J/ApJ/880/120 Photometry of the tidal disruption event PS18kh (Holoien+, 2019)
PS18kh: a new tidal disruption event with a non-axisymmetric accretion disk.
Holoien T.W.-S., Huber M.E., Shappee B.J., Eracleous M., Auchettl K.,
Brown J.S., Tucker M.A., Chambers K.C., Kochanek C.S., Stanek K.Z., Rest A.,
Bersier D., Post R.S., Aldering G., Ponder K.A., Simon J.D., Kankare E.,
Dong D., Hallinan G., Reddy N.A., Sanders R.L., Topping M.W., Bulger J.,
Lowe T.B., Magnier E.A., Schultz A.S.B., Waters C.Z., Willman M., Wright D.,
Young D.R., Dong S., Prieto J.L., Thompson T.A., Denneau L., Flewelling H.,
Heinze A.N., Smartt S.J., Smith K.W., Stalder B., Tonry J.L., Weiland H.
<Astrophys. J., 880, 120 (2019)>
=2019ApJ...880..120H 2019ApJ...880..120H
ADC_Keywords: Photometry, ultraviolet; Photometry, ugriz
Keywords: accretion, accretion disks ; black hole physics ; galaxies: nuclei
Abstract:
We present the discovery of PS18kh, a tidal disruption event
discovered at the center of SDSS J075654.53+341543.6 (d∼322Mpc) by the
Pan-STARRS Survey for Transients. Our data set includes pre-discovery
survey data from Pan-STARRS, the All-sky Automated Survey for
Supernovae, and the Asteroid Terrestrial-impact Last Alert System as
well as high-cadence, multiwavelength follow-up data from ground-based
telescopes and Swift, spanning from 56 days before peak light until
75days after. The optical/UV emission from PS18kh is well-fit as a
blackbody with temperatures ranging from T∼12000K to T∼25000K and it
peaked at a luminosity of L∼8.8x1043erg/s. PS18kh radiated
E=(3.45±0.22)x1050erg over the period of observation, with
(1.42±0.20)x1050erg being released during the rise to peak.
Spectra of PS18kh show a changing, boxy/double-peaked Hα
emission feature, which becomes more prominent over time. We use
models of non-axisymmetric accretion disks to describe the profile of
the Hα line and its evolution. We find that at early times the
high accretion rate leads the disk to emit a wind which modifies the
shape of the line profile and makes it bell-shaped. At late times, the
wind becomes optically thin, allowing the non-axisymmetric
perturbations to show up in the line profile. The line-emitting
portion of the disk extends from rin∼60rg to an outer radius of
rout∼1400rg and the perturbations can be represented either as an
eccentricity in the outer rings of the disk or as a spiral arm in the
inner disk.
Description:
We retrieved archival optical ugriz model magnitudes of
SDSS J075654.53+341543.6 from SDSS Data Release 14 (DR14;
Abolfathi+ 2018ApJS..235...42A 2018ApJS..235...42A) and infrared W1 and W2 magnitudes from
the Wide-field Infrared Survey Explorer (WISE) AllWISE catalog (II/328).
The host is not detected in archival data from, or was not previously
observed by, the Two Micron All-sky Survey, Spitzer, Herschel, the
Hubble Space Telescope, the Chandra X-ray Observatory, the X-ray
Multi-mirror Mission, or the Very Large Array Faint Images of the
Radio Sky at Twenty-cm survey. It is also not detected in Galaxy
Evolution Explorer (GALEX) UV data, but we obtain 3σ 6.0" upper
limits on the UV magnitudes of NUV>23.65 and FUV>23.69 using
single-epoch data obtained on 2008 January 19. See Section 2.1.
The Pan-STARRS1 griz photometry, ASAS-SN photometric measurements, and
ATLAS o-band photometry are presented in Table 3.
The Pan-STARRS1 telescope, located at the summit of Haleakala on Maui,
has a 1.8m diameter primary mirror. See Section 2.2.
The All-sky Automated Survey for Supernovae (ASAS-SN; Shappee+
2014ApJ...788...48S 2014ApJ...788...48S) uses units of four 14cm telescopes on a common
mount located at multiple sites in both hemispheres and hosted by the
Las Cumbres Observatory global telescope network. See Section 2.3.
The Asteroid Terrestrial-impact Last Alert System (ATLAS;
Tonry+ 2018PASP..130f4505T 2018PASP..130f4505T) uses fully robotic 0.5m f/2 Wright Schmidt
telescopes located on the summit of Haleakala and at Mauna Loa
Observatory to monitor the entire sky visible from Hawaii every few days.
See Section 2.4.
After PS18kh was classified as a tidal disruption event (TDE)
candidate, we were awarded 20 epochs of Swift TOO observations of
PS18kh between 2018 March 27 and 2018 May 29, after which it became
Sun-constrained. The UVOT observations were obtained in the V (5468Å),
B (4392Å), U (3465Å), UVW1 (2600Å), UVM2 (2246Å), and
UVW2 (1928Å) filters for all epochs. See Section 2.5.
In addition to the survey data and Swift observations, we obtained
photometric observations from multiple ground observatories. BVgri
observations were obtained from the 2m Liverpool Telescope (LT) and
from the 24 inch Post Observatory (PO) robotic telescopes located in
Mayhill, New Mexico, and Sierra Remote Observatory in California.
Additional u-band data were obtained with MegaCam on the CFHT.
See Section 2.6.
After classifying PS18kh as a TDE candidate, we began a program of
spectroscopic follow-up to complement our photometric follow-up. The
telescopes and instruments used to obtain follow-up spectra as part of
this campaign included SNIFS on the University of Hawaii 88 inch
telescope, the Inamori-Magellan Areal Camera and Spectrograph (IMACS)
on the 6.5m Magellan-Baade telescope, the Gemini Multi-Object
Spectrograph (GMOS) on the 8.2m Gemini North telescope, the
SPectrograph for the Rapid Acquisition of Transients (SPRAT) on the
Liverpool Telescope, the Low-Resolution Imaging Spectrometer (LRIS) on
the Keck I 10m telescope, and the Multi-Object Double Spectrographs
MODS) mounted on the dual 8.4m Large Binocular Telescope (LBT).
See Section 2.7.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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07 56 54.54 +34 15 43.6 18kh = NAME PS 18kh
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 44 441 Host-subtracted photometry of PS18kh
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
VI/64 : Recombination line intensities for hydrogenic ions (Storey+ 1995)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)
J/A+A/451/457 : X-ray properties of AGN in CDFS (Tozzi+, 2006)
J/ApJ/676/944 : GALEX & CFHTLS cand. tidal disruption events (Gezari+, 2008)
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)
J/A+A/562/A34 : UV FeII template from LBQS 2113-4538 (Hryniewicz+, 2014)
J/MNRAS/437/656 : SN PS1-11ap light curves (McCrum+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/MNRAS/448/1206 : Superluminous supernovae in faint galaxies (McCrum+, 2015)
J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)
J/MNRAS/455/2918 : Phot. & line luminosities for ASASSN-14li (Holoien+, 2016)
J/ApJ/844/46 : Phot. of the transient event iPTF16fnl (Blagorodnova+, 2017)
J/ApJS/232/8 : 16yrs of X-ray spectral analyses from 7Ms CDF-S (Liu+, 2017)
J/ApJS/233/17 : Swift/BAT AGN spectroscopic survey. V. X-ray (Ricci+, 2017)
J/AJ/156/241 : A first cat. of var. stars measured by ATLAS (Heinze+, 2018)
J/ApJ/852/72 : Luminosities of tidal disruption flares (van Velzen, 2018)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d sMJD [58137.13/58277.15] Modified Julian Date (1)
11- 19 F9.3 d eMJD [58147.19/58261.31]? End of Modified Julian
Date range (1)
21- 24 A4 --- Filt Photometric Filter
26 A1 --- l_Omag The 3-sigma upper limit flag on Omag
27- 31 F5.2 mag Omag [17.1/21] Observed magnitude in Filter (2)
33- 36 F4.2 mag e_Omag [0.02/0.9]? Uncertainty in Omag
38- 44 A7 --- Tel Telescope or Observatory used (3)
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Note (1): A range of MJDs indicates the MJD range of all observations
combined to obtain a single magnitude measurement.
Note (2): All magnitudes are in the AB system and have been corrected
for Galactic extinction.
Note (3): Telescope as follows:
PS1 = Pan-STARRS (34 occurrences);
ASAS-SN = ASAS-SN survey (34 occurrences);
ATLAS = ATLAS survey (14 occurrences);
CFHT = Canada-France-Hawaii Telescope (12 occurrences);
PO = Post Observatory (160 occurrences);
LT = Liverpool Telescope (13 occurrences);
Swift = Swift UVOT (107 occurrences);
Syn = magnitudes synthesized from follow-up spectra (67 occurrences).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmnanuelle Perret [CDS] 14-Jan-2021