2008A&A...483..137B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST21:08:20

2008A&A...483..137B - Astronomy and Astrophysics, volume 483, 137-149 (2008/5-3)

X-ray spectral variability in PG 1535+547: the changing look of a ``soft X-ray weak'' AGN.

BALLO L., GIUSTINI M., SCHARTEL N., CAPPI M., JIMENEZ-BAILON E., PICONCELLI E., SANTOS-LLEO M. and VIGNALI C.

Abstract (from CDS):

object{PG 1535+547} is a bright Narrow Line Seyfert 1 galaxy, whose high-energy emission shows strong variability both in shape and flux. On the basis of ROSAT observations, it is classified as ``soft X-ray weak quasi-stellar object (QSO)'', a class of objects whose X-ray-to-optical flux ratio is smaller than in typical QSOs. Their X-ray spectra are often characterized by highly-ionized, complex absorbers and/or reflection from the inner accretion disk, and the relative importance of the two is currently debated. Whatever the correct interpretation may be, the presence of such features implies that we are looking at matter located in the innermost regions of these AGN. We want to clarify the nature of the X-ray emission of PG 1535+547, and constrain the physical properties of its innermost regions, where this emission originates. We present new XMM-Newton observations of PG 1535+547 (90ks exposure time, January 2006), from which we obtained two spectra European Photon Imaging Camera (EPIC) separated by about one week. We compare these spectra with those from a previous (November 2002) XMM-Newton observation. These latest observations support the complex and variable nature of the X-ray emission of PG 1535+547. The broadband observed flux increases by a factor ∼2.3 in three years, and then decreases by a factor ∼1.3 in about one week. In the new spectra, strong absorption features at E < 3 keV and a complex spectral shape in the iron-line energy range are evident, coupled with a drop in the emission at higher energies. We describe all the different states in a consistent way, assuming either a warm absorber plus a relativistically-blurred ionized reflection, or a two-phase warm absorber partially covering the source with the addition of a scattered component. The observed variability can be ascribed mostly to warm absorbing gas in the innermost regions of PG 1535+547, which appears to vary in its physical properties on timescales of both years and days. In the blurred reflection scenario, all the analyzed states require a high fraction of reflection from the disk, calling for some mechanisms able to increase the reflection component with respect to the intrinsic continuum. Finally, the strong variability observed in the X-ray band opposed to a more constant emission at optical frequencies, changes the value of the X-ray-to-optical spectral index, implying that PG 1535+547 can not actually be classified as a soft X-ray weak active galactic nucleus (AGN).

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: quasars: individual: PG 1535+547 - X-rays: galaxies

Simbad objects: 19

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Number of rows : 19

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Mrk 335 Sy1 00 06 19.5371542746 +20 12 10.617456059   14.19 13.85     ~ 1091 0
2 Mrk 1501 Sy1 00 10 31.0058529490 +10 58 29.505989476   15.96 15.40 12.22   ~ 639 0
3 3XMM J003915.8-511701 Sy1 00 39 15.8341273306 -51 17 01.480962252   15.77 15.28 15.66   ~ 120 0
4 Mrk 1502 Sy1 00 53 34.9326560879 +12 41 35.927159668   14.41 14.03     ~ 1034 1
5 LB 1727 Sy1 04 26 00.7188445954 -57 12 01.772037544 13.68 14.58 14.37 14.8   ~ 235 0
6 2MASX J04523006-2953353 Sy1 04 52 30.0811 -29 53 35.226 15.07 17.39 15.35 16.06   ~ 118 0
7 IC 450 Sy1 06 52 12.32333 +74 25 37.2376   15.16 14.19     ~ 498 1
8 4U 0708-49 Sy1 07 08 41.4887418009 -49 33 06.308287663   16.02 15.7 12.7   ~ 422 0
9 Ton 951 Sy1 08 47 42.4487014731 +34 45 04.483113429   14.83 14.50     ~ 417 0
10 Mrk 110 Sy1 09 25 12.8479868736 +52 17 10.386808297   16.82 16.41     ~ 510 0
11 Mrk 1239 Sy1 09 52 19.168 -01 36 44.10   14.99 14.39 11.2   ~ 287 0
12 Ton 1388 Sy1 11 19 08.6786143504 +21 19 17.986556889   14.91 14.80     ~ 414 0
13 MCG-03-34-064 Sy2 13 22 24.485 -16 43 42.09   14   13.16   ~ 259 2
14 Mrk 279 Sy1 13 53 03.4356451470 +69 18 29.410672989   15.15 14.46     ~ 693 0
15 Mrk 841 Sy1 15 04 01.1935077982 +10 26 15.778741853   14.50 14.27     ~ 583 0
16 Mrk 486 Sy1 15 36 38.4013129866 +54 33 33.214684833   15.21 14.78     ~ 248 0
17 2MASS J21145258+0607423 Sy1 21 14 52.5774242314 +06 07 42.435724828   16.06 15.77     ~ 198 0
18 QSO J2155-0922 Sy1 21 55 01.5123415724 -09 22 24.351917710   13.9 16.8 14.1   ~ 155 0
19 Mrk 304 Sy1 22 17 12.2638362727 +14 14 20.918554073   15.02 14.66     ~ 317 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-21:08:20

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