XMM-Newton observations of the Seyfert 1 AGN H 0557-385

We present XMM-Newton observations of the Seyfert 1 active galactic nucleus (AGN) H 0557 - 385. We have conducted a study into the warm absorber present in this source, and using high-resolution Reflection Grating Spectrometer (RGS) data we find that the absorption can be characterized by two phases: a phase with log ionization parameter xi of 0.50 (where xi is in units of erg cm s(-1)) and a column of 0.2 x 10(21) cm(-2), and a phase with log xi of 1.62 and a column of 1.3 x 10(22) cm(-2). An iron K alpha line is detected. Neutral absorption is also present in the source, and we discuss possible origins for this. On the assumption that the ionized absorbers originate as an outflow from the inner edge of the torus, we use a new method for finding the volume filling factor. Both phases of H 0557 - 385 have small volume filling factors (<= 1 per cent). We also derive the volume filling factors for a sample of 23 AGN using this assumption and for the absorbers with log xi > 0.7, we find reasonable agreement with the filling factors obtained through the alternative method of equating the momentum flow of the absorbers to the momentum loss of the radiation field. By comparing the filling factors obtained by the two methods, we infer that some absorbers with log xi < 0.7 occur at significantly larger distances from the nucleus than the inner edge of the torus.