2002A&A...390...65D


Query : 2002A&A...390...65D

2002A&A...390...65D - Astronomy and Astrophysics, volume 390, 65-80 (2002/7-4)

A 10-day ASCA observation of the narrow-line Seyfert 1 galaxy IRAS 13224-3809.

DEWANGAN G.C., BOLLER T., SINGH K.P. and LEIGHLY K.M.

Abstract (from CDS):

We present an analysis of a 10-day continuous ASCA observation of the narrow-line Seyfert 1 galaxy IRAS 13224-3809. The total band (0.7-10keV) light curve binned with 500s reveals trough-to-peak variation by a factor ≥37. Rapid X-ray variability with a doubling timescale of 500 s has also been detected. The soft (0.7-1.3keV) and hard (1.3-10keV) X-ray band light curves binned to 5000 s reveal trough-to-peak variations by a factor ≥25 and ∼20, respectively. The light curves in the soft and hard bands are strongly correlated without any significant delay. However, this correlation is not entirely due to changes in the power-law flux alone but also due to changes in the soft X-ray hump emission above the power law. The variability amplitude changes across the observation but is not correlated with the X-ray flux. The presence of a soft X-ray hump below ∼2keV, previously detected in ROSAT and ASCA data, is confirmed. Time resolved spectroscopy using daily sampling reveals changes in the power-law slope, with ΓX in the range 1.74-2.47, however, day-to-day variations in ΓX are not significant. The Soft hump emission is found to dominate the observed variability on a timescale of ∼a week, but on shorter timescales (∼20000s) the power-law component appears to dominate the observed variability. Flux resolved spectroscopy reveals that at high flux levels the power law becomes steeper and the soft hump more pronounced. This result is further confirmed using an earlier ASCA observation in 1994. The steepening of the photon-index with the fluxes in the soft and hard bands can be understood in the framework of disk/corona models in which accretion disk is heated by viscous dissipation as well as by reprocessing of hard X-rays following an X-ray flare resulting from coronal dissipation through magnetic reconnection events. Time dependent accretion disk-corona models are required to understand the observed correlation between the soft hump emission and the power-law flux.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: individual: IRAS 13224-3809 - galaxies: nuclei - galaxies: Seyfert - X-rays: galaxies

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 Ton S 180 Sy1 00 57 20.2038086128 -22 22 56.577563819   14.60 14.34 15.23   ~ 277 0
2 2MASX J10343860+3938277 Sy1 10 34 38.5975589813 +39 38 28.181434249   17.37 16.90     ~ 320 1
3 NGC 4051 Sy1 12 03 09.6098828919 +44 31 52.693714606   11.08 12.92 9.94   ~ 2042 1
4 2MASX J13251937-3824524 Sy1 13 25 19.3805503234 -38 24 52.611897329   16.64 13.80 15.33   ~ 365 0
5 ESO 383-35 Sy1 13 35 53.7686909139 -34 17 44.139127597   13.89 13.61 8.9   ~ 1407 0
6 UGC 12163 Sy1 22 42 39.3364258078 +29 43 31.301194419   14.86 14.16     ~ 637 1

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2021.08.04-08:14:26

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