We report long, pointed ROSAT HRI observations of the hyperluminous galaxies IRAS F00235+1024, F12514+1027, F14481+4454 and F14537+1950. Two of them are optically classified as Seyfert-like. No X-ray sources are detected at the positions of any of the objects, with a mean upper limit LX/LBol ≃ 2.3 × 10-4. This indicates that any active nuclei are either atypically weak at X-ray wavelengths or obscured by column densities NH > 1023 cm-2. They differ markedly from 'ordinary' Seyfert 2 galaxies, bearing a closer resemblance in the soft X-ray band to composite Seyfert 2 galaxies or to some types of starburst.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science