the "natural inflation" model, the inflaton potential is periodic. We show that Planck scale physics may induce corrections to the inflaton potential, which is also periodic with a greater frequency. Such high frequency corrections produce oscillating features in the primordial fluctuation power spectrum, which are not entirely excluded by the current observations and may be detectable in high precision data of cosmic microwave background (CMB) anisotropy and large scale structure (LSS) observations.

scholarly journals 21-cm power spectrum and ionization bias as a probe of long-mode modulated non-Gaussian sky

2019 ◽  
Vol 488 (4) ◽  
pp. 5941-5951
Author(s):  
Shahram Khosravi ◽  
Amirabbas Ghazizadeh ◽  
Shant Baghram
Keyword(s):  
Power Spectrum ◽  
Background Radiation ◽  
Neutral Hydrogen ◽  
Hydrogen Distribution ◽  
Microwave Background ◽  
Power Asymmetry ◽  
Angular Power Spectrum ◽  
Long Wavelength ◽  
Microwave Background Radiation ◽  
Non Gaussian

ABSTRACT The observed hemispherical power asymmetry in cosmic microwave background radiation can be explained by long-wavelength mode (long-mode) modulation. In this paper, we study the possibility of detecting this effect in the angular power spectrum of the 21-cm brightness temperature. For this task, we study the effect of the neutral hydrogen distribution on the angular power spectrum. This is done by formulating the bias parameter of the ionized fraction to the underlying matter distribution. We also discuss the possibility that the long-mode modulation is accompanied by a primordial non-Gaussianity of local type. In this case, we obtain the angular power spectrum with two effects of primordial non-Gaussianity and long-mode modulation. Finally, we show that the primordial non-Gaussianity enhances the long-mode modulated power of the 21-cm signal via the non-Gaussian scale-dependent bias up to four orders of magnitude. Accordingly, observations of the 21-cm signal with upcoming surveys, such as the Square Kilometer Array (SKA), will probably be capable of detecting hemispherical power asymmetry in the context of long-mode modulation.

scholarly journals The kinematic Sunyaev–Zel’dovich effect of the large-scale structure (II): the effect of modified gravity

2018 ◽  
Vol 481 (2) ◽  
pp. 2497-2506 ◽  
Author(s):  
M Roncarelli ◽  
M Baldi ◽  
F Villaescusa-Navarro
Keyword(s):  
Power Spectrum ◽  
Modified Gravity ◽  
Large Scale ◽  
High Redshift ◽  
Analytical Formula ◽  
Microwave Background ◽  
Angular Scale ◽  
South Pole Telescope ◽  
Hydrodynamical Simulation ◽  
Sunyaev Zel'dovich Effect

ABSTRACT The key to understand the nature of dark energy lies in our ability to probe the distant Universe. In this framework, the recent detection of the kinematic Sunyaev–Zel’dovich (kSZ) effect signature in the cosmic microwave background obtained with the South Pole Telescope (SPT) is extremely useful since this observable is sensitive to the high-redshift diffuse plasma. We analyse a set of cosmological hydrodynamical simulation with four different realizations of a Hu & Sawicki f(R) gravity model, parametrized by the values of $\overline{f}_{\rm R,0}$= (0, −10−6, −10−5, −10−4), to compute the properties of the kSZ effect due to the ionized Universe and how they depend on $\overline{f}_{\rm R,0}$ and on the redshift of reionization, zre. In the standard General Relativity limit ($\overline{f}_{\rm R,0}$= 0) we obtain an amplitude of the kSZ power spectrum of $\mathcal {D}^{\rm kSZ}_{3000}$$= 4.1\,$$\mu$K2 (zre= 8.8), close to the +1σ limit of the $\mathcal {D}^{\rm kSZ}_{3000}$$= (2.9\pm 1.3)\,$$\mu$K2 measurement by SPT. This corresponds to an upper limit on the kSZ contribute from patchy reionization of $\mathcal {D}^{\rm kSZ,patchy}_{3000}$$\lt 0.9\,$$\mu$K2 (95 per cent confidence level). Modified gravity boosts the kSZ signal by about 3, 12, and 50 per cent for $\overline{f}_{\rm R,0}$=(− 10−6, −10−5, −10−4), respectively, with almost no dependence on the angular scale. This means that with modified gravity the limits on patchy reionization shrink significantly: for $\overline{f}_{\rm R,0}$=−10−5 we obtain $\mathcal {D}^{\rm kSZ,patchy}_{3000}$$\lt 0.4\,$$\mu$K2. Finally, we provide an analytical formula for the scaling of the kSZ power spectrum with zre and $\overline{f}_{\rm R,0}$ at different multipoles: at ℓ = 3000 we obtain $\mathcal {D}^{\rm kSZ}_{3000}$ ∝ zre$^{0.24}\left(1+\sqrt{\left|\overline{f}_{\rm R,0}\right|}\right)^{41}$.

scholarly journals Cosmological Applications of Hα Surveys

1998 ◽  
Vol 15 (1) ◽  
pp. 111-117 ◽  
Author(s):  
David Valls–Gabaud
Keyword(s):  
Cosmic Microwave Background ◽  
Background Radiation ◽  
Massive Stars ◽  
High Redshift ◽  
Formation Rate ◽  
Cosmic Microwave Background Radiation ◽  
Microwave Background ◽  
Microwave Background Radiation

AbstractWe briefly review three main applications of Hα surveys in cosmology, namely: (1) the diffuse Hα emission as a tracer of the free–free foreground that contaminates the fluctuations in the cosmic microwave background radiation; (2) the Hα emission from galaxies as a measure of the formation rate of massive stars, both at low and high redshift; and (3) the diffuse Hα emission from ionised clouds as a constraint on the local ionising background radiation.

scholarly journals Cosmic calibration: Constraints from the matter power spectrum and the cosmic microwave background

2007 ◽  
Vol 76 (8) ◽  
Author(s):  
Salman Habib ◽  
Katrin Heitmann ◽  
David Higdon ◽  
Charles Nakhleh ◽  
Brian Williams
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Matter Power Spectrum

scholarly journals Latest inflation model constraints from cosmic microwave background measurements: Addendum

2008 ◽  
Vol 78 (8) ◽  
Author(s):  
William H. Kinney ◽  
Edward W. Kolb ◽  
Alessandro Melchiorri ◽  
Antonio Riotto
Keyword(s):  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Inflation Model

scholarly journals Optical and IR Properties of Radio Galaxies as a Function of their Radio Power

1996 ◽  
Vol 171 ◽  
pp. 414-414
Author(s):  
L. Maxfield ◽  
S.G. Djorgovski ◽  
D. Thompson ◽  
M.A. Pahre ◽  
R.R. de Carvalho ◽  
...  
Keyword(s):  
High Redshift ◽  
Spectroscopic Properties ◽  
Radio Galaxies ◽  
Active Nucleus ◽  
Data Set ◽  
Uv Emission ◽  
Two Samples ◽  
Order Of Magnitude ◽  
Ir Photometry ◽  
Radio Power

We compare optical and infrared photometric and spectroscopic properties of high-redshift radio galaxies from the 3CR and B3 surveys. At a given redshift and a fixed restframe frequency, the two samples differ on average by an order of magnitude in radio power, thus providing a fair baseline in radio powerfor a range of redshifts. We present new optical and IR photometry and spectrosopy for a number of B3 sources. We combine these data with the existing corresponding information on B3 and 3CR sources, in order to explore different correlations of source properties with redshift, and among themselves. B3 sources follow the same trend as 3CR's in the K band Hubble diagram, although they do seem to be slightly fainter on average at a given redshift. This trend is slightly more prominent in the Gunn r band. This suggests that some fraction of the observed light in the r and K bands is contributed by an active nucleus, which also powers the radio lobes. The B3's also tend to have lower emission line luminosities than 3CR's at any given redshift, suggesting that there may be a correlation between line luminosity and radio power. Such a correlation is clearly seen and is followed by both samples. It suggests that the UV emission lines are largely powered by the active nucleus, ostensibly a hidden quasar, which is also responsible for the radio emission. We also examine the behavior of the optical and radio PA alignments for the combined B3+3CR data set. We find that high-power and high-redshift subsamples for both B3's and 3CR's show the alignments more prominently, but we still cannot tell which of these variables dominates this effect. This work was supported in part by the NSF PYI award AST-9157412, and the Bressler Foundation.

Imaging the Cosmic Microwave Background with the Arcminute Cosmology Bolometer Array Receiver

2005 ◽  
Vol 216 ◽  
pp. 43-50
Author(s):  
J. B. Peterson ◽  
A. K. Romer ◽  
P. L. Gomez ◽  
P. A. R. Ade ◽  
J. J. Bock ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
Clusters Of Galaxies ◽  
Microwave Background ◽  
Bolometer Array ◽  
The Galaxy ◽  
Millimeter Wave Receiver ◽  
Array Receiver

The Arcminute Cosmology Bolometer Array Receiver (Acbar) is a multifrequency millimeter-wave receiver optimized for observations of the Cosmic Microwave Background (CMB) and the Sunyaev-Zel'dovich (SZ) effect in clusters of galaxies. Acbar was installed on the 2.1 m Viper telescope at the South Pole in January 2001 and the results presented here incorporate data through July 2002. The power spectrum of the CMB at 150 GHz over the range ℓ = 150 — 3000 measured by Acbar is presented along with estimates for the values of the cosmological parameters within the context of ΛCDM models. The inclusion of ΩΛ greatly improves the fit to the power spectrum. Three-frequency images of the SZ decrement/increment are also presented for the galaxy cluster 1E0657–67.

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