SIMBAD references

We analyzed discrete sources in a typical starburst galaxy, NGC 1808, with Chandra in order to study the relation between X-ray and star-forming activities. We detected thirty-eight X-ray sources with an X-ray luminosity (L_X) of > 10³⁷ erg/s in the central 5' x 5' (13.4 kpc x 13.4 kpc) region. About 90% of the hard X-rays previously detected with ASCA came from these discrete sources. Among the detected sources, sixteen sources had an L_X of > 10³⁸ erg/s. The number of luminous sources is nearly equal to that of M 82, although their concentration into the central star-forming region is lower than that of M 82. There are several soft X-ray sources with a temperature of 0.6 keV in the central star-forming region. The X-ray properties of the soft sources are similar to those of a H II region, or a supernova remnant. The existence of both luminous sources and soft X-ray sources indicates the star-forming activity of NGC 1808. However, we detected only a few candidates of high-mass X-ray binaries that would be produced by enhanced star-forming activity. This may be due to the starburst age of NGC 1808.