相关论文: Small-Scale Fluctuations in Cosmic X-ray Backgroun…
Large-angle fluctuations in the cosmic X-ray background are investigated by a new formalism with a simple model of the X-ray sources. Our method is formulated from the Boltzmann equation and a simple extension of the work by Lahav et al. to…
We present an attempt to measure the large angular scale fluctuations in the X-Ray Background (XRB) from the HEAO1-A2 data, expressed in terms of spherical harmonics. We model the harmonic coefficients assuming a power spectrum and an…
Fluctuations of the soft X-ray background are investigated using harmonic analysis. A section of the ROSAT All-Sky Survey around the north galactic pole is used. The flux distribution is expanded into a set of harmonic functions and the…
We review the current status of studies of large-scale structure in the X-ray Universe. After motivating the use X-rays for cosmological purposes, we discuss the various approaches used on different angular scales including X-ray background…
The X-ray background is generated by various classes of objects and variety of emission mechanisms. Relative contribution of individual components depends on energy. The goal is to assess the integral emission of the major components of the…
We have performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal…
We present a formalism for computing time-dependent fluctuations in the cosmological photoionizing radiation background, extending background fluctuations models beyond the steady-state approximation. We apply this formalism to estimate…
The precision of intensity measurements of the extragalactic X-ray Background (XRB) on an angular scale of about a degree is dominated by spatial fluctuations caused by source confusion noise. X-ray source counts at the flux level…
We propose a new, simple, dedicated X-ray mission to measure the power spectrum of density fluctuations in the Universe, by accurately mapping the X-ray background on the whole sky on scales of arounf one sq deg. Since the method relies on…
The angular power spectrum of the Cosmic Microwave Background has been measured out to sufficiently small angular scale to encompass a few acoustic oscillations. We use a phenomenological fit to the angular power spectrum to quantify the…
The search for faint emission or absorption lines in astronomical spectra has received considerable attention in recent years, especially in the X-ray wavelength range. These features usually appear as a deficit or excess of counts in a…
Sources generating most of the X-ray background (XRB) are dispersed over a wide range of redshifts. Thus, statistical characteristics of the source distribution carry information on matter distribution on very large scales. We test the…
We study the cosmic X-ray background (CXB) intensity variations on large angular scales using slew data of the RXTE observatory. We detect intensity variations up to ~2% on angular scales of 20--40deg. These variations are partly correlated…
We describe an attempt to reconstruct the initial conditions for the formation of cosmological large-scale structure. The power spectrum of the primordial fluctuations is affected by bias, nonlinear evolution and redshift-space distortions,…
Working by analogy, we use the description of light fluctuations due to random collisions of the radiating atoms to figure out why the reduction of the coherence for light propagating a cosmological distance in the fluctuating background…
We have studied the fluctuations of the soft (0.9-2 keV) X-ray background intensity for ~10 arcmin and ~2 arcmin beam sizes, using 80 high galactic latitude medium-deep images from the ROSAT position sensitive proportional counter (PSPC).…
Fluctuations in the large-scale structure of the Universe contain significant information about cosmological physics, but are modulated in survey datasets by various observational effects. Building on existing literature, we provide a…
The X-Ray Background (XRB) probes structure on scales intermediate between those explored by local galaxy redshift surveys and by the COBE Microwave Background measurements. We predict the large scale angular fluctuations in the XRB,…
The power spectrum of quantum fluctuations of the electromagnetic field produced by an elementary particle is determined. It is found that in a wide range of practically important frequencies the power spectrum of fluctuations exhibits an…
The shape of the primordial fluctuation spectrum is probed by cosmic microwave background fluctuations which measure density fluctuations at z~1000 on scales of hundreds of Mpc and from galaxy redshift surveys, which measure structure at…