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Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

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Resolving the extragalactic hard X-ray background

Mushotzky¹, Cowie, Barger

¹NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.

|April 13, 2000

Summary

This summary is machine-generated.

Researchers have identified the sources of the hard X-ray background, a cosmic mystery for decades. Deep Chandra observations reveal these sources match the background

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Area of Science:

Cosmic X-ray astronomy
Astrophysics
High-energy astrophysics

Background:

The origin of the hard X-ray background (2-10 keV) remains unexplained for over 35 years.
While soft X-ray background sources (primarily quasars) are identified, their spectral energy distribution does not match the overall background spectrum.

Purpose of the Study:

To investigate and resolve the mystery of the hard X-ray background's origin.
To identify the sources contributing to the hard X-ray background and analyze their properties.

Main Methods:

Utilized the Chandra satellite for a deep X-ray survey.
Analyzed the spectral energy distribution of detected hard X-ray sources.

Main Results:

Detected hard X-ray sources account for at least 75% of the hard X-ray background.
The average spectral energy distribution of these sources closely matches the background spectrum.
Identified sources are associated with either nuclei of bright galaxies or optically faint objects, potentially active galactic nuclei or high-redshift quasars.

Conclusions:

The study significantly resolves the long-standing mystery of the hard X-ray background.
Identified sources provide a strong explanation for the observed hard X-ray background spectrum.
The findings suggest a significant contribution from active galactic nuclei, possibly obscured, or distant quasars.