J/MNRAS/433/1709 PKS 0558-504 UVOT and XRT monitoring (Gliozzi+, 2013)
Long-term monitoring of PKS 0558-504 with Swift: the disc-corona link.
Gliozzi M., Papadakis I.E., Grupe D., Brinkmann W.P., Rath C.
<Mon. Not. R. Astron. Soc., 433, 1709-1717 (2013)>
=2013MNRAS.433.1709G 2013MNRAS.433.1709G
ADC_Keywords: Galaxies, Seyfert ; X-ray sources ; Photometry, UBV ;
Photometry, ultraviolet
Keywords: galaxies: active - galaxies: jets - galaxies: nuclei -
X-rays: galaxies
Abstract:
PKS 0558-504 is a highly-variable, X-ray-bright, radio-loud,
narrow-line Seyfert 1 galaxy with super-Eddington accretion rate and
extended jets that do not dominate the emission beyond the radio band.
Therefore, this source represents an ideal laboratory to shed some
light on the central engine in highly accreting systems and
specifically on the link between accretion disc and corona. Here we
present the results from a 1.5-year monitoring with Swift-XRT and
Swift-UVOT. The simultaneous coverage at several wavelengths confirms
that PKS 0558-504 is highly variable in any band from the optical to
ultraviolet (UV) and X-rays, with the latter showing the largest
amplitude changes but with the UV emission dominating the radiative
output. A cross-correlation analysis reveals a tight link between the
emission in the optical and UV bands and provides suggestive evidence
in favour of a scenario where the variability originates in the outer
part of the accretion flow and propagates inwards before triggering
the activity of the X-ray-emitting corona. Finally, a positive
correlation between the soft-X-ray flux and the hard photon index
suggests that in PKS 0558-504 the seed photons are provided to the
corona by the soft-excess component.
Description:
PKS 0558-504 was observed by Swift between 2008 September 9 and 2010
March 30 with one pointing per week (with a typical exposure per visit
of ∼2ks), with the exception of the first 10-days when the
source was observed on daily basis.
Objects:
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RA (2000) DE Designation(s)
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05 59 47.40 -50 26 52.0 PKS 0558-504 = 2XMM J055947.3-502652
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 77 Observation log of PKS 0558-504
table2.dat 99 77 Swift X-ray count rates and hardness ratios and
UVOT magnitudes of PKS 0558-504
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seg [11/93] Segment number
5- 14 A10 "Y-M-D" Beg.date Start time (UT)
16- 20 A5 "h:m" Beg.time Start time (UT)
22- 31 A10 "Y-M-D" End.date End time (UT)
33- 37 A5 "h:m" End.time End time (UT)
39- 46 F8.2 d MJD Modified Julian date of observation
48- 51 I4 s TXRT X-ray telescope observing time
53- 55 I3 s TV ?=- UVOT V band observing time
57- 59 I3 s TB ?=- UVOT B band observing time
61- 63 I3 s TU ?=- UVOT U band observing time
65- 67 I3 s TUVW1 ?=- UVOT UVW1 band observing time
69- 71 I3 s TUVM2 ?=- UVOT UVM2 band observing time
73- 76 I4 s TUVW2 ?=- UVOT UVW2 band observing time
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 d MJD Modified Julian date of observation
10- 12 I3 --- Seg [11/93] Segment number
14- 17 F4.2 ct/s XCR [0.6/3.1]?=- X-ray count rate
19- 22 F4.2 ct/s e_XCR [0.02/0.1]?=- rms statistical error on XCR
24- 28 F5.2 --- XHR [-1/1] XRT hardness ratio
30- 33 F4.2 --- e_XHR ? rms uncertainty on XHR
35- 39 F5.2 mag Vmag ?=- UVOT V magnitude (1)
41- 44 F4.2 mag e_Vmag ? rms statistical error on Vmag
46- 50 F5.2 mag Bmag ?=- UVOT B magnitude (1)
52- 55 F4.2 mag e_Bmag ? rms statistical error on Bmag
57- 61 F5.2 mag Umag ?=- UVOT U magnitude (1)
63- 66 F4.2 mag e_Umag ? rms statistical error on Umag
68- 72 F5.2 mag UVW1 ?=- UVOT UVW1 magnitude (1)
74- 77 F4.2 mag e_UVW1 ? rms statistical error on UVW1
79- 83 F5.2 mag UVM2 ?=- UVOT UVM2 magnitude (1)
85- 88 F4.2 mag e_UVM2 ? rms statistical error on UVM2
90- 94 F5.2 mag UVW2 ?=- UVOT UVW2 magnitude (1)
96- 99 F4.2 mag e_UVW2 ? rms statistical error on UVW2
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Note (1): the magnitudes were corrected for reddening with E(B-V)=0.044.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 09-Jan-2015