scholarly journals Power Spectrum of the Density of Cold Atomic Gas in the Galaxy toward Cassiopeia A and Cygnus A

2000 ◽  
Vol 543 (1) ◽  
pp. 227-234 ◽  
Author(s):  
A. A. Deshpande ◽  
K. S. Dwarakanath ◽  
W. M. Goss
Keyword(s):  
Power Spectrum ◽  
Cassiopeia A ◽  
Cygnus A ◽  
The Galaxy ◽  
Atomic Gas

scholarly journals A Global View of Molecule-Forming Clouds in the Galaxy

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Steven J. Gibson ◽  
Ward S. Howard ◽  
Christian S. Jolly ◽  
Jonathan H. Newton ◽  
Aaron C. Bell ◽  
...  
Keyword(s):  
Line Emission ◽  
Cloud Models ◽  
Global View ◽  
The Galaxy ◽  
Atomic Gas

AbstractWe have mapped cold atomic gas in 21cm line H i self-absorption (HISA) at arcminute resolution over more than 90% of the Milky Way's disk. To probe the formation of H2 clouds, we have compared our HISA distribution with CO J = 1-0 line emission. Few HISA features in the outer Galaxy have CO at the same position and velocity, while most inner-Galaxy HISA has overlapping CO. But many apparent inner-Galaxy HISA-CO associations can be explained as chance superpositions, so most inner-Galaxy HISA may also be CO-free. Since standard equilibrium cloud models cannot explain the very cold H i in many HISA features without molecules being present, these clouds may instead have significant CO-dark H2.

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.

scholarly journals Perturbation theory approach to predict the covariance matrices of the galaxy power spectrum and bispectrum in redshift space

2020 ◽  
Vol 497 (2) ◽  
pp. 1684-1711 ◽  
Author(s):  
Naonori S Sugiyama ◽  
Shun Saito ◽  
Florian Beutler ◽  
Hee-Jong Seo
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Shot Noise ◽  
Signal To Noise Ratio ◽  
Covariance Matrices ◽  
Theory Approach ◽  
Cross Covariance ◽  
The Galaxy ◽  
The Cross ◽  
Non Gaussian

ABSTRACT In this paper, we predict the covariance matrices of both the power spectrum and the bispectrum, including full non-Gaussian contributions, redshift space distortions, linear bias effects, and shot-noise corrections, using perturbation theory (PT). To quantify the redshift-space distortion effect, we focus mainly on the monopole and quadrupole components of both the power and bispectra. We, for the first time, compute the 5- and 6-point spectra to predict the cross-covariance between the power and bispectra, and the autocovariance of the bispectrum in redshift space. We test the validity of our calculations by comparing them with the covariance matrices measured from the MultiDark-Patchy mock catalogues that are designed to reproduce the galaxy clustering measured from the Baryon Oscillation Spectroscopic Survey Data Release 12. We argue that the simple, leading-order PT works because the shot-noise corrections for the Patchy mocks are more dominant than other higher order terms we ignore. In the meantime, we confirm some discrepancies in the comparison, especially of the cross-covariance. We discuss potential sources of such discrepancies. We also show that our PT model reproduces well the cumulative signal-to-noise ratio of the power spectrum and the bispectrum as a function of maximum wavenumber, implying that our PT model captures successfully essential contributions to the covariance matrices.

scholarly journals Impact of relativistic effects on the primordial non-Gaussianity signature in the large-scale clustering of quasars

2020 ◽  
Vol 499 (2) ◽  
pp. 2598-2607
Author(s):  
Mike (Shengbo) Wang ◽  
Florian Beutler ◽  
David Bacon
Keyword(s):  
Dark Energy ◽  
Power Spectrum ◽  
Luminosity Function ◽  
Large Scale ◽  
Relativistic Effects ◽  
Redshift Range ◽  
Cosmological Background ◽  
Relativistic Corrections ◽  
The Galaxy ◽  
The Impact

ABSTRACT Relativistic effects in clustering observations have been shown to introduce scale-dependent corrections to the galaxy overdensity field on large scales, which may hamper the detection of primordial non-Gaussianity fNL through the scale-dependent halo bias. The amplitude of relativistic corrections depends not only on the cosmological background expansion, but also on the redshift evolution and sensitivity to the luminosity threshold of the tracer population being examined, as parametrized by the evolution bias be and magnification bias s. In this work, we propagate luminosity function measurements from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) to be and s for the quasar (QSO) sample, and thereby derive constraints on relativistic corrections to its power spectrum multipoles. Although one could mitigate the impact on the fNL signature by adjusting the redshift range or the luminosity threshold of the tracer sample being considered, we suggest that, for future surveys probing large cosmic volumes, relativistic corrections should be forward modelled from the tracer luminosity function including its uncertainties. This will be important to quasar clustering measurements on scales $k \sim 10^{-3}\, h\, {\rm Mpc}^{-1}$ in upcoming surveys such as the Dark Energy Spectroscopic Instrument (DESI), where relativistic corrections can overwhelm the expected fNL signature at low redshifts z ≲ 1 and become comparable to fNL ≃ 1 in the power spectrum quadrupole at redshifts z ≳ 2.5.

scholarly journals Gravitational theory of cosmology, galaxies and galaxy clusters

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
J. W. Moffat
Keyword(s):  
Power Spectrum ◽  
Galaxy Clusters ◽  
Degrees Of Freedom ◽  
Galaxy Cluster ◽  
Gravitational Theory ◽  
Baryon Density ◽  
Late Time ◽  
Matter Power Spectrum ◽  
The Galaxy ◽  
Parameter Values

AbstractA modified gravitational theory explains early universe and late time cosmology, galaxy and galaxy cluster dynamics. The modified gravity (MOG) theory extends general relativity (GR) by three extra degrees of freedom: a scalar field G, enhancing the strength of the Newtonian gravitational constant $$G_N$$ G N , a gravitational, spin 1 vector graviton field $$\phi _\mu $$ ϕ μ , and the effective mass $$\mu $$ μ of the ultralight spin 1 graviton. For $$t < t_\mathrm{rec}$$ t < t rec , where $$t_\mathrm{rec}$$ t rec denotes the time of recombination and re-ionization, the density of the vector graviton $$\rho _\phi > \rho _b$$ ρ ϕ > ρ b , where $$\rho _b$$ ρ b is the density of baryons, while for $$t > t_\mathrm{rec}$$ t > t rec we have $$\rho _b > \rho _\phi $$ ρ b > ρ ϕ . The matter density is parameterized by $$\Omega _M=\Omega _b+\Omega _\phi +\Omega _r$$ Ω M = Ω b + Ω ϕ + Ω r where $$\Omega _r=\Omega _\gamma +\Omega _\nu $$ Ω r = Ω γ + Ω ν . For the cosmological parameter values obtained by the Planck Collaboration, the CMB acoustical oscillation power spectrum, polarization and lensing data can be fitted as in the $$\Lambda $$ Λ CDM model. When the baryon density $$\rho _b$$ ρ b dominates the late time universe, MOG explains galaxy rotation curves, the dynamics of galaxy clusters, galaxy lensing and the galaxy clusters matter power spectrum without dominant dark matter.

scholarly journals COSMIC EMULATION: FAST PREDICTIONS FOR THE GALAXY POWER SPECTRUM

2015 ◽  
Vol 810 (1) ◽  
pp. 35 ◽  
Author(s):  
Juliana Kwan ◽  
Katrin Heitmann ◽  
Salman Habib ◽  
Nikhil Padmanabhan ◽  
Earl Lawrence ◽  
...  
Keyword(s):  
Power Spectrum ◽  
The Galaxy

Measuring the Galaxy Power Spectrum with Multiresolution Decomposition. IV. Redshift Distortion

2002 ◽  
Vol 566 (2) ◽  
pp. 630-640 ◽  
Author(s):  
XiaoHu Yang ◽  
Long‐Long Feng ◽  
YaoQuan Chu ◽  
Li‐Zhi Fang
Keyword(s):  
Power Spectrum ◽  
Multiresolution Decomposition ◽  
The Galaxy

scholarly journals The structure of the Cassiopeia A and Cygnus A radio sources measured at 127 Mc/s and 3000 Mc/s

1959 ◽  
Vol 9 ◽  
pp. 309-314
Author(s):  
R. C. Jennison
Keyword(s):  
Position Angle ◽  
Brightness Distribution ◽  
Radio Sources ◽  
Cassiopeia A ◽  
The Third ◽  
Cygnus A ◽  
Main Component ◽  
Main Region

The brightness distribution across the Cassiopeia A source in position angle 90 degrees consists of a primary region of emission 4.1 minutes of arc in width, with a much fainter extension offset from the main region of emission and having a brightness of only 10 per cent of that of the main component. Measurements were made up to the third maximum of the transform (2160 λ), and the position of the first zero was determined at 840 λ.

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