SIMBAD references

The Seyfert 1 galaxy E 1615+061 is a candidate for the strongest variability in soft X-rays, changing from a very steep high state ({GAMMA}≃4), as implied by HEAO1 observations performed in 1977, to a two orders of magnitude dimmer state with a flatter spectrum ({GAMMA}≃2), as observed by EXOSAT in 1985. In this paper we present the results of a campaign of (quasi)-simultaneous observations with IUE, ROSAT and GINGA in 1990-1992. We found that the X-ray luminosity was about 6 times larger than observed by EXOSAT, though the object did not attain the level observed by HEAO-1. The UV to X-ray spectrum observed in our campaign shows the presence of a UV bump and a soft X-ray excess. These components are formally fitted by a standard thin accretion disk model. We find however that this model is not self-consistent, due to the high level of ionization expected for the high value of accretion rate, which leads to an over-production of soft X-rays by reflection. A self-consistent explanation is found in the low accretion rate regime. In this case reflection by mildly ionized regions of the disk produces the soft excess and the direct emission from the disk accounts for the UV emission but does not extend to the soft X-ray region. Some evidence for a line at around 0.6keV, attributed to OVII/OVIII, supports the presence of an ionized reflector. The spectra observed by EXOSAT and HEAO1 can be successfully explained by this model in the regimes of very low and high accretion rates.