J/ApJ/872/198 UV-Opt LC of tidal disruption flare AT2018zr (van Velzen+, 2019)
The first tidal disruption flare in ZTF: from photometric selection to multi-
wavelength characterization.
van Velzen S., Gezari S., Cenko S.B., Kara E., Miller-Jones J.C.A., Hung T.,
Bright J., Roth N., Blagorodnova N., Huppenkothen D., Yan L., Ofek E.,
Sollerman J., Frederick S., Ward C., Graham M.J., Fender R., Kasliwal M.M.,
Canella C., Stein R., Giomi M., Brinnel V., van Santen J., Nordin J.,
Bellm E.C., Dekany R., Fremling C., Golkhou V.Z., Kupfer T., Kulkarni S.R.,
Laher R.R., Mahabal A., Masci F.J., Miller A.A., Neill J.D., Riddle R.,
Rigault M., Rusholme B., Soumagnac M.T., Tachibana Y.
<Astrophys. J., 872, 198 (2019)>
=2019ApJ...872..198V 2019ApJ...872..198V
ADC_Keywords: Photometry; Optical; Photometry, ultraviolet; X-ray sources
Keywords: accretion, accretion disks ; galaxies: nuclei
Abstract:
We present Zwicky Transient Facility (ZTF) observations of the tidal
disruption flare AT2018zr/PS18kh reported by
Holoien+ (2019ApJ...880..120H 2019ApJ...880..120H) and detected during ZTF commissioning.
The ZTF light curve of the tidal disruption event (TDE) samples the
rise-to-peak exceptionally well, with 50 days of g- and r-band
detections before the time of maximum light. We also present our
multi-wavelength follow-up observations, including the detection of a
thermal (kT∼100eV) X-ray source that is two orders of magnitude
fainter than the contemporaneous optical/UV blackbody luminosity, and
a stringent upper limit to the radio emission. We use observations of
128 known active galactic nuclei (AGNs) to assess the quality of the
ZTF astrometry, finding a median host-flare distance of 0.2" for
genuine nuclear flares. Using ZTF observations of variability from
known AGNs and supernovae we show how these sources can be separated
from TDEs. A combination of light-curve shape, color, and location in
the host galaxy can be used to select a clean TDE sample from
multi-band optical surveys such as ZTF or the Large Synoptic Survey
Telescope.
Description:
On 2018 March 6, the source ZTF18aabtxvd was identified as a nuclear
transient by our Zwicky Transient Facility (ZTF) alert pipeline. We
obtained a spectroscopic follow-up observation using the Spectral
Energy Distribution Machine (SEDM) on 2018, March 7.
We triggered HST UV spectroscopic observations on 2018 March 27. We
report these observations, plus our spectroscopic monitoring with
several ground-based telescopes, in Hung+ 2018ApJS..238...15H 2018ApJS..238...15H, from
which we determine a redshift of z=0.071.
Observations with Swift/UVOT started on 2018 March 27 (PI: Holoien).
In addition to the Swift/UVOT and ZTF photometry, our light curve also
includes P60/SEDM photometric data.
X-ray follow-up observations of AT2018zr were obtained using
XMM-Newton (program 082204, PI: Gezari). Two epochs of XMM-Newton
observations of the source were taken on 2018 April 11, and 2018 May 3.
See Section 2.4.
Radio observations of AT2018zr were obtained using the Arcminute
Microkelvin Imager Large Array (AMI-LA) and the Karl G. Jansky VLA
(program 18A-373, PI: van Velzen). AMI observed on 2018 March 28,
followed by the VLA on 2018 March 30 and April 28. The source was not
detected in any of our radio observations. See Section 2.5.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
07 56 54.54 +34 15 43.6 AT2018zr = ZTF18aabtxvd
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 38 155 Optical/UV photometry
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
B/xmm : XMM-Newton Obs .Log (XMM-Newton Science Operation Center, 2012)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
VII/273 : The Half Million Quasars (HMQ) catalogue (Flesch, 2015)
VII/283 : The Million Quasars (Milliquas) catalog (6.3) (Flesch, 2019)
J/MNRAS/404/1639 : MILES base models & new line index system (Vazdekis+, 2010)
J/MNRAS/429/3330 : AMI Galactic Plane Survey at 16GHz. I. (Perrott+, 2013)
J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/MNRAS/446/2985 : Double-lobed radio sources catalog (van Velzen+, 2015)
J/A+A/593/A68 : PTF12os & iPTF13bvn spectra & light curves (Fremling+, 2016)
J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)
J/MNRAS/455/2918 : Photom. & line luminosities for ASASSN-14li (Holoien+, 2016)
J/ApJ/844/46 : Transient event iPTF16fnl photometry (Blagorodnova+, 2017)
J/ApJ/852/72 : LFs of tidal disruption flares (van Velzen, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d MJD [58099.48/58438.78] Modified Julian Date
(JD-2400000.5)
11- 20 A10 --- Tel Observatory (1)
22- 25 A4 --- Filt Filter (U,B,V,UVW1,UVM2,UVW2, g,r)
27- 27 A1 --- l_mag Limit flag on mag
29- 33 F5.2 mag mag [17.5/22.1] Extinction corrected (AB) magnitude
in Filt
35- 38 F4.2 mag e_mag [0.01/0.48]? Uncertainty in mag
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Note (1): Observatory as follows:
SEDM/P60 = Spectral Energy Distribution Machine, Palomar 60in;
Swift/UVOT = Ultraviolet/Optical Telescope, Neil Gehrels Swift Observatory;
ZTF/P48 = Zwicky Transient Facility, Palomar 48in.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Aug-2020