Suzaku broad-band observations of the Seyfert 1 galaxies Mrk 509 and Mrk 841

TL;DR

This study presents Suzaku broad-band X-ray observations of Seyfert 1 galaxies Mrk 509 and Mrk 841, analyzing their spectra with various models to understand the soft excess and iron line features, and comparing reflection and absorption explanations.

Contribution

It provides the first simultaneous broad-band X-ray spectra analysis of these galaxies and evaluates competing models for the soft excess, highlighting the strengths of the blurred reflection model.

Findings

Soft excess is weaker than in previous observations.

Broad Fe emission line is consistently required in models for Mrk 509.

The blurred reflection model best fits the broad-band spectrum for Mrk 841.

Abstract

We report an analysis and modelling of new Suzaku observations of the Seyfert 1 galaxies Mrk509 and Mrk841, taken between April and November 2006,for Mrk509,and between January and July 2007,for Mrk841,for a total exposure time of ~100 ks each.Data from XIS and HXD/PIN instruments,going from 0.5 to 60 keV,represent the highest spectral resolution simultaneous broad-band X-ray spectrum for these objects.We fitted the broad-band spectrum of both sources with a double Comptonisation model,adding neutral reflection from distant material and a two-phase warm absorber.We then studied the two competing models developed to explain the soft excess in terms of atomic processes:a blurred ionised disc reflection and an ionised absorption by a high velocity material.When fitting the data in the 3-10 keV range with a power law spectrum,and extrapolating this result to low energies,a soft excess is clearly observed below 2 keV:its strength is however weak compared to previous observations of both sources.A moderate hard excess is seen at energies greater than 10 keV,together with a neutral Fe K_a narrow emission line at E~6.4 keV and a broad Fe emission line.For Mrk509,the broad Fe emission line is required in all the three physical models in order to have a good fit to the data:this finding suggests that the blurred reflection model correctly describes the soft excess,but that it underestimates the broad Fe emission line.For the smeared absorption model,this suggests instead that the continuum spectrum absorbed by the outflowing gas should contain indeed a reflected component.For Mrk841,all three models that we tested provide a good fit to the data,and we cannot invalidate any of them.A broad emission line is required in the double Comptonisation and smeared absorption models,while the blurred reflection model consistently fits the broad-band spectrum,without adding any extra emission-line component.