Query : 2007A&A...473...85P

2007A&A...473...85P - Astronomy and Astrophysics, volume 473, 85-89 (2007/10-1)

The XMM-Newton view of IRAS 09104+4109: evidence for a changing-look Type 2 quasar?


Abstract (from CDS):

We report on a 14ks XMM-Newton observation of the hyperluminous infrared galaxy IRAS 09104+4109, which harbors a type 2 quasar in its nucleus. Our analysis was aimed at studying the properties of the absorbing matter and the Fe K complex at 6-7keV in this source. We analyzed the spectroscopic data from the PN and the MOS cameras in the 0.4-10keV band. We also used an archival BeppoSAX 1-50keV observation of IRAS 09104+4109 to investigate possible variations of the quasar emission. The X-ray emission in the EPIC band is dominated by the intra-cluster medium thermal emission. We found that the quasar contributes ∼35% of the total flux in the 2-10keV band. Both a transmission- (through a Compton-thin absorber with a Compton optical depth of τC∼0.3, i.e. NH∼5x1023cm–2) and a reflection-dominated (τC>1) model provide an excellent fit to the quasar continuum emission. However, the value measured for the EW of Fe Kα emission line is only marginally consistent with the presence of a Compton-thick absorber in a reflection-dominated scenario, which had been suggested by a previous, marginal (i.e. 2.5σ) detection with the hard X-ray (15-50keV), non-imaging BeppoSAX/PDS instrument. Moreover, the value of luminosity in the 2-10 keV band measured by the transmission-dominated model is fully consistent with that expected on the basis of the bolometric luminosity of IRAS 09104+4109. From the analysis of the XMM-Newton data we therefore suggest the possibility that the absorber along the line of sight to the nucleus of IRAS 09104+4109 is Compton-thin. Alternatively, the absorber column density could have changed from Compton-thick to -thin in the five years elapsed between the observations. If this is the case, then IRAS 09104+4109 is the first ``changing-look'' quasar ever detected.

Abstract Copyright:

Journal keyword(s): galaxies: individual: IRAS 09104+4109 - galaxies: active - galaxies: nuclei - X-ray: galaxies

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NGC 1365 Sy1 03 33 36.458 -36 08 26.37 10.48 10.08 9.63 8.79 9.7 ~ 1721 2
2 2MASS J09134545+4056282 Sy2 09 13 45.4951283928 +40 56 28.215343572   19.69 19.21     ~ 247 2
3 NGC 2782 Sy2 09 14 05.120 +40 06 49.68 12.29 12.30 11.63     ~ 452 3
4 NGC 3227 GiP 10 23 30.5765149296 +19 51 54.282206700   12.61 11.79     ~ 1658 1

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