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Astron. Astrophys. 334, L13-L16 (1998)

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Letter to the Editor

The cosmic X-ray background spectrum observed with ROSAT
and ASCA

T. Miyaji 1, 2, Y. Ishisaki 3, Y. Ogasaka 4, 5, Y. Ueda 5, M.J. Freyberg 2, G. Hasinger 1 and Y. Tanaka 2

1 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
2 Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching bei München, Germany
3 Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, 192-03, Japan
4 Code 662, NASA Goddard Space Flight Center, MD 20771, USA
5 The Institute of Space and Astronautical Sciences, 3-1-1, Yoshinodai, Sagamihara, 229, Japan

Received 16 September 1997 / Accepted 20 March 1998


We have made a series of joint spectral fits for two blank fields, the Lockman Hole and the Lynx-3A field, where a significant amount of both ASCA and ROSAT PSPC data exist after thorough screenings. The ASCA SIS, GIS and ROSAT PSPC spectra from these fields have been fitted simultaneously. Comparison at [FORMULA] keV shows general agreement within 10% in the Lockman Hole data and a [FORMULA] disagreement in the Lynx-3A data, indicating remaining observation-dependent systematic problems. In both cases, satisfactory fits have been found for the overall 0.1-10 keV spectrum with an extragalactic power-law component (or a broken power-law component with steepening at [FORMULA] keV), a hard thermal component with plasma temperature of [FORMULA] keV and a soft thermal component [FORMULA] keV.

Key words: ISM: bubbles – galaxy: halo – cosmology: diffuse radiation – X-rays: general

Send offprint requests to: T. Miyaji (tmiyaji@aip.de)


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© European Southern Observatory (ESO) 1998

Online publication: May 12, 1998