By Liu Honghui

We looked into all archival high-resolution data of the narrow-line Seyfert 1 Mrk 335 observed by the Reflection Grating Spectrometers (RGS) onboard XMM-Newton. We find that the X-ray lines are significantly less variable than the X-ray continuum, but it is difficult to constrain the size of the geometry of the line emitting gas.

Simulations with an exposure of 100 ks show that Athena/X-IFU (see inset spectra in the image) can provide very high signal-to-noise data of this source, which can be used to constrain tightly the density and ionization parameter of the X-ray line emitting gas. This is important for estimating the location of the gas in the system.

Access to the manuscript in ADS.