Stephen P. Boughn

A correlation between the cosmic microwave background and large-scale structure in the Universe

Observations of distant supernovae and the fluctuations in the cosmic microwave background (CMB) indicate that the expansion of the Universe may be accelerating under the action of a ‘cosmological constant’ or some other form of ‘dark energy’. This dark energy now appears to dominate the Universe and not only alters its expansion rate, but also affects the evolution of fluctuations in the density of matter, slowing down the gravitational collapse of material (into, for example, clusters of galaxies) in recent times. Additional fluctuations in the temperature of CMB photons are induced as they pass through large-scale structures and these fluctuations are necessarily correlated with the distribution of relatively nearby matter. Here we report the detection of correlations between recent CMB data and two probes of large-scale structure: the X-ray background and the distribution of radio galaxies. These correlations are consistent with those predicted by dark energy, indicating that we are seeing the imprint of dark energy on the growth of structure in the Universe.The fluctuations in the cosmic microwave background (CMB) have proved an invaluable tool for uncovering the nature of our universe. The recent dramatic data provided by the WMAP satellite [1] have confirmed previous indications that the expansion of the universe may be accelerating[2], driven by a cosmological constant or similar dark energy component. One consequence of dark energy is the suppression of the rate of gravitational collapse of matter at relatively recent times. This causes fluctuations in the CMB to be created as the photons pass through nearby large scale structures, a phenomenon known as the integrated Sachs-Wolfe (ISW) effect. The result is additional large scale fluctuations in the CMB which are correlated with the relatively nearby (i.e., at redshift z ∼ 1) matter distribution [3]. Here we report evidence of correlations between the WMAP data and two all sky probes of large scale structure, the hard X-ray background observed by the HEAO-1 satellite [4] and the NVSS survey of radio galaxies [5]. Both observed correlations are consistent with an ISW origin, indicating that we are seeing the impact of dark energy on the growth of structure.

Combined analysis of the integrated Sachs-Wolfe effect and cosmological implications

We present a global measurement of the integrated Sachs-Wolfe (ISW) effect obtained by cross correlating all relevant large-scale galaxy data sets with the cosmic microwave background radiation map provided by the Wilkinson Microwave Anisotropy Probe. With these measurements, the overall ISW signal is detected at the

Can Gravitons Be Detected

\ensuremath{\sim}4.5\ensuremath{\sigma}

Galactic Emission at 19 GHz

level. We also examine the cosmological implications of these measurements, particularly the dark energy equation of state

Correlations Between the Cosmic X-ray and Microwave Backgrounds: Constraints on a Cosmological Constant

w

Dipole and quadrupole anisotropy of the 2. 7 K radiation

, its sound speed

Cross correlation of the cosmic microwave background with radio sources: constraints on an accelerating universe

{c}_{s}

Radio/X-Ray Luminosity Relation for Advection-dominated Accretion: Implications for Emission-Line Galaxies and the X-Ray Background

, and the overall curvature of the Universe. The flat

Observations with a Low-Temperature, Resonant Mass, Gravitational Radiation Detector

\ensuremath{\Lambda}\mathrm{CDM}

THE LARGE-SCALE STRUCTURE OF THE X-RAY BACKGROUND AND ITS COSMOLOGICAL IMPLICATIONS

model is a good fit to the data and, assuming this model, we find that the ISW data constrain