J/ApJ/903/31 Photometry AT 2018hyz with Swift XRT, UVOT and Swope (Hung+, 2020)
Double-peaked Balmer Emission Indicating Prompt Accretion Disk Formation in an
X-Ray Faint Tidal Disruption Event.
Hung T., Foley R.J., Ramirez-Ruiz E., Dai J.L., Auchettl K.,
Kilpatrick C.D., Mockler B., Brown J.S., Coulter D.A., Dimitriadis G.,
Holoien T.W.-S., Law-Smith J.A.P., Piro A.L., Rest A., Rojas-Bravo C.,
Siebert M.R.
<Astrophys. J., 903, 31 (2020)>
=2020ApJ...903...31H 2020ApJ...903...31H
ADC_Keywords: Supernovae; Photometry, UVBGRI; X-ray sources
Keywords: Galaxy accretion disks ; Black hole physics ; High energy
astrophysics
Abstract:
We present the multiwavelength analysis of the tidal disruption event
(TDE) AT2018hyz (ASASSN-18zj). From follow-up optical spectroscopy, we
detect the first unambiguous case of resolved double-peaked Balmer
emission in a TDE. The distinct line profile can be well-modeled by a
low eccentricity (e∼0.1) accretion disk extending out to ∼100Rp and a
Gaussian component originating from non-disk clouds, though a bipolar
outflow origin cannot be completely ruled out. Our analysis indicates
that in AT2018hyz, disk formation took place promptly after the
most-bound debris returned to pericenter, which we estimate to be
roughly tens of days before the first detection. Redistribution of
angular momentum and mass transport, possibly through shocks, must
occur on the observed timescale of about a month to create the large
Hα-emitting disk that comprises ≲5% of the initial stellar
mass. With these new insights from AT2018hyz, we infer that
circularization is efficient in at least some, if not all optically
bright, X-ray faint TDEs. In these efficiently circularized TDEs, the
detection of double-peaked emission depends on the disk inclination
angle and the relative strength of the disk contribution to the
non-disk component, possibly explaining the diversity seen in the
current sample.
Description:
AT2018hyz was observed by the Ultraviolet Optical Telescope (UVOT) and
simultaneously by the X-ray Telescope (XRT) on board the Neil Gehrels
Swift Observatory as well as the Swope telescope at the Las Campanas
Observatory.
Optical photometry of AT2018hyz in gri was obtained with the 1m Swope
telescope from 2018 November 16 to 2019 June 16 with a 2-5day cadence.
Objects:
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RA (2000) DE Designation(s)
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10 06 59.6 +01 47 56.3 AT 2018hyz = ASASSN -18zj
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 25 37 Swift XRT observations
tablea2.dat 31 270 Photometric data of AT 2018hyz
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See also:
J/MNRAS/425/1789 : Berkeley supernova Ia program. I. (Silverman+, 2012)
J/ApJS/208/20 : Nine-year WMAP point source catalogs (Bennett+, 2013)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)
J/ApJ/795/44 : PS1 SNe Ia (0.02<z<0.7) griz light curves (Rest+, 2014)
J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
J/MNRAS/455/2918 : Photometry & line luminosities ASASSN-14li (Holoien+, 2016)
J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)
J/ApJ/844/46 : Photometry of transient event iPTF16fnl (Blagorodnova+, 2017)
J/ApJ/872/198 : UV-Opt LC tidal disruption flare AT2018zr (van Velzen+, 2019)
J/ApJ/873/92 : Opt. & UV evolution of the TDE iPTF15af (Blagorodnova+, 2019)
J/ApJ/880/120 : Photometry of tidal disruption event PS18kh (Holoien+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 d MJD [58432/58667] Modified Julian Date; MJD-2400000.5
10- 13 I4 s Tint [782/2595] Integration time
15 A1 --- l_Flux [<] Limit flag on Flux
17- 20 F4.2 --- Flux [3.95/9.67] Flux in 10-14erg/s/cm2
22- 25 F4.2 --- e_Flux [2.58/3.88]? Error on Flux
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.3 d MJD [58432/58675] Modified Julian Date; MJD-2400000.5
11- 15 F5.2 mag mag [15.96/19.79] Apparent magnitude in Filter
17- 20 F4.2 mag e_mag [0.01/0.11] Uncertainty in mag
22- 25 A4 --- Filt Filter used
27- 31 A5 --- Tel Telescope used (Swift or Swope)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Jan-2022