J/MNRAS/465/L114 OGLE16aaa UVOT light curves (Wyrzykowski+, 2017)
OGLE16aaa - a signature of a hungry supermassive black hole.
Wyrzykowski L., Zielinski M., Kostrzewa-Rutkowska Z., Hamanowicz A.,
Jonker P.G., Arcavi I., Guillochon J., Brown P.J., Kozlowski S.,
Udalski A., Szymanski M.K., Soszynski I., Poleski R., Pietrukowicz P.,
Skowron J., Mroz P., Ulaczyk K., Pawlak M., Rybicki K.A., Greiner J.,
Kruhler T., Bolmer J., Smartt S.J., Maguire K., Smith K.
<Mon. Not. R. Astron. Soc., 465, L114-118 (2017)>
=2017MNRAS.465L.114W 2017MNRAS.465L.114W (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Photometry, ultraviolet ; Photometry, VRI
Keywords: black hole physics - galaxies: active -
galaxies: individual: OGLE16aaa
Abstract:
We present the discovery and first three months of follow-up
observations of a currently on-going unusual transient detected by the
Optical Gravitational Lensing Experiment (OGLE-IV) survey, located in
the centre of a galaxy at redshift z=0.1655. The long rise to
absolute magnitude of -20.5mag, slow decline, very broad He and H
spectral features make OGLE16aaa similar to other optical/UV tidal
disruption events (TDEs). Weak narrow emission lines in the spectrum
and archival photometric observations suggest the host galaxy is a
weak-line active galactic nucleus, which has been accreting at higher
rate in the past. OGLE16aaa, along with SDSS J0748, seems to form a
sub-class of TDEs by weakly or recently active supermassive black
holes (SMBHs). This class might bridge the TDEs by quiescent SMBHs and
flares observed as "changing-look quasars", if we interpret the
latter as TDEs. If this picture is true, the previously applied
requirement for identifying a flare as a TDE that it had to come from
an inactive nucleus, could be leading to observational bias in TDE
selection, thus affecting TDE-rate estimations.
Description:
OGLE16aaa was discovered by the OGLE transient detection system
(Wyrzykowski et al., 2014, Cat. J/AcA/64/197), a programme within the
Optical Gravitational Lensing Experiment (OGLE-IV; Udalski, Szymanski
& Szymanski, 2015AcA....65....1U 2015AcA....65....1U).
The transient was then followed-up from the ground with the Gamma-Ray
Burst Optical/Near-Infrared Detector (GROND) instrument on the Max
Planck Institute for Extraterrestial Physics (MPE) 2.2m telescope in
La Silla and with Swift satellite's Ultra-Violet Optical Telescope
(UVOT) from 2016-01-19.
Difference imaging photometry conducted by OGLE on the densely sampled
pre-discovery images spanning about 3.5 yr showed no prior flaring nor
variable activities in the core of this galaxy at a level below 1 per
cent. The last non-detection on HJD 2457364.61144 and first detection
on 2457373.5795 at 21.1±0.4mag, allow us to constrain the beginning
of the event to about HJD=2457369±4d
swift.dat data generated Wed May 25 15:52:36 CDT 2016 using version
2015.1 of Peter Brown's photometry pipeline and version
SwiftRel4.5(Bld34)27Jul2015 of HEASOFT.Data comes from the Swift
Data Center A 5 arcsec aperture is used to measure the counts for the
coincidence loss correction, a 3 or 5 arcsec source aperture (based on
the error) was used for the aperture photometry subtracting off the
galaxy count rate in a template image (if available), and applying an
aperture correction as appropriate (based on average psf in Swift
CALDB) and zeropoints from Breeveld et al. (2011, in AIP Conf. Proc.
1358, 373) which update Poole et al. (2008MNRAS.383..627P 2008MNRAS.383..627P) including a
time-dependent sensitivity loss to put the magnitudes on the UVOT
photometric system described in that paper. The sensitivity correction
has been updated based on the 2015 redetermination. No pre-outburst
galaxy template for subtraction.
Objects:
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RA (2000) DE Designation(s)
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01 07 20.88 -64 16 20.7 OGLE16aaa = OGLE16aaa
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
oglev.dat 26 8 OGLE16aaa OGLE V light curve
oglei.dat 26 30 OGLE16aaa OGLE I light curve
swift.dat 102 37 OGLE16aaa magnitudes from Swift UVOT
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See also:
J/AcA/64/197 : OGLE-IV 2012-2014 transients (Wyrzykowski+, 2014)
Byte-by-byte Description of file: oglev.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD Julian date
15- 20 F6.3 mag Vmag OGLE V magnitude
22- 26 F5.3 mag e_Vmag rms uncertainty on Vmag
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Byte-by-byte Description of file: oglei.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD Julian date
15- 20 F6.3 mag Imag OGLE I magnitude
22- 26 F5.3 mag e_Imag ?=- rms uncertainty on Imag
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Byte-by-byte Description of file: swift.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Filter [UVM2 UVW1 UVW2] Filter
10- 19 F10.4 d MJD Modified Julian date
22- 27 F6.3 mag mag Magnitude in filter
31- 35 F5.3 mag e_mag rms uncertainty on mag
38- 43 F6.3 mag lmag 3σ limiting magnitude
46- 51 F6.3 mag Sat Saturation limit (0.98SatLim)
55- 59 F5.3 ct/s Rate Count rate
63- 67 F5.3 ct/s e_Rate rms uncertainty on Rate
70- 72 F3.1 arcsec Ap [3] Aperture radius
75- 80 F6.4 s Frametime Frame time (1)
85- 91 F7.2 s ExpTime Exposure time
95-102 F8.2 s Telapse Elapsed time of observation (TSTOP - TSTART)
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Note (1): The calculated frame exposure interval which is a function of the
UVOT detector hardware window size. This is usually the full 2048
by 2048 but can be smaller for exposures in the White filter, to
reduce telemetry volume.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Jun-2018