The combination of seven-year data from WMAP and improved astrophysical data rigorously tests the standard cosmological model and places new constraints on its basic parameters and extensions. By combining the WMAP data with the latest distance measurements from the baryon acoustic oscillations (BAO) in the distribution of galaxies and the Hubble constant (H0) measurement, we determine the parameters of the simplest six-parameter ΛCDM model. The power-law index of the primordial power spectrum is ns = 0.968 ± 0.012 (68% CL) for this data combination, a measurement that excludes the Harrison–Zel’dovich–Peebles spectrum by 99.5% CL. The other parameters, including those beyond the minimal set, are also consistent with, and improved from, the five-year results. We find no convincing deviations from the minimal model. The seven-year temperature power spectrum gives a better determination of the third acoustic peak, which results in a better determination of the redshift of the matter-radiation equality epoch. Notable examples of improved parameters are the total mass of neutrinos, � mν < 0.58 eV (95% CL), and the effective number of neutrino species, Neff = 4.34 +0.86 −0.88 (68% CL), which benefit from better determinations of the third peak and H0. The limit on a constant dark energy equation of state parameter from WMAP+BAO+H0, without high-redshift Type Ia supernovae, is w =− 1.10 ± 0.14 (68% CL). We detect the effect of primordial helium on the temperature power spectrum and provide a new test of big bang nucleosynthesis by measuring Yp = 0.326 ± 0.075 (68% CL). We detect, and show on the map for the first time, the tangential and radial polarization patterns around hot and cold spots of temperature fluctuations, an important test of physical processes at z = 1090 and the dominance of adiabatic scalar fluctuations. The seven-year polarization data have significantly improved: we now detect the temperature–E-mode polarization cross power spectrum at 21σ , compared with 13σ from the five-year data. With the seven-year temperature–B-mode cross power spectrum, the limit on a rotation of the polarization plane due to potential parity-violating effects has improved by 38% to Δα =− 1. 1 ± 1. 4(statistical) ± 1. 5(systematic) (68% CL). We report significant detections of the Sunyaev–Zel’dovich (SZ) effect at the locations of known clusters of galaxies. The measured SZ signal agrees well with the expected signal from the X-ray data on a cluster-by-cluster basis. However, it is a factor of 0.5–0.7 times the predictions from “universal profile” of Arnaud et al., analytical models, and hydrodynamical simulations. We find, for the first time in the SZ effect, a significant difference between the cooling-flow and non-cooling-flow clusters (or relaxed and non-relaxed clusters), which can explain some of the discrepancy. This lower amplitude is consistent with the lower-than-theoretically expected SZ power spectrum recently measured by the South Pole Telescope Collaboration.

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Seven-year wilkinson microwave anisotropy probe (wmap *) observations: cosmological interpretation

?????The NRAO VLA Sky Survey (NVSS) covers the sky north of J2000.0 ? = -40? (82% of the celestial sphere) at 1.4 GHz. The principal data products are (1) a set of 2326 4? ? 4? continuum cubes with three planes containing Stokes I, Q, and U images plus (2) a catalog of almost 2 ? 106 discrete sources stronger than S ? 2.5 mJy. The images all have ? = 45'' FWHM resolution and nearly uniform sensitivity. Their rms brightness fluctuations are ? ? 0.45 mJy beam-1 ? 0.14 K (Stokes I) and ? ? 0.29 mJy beam-1 ? 0.09 K (Stokes Q and U). The rms uncertainties in right ascension and declination vary from 1'' for the N ? 4 ? 105 sources stronger than 15 mJy to 7'' at the survey limit. The NVSS was made as a service to the astronomical community. All data products, user software, and updates are being released via the World Wide Web as soon as they are produced and verified.

https://iopscience.iop.org/article/10.1086/300337/pdf

The NRAO VLA Sky Survey

Modified Gravity and Cosmology

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed and updated. Einstein’s equivalence principle (EEP) is well supported by experiments such as the Eotvos experiment, tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, the Nordtvedt effect in lunar motion, and frame-dragging. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and a growing family of other binary pulsar systems is yielding new tests, especially of strong-field effects. Current and future tests of relativity will center on strong gravity and gravitational waves.

/pdf/the-confrontation-between-general-relativity-and-experiment-5dqdube5p9.pdf

The Confrontation Between General Relativity and Experiment

We have observed 1 10 -1 01 (18.3 GHz) transition of ortho-cyclopropenylidene, C 3 H 2 , at 24 positions in the unusual dense cloud G1.6-0.025. Except for one position, the transition is refrigerated, a phenomenon which has not been seen in this transition before and was not predicted to occur. In general, the absorption correlates with the absorption seen in the 2 0 -3 −1 (12.2 GHz) transition of methanol, but there are significant differences. We suspect that collisional excitation at relatively high kinetic temperature (50 K) enhanced by photon trapping is responsible for the refrigeration

Refrigeration of the 18.3 GHz C_3H_2 Transition in Dark Clouds G1.6-0.25

The Origin of Intra-Day Variability

Intra-day variability (IDV) of active galactic nuclei (AGN) has been detected from gamma-rayenergies to radio wavelengths. At high energies, such variability appears to be intrinsic to thesources themselves. However, at radio wavelengths, brightness temperatures as high as 1018 to1021 K are encountered if the mv is intrinsic to the source. We discuss here the accumulating evidenceshowing that, at radio wavelengths where the highest brightness temperatures are encountered,interstellar scintillation (ISS) is the principal mechanism causing IDV. While ISS reduces the impliedbrightness temperatures, they still remain uncomfortably high.

Radio Intra-Day Variability: Answers and Questions

We present results from the first intercontinental test of the Canadian S-2 recording system. In 1993 November a number of continuum and OH maser sources were observed with bandwidths of 16 and 4 MHz, respectively, and two-bit sampling. In this report we concentrate on the OH maser sources for which 1665- and 1667-MHz transitions were detected. Continuum results will be reported separately. The measured upper limits on the scattered angular size are an order of magnitude lower than the average scattered size calculated from the Galactic model of scattering distribution by Cordes, Weisberg & Boriakoff. Our results are consistent with a patchy distribution of the scattering material in the Galactic disc, with some OH masers located in regions of low interstellar scattering.

/pdf/vlbi-observations-of-oh-masers-with-the-s-2-recording-system-1vkaepy7fu.pdf

John Reynolds

Papers

Refrigeration of the 18.3 GHz C_3H_2 Transition in Dark Clouds G1.6-0.25

The Origin of Intra-Day Variability

Radio Intra-Day Variability: Answers and Questions

VLBI observations of OH masers with the S-2 recording system

VSOP and ATCA observations of PKS 0637-752