J/AJ/146/78 Long-term Swift monitoring of WPVS 007 (Grupe+, 2013)
Strong UV and X-ray variability of the narrow line Seyfert 1 galaxy WPVS 007-on
the nature of the X-ray low state.
Grupe D., Komossa S., Scharwachter J., Dietrich M., Leighly K.M., Lucy A.,
Barlow B.N.
<Astron. J., 146, 78 (2013)>
=2013AJ....146...78G 2013AJ....146...78G
ADC_Keywords: Galaxies, Seyfert ; Active gal. nuclei ; Photometry, UBV ;
Photometry, ultraviolet ; X-ray sources
Keywords: galaxies: active - galaxies: individual: WPVS 007
Abstract:
We report on multi-wavelength observations of the X-ray transient
Narrow Line Seyfert 1 (NLS1) galaxy WPVS007. The galaxy was monitored
with Swift between 2005 October and 2013 July, after it had previously
undergone a dramatic drop in its X-ray flux. For the first time, we
are able to repeatedly detect this NLS1 in X-rays again. This
increased number of detections in the last couple of years may suggest
that the strong absorber that has been found in this active galactic
nucleus (AGN) is starting to become leaky and may eventually
disappear. The X-ray spectra obtained for WPVS007 are all consistent
with a partial covering absorber model. A spectrum based on the data
during the extreme low X-ray flux states shows that the absorption
column density is of the order of 4x1023/cm2 with a covering
fraction of 95%. WPVS007 also displays one of the strongest UV
variabilities seen in NLS1s. The UV continuum variability
anti-correlates with the optical/UV slope αUV, which suggests
that the variability may be primarily due to reddening. The UV
variability timescales are consistent with moving dust "clouds"
located beyond the dust sublimation radius of Rsub~20lt-days.
We present for the first time near-infrared JHK data of WPVS007, which
reveal a rich emission-line spectrum. Recent optical spectroscopy does
not indicate significant variability in the broad permitted and FeII
emission lines, implying that the ionizing continuum seen by those gas
clouds has not significantly changed over the last decades. All X-ray
and UV observations are consistent with a scenario in which an
evolving broad absorption line (BAL) flow obscures the continuum
emission. As such, WPVS007 is an important target for our
understanding of BAL flows in low-mass AGNs.
Description:
We present the results from our long-term monitoring campaign of WPVS
007 in the near-infrared with Swift X-ray Telescope (XRT) and in the
optical with Swift UV-Optical Telescope (UVOT) between 2005 October
and 2013 July.
Table1 presents the Swift observations of WPVS 007 between 2008
January 15 and 2013 July. The lists of the previous Swift observations
between 2005 October and 2007 December can be found in Grupe et al.
(2007AJ....133.1988G 2007AJ....133.1988G) and Grupe et al. (2008AJ....136.2343G 2008AJ....136.2343G).
Objects:
---------------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------------
00 39 15.86 -51 17 01.4 WPVS 007 = 2MASS J00391583-5117014
---------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 87 144 Swift observation log of WPVS 007 after 2008 January
table2.dat 94 160 Swift UVOT magnitudes of WPVS 007
table3.dat 24 137 Swift XRT 3σ upper limits of WPVS 007
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See also:
J/ApJS/187/64 : The simultaneous optical-to-X-ray SED of AGNs (Grupe+, 2010)
J/AJ/127/156 : Soft X-Ray-Selected AGNs complete sample (Grupe+, 2004)
J/A+A/350/805 : X-ray selected ROSAT AGN spectra (Grupe+, 1999)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ObsID [30334/91017] Observation identifier
7- 9 I3 --- Seg [1/77] Segment number
11- 21 A11 "Y:M:D" Dstart UT starting date of observation
23- 27 A5 "h:m" Tstart UT starting time of observation
29- 39 A11 "Y:M:D" Dend UT ending date of observation
41- 45 A5 "h:m" Tend UT ending time of observation
47- 54 F8.2 d MJD Modified Julian Date
56- 59 I4 s TXRT Total exposure time with the Swift X-Ray
Telescope (XRT)
61- 63 I3 s TV ? Total exposure time with UVOT V filter (G1)
65- 67 I3 s TB ? Total exposure time with UVOT B filter (G1)
69- 72 I4 s TU ? Total exposure time with UVOT U filter (G1)
74- 77 I4 s Tw1 ? Total exposure time with UVOT UVW1 filter (G1)
79- 82 I4 s Tm2 ? Total exposure time with UVOT UVM2 filter (G1)
84- 87 I4 s Tw2 ? Total exposure time with UVOT UVW2 filter (G1)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ObsID [30334/91017] Observation identifier
7- 9 I3 --- Seg [1/77] Segment
11- 18 F8.2 d MJD [53663/56487] Modified Julian Date
20- 24 F5.2 mag Vmag ? Swift/UVOT V filter magnitude (G1)
26- 29 F4.2 mag e_Vmag ? Uncertainty in Vmag
31- 35 F5.2 mag Bmag ? Swift/UVOT B filter magnitude (G1)
37- 40 F4.2 mag e_Bmag ? Uncertainty in Bmag
42- 46 F5.2 mag Umag ? Swift/UVOT U filter magnitude (G1)
48- 51 F4.2 mag e_Umag ? Uncertainty in Umag
53- 57 F5.2 mag w1mag ? Swift/UVOT UVW1 filter magnitude (G1)
59- 62 F4.2 mag e_w1mag ? Uncertainty in w1mag
64- 68 F5.2 mag m2mag ? Swift/UVOT UVM2 filter magnitude (G1)
70- 73 F4.2 mag e_m2mag ? Uncertainty in m2mag
75- 79 F5.2 mag w2mag ? Swift/UVOT UVW2 filter magnitude (G1)
81- 84 F4.2 mag e_w2mag ? Uncertainty in w2mag
86- 89 F4.2 --- aUV ? Optical/UV spectral slope αUV (1)
91- 94 F4.2 --- e_aUV ? Uncertainty in aUV
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Note (1): Determined from a power-law fit to the UVOT data.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ObsID [30334/91017] Observation identifier
7- 9 I3 --- Seg [1/77] Segment
11- 18 F8.2 --- MJD [53663/56487] Modified Julian Date
20- 24 F5.2 ct/ks Limit Swift XRT 3σ upper limit (1)
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Note (1): Calculated using the method of Kraft et al. (1991ApJ...374..344K 1991ApJ...374..344K).
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Global Notes:
Note (G1): UVOT = Swift UV-Optical Telescope.
History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 15-Jul-2014