J/ApJ/844/46 Photometry of the transient event iPTF16fnl (Blagorodnova+, 2017)
iPTF16fnl: a faint and fast tidal disruption event in an E+A galaxy.
Blagorodnova N., Gezari S., Hung T., Kulkarni S.R., Cenko S.B., Pasham D.R.,
Yan L., Arcavi I., Ben-Ami S., Bue B.D., Cantwell T., Cao Y.,
Castro-Tirado A.J., Fender R., Fremling C., Gal-Yam A., Ho A.Y.Q.,
Horesh A., Hosseinzadeh G., Kasliwal M.M., Kong A.K.H., Laher R.R.,
Leloudas G., Lunnan R., Masci F.J., Mooley K., Neill J.D., Nugent P.,
Powell M., Valeev A.F., Vreeswijk P.M., Walters R., Wozniak P.
<Astrophys. J., 844, 46 (2017)>
=2017ApJ...844...46B 2017ApJ...844...46B
ADC_Keywords: Photometry, UBV ; Photometry, ultraviolet ; Photometry, SDSS
Keywords: accretion, accretion disks; black hole physics; galaxies: nuclei;
stars: individual (iPTF16fnl)
Abstract:
We present ground-based and Swift observations of iPTF16fnl, a likely
tidal disruption event (TDE) discovered by the intermediate Palomar
Transient Factory (iPTF) survey at 66.6Mpc. The light curve of the
object peaked at an absolute mag Mg=-17.2. The maximum bolometric
luminosity (from optical and UV) was Lp~(1.0±0.15)x1043erg/s, an
order of magnitude fainter than any other optical TDE discovered so
far. The luminosity in the first 60 days is consistent with an
exponential decay, with L∝e-(t-t0_)/τ^, where
t0=57631.0 (MJD) and τ∼15 days. The X-ray shows a marginal
detection at LX=2.4-1.11.9x1039erg/s (Swift X-ray Telescope).
No radio counterpart was detected down to 3σ, providing upper
limits for monochromatic radio luminosities of
νLν<2.3x1036erg/s and νLν<1.7x1037erg/s (Very
Large Array, 6.1 and 22GHz). The blackbody temperature, obtained from
combined Swift UV and optical photometry, shows a constant value of
19000K. The transient spectrum at peak is characterized by broad HeII
and Hα emission lines, with FWHMs of about 14000km/s and
10000km/s, respectively. HeI lines are also detected at
λλ5875 and 6678. The spectrum of the host is dominated
by strong Balmer absorption lines, which are consistent with a
post-starburst (E+A) galaxy with an age of ∼650Myr and solar
metallicity. The characteristics of iPTF16fnl make it an outlier on
both luminosity and decay timescales, as compared to other optically
selected TDEs. The discovery of such a faint optical event suggests a
higher rate of tidal disruptions, as low-luminosity events may have
gone unnoticed in previous searches.
Description:
On the night after discovery (2016 August 29th), we observed the
source with the FLOYDS spectrograph on the Las Cumbres Observatory
(LCO) 2m telescope and the Spectral Energy Distribution Machine (SEDM)
on the Palomar 60 inch (P60) telescope. The SEDM is a ultra-low
resolution (R∼100) integral-field-unit (IFU) spectrograph.
Following spectroscopic identification of iPTF16fnl as a tidal
disruption event (TDE) candidate, the source was monitored at Palomar
and by the Ultraviolet and Optical Telescope (UVOT) on board the Swift
observatory. The UVOT observations were taken in UVW2, UVM2, UVW1, U,
B, and V.
At Palomar, photometry in the g and Mould-R bands were obtained with
the iPTF mosaic wide-field camera on the Palomar 48-inch telescope
(P48).
Table 3 reports the measured Swift aperture photometry magnitudes and
the difference-imaging photometry for the Palomar data spanning 2016
Aug to 2016 Dec.
Radio follow-up observations of iPTF16fnl were taken with the Jansky
Very Large Array (VLA; PI A. Horesh), the Arcminute Microkelvin Imager
(AMI; PI K. Mooley) and the James Clerk Maxwell Telescope and the
Submillimetre Common-User Bolometer Array 2 (JCMT/SCUBA-2; PI A. K. H.
Kong).
We also observed the location of iPTF16fnl with the X-Ray Telescope
(XRT) on board the Swift satellite beginning at 19:32 UT on 30 August
2016. Regular monitoring of the field in photon counting mode
continued over the course of the next four months (PIs T. Holoien and
B. Cenko).
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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00 29 57.04 +32 53 37.5 iPTF16fnl = iPTF 16fnl
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 130 69 Optical and UV photometry of iPTF16fnl
in AB magnitude system
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/313 : Palomar Transient Factory (PTF) catalog 1.0 (Ofek+, 2012)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/AJ/116/1094 : MAPS-PP catalog of galaxies (Cabanela+, 1998)
J/ApJS/122/51 : Spectroscopy of 10 rich galaxy clusters (Dressler+ 1999)
J/ApJS/170/33 : Optical properties of Markarian galaxies (Petrosian+, 2007)
J/ApJ/676/944 : GALEX & CFHTLS cand. tidal disruption events (Gezari+, 2008)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/ApJ/793/38 : PTF photometric observations (Arcavi+, 2014)
J/A+A/593/A68 : PTF12os & iPTF13bvn spectra & light curves (Fremling+, 2016)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 d MJD [57626.4/57724.7] Modified Julian Date,
JD-240000.5
9- 18 A10 --- Tel Telescope+Instrument Used (Swift+UVOT,
P48+CFH12k or P60+SEDM)
20- 24 F5.2 mag UVW1mag [16.8/18.9]? Swift/UVOT UVW1 passband AB
magnitude
26- 29 F4.2 mag e_UVW1mag [0.04/0.08]? Uncertainty in UVW1mag
31- 35 F5.2 mag UVM2mag [16.9/19.4]? Swift/UVOT UVM2 passband AB
magnitude
37- 40 F4.2 mag e_UVM2mag [0.04/0.2]? Uncertainty in UVM2mag
42- 46 F5.2 mag UVW2mag [16.6/19.5]? Swift/UVOT UVW2 passband AB
magnitude
48- 51 F4.2 mag e_UVW2mag [0.04/0.08]? Uncertainty in UVW2mag
53- 57 F5.2 mag Umag [16.3/17.5]? Swift/UVOT U passband AB
magnitude
59- 62 F4.2 mag e_Umag [0.04/0.07]? Uncertainty in Umag
64- 68 F5.2 mag Bmag [15.6/16.1]? Swift/UVOT B passband AB
magnitude
70- 73 F4.2 mag e_Bmag [0.03/0.05]? Uncertainty in Bmag
75- 79 F5.2 mag Vmag [15.1/15.7]? Swift/UVOT V passband AB
magnitude
81- 84 F4.2 mag e_Vmag [0.04/0.07]? Uncertainty in Vmag
86- 90 F5.2 mag umag [17.1/19.8]? Palomar u' passband AB magnitude
in SDSS system
92- 95 F4.2 mag e_umag [0.07/0.3]? Uncertainty in umag
97-101 F5.2 mag gmag [17.1/20.8]? Palomar g' passband AB magnitude
in SDSS system (1)
103-107 F5.2 mag e_gmag [0.06/0.4]? Uncertainty in gmag
109-113 F5.2 mag rmag [17.3/20.9]? Palomar r' passband AB magnitude
in SDSS system (1)
115-119 F5.2 mag e_rmag [0.06/0.4]? Uncertainty in rmag
121-125 F5.2 mag imag [17.2/19]? Palomar i' passband AB magnitude,
in SDSS system
127-130 F4.2 mag e_imag [0.07/0.4]? Uncertainty in image
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Note (1): If the uncertainty in a measured magnitude is null (blank) then
the magnitude value should be considered an upper limit.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 06-Mar-2018