Spatial Power Spectral Analysis of the Suzaku X-ray Background

Abstract

Power spectra of spatial fluctuations of X-ray emission may impose constraints on the origins of the emission independent of that from the energy spectra. We generated spatial power spectrum densities (PSD) of blank X-ray skies observed with Suzaku X-ray observatory utilizing the modified $\Delta$-variance method. Using the total measured count rate as the diagnostic tool, we found that a model consisting of the sum of two components, one for the unresolved faint point sources and one for the uniform flat-field emission, can well represent the observed PSD in three different energy bands (0.2-0.5 keV, 0.5-2 keV, and 2-10 keV); only an upper limit is obtained for the latter component in 2-10 keV. X-ray counting rates corresponding to the best-fit PSD model functions and diffuse emission fractions were estimated, and we confirmed that the sum of the counting rates of two model components is consistent with those actually observed with the detector for all energy bands. The ratio of the flat-field counting rate to the total in 0.5-2 keV, however, is significantly larger than the diffuse emission fraction estimated from the model fits of energy spectra. We discussed that this discrepancy can be reconciled by systematic effects in the PSD and energy spectrum analyses. The present study demonstrates that the spatial power spectrum is powerful in constraining the origins of the X-ray emission.

arXiv comment12 pages, 4 figures, Accepted for publication in Astrophysical Journal

References in corpus (18)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Where are the Baryons?
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• Monte-Carlo Simulator and Ancillary Response Generator of Suzaku XRT/XIS System for Spatially Extended Source Analysis
• A High Spectral Resolution Observation of the Soft X-ray Diffuse Background with Thermal Detectors
• The resolved fraction of the Cosmic X-ray Background
• Reproducibility of Non-X-ray Background for the X-ray Imaging Spectrometer aboard Suzaku
• The 4 Ms Chandra Deep Field-South Number Counts Apportioned by Source Class: Pervasive Active Galactic Nuclei and the Ascent of Normal Galaxies
• The Nature of the Hard X-ray Background Sources: Optical, Near-infrared, Submillimeter, and Radio Properties
• Energy Spectra of the Soft X-ray Diffuse Emission in Fourteen Fields Observed with Suzaku
• Cosmic Infrared Background and Early Galaxy Evolution
• The origin of the 'local' 1/4 keV X-ray flux in both charge exchange and a hot bubble
• The Structure of the Local Hot Bubble
• A Mexican Hat with holes: calculating low resolution power spectra from data with gaps
• The nature of the unresolved extragalactic soft CXB
• The Submillimeter Properties of the 1 Ms Chandra Deep Field North X-ray Sample
• Evidence for the Missing Baryons in the Angular Correlation of the Diffuse X-ray Background
• X-Ray Emission from the Warm Hot Intergalactic Medium

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