The low-energy cosmic X-ray background spectrum observed by the BeppoSAX LECS

The spectrum of the 0.1-7.0 keV cosmic X-ray background (CXB) at galactic l atitudes >\25\degrees has been measured using the BeppoSAX Low-Energy Spect rometer Concentrator (LECS). Above 1 keV the spectrum is consistent with a power-law of photon index 1.47 +/- 0.10 and normalization 11.0 +/- 0.8 phot on cm(-2) s(-1) keV(-1) sr(-1) at 1 keV. The overall spectrum can be modele d by a power-law with 2 thermal components, or by a broken power-law and a single thermal component. In both cases the softer thermal emission dominat es less than or similar to 0.3 keV and is seen through a column, N-H, of a few 10(19) atom cm(-2). The other components have NH consistent with the me an line of sight value, The metal abundances for the thermal components are poorly constrained, but consistent with cosmic values. The power-law toget her with 2 thermal components model has been used to fit recent combined AS CA and ROSAT CXB measurements. Here, the soft thermal component is interpre ted as emission from the local hot bubble and the hard thermal component as emission from a more distant absorbed region. While such a 2 component the rmal model is consistent with the LEGS spectrum, it is not required, and th e hard thermal component may result from inadequate modeling of the extraga lactic contribution. The observed low-energy spectral complexity may theref ore originate primarily in the local hot bubble. There is no evidence for t he presence of a very soft CXB component with a temperature less than or si milar to 0.1 keV. The emission measure seen by ROSAT is rejected at 90% con fidence.